Re: [DISCUSS] FLIP-111: Docker image unification

[Andrey Zagrebin]

Thanks for summarising the discussion points, Till.

# Configuration

## Env variables
Agree, this looks like an independent effort.

## dynamic program arguments
Indeed, jobmanager.sh needs small extension. It can be addressed
independently but I think it has chance to be addressed in this release
cycle.
taskmanager.sh/flink-console.sh/flink-daemon.sh look already fit for this
from what I see.
On the other hand, we already have FLINK_PROPERTIES and indeed we can keep
it until we have env vars.

## FLINK_PROPERTIES
I am not really saying to remove this right now. Indeed, it has been
already exposed and should stay for the backwards-compatibility at the
moment.
I was just wondering whether we could maintain/advertise less approaches in
future but which are good enough for users.
The benefit of env vars / dynamic args approaches is that they are supposed
to be already supported by Flink scripts out of the box
and would have almost no maintenance for us on the docker side.
On the other hand, I can also see that setting FLINK_PROPERTIES may be
easier in certain cases comparing to generation of env vars / dynamic args.

@Thomas Weise 
The current duplication may be fixed by setting the hardcoded ports
after FLINK_PROPERTIES if they are not set.
We can look at it during implementation in detail.

## flink_docker_utils configure "option.name" “value”
The previously discussed options are mostly for running the official image.
This scripted action is mostly for custom Dockerfiles or custom entry point
scripts extending the official image
where somebody wants to ship a preconfigured custom image.
This action would already deduplicate a lot of code for the ports which are
set to hardcoded values in the entry point script of the official
Dockerfile:

if grep -E "^blob\.server\.port:.*" "${CONF_FILE}"; then
sed -i -e "s/blob.server.port:*/blob.server.port: 6124/g" "${CONF_FILE}"
else
echo "blob.server.port: 6124" >> "${CONF_FILE}"
fi

If we are in doubt to document this for the users and expose as API, we do
not have to do it and expose later if needed.
I am ok to remove 'flink_docker_utils set_web_ui_port 8081' from FLIP.

# Logging

## Logging
The idea was to fix the existing console logging properties to log also
into files to fix Web UI [1].
Then we can just use Flink scripts with 'start-foreground' argument to log
into the stdout and files.

## Stdout/err

### Console
I think the stdout/stderr of Flink process might end up in the
container stdout/stderr if we run it in 'start-foreground' mode [2] (needs
checking).

### Local files
The proposal with the *tee* command looks promising. I would prefer to
write stdout/err into separate files and preserve them as stdout/err for
container logs.
This needs more experiments but may be possible with the *tee* command. I
suggest to check the details in PRs.

# Java/Python/Dev versiona
Shipping official images with various versions can be addressed
independently.

Best,
Andrey

[1]
https://cwiki.apache.org/confluence/display/FLINK/FLIP-111%3A+Docker+image+unification#FLIP-111:Dockerimageunification-Logging
[2] https://docs.docker.com/config/containers/logging

On Wed, Mar 18, 2020 at 2:14 PM Till Rohrmann  wrote:

> Thanks for creating this FLIP Andrey. I like the general idea pretty much.
>
> I tried to group some of the above-mentioned points in order to give my 50
> cent.
>
> # Configuration
>
> How to configure the Flink process seems to be the biggest question. Due
> to historical reasons we have a plethora of different ways on how to
> configure the Flink Docker image.
>
> I think the most general approach would be the configuration via
> environment variables where one can specify env variables with the form
> FLINK_= which will overwrite  with 
> in the effective configuration. However, this is something which deserves a
> separate effort and is out of scope for this proposal.
>
> The next best thing for configuring Flink (not the Flink process) would be
> dynamic program arguments. For this to work, we would need to extend the
> jobmanager.sh and taskmanager.sh scripts. I think this is strictly speaking
> also an orthogonal task and could happen as a follow up/independently.
>
> This leaves us with the envsubst and FLINK_PROPERTIES approaches. Even
> though I'm not a huge fan of these approaches, I think we should still
> support them for backwards compatibility reasons. Once we support
> configuration via env variables we should deprecate these methods and
> remove them in a subsequent release.
>
> Given this, I am bit unsure about introducing yet another way
> via flink_docker_utils configure "option.name" “value”. I think we should
> only offer this option if we are sure that we want to keep it in the future
> and that it won't be superceded by the env variables approach. Otherwise it
> will only add more maintenance burden.
>
> Long story short, with the existing configuration options (envsubts,
> FLINK_PROPERTIES) we can already configure the Flink proce

Re: [DISCUSS] FLIP-111: Docker image unification

[Till Rohrmann]

Thanks for creating this FLIP Andrey. I like the general idea pretty much.

I tried to group some of the above-mentioned points in order to give my 50
cent.

# Configuration

How to configure the Flink process seems to be the biggest question. Due to
historical reasons we have a plethora of different ways on how to configure
the Flink Docker image.

I think the most general approach would be the configuration via
environment variables where one can specify env variables with the form
FLINK_= which will overwrite  with 
in the effective configuration. However, this is something which deserves a
separate effort and is out of scope for this proposal.

The next best thing for configuring Flink (not the Flink process) would be
dynamic program arguments. For this to work, we would need to extend the
jobmanager.sh and taskmanager.sh scripts. I think this is strictly speaking
also an orthogonal task and could happen as a follow up/independently.

This leaves us with the envsubst and FLINK_PROPERTIES approaches. Even
though I'm not a huge fan of these approaches, I think we should still
support them for backwards compatibility reasons. Once we support
configuration via env variables we should deprecate these methods and
remove them in a subsequent release.

Given this, I am bit unsure about introducing yet another way
via flink_docker_utils configure "option.name" “value”. I think we should
only offer this option if we are sure that we want to keep it in the future
and that it won't be superceded by the env variables approach. Otherwise it
will only add more maintenance burden.

Long story short, with the existing configuration options (envsubts,
FLINK_PROPERTIES) we can already configure the Flink process and Flink
itself. Since maintaining backwards compatibility is important, we could
rely on these mechanisms until we have proper env variable configuration
and don't have to introduce a new way to change the configuration.

# Logging & Stdout/err

## Logging

I think Konstantin is right and we should provide a log4j.properties file
which, per default, specifies the file and console appender. We could add a
special log4j.properties file to apache/flink-docker which we include in
the Dockerfile.

This approach will give users the most flexibility w/o relying on magic
(e.g. tailing the log files after starting the process in the background).

## Stdout/err

I think for printing the stdout/err output to STDOUT/ERR and to capture it
in a file there are solutions. For example, one could use `program &2>1 |
tee flink-user-taskexecutor.out` to achieve this.

# Java version

I agree that it would be nice to also offer a Java 11 Dockerfile. For the
sake of limiting the scope of this proposal I would suggest to do this as a
follow up issue.

# Dev version

Tooling to create a Docker image from the current Flink repository is
indeed very nice for development. As Andrey suggested, I think this would
be a good follow up for this proposal. I don't think that Andrey's current
proposal would block any future developments in this direction.

# Scripts

At the moment, I would be in favour of placing the Dockerfile scripts under
apache/flink-docker since they belong more to the Dockerfile than to
Flink's binary distribution. If we see that we might be able to reuse them
for the developer Dockerfile, then we can still move them to the Flink
repository.

I would refrain from offering special commands to set individual
configuration options (e.g., flink_docker_utils set_web_ui_port 8081). It
should be fine enough to do it via flink_docker-utils conifgure rest.port
8081 if we cannot solve it via the general configuration mechanism.

Cheers,
Till

On Wed, Mar 18, 2020 at 6:38 AM Yangze Guo  wrote:

> I second Thomas that we can support both Java 8 and 11.
>
> Best,
> Yangze Guo
>
> On Wed, Mar 18, 2020 at 12:12 PM Thomas Weise  wrote:
> >
> > -->
> >
> > On Mon, Mar 16, 2020 at 1:58 AM Andrey Zagrebin 
> wrote:
> >>
> >> Thanks for the further feedback Thomas and Yangze.
> >>
> >> > A generic, dynamic configuration mechanism based on environment
> variables
> >> is essential and it is already supported via envsubst and an environment
> >> variable that can supply a configuration fragment
> >>
> >> True, we already have this. As I understand this was introduced for
> >> flexibility to template a custom flink-conf.yaml with env vars, put it
> into
> >> the FLINK_PROPERTIES and merge it with the default one.
> >> Could we achieve the same with the dynamic properties (-Drpc.port=1234),
> >> passed as image args to run it, instead of FLINK_PROPERTIES?
> >> They could be also parametrised with env vars. This would require
> >> jobmanager.sh to properly propagate them to
> >> the StandaloneSessionClusterEntrypoint though:
> >>
> https://github.com/docker-flink/docker-flink/pull/82#issuecomment-525285552
> >> cc @Till
> >> This would provide a unified configuration approach.
> >>
> >
> > How would that look like for the various use cases? The k8

Re: [DISCUSS] FLIP-111: Docker image unification

[Yangze Guo]

I second Thomas that we can support both Java 8 and 11.

Best,
Yangze Guo

On Wed, Mar 18, 2020 at 12:12 PM Thomas Weise  wrote:
>
> -->
>
> On Mon, Mar 16, 2020 at 1:58 AM Andrey Zagrebin  wrote:
>>
>> Thanks for the further feedback Thomas and Yangze.
>>
>> > A generic, dynamic configuration mechanism based on environment variables
>> is essential and it is already supported via envsubst and an environment
>> variable that can supply a configuration fragment
>>
>> True, we already have this. As I understand this was introduced for
>> flexibility to template a custom flink-conf.yaml with env vars, put it into
>> the FLINK_PROPERTIES and merge it with the default one.
>> Could we achieve the same with the dynamic properties (-Drpc.port=1234),
>> passed as image args to run it, instead of FLINK_PROPERTIES?
>> They could be also parametrised with env vars. This would require
>> jobmanager.sh to properly propagate them to
>> the StandaloneSessionClusterEntrypoint though:
>> https://github.com/docker-flink/docker-flink/pull/82#issuecomment-525285552
>> cc @Till
>> This would provide a unified configuration approach.
>>
>
> How would that look like for the various use cases? The k8s operator would 
> need to generate the -Dabc .. -Dxyz entry point command instead of setting 
> the FLINK_PROPERTIES environment variable? Potentially that introduces 
> additional complexity for little gain. Do most deployment platforms that 
> support Docker containers handle the command line route well? Backward 
> compatibility may also be a concern.
>
>>
>> > On the flip side, attempting to support a fixed subset of configuration
>> options is brittle and will probably lead to compatibility issues down the
>> road
>>
>> I agree with it. The idea was to have just some shortcut scripted functions
>> to set options in flink-conf.yaml for a custom Dockerfile or entry point
>> script.
>> TASK_MANAGER_NUMBER_OF_TASK_SLOTS could be set as a dynamic property of
>> started JM.
>> I am not sure how many users depend on it. Maybe we could remove it.
>> It also looks we already have somewhat unclean state in
>> the docker-entrypoint.sh where some ports are set the hardcoded values
>> and then FLINK_PROPERTIES are applied potentially duplicating options in
>> the result flink-conf.yaml.
>
>
> That is indeed possible and duplicate entries from FLINK_PROPERTIES prevail. 
> Unfortunately, the special cases you mention were already established and the 
> generic mechanism was added later for the k8s operators.
>
>>
>>
>> I can see some potential usage of env vars as standard entry point args but
>> for purposes related to something which cannot be achieved by passing entry
>> point args, like changing flink-conf.yaml options. Nothing comes into my
>> mind at the moment. It could be some setting specific to the running mode
>> of the entry point. The mode itself can stay the first arg of the entry
>> point.
>>
>> > I would second that it is desirable to support Java 11
>>
>> > Regarding supporting JAVA 11:
>> > - Not sure if it is necessary to ship JAVA. Maybe we could just change
>> > the base image from openjdk:8-jre to openjdk:11-jre in template docker
>> > file[1]. Correct me if I understand incorrectly. Also, I agree to move
>> > this out of the scope of this FLIP if it indeed takes much extra
>> > effort.
>>
>> This is what I meant by bumping up the Java version in the docker hub Flink
>> image:
>> FROM openjdk:8-jre -> FROM openjdk:11-jre
>> This can be polled dependently in user mailing list.
>
>
> That sounds reasonable as long as we can still support both Java versions 
> (i.e. provide separate images for 8 and 11).
>
>>
>>
>> > and in general use a base image that allows the (straightforward) use of
>> more recent versions of other software (Python etc.)
>>
>> This can be polled whether to always include some version of python into
>> the docker hub image.
>> A potential problem here is once it is there, it is some hassle to
>> remove/change it in a custom extended Dockerfile.
>>
>> It would be also nice to avoid maintaining images for various combinations
>> of installed Java/Scala/Python in docker hub.
>>
>> > Regarding building from local dist:
>> > - Yes, I bring this up mostly for development purpose. Since k8s is
>> > popular, I believe more and more developers would like to test their
>> > work on k8s cluster. I'm not sure should all developers write a custom
>> > docker file themselves in this scenario. Thus, I still prefer to
>> > provide a script for devs.
>> > - I agree to keep the scope of this FLIP mostly for those normal
>> > users. But as far as I can see, supporting building from local dist
>> > would not take much extra effort.
>> > - The maven docker plugin sounds good. I'll take a look at it.
>>
>> I would see any scripts introduced in this FLIP also as potential building
>> blocks for a custom dev Dockerfile.
>> Maybe, this will be all what we need for dev images or we write a dev
>> Dockerfile, highly parametrised

Re: [DISCUSS] FLIP-111: Docker image unification

[Thomas Weise]

-->

On Mon, Mar 16, 2020 at 1:58 AM Andrey Zagrebin 
wrote:

> Thanks for the further feedback Thomas and Yangze.
>
> > A generic, dynamic configuration mechanism based on environment variables
> is essential and it is already supported via envsubst and an environment
> variable that can supply a configuration fragment
>
> True, we already have this. As I understand this was introduced for
> flexibility to template a custom flink-conf.yaml with env vars, put it into
> the FLINK_PROPERTIES and merge it with the default one.
> Could we achieve the same with the dynamic properties (-Drpc.port=1234),
> passed as image args to run it, instead of FLINK_PROPERTIES?
> They could be also parametrised with env vars. This would require
> jobmanager.sh to properly propagate them to
> the StandaloneSessionClusterEntrypoint though:
> https://github.com/docker-flink/docker-flink/pull/82#issuecomment-525285552
> cc @Till
> This would provide a unified configuration approach.
>
>
How would that look like for the various use cases? The k8s operator would
need to generate the -Dabc .. -Dxyz entry point command instead of setting
the FLINK_PROPERTIES environment variable? Potentially that introduces
additional complexity for little gain. Do most deployment platforms that
support Docker containers handle the command line route well? Backward
compatibility may also be a concern.


> > On the flip side, attempting to support a fixed subset of configuration
> options is brittle and will probably lead to compatibility issues down the
> road
>
> I agree with it. The idea was to have just some shortcut scripted functions
> to set options in flink-conf.yaml for a custom Dockerfile or entry point
> script.
> TASK_MANAGER_NUMBER_OF_TASK_SLOTS could be set as a dynamic property of
> started JM.
> I am not sure how many users depend on it. Maybe we could remove it.
> It also looks we already have somewhat unclean state in
> the docker-entrypoint.sh where some ports are set the hardcoded values
> and then FLINK_PROPERTIES are applied potentially duplicating options in
> the result flink-conf.yaml.
>

That is indeed possible and duplicate entries from FLINK_PROPERTIES
prevail. Unfortunately, the special cases you mention were already
established and the generic mechanism was added later for the k8s operators.


>
> I can see some potential usage of env vars as standard entry point args but
> for purposes related to something which cannot be achieved by passing entry
> point args, like changing flink-conf.yaml options. Nothing comes into my
> mind at the moment. It could be some setting specific to the running mode
> of the entry point. The mode itself can stay the first arg of the entry
> point.
>
> > I would second that it is desirable to support Java 11
>
> > Regarding supporting JAVA 11:
> > - Not sure if it is necessary to ship JAVA. Maybe we could just change
> > the base image from openjdk:8-jre to openjdk:11-jre in template docker
> > file[1]. Correct me if I understand incorrectly. Also, I agree to move
> > this out of the scope of this FLIP if it indeed takes much extra
> > effort.
>
> This is what I meant by bumping up the Java version in the docker hub Flink
> image:
> FROM openjdk:8-jre -> FROM openjdk:11-jre
> This can be polled dependently in user mailing list.
>

That sounds reasonable as long as we can still support both Java versions
(i.e. provide separate images for 8 and 11).


>
> > and in general use a base image that allows the (straightforward) use of
> more recent versions of other software (Python etc.)
>
> This can be polled whether to always include some version of python into
> the docker hub image.
> A potential problem here is once it is there, it is some hassle to
> remove/change it in a custom extended Dockerfile.
>
> It would be also nice to avoid maintaining images for various combinations
> of installed Java/Scala/Python in docker hub.
>
> > Regarding building from local dist:
> > - Yes, I bring this up mostly for development purpose. Since k8s is
> > popular, I believe more and more developers would like to test their
> > work on k8s cluster. I'm not sure should all developers write a custom
> > docker file themselves in this scenario. Thus, I still prefer to
> > provide a script for devs.
> > - I agree to keep the scope of this FLIP mostly for those normal
> > users. But as far as I can see, supporting building from local dist
> > would not take much extra effort.
> > - The maven docker plugin sounds good. I'll take a look at it.
>
> I would see any scripts introduced in this FLIP also as potential building
> blocks for a custom dev Dockerfile.
> Maybe, this will be all what we need for dev images or we write a dev
> Dockerfile, highly parametrised for building a dev image.
> If scripts stay in apache/flink-docker, it is also somewhat inconvenient to
> use them in the main Flink repo but possible.
> If we move them to apache/flink then we will have to e.g. include them into
> the release to make them e

Re: [DISCUSS] FLIP-111: Docker image unification

[Yang Wang]

Hi Andrey,

Thanks for your explanation.

> About the logging
What i mean is we could not forward the stdout/stderr to local files and
docker stdout
at the same time by using log4j. For the jobmanager.log/taskmanager.log, it
works
quite well since we only need to add a console appender in
the log4j.properties.

I am just curious how to forward the stdout/stderr to local files and
docker stdout
at the same time by using log4j :)


Best,
Yang

Andrey Zagrebin  于2020年3月16日周一 下午4:58写道：

> Thanks for the further feedback Thomas and Yangze.
>
> > A generic, dynamic configuration mechanism based on environment
> variables is essential and it is already supported via envsubst and an
> environment variable that can supply a configuration fragment
>
> True, we already have this. As I understand this was introduced for
> flexibility to template a custom flink-conf.yaml with env vars, put it into
> the FLINK_PROPERTIES and merge it with the default one.
> Could we achieve the same with the dynamic properties (-Drpc.port=1234),
> passed as image args to run it, instead of FLINK_PROPERTIES?
> They could be also parametrised with env vars. This would require
> jobmanager.sh to properly propagate them to
> the StandaloneSessionClusterEntrypoint though:
> https://github.com/docker-flink/docker-flink/pull/82#issuecomment-525285552
> cc @Till
> This would provide a unified configuration approach.
>
> > On the flip side, attempting to support a fixed subset of configuration
> options is brittle and will probably lead to compatibility issues down the
> road
>
> I agree with it. The idea was to have just some shortcut scripted
> functions to set options in flink-conf.yaml for a custom Dockerfile or
> entry point script.
> TASK_MANAGER_NUMBER_OF_TASK_SLOTS could be set as a dynamic property of
> started JM.
> I am not sure how many users depend on it. Maybe we could remove it.
> It also looks we already have somewhat unclean state in
> the docker-entrypoint.sh where some ports are set the hardcoded values
> and then FLINK_PROPERTIES are applied potentially duplicating options in
> the result flink-conf.yaml.
>
> I can see some potential usage of env vars as standard entry point args
> but for purposes related to something which cannot be achieved by passing
> entry point args, like changing flink-conf.yaml options. Nothing comes into
> my mind at the moment. It could be some setting specific to the running
> mode of the entry point. The mode itself can stay the first arg of the
> entry point.
>
> > I would second that it is desirable to support Java 11
>
> > Regarding supporting JAVA 11:
> > - Not sure if it is necessary to ship JAVA. Maybe we could just change
> > the base image from openjdk:8-jre to openjdk:11-jre in template docker
> > file[1]. Correct me if I understand incorrectly. Also, I agree to move
> > this out of the scope of this FLIP if it indeed takes much extra
> > effort.
>
> This is what I meant by bumping up the Java version in the docker hub
> Flink image:
> FROM openjdk:8-jre -> FROM openjdk:11-jre
> This can be polled dependently in user mailing list.
>
> > and in general use a base image that allows the (straightforward) use of
> more recent versions of other software (Python etc.)
>
> This can be polled whether to always include some version of python into
> the docker hub image.
> A potential problem here is once it is there, it is some hassle to
> remove/change it in a custom extended Dockerfile.
>
> It would be also nice to avoid maintaining images for various combinations
> of installed Java/Scala/Python in docker hub.
>
> > Regarding building from local dist:
> > - Yes, I bring this up mostly for development purpose. Since k8s is
> > popular, I believe more and more developers would like to test their
> > work on k8s cluster. I'm not sure should all developers write a custom
> > docker file themselves in this scenario. Thus, I still prefer to
> > provide a script for devs.
> > - I agree to keep the scope of this FLIP mostly for those normal
> > users. But as far as I can see, supporting building from local dist
> > would not take much extra effort.
> > - The maven docker plugin sounds good. I'll take a look at it.
>
> I would see any scripts introduced in this FLIP also as potential building
> blocks for a custom dev Dockerfile.
> Maybe, this will be all what we need for dev images or we write a dev
> Dockerfile, highly parametrised for building a dev image.
> If scripts stay in apache/flink-docker, it is also somewhat inconvenient
> to use them in the main Flink repo but possible.
> If we move them to apache/flink then we will have to e.g. include them
> into the release to make them easily available in apache/flink-docker and
> maintain them in main repo, although they are only docker specific.
> All in all, I would say, once we implement them, we can revisit this topic.
>
> Best,
> Andrey
>
> On Wed, Mar 11, 2020 at 8:58 AM Yangze Guo  wrote:
>
>> Thanks for the reply, Andrey.
>>
>> Regarding build

Re: [DISCUSS] FLIP-111: Docker image unification

[Andrey Zagrebin]

Thanks for the further feedback Thomas and Yangze.

> A generic, dynamic configuration mechanism based on environment variables
is essential and it is already supported via envsubst and an environment
variable that can supply a configuration fragment

True, we already have this. As I understand this was introduced for
flexibility to template a custom flink-conf.yaml with env vars, put it into
the FLINK_PROPERTIES and merge it with the default one.
Could we achieve the same with the dynamic properties (-Drpc.port=1234),
passed as image args to run it, instead of FLINK_PROPERTIES?
They could be also parametrised with env vars. This would require
jobmanager.sh to properly propagate them to
the StandaloneSessionClusterEntrypoint though:
https://github.com/docker-flink/docker-flink/pull/82#issuecomment-525285552
cc @Till
This would provide a unified configuration approach.

> On the flip side, attempting to support a fixed subset of configuration
options is brittle and will probably lead to compatibility issues down the
road

I agree with it. The idea was to have just some shortcut scripted functions
to set options in flink-conf.yaml for a custom Dockerfile or entry point
script.
TASK_MANAGER_NUMBER_OF_TASK_SLOTS could be set as a dynamic property of
started JM.
I am not sure how many users depend on it. Maybe we could remove it.
It also looks we already have somewhat unclean state in
the docker-entrypoint.sh where some ports are set the hardcoded values
and then FLINK_PROPERTIES are applied potentially duplicating options in
the result flink-conf.yaml.

I can see some potential usage of env vars as standard entry point args but
for purposes related to something which cannot be achieved by passing entry
point args, like changing flink-conf.yaml options. Nothing comes into my
mind at the moment. It could be some setting specific to the running mode
of the entry point. The mode itself can stay the first arg of the entry
point.

> I would second that it is desirable to support Java 11

> Regarding supporting JAVA 11:
> - Not sure if it is necessary to ship JAVA. Maybe we could just change
> the base image from openjdk:8-jre to openjdk:11-jre in template docker
> file[1]. Correct me if I understand incorrectly. Also, I agree to move
> this out of the scope of this FLIP if it indeed takes much extra
> effort.

This is what I meant by bumping up the Java version in the docker hub Flink
image:
FROM openjdk:8-jre -> FROM openjdk:11-jre
This can be polled dependently in user mailing list.

> and in general use a base image that allows the (straightforward) use of
more recent versions of other software (Python etc.)

This can be polled whether to always include some version of python into
the docker hub image.
A potential problem here is once it is there, it is some hassle to
remove/change it in a custom extended Dockerfile.

It would be also nice to avoid maintaining images for various combinations
of installed Java/Scala/Python in docker hub.

> Regarding building from local dist:
> - Yes, I bring this up mostly for development purpose. Since k8s is
> popular, I believe more and more developers would like to test their
> work on k8s cluster. I'm not sure should all developers write a custom
> docker file themselves in this scenario. Thus, I still prefer to
> provide a script for devs.
> - I agree to keep the scope of this FLIP mostly for those normal
> users. But as far as I can see, supporting building from local dist
> would not take much extra effort.
> - The maven docker plugin sounds good. I'll take a look at it.

I would see any scripts introduced in this FLIP also as potential building
blocks for a custom dev Dockerfile.
Maybe, this will be all what we need for dev images or we write a dev
Dockerfile, highly parametrised for building a dev image.
If scripts stay in apache/flink-docker, it is also somewhat inconvenient to
use them in the main Flink repo but possible.
If we move them to apache/flink then we will have to e.g. include them into
the release to make them easily available in apache/flink-docker and
maintain them in main repo, although they are only docker specific.
All in all, I would say, once we implement them, we can revisit this topic.

Best,
Andrey

On Wed, Mar 11, 2020 at 8:58 AM Yangze Guo  wrote:

> Thanks for the reply, Andrey.
>
> Regarding building from local dist:
> - Yes, I bring this up mostly for development purpose. Since k8s is
> popular, I believe more and more developers would like to test their
> work on k8s cluster. I'm not sure should all developers write a custom
> docker file themselves in this scenario. Thus, I still prefer to
> provide a script for devs.
> - I agree to keep the scope of this FLIP mostly for those normal
> users. But as far as I can see, supporting building from local dist
> would not take much extra effort.
> - The maven docker plugin sounds good. I'll take a look at it.
>
> Regarding supporting JAVA 11:
> - Not sure if it is necessary to ship JAVA. Maybe we c

Re: [DISCUSS] FLIP-111: Docker image unification

[Yangze Guo]

Thanks for the reply, Andrey.

Regarding building from local dist:
- Yes, I bring this up mostly for development purpose. Since k8s is
popular, I believe more and more developers would like to test their
work on k8s cluster. I'm not sure should all developers write a custom
docker file themselves in this scenario. Thus, I still prefer to
provide a script for devs.
- I agree to keep the scope of this FLIP mostly for those normal
users. But as far as I can see, supporting building from local dist
would not take much extra effort.
- The maven docker plugin sounds good. I'll take a look at it.

Regarding supporting JAVA 11:
- Not sure if it is necessary to ship JAVA. Maybe we could just change
the base image from openjdk:8-jre to openjdk:11-jre in template docker
file[1]. Correct me if I understand incorrectly. Also, I agree to move
this out of the scope of this FLIP if it indeed takes much extra
effort.

Regarding the custom configuration, the mechanism that Thomas mentioned LGTM.

[1] 
https://github.com/apache/flink-docker/blob/master/Dockerfile-debian.template

Best,
Yangze Guo

On Wed, Mar 11, 2020 at 5:52 AM Thomas Weise  wrote:
>
> Thanks for working on improvements to the Flink Docker container images. This 
> will be important as more and more users are looking to adopt Kubernetes and 
> other deployment tooling that relies on Docker images.
>
> A generic, dynamic configuration mechanism based on environment variables is 
> essential and it is already supported via envsubst and an environment 
> variable that can supply a configuration fragment:
>
> https://github.com/apache/flink-docker/blob/09adf2dcd99abfb6180e1e2b5b917b288e0c01f6/docker-entrypoint.sh#L88
> https://github.com/apache/flink-docker/blob/09adf2dcd99abfb6180e1e2b5b917b288e0c01f6/docker-entrypoint.sh#L85
>
> This gives the necessary control for infrastructure use cases that aim to 
> supply deployment tooling other users. An example in this category this is 
> the FlinkK8sOperator:
>
> https://github.com/lyft/flinkk8soperator/tree/master/examples/wordcount
>
> On the flip side, attempting to support a fixed subset of configuration 
> options is brittle and will probably lead to compatibility issues down the 
> road:
>
> https://github.com/apache/flink-docker/blob/09adf2dcd99abfb6180e1e2b5b917b288e0c01f6/docker-entrypoint.sh#L97
>
> Besides the configuration, it may be worthwhile to see in which other ways 
> the base Docker images can provide more flexibility to incentivize wider 
> adoption.
>
> I would second that it is desirable to support Java 11 and in general use a 
> base image that allows the (straightforward) use of more recent versions of 
> other software (Python etc.)
>
> https://github.com/apache/flink-docker/blob/d3416e720377e9b4c07a2d0f4591965264ac74c5/Dockerfile-debian.template#L19
>
> Thanks,
> Thomas
>
> On Tue, Mar 10, 2020 at 12:26 PM Andrey Zagrebin  wrote:
>>
>> Hi All,
>>
>> Thanks a lot for the feedback!
>>
>> *@Yangze Guo*
>>
>> - Regarding the flink_docker_utils#install_flink function, I think it
>> > should also support build from local dist and build from a
>> > user-defined archive.
>>
>> I suppose you bring this up mostly for development purpose or powerful
>> users.
>> Most of normal users are usually interested in mainstream released versions
>> of Flink.
>> Although, you are bring a valid concern, my idea was to keep scope of this
>> FLIP mostly for those normal users.
>> The powerful users are usually capable to design a completely
>> custom Dockerfile themselves.
>> At the moment, we already have custom Dockerfiles e.g. for tests in
>> flink-end-to-end-tests/test-scripts/docker-hadoop-secure-cluster/Dockerfile.
>> We can add something similar for development purposes and maybe introduce a
>> special maven goal. There is a maven docker plugin, afaik.
>> I will add this to FLIP as next step.
>>
>> - It seems that the install_shaded_hadoop could be an option of
>> > install_flink
>>
>> I woud rather think about this as a separate independent optional step.
>>
>> - Should we support JAVA 11? Currently, most of the docker file based on
>> > JAVA 8.
>>
>> Indeed, it is a valid concern. Java version is a fundamental property of
>> the docker image.
>> To customise this in the current mainstream image is difficult, this would
>> require to ship it w/o Java at all.
>> Or this is a separate discussion whether we want to distribute docker hub
>> images with different Java versions or just bump it to Java 11.
>> This should be easy in a custom Dockerfile for development purposes though
>> as mentioned before.
>>
>> - I do not understand how to set config options through
>>
>> "flink_docker_utils configure"? Does this step happen during the image
>> > build or the container start? If it happens during the image build,
>> > there would be a new image every time we change the config. If it just
>> > a part of the container entrypoint, I think there is no need to add a
>> > configure command, we could just add all dynam

Re: [DISCUSS] FLIP-111: Docker image unification

[Thomas Weise]

Thanks for working on improvements to the Flink Docker container images.
This will be important as more and more users are looking to adopt
Kubernetes and other deployment tooling that relies on Docker images.

A generic, dynamic configuration mechanism based on environment variables
is essential and it is already supported via envsubst and an environment
variable that can supply a configuration fragment:

https://github.com/apache/flink-docker/blob/09adf2dcd99abfb6180e1e2b5b917b288e0c01f6/docker-entrypoint.sh#L88
https://github.com/apache/flink-docker/blob/09adf2dcd99abfb6180e1e2b5b917b288e0c01f6/docker-entrypoint.sh#L85

This gives the necessary control for infrastructure use cases that aim to
supply deployment tooling other users. An example in this category this is
the FlinkK8sOperator:

https://github.com/lyft/flinkk8soperator/tree/master/examples/wordcount

On the flip side, attempting to support a fixed subset of configuration
options is brittle and will probably lead to compatibility issues down the
road:

https://github.com/apache/flink-docker/blob/09adf2dcd99abfb6180e1e2b5b917b288e0c01f6/docker-entrypoint.sh#L97

Besides the configuration, it may be worthwhile to see in which other ways
the base Docker images can provide more flexibility to incentivize wider
adoption.

I would second that it is desirable to support Java 11 and in general use a
base image that allows the (straightforward) use of more recent versions of
other software (Python etc.)

https://github.com/apache/flink-docker/blob/d3416e720377e9b4c07a2d0f4591965264ac74c5/Dockerfile-debian.template#L19

Thanks,
Thomas

On Tue, Mar 10, 2020 at 12:26 PM Andrey Zagrebin 
wrote:

> Hi All,
>
> Thanks a lot for the feedback!
>
> *@Yangze Guo*
>
> - Regarding the flink_docker_utils#install_flink function, I think it
> > should also support build from local dist and build from a
> > user-defined archive.
>
> I suppose you bring this up mostly for development purpose or powerful
> users.
> Most of normal users are usually interested in mainstream released versions
> of Flink.
> Although, you are bring a valid concern, my idea was to keep scope of this
> FLIP mostly for those normal users.
> The powerful users are usually capable to design a completely
> custom Dockerfile themselves.
> At the moment, we already have custom Dockerfiles e.g. for tests in
>
> flink-end-to-end-tests/test-scripts/docker-hadoop-secure-cluster/Dockerfile.
> We can add something similar for development purposes and maybe introduce a
> special maven goal. There is a maven docker plugin, afaik.
> I will add this to FLIP as next step.
>
> - It seems that the install_shaded_hadoop could be an option of
> > install_flink
>
> I woud rather think about this as a separate independent optional step.
>
> - Should we support JAVA 11? Currently, most of the docker file based on
> > JAVA 8.
>
> Indeed, it is a valid concern. Java version is a fundamental property of
> the docker image.
> To customise this in the current mainstream image is difficult, this would
> require to ship it w/o Java at all.
> Or this is a separate discussion whether we want to distribute docker hub
> images with different Java versions or just bump it to Java 11.
> This should be easy in a custom Dockerfile for development purposes though
> as mentioned before.
>
> - I do not understand how to set config options through
>
> "flink_docker_utils configure"? Does this step happen during the image
> > build or the container start? If it happens during the image build,
> > there would be a new image every time we change the config. If it just
> > a part of the container entrypoint, I think there is no need to add a
> > configure command, we could just add all dynamic config options to the
> > args list of "start_jobmaster"/"start_session_jobmanager". Am I
> > understanding this correctly?
>
>  `flink_docker_utils configure ...` can be called everywhere:
> - while building a custom image (`RUN flink_docker_utils configure ..`) by
> extending our base image from docker hub (`from flink`)
> - in a custom entry point as well
> I will check this but if user can also pass a dynamic config option it also
> sounds like a good option
> Our standard entry point script in base image could just properly forward
> the arguments to the Flink process.
>
> @Yang Wang
>
> > About docker utils
> > I really like the idea to provide some utils for the docker file and
> entry
> > point. The
> > `flink_docker_utils` will help to build the image easier. I am not sure
> > about the
> > `flink_docker_utils start_jobmaster`. Do you mean when we build a docker
> > image, we
> > need to add `RUN flink_docker_utils start_jobmaster` in the docker file?
> > Why do we need this?
>
> This is a scripted action to start JM. It can be called everywhere.
> Indeed, it does not make too much sense to run it in Dockerfile.
> Mostly, the idea was to use in a custom entry point. When our base docker
> hub image is started its entry point can be also compl

Re: [DISCUSS] FLIP-111: Docker image unification

[Andrey Zagrebin]

Hi All,

Thanks a lot for the feedback!

*@Yangze Guo*

- Regarding the flink_docker_utils#install_flink function, I think it
> should also support build from local dist and build from a
> user-defined archive.

I suppose you bring this up mostly for development purpose or powerful
users.
Most of normal users are usually interested in mainstream released versions
of Flink.
Although, you are bring a valid concern, my idea was to keep scope of this
FLIP mostly for those normal users.
The powerful users are usually capable to design a completely
custom Dockerfile themselves.
At the moment, we already have custom Dockerfiles e.g. for tests in
flink-end-to-end-tests/test-scripts/docker-hadoop-secure-cluster/Dockerfile.
We can add something similar for development purposes and maybe introduce a
special maven goal. There is a maven docker plugin, afaik.
I will add this to FLIP as next step.

- It seems that the install_shaded_hadoop could be an option of
> install_flink

I woud rather think about this as a separate independent optional step.

- Should we support JAVA 11? Currently, most of the docker file based on
> JAVA 8.

Indeed, it is a valid concern. Java version is a fundamental property of
the docker image.
To customise this in the current mainstream image is difficult, this would
require to ship it w/o Java at all.
Or this is a separate discussion whether we want to distribute docker hub
images with different Java versions or just bump it to Java 11.
This should be easy in a custom Dockerfile for development purposes though
as mentioned before.

- I do not understand how to set config options through

"flink_docker_utils configure"? Does this step happen during the image
> build or the container start? If it happens during the image build,
> there would be a new image every time we change the config. If it just
> a part of the container entrypoint, I think there is no need to add a
> configure command, we could just add all dynamic config options to the
> args list of "start_jobmaster"/"start_session_jobmanager". Am I
> understanding this correctly?

 `flink_docker_utils configure ...` can be called everywhere:
- while building a custom image (`RUN flink_docker_utils configure ..`) by
extending our base image from docker hub (`from flink`)
- in a custom entry point as well
I will check this but if user can also pass a dynamic config option it also
sounds like a good option
Our standard entry point script in base image could just properly forward
the arguments to the Flink process.

@Yang Wang

> About docker utils
> I really like the idea to provide some utils for the docker file and entry
> point. The
> `flink_docker_utils` will help to build the image easier. I am not sure
> about the
> `flink_docker_utils start_jobmaster`. Do you mean when we build a docker
> image, we
> need to add `RUN flink_docker_utils start_jobmaster` in the docker file?
> Why do we need this?

This is a scripted action to start JM. It can be called everywhere.
Indeed, it does not make too much sense to run it in Dockerfile.
Mostly, the idea was to use in a custom entry point. When our base docker
hub image is started its entry point can be also completely overridden.
The actions are also sorted in the FLIP: for Dockerfile or for entry point.
E.g. our standard entry point script in the base docker hub image can
already use it.
Anyways, it was just an example, the details are to be defined in Jira, imo.

> About docker entry point
> I agree with you that the docker entry point could more powerful with more
> functionality.
> Mostly, it is about to override the config options. If we support dynamic
> properties, i think
> it is more convenient for users without any learning curve.
> `docker run flink session_jobmanager -D rest.bind-port=8081`

Indeed, as mentioned before, it can be a better option.
The standard entry point also decides at least what to run JM or TM. I
think we will see what else makes sense to include there during the
implementation.
Some specifics may be more convenient to set with env vars as Konstantin
mentioned.

> About the logging
> Updating the `log4j-console.properties` to support multiple appender is a
> better option.
> Currently, the native K8s is suggesting users to debug the logs in this
> way[1]. However,
> there is also some problems. The stderr and stdout of JM/TM processes could
> not be
> forwarded to the docker container console.

Strange, we should check maybe there is a docker option to query the
container's stderr output as well.
If we forward Flink process stdout as usual in bash console, it should not
be a problem. Why can it not be forwarded?

@Konstantin Knauf

For the entrypoint, have you considered to also allow setting configuration
> via environment variables as in "docker run -e FLINK_REST_BIN_PORT=8081
> ..."? This is quite common and more flexible, e.g. it makes it very easy to
> pass values of Kubernetes Secrets into the Flink configuration.

This is indeed an interesting option to 

Re: [DISCUSS] FLIP-111: Docker image unification

[Konstantin Knauf]

Hi Andrey,

thanks a lot for this proposal. The variety of Docker files in the project
has been causing quite some confusion.

For the entrypoint, have you considered to also allow setting configuration
via environment variables as in "docker run -e FLINK_REST_BIN_PORT=8081
..."? This is quite common and more flexible, e.g. it makes it very easy to
pass values of Kubernetes Secrets into the Flink configuration.

With respect to logging, I would opt to keep this very basic and to only
support logging to the console (maybe with a fix for the web user
interface). For everything else, users can easily build their own images
based on library/flink (provide the dependencies, change the logging
configuration).

Cheers,

Konstantin


On Thu, Mar 5, 2020 at 11:01 AM Yang Wang  wrote:

> Hi Andrey,
>
>
> Thanks for driving this significant FLIP. From the user ML, we could also
> know there are
> many users running Flink in container environment. Then the docker image
> will be the
> very basic requirement. Just as you say, we should provide a unified place
> for all various
> usage(e.g. session, job, native k8s, swarm, etc.).
>
>
> > About docker utils
>
> I really like the idea to provide some utils for the docker file and entry
> point. The
> `flink_docker_utils` will help to build the image easier. I am not sure
> about the
> `flink_docker_utils start_jobmaster`. Do you mean when we build a docker
> image, we
> need to add `RUN flink_docker_utils start_jobmaster` in the docker file?
> Why do we need this?
>
>
> > About docker entry point
>
> I agree with you that the docker entry point could more powerful with more
> functionality.
> Mostly, it is about to override the config options. If we support dynamic
> properties, i think
> it is more convenient for users without any learning curve.
> `docker run flink session_jobmanager -D rest.bind-port=8081`
>
>
> > About the logging
>
> Updating the `log4j-console.properties` to support multiple appender is a
> better option.
> Currently, the native K8s is suggesting users to debug the logs in this
> way[1]. However,
> there is also some problems. The stderr and stdout of JM/TM processes
> could not be
> forwarded to the docker container console.
>
>
> [1].
> https://ci.apache.org/projects/flink/flink-docs-master/ops/deployment/native_kubernetes.html#log-files
>
>
> Best,
> Yang
>
>
>
>
> Andrey Zagrebin  于2020年3月4日周三 下午5:34写道：
>
>> Hi All,
>>
>> If you have ever touched the docker topic in Flink, you
>> probably noticed that we have multiple places in docs and repos which
>> address its various concerns.
>>
>> We have prepared a FLIP [1] to simplify the perception of docker topic in
>> Flink by users. It mostly advocates for an approach of extending official
>> Flink image from the docker hub. For convenience, it can come with a set
>> of
>> bash utilities and documented examples of their usage. The utilities allow
>> to:
>>
>>- run the docker image in various modes (single job, session master,
>>task manager etc)
>>- customise the extending Dockerfile
>>- and its entry point
>>
>> Eventually, the FLIP suggests to remove all other user facing Dockerfiles
>> and building scripts from Flink repo, move all docker docs to
>> apache/flink-docker and adjust existing docker use cases to refer to this
>> new approach (mostly Kubernetes now).
>>
>> The first contributed version of Flink docker integration also contained
>> example and docs for the integration with Bluemix in IBM cloud. We also
>> suggest to maintain it outside of Flink repository (cc Markus Müller).
>>
>> Thanks,
>> Andrey
>>
>> [1]
>>
>> https://cwiki.apache.org/confluence/display/FLINK/FLIP-111%3A+Docker+image+unification
>>
>

-- 

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+49 160 91394525


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Re: [DISCUSS] FLIP-111: Docker image unification

[Yang Wang]

 Hi Andrey,


Thanks for driving this significant FLIP. From the user ML, we could also
know there are
many users running Flink in container environment. Then the docker image
will be the
very basic requirement. Just as you say, we should provide a unified place
for all various
usage(e.g. session, job, native k8s, swarm, etc.).


> About docker utils

I really like the idea to provide some utils for the docker file and entry
point. The
`flink_docker_utils` will help to build the image easier. I am not sure
about the
`flink_docker_utils start_jobmaster`. Do you mean when we build a docker
image, we
need to add `RUN flink_docker_utils start_jobmaster` in the docker file?
Why do we need this?


> About docker entry point

I agree with you that the docker entry point could more powerful with more
functionality.
Mostly, it is about to override the config options. If we support dynamic
properties, i think
it is more convenient for users without any learning curve.
`docker run flink session_jobmanager -D rest.bind-port=8081`


> About the logging

Updating the `log4j-console.properties` to support multiple appender is a
better option.
Currently, the native K8s is suggesting users to debug the logs in this
way[1]. However,
there is also some problems. The stderr and stdout of JM/TM processes could
not be
forwarded to the docker container console.


[1].
https://ci.apache.org/projects/flink/flink-docs-master/ops/deployment/native_kubernetes.html#log-files


Best,
Yang




Andrey Zagrebin  于2020年3月4日周三 下午5:34写道：

> Hi All,
>
> If you have ever touched the docker topic in Flink, you
> probably noticed that we have multiple places in docs and repos which
> address its various concerns.
>
> We have prepared a FLIP [1] to simplify the perception of docker topic in
> Flink by users. It mostly advocates for an approach of extending official
> Flink image from the docker hub. For convenience, it can come with a set of
> bash utilities and documented examples of their usage. The utilities allow
> to:
>
>- run the docker image in various modes (single job, session master,
>task manager etc)
>- customise the extending Dockerfile
>- and its entry point
>
> Eventually, the FLIP suggests to remove all other user facing Dockerfiles
> and building scripts from Flink repo, move all docker docs to
> apache/flink-docker and adjust existing docker use cases to refer to this
> new approach (mostly Kubernetes now).
>
> The first contributed version of Flink docker integration also contained
> example and docs for the integration with Bluemix in IBM cloud. We also
> suggest to maintain it outside of Flink repository (cc Markus Müller).
>
> Thanks,
> Andrey
>
> [1]
>
> https://cwiki.apache.org/confluence/display/FLINK/FLIP-111%3A+Docker+image+unification
>

[DISCUSS] FLIP-111: Docker image unification

[Andrey Zagrebin]

Hi All,

If you have ever touched the docker topic in Flink, you
probably noticed that we have multiple places in docs and repos which
address its various concerns.

We have prepared a FLIP [1] to simplify the perception of docker topic in
Flink by users. It mostly advocates for an approach of extending official
Flink image from the docker hub. For convenience, it can come with a set of
bash utilities and documented examples of their usage. The utilities allow
to:

   - run the docker image in various modes (single job, session master,
   task manager etc)
   - customise the extending Dockerfile
   - and its entry point

Eventually, the FLIP suggests to remove all other user facing Dockerfiles
and building scripts from Flink repo, move all docker docs to
apache/flink-docker and adjust existing docker use cases to refer to this
new approach (mostly Kubernetes now).

The first contributed version of Flink docker integration also contained
example and docs for the integration with Bluemix in IBM cloud. We also
suggest to maintain it outside of Flink repository (cc Markus Müller).

Thanks,
Andrey

[1]
https://cwiki.apache.org/confluence/display/FLINK/FLIP-111%3A+Docker+image+unification