Ben,
You have been very helpful. I am sincerely thankful.
> I still think you'll get more mileage by trying to use the system as it
> was designed to be used(build an image with your compiled source built
> in) instead of trying to force a different workflow onto it.
I understand and agree. Accordingly I need to working on 2 step solution
1. First step is to get my dockers up and running in a day or two.
Considering how long it is taking me to understand the system, I want to
do it the short way first. I.e. able to run following command from
within openshift
"docker run --rm -it -v /my/host/folder:/usr/src/myapp -w /usr/src/myapp
openjdk:8-jre-alpine java myClass"
This means
- download jars/files from source control to a host folder foobar
- mount the host folder foobar, that has my class files/jars into a java
docker at /usr/src/myapp
- run java docker (along with -w flag)
2. Once I can get system up, I will continue to understand how to make
S2I operational and switch to it once I have enough confidence. I am
struggling with the fact that running php through S2I seems to be
straightforward. No special config etc is needed. However to run Java or
Node code, the repo should have particular images or package.json etc.
and so far I am not able to understand what I need to add to the repo to
make it S2I compatible.
In other words, if I create one php file, put in a repo, mention the git
url in S2I, it works. If I create a single node file or java file or
even jboss example git
(https://github.com/jboss-developer/jboss-eap-quickstarts) in S2I, the
build fails.
I hope that makes sense.
Regards
On 9/5/2016 7:33 PM, Ben Parees wrote:
On Fri, Sep 2, 2016 at 4:27 PM, Ravi <ravikapoor...@gmail.com
<mailto:ravikapoor...@gmail.com>> wrote:
Ben, thanks for pointing me in right direction. However, after a
week, I am still struggling and need help.
The questions you raised are genuine issues which, if managed by
openshift will be easy to handle, however if openshift does not
manage them, then manually managing them is certainly a difficult task.
Leaving that aside, I have been struggling with running my app on
openshift. Here is a list of everything I tried
As suggested by you, I tried to create a volume and run java docker
with it. I am getting really lost in variety of issues, here are some:
I still think you'll get more mileage by trying to use the system as it
was designed to be used(build an image with your compiled source built
in) instead of trying to force a different workflow onto it.
- unless I login with service:admin user (no password), I am not
authorized to mount a volume.
what type of volume? what do you mean by "mount a volume"? what
commands are you running? how is your pod or deployment config defined?
- I can only login with service:admin on command line, the UI gives
me error. So basically I cannot visually see mounted volumes
- There is no way from UI to create a Volume Claim, I must define a
JSON
- I was unable to find any documentation for this JSON and had to
copy from other places
you can use "oc set volumes" to add volume claims to a deployment
config, once you have (as an administrator) defined persistent volumes
in your cluster.
you can also "attach storage" to a deployment config from within the
openshift console, but that does not apply to your scenario since you
are trying to mount a "specific" volume into your pod instead of just
requesting persistent storage.
- After all this, how do I know which volume is being attached to
which volume claim?
you aren't supposed to care. You ask for persistent storage, the
system finds persistent storage to meet those needs, and you use it.
If you're trying to set up a specific persistent volume definition with
existing content, and then ensure that particular PV gets assigned to
your Pod then you don't use a PVC, you just reference the volume
directly in the Pod definition as with the git repo volume example.
- I copied mongodb.json and switched image to java.json, this did
not work
- I decided, this was too complex, lets just do S2I. However, when I
cannot find any documentation how to do it. The example images work
but when i try my own node or JEE project, S2I fails. I am guessing
it needs some specific files in source to do this.
- While PHP project https://github.com/gshipley/simplephp
<https://github.com/gshipley/simplephp> works with S2I with only a
php file, when I create a nodejs file, it does not work. I could not
find documentation on how to get my node file to run.
https://github.com/openshift/nodejs-ex
<https://github.com/openshift/nodejs-ex>
https://docs.openshift.org/latest/using_images/s2i_images/nodejs.html
<https://docs.openshift.org/latest/using_images/s2i_images/nodejs.html>
- I tried to do walkthroughs, but most of them are using openshift
online and a command "rhc" that is not available to me.
i'm not sure what walkthroughs you found, but "rhc" is a command like
tool for the previous version of openshift, v2. So that is irrelevant
to what you're trying to do. The v3 online environment is here:
https://console.preview.openshift.com/console/
<https://console.preview.openshift.com/console/>
and you can find a tutorial here:
https://github.com/openshift/origin/tree/master/examples/sample-app
<https://github.com/openshift/origin/tree/master/examples/sample-app>
(if you already have an openshift cluster, you can start at step 7,
"Create a new project in OpenShift. "
And all I wanted to do was run one simple command:
docker run --rm -it -v /my/host/folder:/usr/src/myapp -w /usr/src/myapp
openjdk:8-jre-alpine java myClass
ARGGG!! HELP please.
On 8/26/2016 3:24 PM, Ben Parees wrote:
On Fri, Aug 26, 2016 at 6:10 PM, Ravi Kapoor
<ravikapoor...@gmail.com <mailto:ravikapoor...@gmail.com>
<mailto:ravikapoor...@gmail.com
<mailto:ravikapoor...@gmail.com>>> wrote:
Ben,
Thank you so much for taking the time to explain. This is
very helpful.
If I may, I have a few followup questions:
> That is not a great approach to running code. It's fine
for development, but you really want to be producing immutable
images that a developer can hand to QE has tested it, they can
hand that exact same image to prod, and there's no risk that
pieces have changed.
Q1: It seems like Lyft uses the approach I was mentioning i.e.
inject code into dockers rather than copy code inside dockers
(ref: https://youtu.be/iC2T3gJsB0g?t=595
<https://youtu.be/iC2T3gJsB0g?t=595>
<https://youtu.be/iC2T3gJsB0g?t=595
<https://youtu.be/iC2T3gJsB0g?t=595>>). In this approach there are
only two elements - the image (which will not change) and
the code
build/tag which will also not change. So what else can change?
Since you're mounting the code from the local filesystem into the
running container, how do you know the code is the same on every
machine
that you're running the container on?
If you have 15 nodes in your cluster, what happens when only 14
of them
get the latest code update and the 15th one is still mounting an
old file?
Or your admin accidentally copies a dev version of the code to
one of
the nodes?
When you look at a running container how do you know what
version of the
application it's running, short of inspecting the mounted content?
When you bring a new node online in your cluster, how do you get
all the
right code onto that node so all your images (thousands
possibly!) are
able to mount what they need when they start up?
Do you put all the code for all your applications on all your
nodes so
that you can run any application on any node? Do you build your own
infrastructure to copy the right code to the right place before
starting
an application? Do you rely on a shared filesystem mounted to
all your
nodes to make the code accessible?
These are questions you don't have to answer when the image *is* the
application.
> running things in that way means you need to get both the
image and
your class files into paths on any machine where the image
is going
to be run, and then specify that mount path correctly
Q2: I would think that openshift has a mechanism to pull
files from
git to a temp folder and way to volume mount that temp
folder into
any container it runs.Volume mounts are very basic feature of
dockers and I am hoping they are somehow workable with
openshift.
Are they not? Don't we need them for lets say database
dockers? Lets
say a mongodb container is running, it is writing data to a
volume
mounted disk. If container crashes, is openshift able to
start a new
container with previous saved data?
Openshift does support git-based volumes if you want to go that
approach:
https://docs.openshift.org/latest/dev_guide/volumes.html#adding-volumes
<https://docs.openshift.org/latest/dev_guide/volumes.html#adding-volumes>
i'm not sure whether you can provide git credentials to that volume
definition to handle private git repositories however.
Q3: Even if you disagree, I would still like to know (if nothing
else then for learning/education) about how to run external
images
with volume mounts and other parameters being passed into
the image.
I am having very hard time finding this.
https://docs.openshift.org/latest/dev_guide/volumes.html
<https://docs.openshift.org/latest/dev_guide/volumes.html>
https://docs.openshift.org/latest/architecture/additional_concepts/storage.html
<https://docs.openshift.org/latest/architecture/additional_concepts/storage.html>
regards
Ravi
On Fri, Aug 26, 2016 at 10:29 AM, Ben Parees
<bpar...@redhat.com <mailto:bpar...@redhat.com>
<mailto:bpar...@redhat.com <mailto:bpar...@redhat.com>>> wrote:
On Fri, Aug 26, 2016 at 1:07 PM, Ravi
<ravikapoor...@gmail.com <mailto:ravikapoor...@gmail.com>
<mailto:ravikapoor...@gmail.com
<mailto:ravikapoor...@gmail.com>>> wrote:
So I am trying to use openshift to manage our dockers.
First problem I am facing is that most of
documentation and
image templates seem to be about S2I. We are
When it comes to building images, openshift supports
basically
4 approaches, in descending order of recommendation and
increasing order of flexibility:
1) s2i (you supply source and pick a builder image, we
build a
new application image and push it somewhere)
2) docker-type builds (you supply the dockerfile and
content, we
run docker build for you and push the image somewhere)
3) custom (you supply an image, we'll run that image,
it can do
whatever it wants to "build" something and push it
somewhere,
whether that something is an image, jar file, etc)
4) build your images externally on your own
infrastructure and
just use openshift to run them.
The first (3) of those are discussed here:
https://docs.openshift.org/latest/architecture/core_concepts/builds_and_image_streams.html#builds
<https://docs.openshift.org/latest/architecture/core_concepts/builds_and_image_streams.html#builds>
<https://docs.openshift.org/latest/architecture/core_concepts/builds_and_image_streams.html#builds
<https://docs.openshift.org/latest/architecture/core_concepts/builds_and_image_streams.html#builds>>
considering a continuous builds for multiple
projects and
building an image every 1 hour for multiple projects
would
create total 20GB images every day.
I'm not sure how this statement relates to s2i. Do yo
have a
specific concern about s2i with respect to creating these
images? Openshift does offer image pruning to help deal
with
the number of images you sound like you'll be creating, if
you're interested in that.
Q1: Is this right way of thinking? Since today most
companies are doing CI, this should be a common
problem. Why
is S2I considered impressive feature?
S2I really has little to do with CI/CD. S2I is one way to
produce docker images, there are others as I listed
above. Your
CI flow is going to be something like:
1) change source
2) build that source into an image (in whatever way you
want,
s2i is one mechanism)
3) test the new image
4) push the new image into production
The advantages to using s2i are not about how it
specifically
works well with CI, but rather with the advantages it offers
around building images in a quick, secure, convenient
way, as
described here:
https://docs.openshift.org/latest/architecture/core_concepts/builds_and_image_streams.html#source-build
<https://docs.openshift.org/latest/architecture/core_concepts/builds_and_image_streams.html#source-build>
<https://docs.openshift.org/latest/architecture/core_concepts/builds_and_image_streams.html#source-build
<https://docs.openshift.org/latest/architecture/core_concepts/builds_and_image_streams.html#source-build>>
So, I am trying to use off the shelf images and inject
code/conf into them. I know how to do this from docker
command line (example: docker run --rm -it -v
/my/host/folder:/usr/src/myapp -w /usr/src/myapp
openjdk:8-jre-alpine java myClass )
That is not a great approach to running code. It's
fine for
development, but you really want to be producing immutable
images that a developer can hand to QE has tested it,
they can
hand that exact same image to prod, and there's no risk that
pieces have changed.
Also running things in that way means you need to get
both the
image and your class files into paths on any machine
where the
image is going to be run, and then specify that mount path
correctly. It's not a scalable model. You want to build
runnable images, not images that need the application
side-loaded via a mount.
Q2: How do I configure exact same command from
openshift? I
will need to do following steps
You shouldn't. Strictly speaking you can, via pod mount
definitions and hostpath volume definitions, but it's
not the
right way to think about creating and running images in a
clustered environment.
1. Jenkins is pushing compiled jar files to git
repository.
First step will be to pull the files down.
2. I may have to unzip some files (in case it is
bunch of
configurations etc.)
3. Openshift should use docker run to create containers.
Assuming you want to continue building jars via jenkins and
pushing them somewhere (doesn't have to be git), i'd
suggest the
following flow:
1) jenkins builds jar and pushes it somewhere
2) an s2i(or docker) build in openshift pulls from that
somewhere (either it's pulling the git source that
includes the
jar, or you can write your own assemble script which
pulls the
jar from a nexus repo(or a dockerfile which does so) or some
other location. This is discussed here:
https://docs.openshift.org/latest/dev_guide/builds.html#using-external-artifacts
<https://docs.openshift.org/latest/dev_guide/builds.html#using-external-artifacts>
<https://docs.openshift.org/latest/dev_guide/builds.html#using-external-artifacts
<https://docs.openshift.org/latest/dev_guide/builds.html#using-external-artifacts>>)
You can also do binary builds which don't require you
put the
content in a git repo:
https://docs.openshift.org/latest/dev_guide/builds.html#binary-source
<https://docs.openshift.org/latest/dev_guide/builds.html#binary-source>
<https://docs.openshift.org/latest/dev_guide/builds.html#binary-source
<https://docs.openshift.org/latest/dev_guide/builds.html#binary-source>>
in which case the jenkins job would build the jar
locally and
then invoke "oc start-build yourbuild --from-file your.jar"
3) the image will get pushed to a docker registry as
part of
the build
4) the image gets deployed on openshift, it is fully
self-contained and does not need any external mounts.
It can
scale up and move between host nodes without any
adminstrative
maintenance.
Hope that helps.
thanks so much for help
Ravi
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