Re: [Proposal] Extension of the Apex configuration to add dependent jar files in runtime.

[Vlad Rozov]

+1 assuming that support for merge/override will be generic for all 
attributes that support list/set of values and not limited to 
LIBRARY_JARS attribute only.

Thank you,
Vlad

On 2/3/18 09:13, Pramod Immaneni wrote:
I too agree that the discussion has veered off from the original topic. Why
can't LIBRARY_JARS be used for this, albeit with a minor improvement?
Currently, our attribute layering is an override, so if you have an
attribute that is specified as apex.application.<appname>.attr.<attrname>
it overrides apex.attr.<attrname> for that application. What if were to
expand the attribute definition to allow for the specification of how the
layering of attributes will be combined, override being one option, merge
being another with these being implemented with a combiner interface? This
way a set of common jars could be specified using dt.attr.LIBRARY_JARS and
applications can still add extra jars on top.

On Fri, Feb 2, 2018 at 6:32 PM, Vlad Rozov <vro...@apache.org> wrote:

IMO, support for Kubernetes, Docker images, Mesos and anything outside of
Yarn deployments is a topic by itself and design for such support needs to
be discussed. I do not want to propose any specific design, but assume that
logic to create proper execution environment would be coded into Apex
client. Whether it (hardcoded logic to create an execution environment) can
be expressed simply as a list of dependent classes or jars is at minimum
questionable. Until design is proposed and agreed upon, I'd prefer to use
plugins for the subject.

Thank you,

Vlad


On 2/2/18 13:17, Sanjay Pujare wrote:

In cases where we have an "über" docker image containing support for
multiple execution environments it might be useful for the Apex core to
infer what kind of execution environment to use for a particular
invocation  (say based on configuration values/environment variables) and
in that case the core will load the corresponding libraries. And I think
this kind of flexibility or support would be difficult through the plugins
hence I think Sergey's proposal will be useful.

Sanjay


On Fri, Feb 2, 2018 at 11:18 AM, Sergey Golovko <ser...@datatorrent.com>
wrote:

Unfortunately the moving of .apa file to a docker image cannot resolve all
problems with the dependencies. If we assume an Apex application should
be
run in different execution environments, the application docker image
must
contain all possible execution environment dependencies.

I think the better way is to assume that the original application docker
image like the current .apa file should contain the application specific
dependencies only. And some smart client tool should create the
executable
application docker image form the original one and include the execution
specific environment dependencies into the target application docker
image.
It means anyway an smart client Apex tool should have an interface to
define different environment dependencies or combination of different
dimensions of the environment dependencies.

Thanks,
Sergey


On Fri, Feb 2, 2018 at 10:23 AM, Thomas Weise <t...@apache.org> wrote:

The current dependencies are based on how Apex YARN client works. YARN
depends on a DFS implementation for deployment (not necessarily HDFS).

I think a better way to look at this is to consider that instead of an

.apa

file the application is a docker image, which would contain Apex and all
dependencies that the "StramClient"  today adds for YARN.

In that world there would be no Apex CLI or Apex specific client.

Thomas



On Thu, Feb 1, 2018 at 5:57 PM, Sergey Golovko <ser...@datatorrent.com>
wrote:

I agree. It can be implemented with usage of plugins. But if I need to
enable and configurate the plugin I need to put this information into
dt-site.xml. It means The plugin and its parameter must be documented

and
the list of the added specific jars will be visible and available for
updates to the end-user. The implementation via plugins is more dynamic
solution that is more convenient for the application developers. But

I'm
talking about the static configuration of the Apex build or
installation
that relates more to the platform development.
The current Apex core implementation uses the static unchanged list of

jars

for long time, because the Apex implementation still contains several

basic

static assumptions (for instance, the usage of YARN, HDSF, etc.). And

the
current Apex assumptions are hardcoded in the implementation. But if we
are

going to improve Apex and use Java interfaces in generic Apex
implementation, the current static approach in Apex code to hardcode a

list

of dependent jars will not work anymore. It will require to include a

new
solution to add/change jars in specific Apex builds/configurations.
And I
don't think the usage of the plugins will be good for that.
Thanks,
Sergey


On Thu, Feb 1, 2018 at 1:47 PM, Vlad Rozov <vro...@apache.org> wrote:

There is a way to get the same end result by using plugins. It will
be
good to understand why plugin can't be used and can they be extended
to
provide the required functionality.
Thank you,

Vlad


On 1/29/18 15:14, Sergey Golovko wrote:

Hello All,
In Apex there are two ways to deploy non-Hadoop jars to the deployed
cluster.

The first approach is static (hardcoded) and it is used by Apex

platform
developers only. There are several final static arrays of Java
classes
in StramClient.java
that define which of the available jars should be included into

deployment
for every Apex application.
The second approach is to add paths of all dependent jar-files to

the
value
of the attribute LIB_JARS. The end-user can set/update the value of

the
attribute LIB_JARS via dt-site.xml files, command line parameters,
application properties and plugins. The usage of the
attribute LIB_JARS is the official documented way for all Apex users

to
manage by the deployment jars.
But some of the dependent jars (not from the Apex core) can be

common
for
all customer's applications for a specific installation and/or
execution
environment. Unfortunately the Apex implementation does not contain
the
middle solution that would allow the Apex developers and customer
support
to
define and add new dependent jar-files (jars that should not be
configurable/managed by the end-user) without the

updates/recompilation
of

the Apex Java code during the Apex building process and/or
installation/configuration.

Also the having of such kind of flexibility would allow the Apex

core
developers to use Java interfaces during the development to define
an
abstraction layer in Apex implementation and configurate Apex core
to
add
some specific jars to all Apex applications without recompilation of
the
Apex source code.
For instance, now the usage of HDFS is hardcoded in Apex platform

code
but
it can be replaced with any other distributed or cloud base file
system.
The Apex core code can use an interface for all I/O operations but
the
supporting of a real specific file system implementation can be
added
as

an
independent jar-file. Or if the implementation of some of Apex

operators
depend on a specific service, and it is necessary to add some of the
service jars to every Apex application implicitly.

The proposal:

- add a predefined configuration text file (we can make any choice

for
the
file syntax: XML, JSON or Properties) to Apex engine resources with
predefined values of some of the Apex attributes (now we can include
LIB_JARS
attribute only);
- allow to have a configuration text file with the same

functionality
in

the Apex installation folder "conf";
- read the content of the predefined configuration text files by the

stram
client in runtime and add the jars to the list of the dependent
jars;
- allow to use paths to jars and Java classes to refer to the
dependent
jars (the references can have the extensions: .class and .jar).
Thanks,
Sergey