You're raising good points, now i see why having the version in the name
is useful.
I'll adjust my PR accordingly. And yes, ideally we only release the
modified modules, not everything again.
On 26.06.2017 14:29, Stephan Ewen wrote:
How should it work when one of the shaded dependencies is updated? We
probably do not want to release all of them, just because the overall
version number is in their version number.
How about that:
- Under normal circumstances, we only increase the version of the root
project, when we add / bump a shaded dependency version
- Shaded dependencies include the version in the same. That way we can
possibly have two different versions of a dependency, such as
"flink-shaded-kryo-2" and "flink-shaded-kryo-3".
- Shaded dependencies should have the version in the relocation pattern
as well, for the same reason as above (unless the two versions have
separate namespaces already).
- The released version of the module and artifact is always "1.0" unless
we find that we did shading/relocation errors, in which case we need to
re-release that artifact (1.1, 1.2, ...)
On Mon, Jun 26, 2017 at 2:23 PM, Chesnay Schepler <ches...@apache.org>
wrote:
the guava version is already included in the version of the flink-shaded
module.
For example, for the first release of flink-shaded-guava the version would
be 1-18.0.
1 is the version of flink-shaded itself, 18.0 is the guava version.
On 26.06.2017 14:01, Stephan Ewen wrote:
Looks good, thanks Chesnay!.
How about including the dependency version names in the module names, like
"flink-shaded-guava-18.0"?
On Mon, Jun 26, 2017 at 11:49 AM, Chesnay Schepler <ches...@apache.org>
wrote:
The new repo was created and is accessible here:
https://github.com/apache/flink-shaded
I've already opened a PR to add a shaded guava module.
Once the shaded-guava module is merged I would like to do a first release
of flink-shaded,
only containing guava. I already have a branch with all the changes
necessary to
integrate this dependency into Flink.
The alternative would be to first create shaded modules for all
dependencies and make a
single release, but I feel that would delay things quite a bit.
On 21.06.2017 17:00, Robert Metzger wrote:
Okay, I'll request a repo for the shading.
On Wed, Jun 21, 2017 at 1:38 PM, Chesnay Schepler <ches...@apache.org>
wrote:
I like your suggestion Robert. A lot actually.
Having the actual dependency version (i.e 18 for guava) in the version
should improve clarity a lot.
Originally i intended to release 1 artifact per Flink version, with the
normal versioning scheme
that we use. But given that the shaded dependencies aren't changed
often
(even rarely might be a stretch),
and aren't actually coupled to the Flink release cycle this doesn't
make
a
lot of sense.
Having separate repos looks like a reasonable separation of concerns.
The
release for Flink itself
would work just like it does now; we don't have to modify any scripts
or
do extra steps.
Since the build, release and development process are separate (since
flink-shaded isn't part of Flink build
process, has a separate release process and changes to it will /never
/require immediate changes to Flink)
it seems like a very good candidate to move it into a separate repo.
On 21.06.2017 11:26, Robert Metzger wrote:
Its not completely clear to me how we want to version the shaded
dependencies, and where we are putting them.
One concern are the official apache release rules. If we want to
release
something to maven central, we need to do a proper vote over a source
archive.
I would propose to create a new repository "flink-shaded.git" that
contains
the following maven module structure:
- flink-shaded: 1
- flink-shaded-asm: 1-5.2
- flink-shaded-guava: 1-18.0
- ...
The number indicates the version (for ASM, I've just guessed).
The version for the parent "flink-shaded" needs to be updated on each
parent pom change (new module added, new / changed plugins, ...)
We could create a separate release script in this repository that
creates
the flink-shaded-src.zip from the code and deploys the artifacts to
the
maven staging area.
The advantage of a separate repo would be that we don't need to
maintain
separate maven projects in the same git repo.
Also, the src archives for the release vote can be created from the
repo
content (without much filtering).
On Tue, Jun 20, 2017 at 9:44 PM, Stephan Ewen <se...@apache.org>
wrote:
I like this approach.
Two additional things can be mention here:
- We need to deploy these artifacts independently and not as
part
of
the
build. That is a manual step once per "bump" in the dependency of
that
library.
- We reduce the shading complexity of the original build and
should
thus
also speed up build times :-)
Stephan
On Tue, Jun 20, 2017 at 1:15 PM, Chesnay Schepler <
ches...@apache.org>
wrote:
I would like to start working on this.
I've looked into adding a flink-shaded-guava module. Working against
the
shaded namespaces seems
to work without problems from the IDE, and we could forbid un-shaded
usages with checkstyle.
So for the list of dependencies that we want to shade we currently
got:
* asm
* guava
* netty
* hadoop
* curator
I've had a chat with Stephan Ewan and he brought up kryo + chill as
well.
The nice thing is that we can do this incrementally, one dependency
at a
time. As such i would propose
to go through the whole process for guava and see what problems
arise.
This would include adding a flink-shaded module and a child
flink-shaded-guava module to the flink repository
that are not part of the build process, replacing all usages of
guava
in
Flink, adding the
checkstyle rule (optional) and deploying the artifact to maven
central.
On 11.05.2017 10:54, Stephan Ewen wrote:
@Ufuk - I have never set up artifact deployment in Maven, could
need
some
help there.
Regarding shading Netty, I agree, would be good to do that as
well...
On Thu, May 11, 2017 at 10:52 AM, Ufuk Celebi <u...@apache.org>
wrote:
The advantages you've listed sound really compelling to me.
- Do you have time to implement these changes or do we need a
volunteer?
;)
- I assume that republishing the artifacts as you propose doesn't
have
any new legal implications since we already publish them with our
JARs, right?
- We might think about adding Netty to the list of shaded
artifacts
since some dependency conflicts were reported recently. Would have
to
double check the reported issues before doing that though. ;-)
– Ufuk
On Wed, May 10, 2017 at 8:45 PM, Stephan Ewen <se...@apache.org>
wrote:
@chesnay: I used ASM as an example in the proposal. Maybe I did not
say
that clearly.
If we like that approach, we should deal with the other libraries
(at
least
the frequently used ones) in the same way.
I would imagine to have a project layout like that:
flink-shaded-deps
- flink-shaded-asm
- flink-shaded-guava
- flink-shaded-curator
- flink-shaded-hadoop
"flink-shaded-deps" would not be built every time (and not be
released
every time), but only when needed.
On Wed, May 10, 2017 at 7:28 PM, Chesnay Schepler <
ches...@apache.org
wrote:
I like the idea, thank you for bringing it up.
Given that the raised problems aren't really ASM specific would
it
make
sense to create one flink-shaded module that contains all
frequently
shaded
libraries? (or maybe even all shaded dependencies by core modules)
The
proposal limits the scope of this to ASM and i was wondering why.
I also remember that there was a discussion recently about why
we
shade
things at all, and the idea of working against the shaded
namespaces
was
brought up. Back then i was expressing doubts as to whether IDE's
would
properly support this; what's the state on that?
On 10.05.2017 18:18, Stephan Ewen wrote:
Hi!
This is a discussion about altering the way we handle
dependencies
and
shading in Flink.
I ran into quite a view problems trying to adjust / fix some
shading
issues
during release validation.
The issue is tracked under: https://issues.apache.org/jira
/browse/FLINK-6529
Bring this discussion thread up because it is a bigger issue
*Problem*
Currently, Flink shades dependencies like ASM and Guava into
all
jars
of
projects that reference it and relocate the classes.
There are some drawbacks to that approach, let's discuss them at
the
example of ASM:
- The ASM classes are for example in flink-core,
flink-java,
flink-scala,
flink-runtime, etc.
- Users that reference these dependencies have the
classes
multiple
times
in the classpath. That is unclean (works, through, because the
classes
are
identical). The same happens when building the final dist. jar.
- Some of these dependencies require to include license
files
in
the
shaded jar. It is hard to impossible to build a good automatic
solution
for
that, partly due to Maven's very poor cross-project path
support
- Most importantly: Scala does not support shading
really
well.
Scala
classes have references to classes in more places than just the
class
names
(apparently for Scala reflect support). Referencing a Scala
project
with
shaded ASM still requires to add a reference to unshaded ASM
(at
least
as
a
compile dependency).
*Proposal*
I propose that we build and deploy a asm-flink-shaded version
of
ASM
and
directly program against the relocated namespaces. Since we
never
use
classes that we relocate in public interfaces, Flink users will
never
see
the relocated class names. Internally, it does not hurt to use
them.
- Proper maven dependency management, no hidden (shaded)
dependencies
- One copy of each class for shaded dependencies
- Proper Scala interoperability
- Natural License management (license is part of deployed
asm-flink-shaded jar)
Happy to hear thoughts!
Stephan
