Conan package support (#4522)

[uilianries]

Hi!

This PR is about the issue #4522

I just bring the Conan recipe, to build and package.
Also, I added a job on Travis to build Flatbuffer package, just to make sure that is working.

On next PR, I want to create multi packages (os x arch x build type x options) and submit all built packages to Bintray.

/cc @memsharded @lasote @zamazan4ik

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[uilianries]

I signed it!

[googlebot]

CLAs look good, thanks!

[aardappel]

So.. Conan needs to inject itself into CMake files using Python to work? Doesn't sound very elegant to me, but oh well.

Also, as for submitting to Bintray, having binary packages available seems useful to me, though only on release versions, not every commit?

[uilianries]

I agree with you Injection is ugly. In general we use a wrapper to call conan_setup_tools and include the original Cmake:

cmake_minimum_required(VERSION 2.8)

include(${CMAKE_BINARY_DIR}/conanbuildinfo.cmake)
conan_basic_setup()

include(CMakeLists.txt)

In fact, we need to load Conan setup by such method. This method fills env vars, directory paths ...
Anyway, when Conan builds the package, it copies all listed files on exports_sources to a build directory, this include your cmake. But as a copy, your original cmake won't be changed.
Also, we can't change your original cmake directly, because this will force to run Conan by default.

I could create a directory with the cmake wrapper to avoid the injection. This can be done on next PR.

About Bintray, my suggestion is build at least using gcc (linux), clang (linux and mac) and msvc (windows). Flatbuffers take some minutes to be built and I agree that build on each commit will increase so much your CI time.
It's possible to build only when a new release is created by branch name or CI vars. I'll provide this feature on next PR.

Also will be necessary that you or some maintainer create a Bintray account to push the packages.
There is a good documentation about this here
Shortly, you need:

• Create a new account
• Create a Conan repository
• Set CI environment (Travis and Appveyor)
  • CONAN_LOGIN_USERNAME: <your_bintray_username>
  • CONAN_PASSWORD: <you_bintray_api_key>
    You can obtain the API key by your Bintray profile

Any question, please feel free to ask!

Regards!

[aardappel]

@uilianries Conan appears to breaking unrelated PRs, see e.g. https://travis-ci.org/google/flatbuffers/jobs/337010509
Can you fix?

[uilianries]

Of course! I'll check ASAP! Thanks for report!

[uilianries]

The error started during apt-get update, the remotes were not achieved:
W: Failed to fetch http://ppa.launchpad.net/openjdk-r/ppa/ubuntu/dists/trusty/InRelease Could not connect to ppa.launchpad.net:80 (91.189.95.83), connection timed out

After that, was not possible to run gcc: [gcc]: command not found.

Indeed, the error occurred before to build anything:
The command "if [ "$TRAVIS_OS_NAME" == "linux" ]; then sudo apt-get install -qq g++-$GCC_VERSION; fi" failed and exited with 100 during .

I just re-ran the master branch and I didn't see any server error: https://travis-ci.org/uilianries/flatbuffers/builds/337763849

Could you re-run the build? It looks like some temporary server error.

Regards!

[aardappel]

CI that relies on heavy software installation is just a bad idea.. but that wasn't your fault.
I guess we'll need to live with it occasionally being flakey.

[uilianries]

Travis supports some cache option, but AFAIK it's a paid feature. So, no free lunch.

Regards.

[aardappel]

@uilianries the Python code in here appears to be generating CI failures: https://travis-ci.org/google/flatbuffers/jobs/367231754

Any ideas how that can be improved?

[uilianries]

Hi @aardappel !

Actually there is a problem with pypi service: https://status.python.org/

It's global, so we have no power to fix :(

[aardappel]

@uilianries We currently have CI errors: https://travis-ci.org/google/flatbuffers/jobs/561038298 that may be Conan related? Any idea what the problem is?

[rw]

@uilianries @aardappel This looks related (but not the cause): conan-io/conan#5094

[uilianries]

looking it now

[uilianries]

@aardappel @rw #5449