`ament_vendor` - Allow specifying VCS retries

[roncapat]

https://github.com/ament/ament_cmake/blob/7f8f485aedd76548f6d4280f26289528fed7ef92/ament_cmake_vendor_package/cmake/ament_vendor.cmake#L282C7-L282C106

There is no way to speficy --retry N. It would be nice to do so.

[christophebedard]

Can you explain why you'd like to add this? Are you facing any particular issue? Note that vcs import retries twice by default:

$ vcs import --help
...
  --retry N            Retry commands requiring network access N times on failure (default: 2)
...

If you're having issues with GitHub, please note that GitHub recently changed/reduced limits on unauthenticated requests, so retrying may not even really help. See a recent conversation here: colcon/colcon-mixin#48.

[roncapat]

@christophebedard mostly, repeated, local and custom docker image builds using non-ideal network providers, like corporate mobile flat plans.

I believe that the burst and the amount of requests, most of them pointing to github, triggers some random traffic limitation.

I solved by tuning both concurrency and retries (by patching the cmake script).

[christophebedard]

I see, thanks for the info. There might still be a fundamental rate limitation issue, but a way to retry N times would make sense for non-ideal networks. It would probably make a lot of sense as a global CMake option (cache entry) that you can set for all packages being built.