When action `StampWithIjar` runs it does not allow environment variables to be passed in using `--action_env`

[adam-singer]

When action StampWithIjar runs it does not allow environment variables to be passed in using --action_env command line flag. This can lead to problems when ijar is executed on systems that have compiled it with a tool chain picked up from the environment but not available on the host system in standard locations.

A common solution applied is to allow durning action run use_default_shell_env = True as done in twitter-forks#8

[liucijus]

@adam-singer do you need your scala imports to be stamped? If not can you disable it with a setting:
https://github.com/bazelbuild/rules_scala/blob/master/docs/scala_import.md#scala_import

If you don't need stamping, I would prefer to hold off from applying use_default_shell_env = True to prevent non-deterministic builds. If stamping is something you really need now, then we need to ask this to be released bazelbuild/bazel#12730 and, maybe it's ok for a short time to enable use_default_shell_env = True to unblock you.

[adam-singer]

@liucijus let's say we don't ship this, long term what would be the solution or approach used? Based on some of the source code reading and commit logs, it seemed this feature was under development and forked a bit from the provided implementation in rules_java code base, so I think it would be smart for us to avoid it. My understanding is we do prevent some amount of rebuilding if we do use stamped imports.

[liucijus]

Can you send a PR with a use_default_shell_env = True? If you need stamping, there are no other working alternatives that I know.

[wisechengyi]

We were able to get our code working by turning off stamping for scala_import, since ijar is no longer invoked.

That said, I think @adam-singer has found use_default_shell_env = True to be common pattern for native tools. So if ijar was compiled with access to env vars, I'd say we should set use_default_shell_env = True when invoking it as well to maintain the consistency.

[adam-singer]

@wisechengyi I'm testing out build --@io_bazel_rules_scala//scala/settings:stamp_scala_import=False in the .bazelrc file, locally it worked, but I would like to confirm on CI. Some discussion moved from slack https://bazelbuild.slack.com/archives/CA31HN1T3/p1614634162181200 back to this github thread.

[adam-singer]

@liucijus build --@io_bazel_rules_scala//scala/settings:stamp_scala_import=False in the .bazelrc worked great after we removed use_default_shell_env = True. Huge Thanks !