patch[RFC] travis-ci: remove bogus 'pyenv' in the Linux jobs

In our test suite, when 'git p4' invokes a Git command as a subprocesses, then it should run the 'git' binary we are testing. Unfortunately, this is not the case in the 'linux-clang' and 'linux-gcc' jobs on Travis CI, where 'git p4' runs the system '/usr/bin/git' instead.

Travis CI's default Linux image includes 'pyenv', and all Python invocations that involve PATH lookup go through 'pyenv', e.g. our 'PYTHON_PATH=$(which python3)' sets '/opt/pyenv/shims/python3' as PYTHON_PATH, which in turn will invoke '/usr/bin/python3'. Alas, the 'pyenv' version included in this image is buggy, and prepends the directory containing the Python binary to PATH even if that is a system directory already in PATH near the end. Consequently, 'git p4' in those jobs ends up with its PATH starting with '/usr/bin', and then runs '/usr/bin/git'.

So remove 'pyenv' in Travis CI's Linux jobs to prevet it from interfering with our 'git p4' tests.

Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
---

Notes:
    This issue triggered test failures in all 'git p4' test scripts in the
    recent GIT_TEST_DEFAULT_HASH=sha256 test runs, because the system Git
    doesn't understand the 'objectformat' extension, e.g.:
    
      https://travis-ci.org/github/git/git/jobs/710159470#L3267
    
    This is not an issue in Travis CI's macOS jobs or on Azure Pipelines,
    because they don't use 'pyenv'.
    
    However, perhaps removing 'pyenv' is not the best solution here.
    
    We set PYTHON_PATH in 'ci/lib.sh', which is sourced at the beginning
    of (almost) all of our CI scripts.  Consequently, in these jobs we
    first run 'ci/install-dependencies.sh', which sources 'ci/lib.sh',
    assigns PYTHON_PATH=/opt/pyenv/shims/python3 (which is never used),
    and removes 'pyenv', and then run 'ci/run-build-and-test.sh', which
    sources 'ci/lib.sh' and assigns PYTHON_PATH=/usr/bin/python3 (which is
    then used in the build process to set 'pit p4's shebang line).  Not
    really nice, is it.
    
    Alternatively, we could avoid the PATH lookup and thus the bogus
    'pyenv' by explicitly using '/usr/bin/python{2,3}'.  The Linux images
    in both Travis CI and Azure Pipelines are standard Ubuntu images, so I
    think we can safely rely on these Python paths.

 ci/install-dependencies.sh | 8 ++++++++
 1 file changed, 8 insertions(+)

On Tue, Jul 21, 2020 at 12:12 PM SZEDER Gábor <szeder.dev@gmail.com> wrote:

s/prevet/prevent/

I wonder if this comment should give more precise detail about exactly how it "messes up" PATH.

SZEDER Gábor <szeder.dev@gmail.com> writes:

That sounds quite sensible, actually. The CI environment being "special" in the sense that we have certain control over it makes this rather straight-forward.

In our test suite, when 'git p4' invokes a Git command as a subprocesses, then it should run the 'git' binary we are testing. Unfortunately, this is not the case in the 'linux-clang' and 'linux-gcc' jobs on Travis CI, where 'git p4' runs the system '/usr/bin/git' instead.

Travis CI's default Linux image includes 'pyenv', and all Python invocations that involve PATH lookup go through 'pyenv', e.g. our 'PYTHON_PATH=$(which python3)' sets '/opt/pyenv/shims/python3' as PYTHON_PATH, which in turn will invoke '/usr/bin/python3'. Alas, the 'pyenv' version included in this image is buggy, and prepends the directory containing the Python binary to PATH even if that is a system directory already in PATH near the end. Consequently, 'git p4' in those jobs ends up with its PATH starting with '/usr/bin', and then runs '/usr/bin/git'.

So use the absolute paths '/usr/bin/python{2,3}' explicitly when setting PYTHON_PATH in those Linux jobs to avoid the PATH lookup and thus the bogus 'pyenv' from interfering with our 'git p4' tests. Don't bother with special-casing Travis CI: while this issue doesn't affect the corresponding Linux jobs on GitHub Actions, both CI systems use Ubuntu LTS-based images, so we can safely rely on these Python paths.

Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
---

Junio, I see that you picked up the first/RFC version and applied it on top of v2.26.2. This patch won't work on v2.26.2, because its 'git p4' is not compatible with python3 yet.

 ci/lib.sh | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

SZEDER Gábor <szeder.dev@gmail.com> writes:

Good. This does not need to touch pyenv but take advantage of the fact that we know where Python 2 and 3 are. Nice.

Thanks. Which means that we do not need to touch maint track (not that we'd be merging the SHA-256 topic down to the maint track anyway).

Will queue.

On Thu, Jul 23, 2020 at 03:31:56PM -0700, Junio C Hamano wrote:

Yeah, that system Git is v2.21.x, as far as I remember, but apparently 'git p4' doesn't use any shiny new features since then, because all its test succeeded even with that old version.

It might be worth applying the final SHA-256 topic on top of this, though, so Travis CI builds of that branch on its own can succeed.

On 2020-07-21 at 16:12:25, SZEDER Gábor wrote:

Ouch. So we're testing git-p4, but not the git binary underlying it. Fixing this definitely seems like a good idea.