Add graph exports to job artifacts when Gemnasium fails

Release notes

Problem to solve

As a user of Dependency Scanning, I want the dependency graph exports created by gemnasium-maven and gemnasium-python to be uploaded as CI job artifacts when the scanning job fails, so that I can investigate and report the issue.

Also, I want these graph exports to be available when running Dependency Scanning in debug mode, so that I can investigate unexpected results in GitLab UI (Dependency List, Vulnerability Report, etc.) or in the Dependency Scanning report.

As developer of Gemnasium, or as a support engineering at GitLab, I also want these graph exports to be easily accessible to users experiencing problems with gemnasium-maven and gemnasium-python, so that I can directly help them without asking them to tweak their CI config file and trigger a new pipeline.

Intended users

User experience goal

As a user, I notice that a Dependency Scanning job has failed in my project pipeline. I then Browse the artifacts of the failing job, and download a graph export generated by gemnasium-maven or gemnasium-python. I can attach this graph export to a bug issue I create on GitLab, or to a ZenDesk ticket.

Proposal

Change the job definitions of the Gemnasium CI jobs so that the generated graph exports are uploaded when the job fails ~~OR when SECURE_LOG_LEVEL is set to debug~~. For instance, change the job definition of gemnasium-maven so that it uploads the DOT exports it creates using the dependencyDot task of the sbt-dependency-graph plugin.

The change would be limited to gemnasium-maven-dependency_scanning and gemnasium-python-dependency_scanning since these are the only Dependency Scanning jobs that generate graph exports. See https://gitlab.com/gitlab-org/gitlab/blob/master/lib/gitlab/ci/templates/Security/Dependency-Scanning.gitlab-ci.yml#L68

See https://docs.gitlab.com/ee/ci/yaml/#artifactswhen

Further details

Implementation plan

Update Dependency Scanning CI template; see proposal and MR
Change existing job integration tests to make them compatible with these changes; see Use GraphQL API to fetch reports in job integra... (#343871 - closed)
Create dedicated job integration tests; see Availability & Testing and Testing graph exports to job artifacts when Gem... (#350896)
Update user documentation; see documentation

Permissions and Security

No change

Documentation

To be documented in the troubleshooting section of Dependency Scanning user documentation under a new subsection titled Gemnasium Dependency Scanning job fails. Make sure you cover the following items:

Dependency graph exports might be exposed as jobs artifacts to investigate the issue.
These can be used to investigate a bug where the analyzer can't parse these graph exports.
They might not be available, depending on the job and on the bug.

Availability & Testing

To be tested in 2-stage pipelines:

The test stage runs the scanning job. The job script is altered to make it fail with a specific exit code, and the job is allowed to fail on that exit code, so the pipeline isn't stopped. The artifacts param of the job isn't altered.
The qa stage runs a job that compares the CI artifacts/graph exports to what's expected. The Dependency Scanning report isn't checked.

The QA CI template can't be used for this: the artifacts param shouldn't be altered because we wouldn't test the upload of the CI artifacts–this feature.

Scenarios to be covered:

Graph exports are uploaded as CI artifacts when the /analyzer command returns a non-zero exit code.
~~Graph exports are uploaded as CI artifacts when the command returns a zero exit code and SECURE_LOG_LEVEL is debug.~~
~~Graph exports are NOT uploaded when the command returns a zero exit code and SECURE_LOG_LEVEL is info (or not set).~~

These don't check the generated security report, so they can't be implemented using the existing Dependency Scanning QA CI template. Instead, we need a new pipeline with a CI job that checks the CI artifacts of the scanning job.

This should be tested in complex/composite test projects that generate multiple graph exports:

Available Tier

Ultimate/Gold

What does success look like, and how can we measure that?

Users can easily access the graph exports generated by gemnasium-maven and gemnasium-python scanning jobs when these jobs fail or when they want to investigate unexpected results.