Cscs CI

What CSCS CI is

CSCS use GitLab CI through a middleware (cicd-ext-mw.cscs.ch). GitHub repositories are registered with CSCS; a webhook pushes a mirror to GitLab and pipelines run there. GitHub check-run details_urls point to the CSCS viewer, not to GitLab directly. Status is posted back to GitHub as check runs/statuses.

CI status names on GitHub follow the format cscs/<pipeline_name> (e.g. cscs/default, cscs/distributed). This is how CSCS pipelines appear in gh pr checks output and the GitHub PR UI.

CI may trigger automatically on push or PR events depending on how the project is configured (CI-enabled branches and trusted users, set on the CSCS CI setup page). This is project-specific. If it is not explicitly stated for the current project, ask the user before assuming CI will run or won't run on its own.

cscs-ci run is NOT a shell command

This is a PR comment posted on GitHub to trigger a specific pipeline. Do not try to run it in a shell.

Syntax:

• cscs-ci run: triggers the single (default) pipeline
• cscs-ci run PIPELINE_NAME: triggers a named pipeline
• cscs-ci run PIPELINE_1,PIPELINE_2: multiple pipelines, comma-separated
• cscs-ci run PIPELINE;VAR=value;VAR2=value2: injects variables as environment variables into the pipeline

Rules:

• Disallowed characters in pipeline name, variable name, and variable value: ,;= (they serve as separators between components)
• Only the first line of the comment is evaluated; lines 2+ are free context
• Only works if the commenting user is in the pipeline's trusted users list
• The target branch is ignored; you can trigger a pipeline even if the target branch is not in the pipeline's CI-enabled branches

Fetching logs

The &type=gitlab gotcha

GitHub check-run details_urls for CSCS CI end in &type=gitlab. This forces an OAuth login and cannot be fetched by text-mode tools. Always strip &type=gitlab from the URL first.

CSCS viewer URLs

Pipeline result page (without &type=gitlab):

https://cicd-ext-mw.cscs.ch/ci/pipeline/results/{namespace}/{project_id}/{pipeline_id}?iid={pr_id}

This static HTML page contains the job list. Per-job result pages:

https://cicd-ext-mw.cscs.ch/ci/job/result/{namespace}/{project_id}/{job_id}?iid={pr_id}

GitLab raw traces

The GitLab API endpoints /jobs/{id} and /jobs/{id}/trace require authentication and return 401 even for public projects. Use the raw trace endpoint instead. It is publicly accessible:

https://gitlab.com/{encoded-path}/-/jobs/{id}/raw

Encode the project path: replace / with %2F. Do not conclude auth is required before trying /raw.

Download procedure

CI logs can be large (100k+ lines). Never fetch full logs into context. Always download to a temp file and grep:

LOGFILE=$(mktemp /tmp/cscs-log.XXXXXX.log)
curl -sL "<stripped-url>" -o "$LOGFILE"
wc -l "$LOGFILE"

If the fetched page is empty (traces are sometimes JavaScript-loaded), ask the user to manually export the log from the CSCS viewer and provide the file path.

CSCS CI-specific pitfalls

These differ from standard GitLab CI:

• CI_PIPELINE_SOURCE is always trigger, never push or merge_request or any other value from GitLab's predefined variables.
• rules: changes will not work; pipelines are always triggered via the middleware, never as branch or merge request pipelines.
• only/except and rules can restrict jobs to specific branches, but a pipeline is only triggered if it matches the rules defined on the repository's CI setup page (not just the YAML).
• Trigger jobs for child pipelines must use trigger: forward: pipeline_variables: true to propagate parent variables. Without this, child pipelines will not receive variables like CSCS_CI_MW_URL.

Key CI variables

Runner types

Runners are referenced by including the CSCS config:

include:
  - remote: 'https://gitlab.com/cscs-ci/recipes/-/raw/master/templates/v2/.ci-ext.yml'

Runner naming: .<type>-<cluster>-<microarchitecture> (e.g. .container-runner-daint-gh200). The cluster and microarchitecture determine which hardware the job runs on.

Links

• Clusters: https://docs.cscs.ch/clusters/: available clusters on Alps with hardware descriptions (Daint GH200, Eiger zen2, Clariden GH200, Santis GH200, Bristen A100, etc.).
• CI/CD docs: https://docs.cscs.ch/services/cicd/: full setup guide, runner reference with all variables and example jobs, best practices, and common pitfalls.