# This file defines the static Buildkite pipeline which attempts to
# create the dynamic pipeline of all depot targets.
#
# If something fails during the creation of the pipeline, the fallback
# is executed instead which will simply report an error to Gerrit.
---
steps:
  - label: ":llama:"
    key: "pipeline-gen"
    command: |
      set -ue

      if test -n "$${GERRIT_CHANGE_URL-}"; then
        echo "This is a build of [cl/$$GERRIT_CHANGE_ID]($$GERRIT_CHANGE_URL) (at patchset #$$GERRIT_PATCHSET)" | \
          buildkite-agent annotate
      fi

      # Attempt to fetch a target map from a parent commit on canon,
      # except on builds of canon itself.
      [ "${BUILDKITE_BRANCH}" != "refs/heads/canon" ] && \
        ops/pipelines/fetch-parent-targets.sh

      PIPELINE_ARGS=""
      if [[ -f ./parent-target-map.json ]]; then
        PIPELINE_ARGS="--arg parentTargetMap ./parent-target-map.json"
      fi

      nix-build -A ops.pipelines.depot -o pipeline --show-trace $$PIPELINE_ARGS

      # Steps need to be uploaded in reverse order because pipeline
      # upload prepends instead of appending.
      ls pipeline/chunk-*.json | tac | while read chunk; do
        buildkite-agent pipeline upload $$chunk
      done

      buildkite-agent artifact upload pipeline/drvmap.json

  # Wait for all previous steps to complete.
  - wait: null
    continue_on_failure: true

  # Exit with success or failure depending on whether any other steps
  # failed.
  #
  # This information is checked by querying the Buildkite GraphQL API
  # and fetching the count of failed steps.
  #
  # This step must be :duck: (yes, really!) because the post-command
  # hook will inspect this name.
  #
  # Note that this step has requirements for the agent environment, which
  # are enforced in our NixOS configuration:
  #
  #  * curl and jq must be on the $PATH of build agents
  #  * besadii configuration must be readable to the build agents
  - label: ":duck:"
    key: ":duck:"
    command: |
      set -ueo pipefail

      readonly FAILED_JOBS=$(curl 'https://graphql.buildkite.com/v1' \
        --silent \
        -H "Authorization: Bearer $(cat /run/agenix/buildkite-graphql-token)" \
        -d "{\"query\": \"query BuildStatusQuery { build(uuid: \\\"$BUILDKITE_BUILD_ID\\\") { jobs(passed: false) { count } } }\"}" | \
        jq -r '.data.build.jobs.count')

      echo "$$FAILED_JOBS build jobs failed."

      if (( $$FAILED_JOBS > 0 )); then
        exit 1
      fi

  # After duck, on success, create a gcroot if the build branch is
  # canon.
  #
  # We care that this anchors *most* of the depot, in practice it's
  # unimportant if there is a build race and we get +-1 of the
  # targets.
  #
  # Unfortunately this requires a third evaluation of the graph, but
  # since it happens after :duck: it should not affect the timing of
  # status reporting back to Gerrit.
  - label: ":anchor:"
    if: "build.branch == 'refs/heads/canon'"
    command: |
      nix-build -A ci.gcroot --out-link /nix/var/nix/gcroots/depot/canon
    depends_on:
      - step: ":duck:"
        allow_failure: false

  # Create a revision number for the current commit for builds on
  # canon.
  #
  # This writes data back to Gerrit using the Buildkite agent
  # credentials injected through a git credentials helper.
  #
  # Revision numbers are defined as the number of commits in the
  # lineage of HEAD, following only the first parent of merges.
  - label: ":git:"
    if: "build.branch == 'refs/heads/canon'"
    command: |
      git -c 'credential.helper=gerrit-creds' \
        push origin "HEAD:refs/r/$(git rev-list --count --first-parent HEAD)"