aspect ci warming - Aspect Build

aspect ci warming fills a runner’s Bazel caches so the runner group’s jobs start warm. It’s the one command a scheduled warming job runs.

aspect ci warming --task:name warming -- //...

In order, it:

Runs the runner health check, the same one every task runs during setup.
Clears the previous Bazel state under the runner’s storage mount (ASPECT_WORKFLOWS_RUNNER_STORAGE_PATH), when that’s set.
Runs bazel build --nobuild against the target patterns, which fetches external repositories and fills the repository and output caches without building anything.
On an Aspect Workflows runner, uploads the populated caches as the warming archive.

Off a Workflows runner, the upload is reported as skipped and the task passes. The whole run reports as one status check, covering both the populate and the archive phases.

Requires Aspect CLI v2026.39.10 or newer. For turning warming on for a runner group, see runner warming.

Options

Flag	Default	What it does
positional targets	`...`	Target patterns to warm. `...` is every rule target in the package at and beneath the current directory. Separate hyphen-led patterns from flags with `--`
`--bazel-flag <flag>`	none	Extra Bazel flag for the warming build. Repeatable. Only needed when a Bazel flag collides with one of the task’s own
`--bazel-startup-flag <flag>`	none	Extra Bazel startup flag. Repeatable. Changing startup flags restarts the Bazel server
`--announce-bazel-rc`	`auto`	Print the resolved `.bazelrc` flags before the build. `auto` prints on CI and stays quiet locally; `true` or `false` forces it
`--announce-bazel-version`	`auto`	Print the detected Bazel version before the build
`--announce-bazel-command`	`auto`	Print the exact `bazel` command line before the build
`--bes-backend <uri>`	none	Extra Build Event Service backend the CLI streams to. Repeatable
`--bes-header <key=value>`	none	Header sent on every CLI-streamed BES stream. Repeatable

Bazel flags the task doesn’t recognize are forwarded to Bazel as they are: after the task name as command options, before it as startup options. See Flag passthrough. There’s no --output-base flag. On a Workflows runner the output base comes from the runner.

aspect ci warming -- //...                         # warm everything
aspect ci warming -- //services/... //libs/...     # warm a subset
aspect ci warming --config=ci -- //...             # a Bazel flag, forwarded

CI example

Run it on a schedule against your main branch, on the runner group you want warm. Per-provider examples are in Migrating from YAML: aspect ci warming.

GitHub Actions

on:
  schedule:
    - cron: '0 12 * * *'
  workflow_dispatch:

permissions:
  contents: read    # actions/checkout
  id-token: write   # artifact uploads and the PR summary comment

jobs:
  warming:
    runs-on: [self-hosted, aspect-workflows, aspect-default]
    steps:
      - uses: actions/checkout@v6
      - uses: aspect-build/setup-aspect@ebca96eb49ef58c00d4226de8bd3a0813507dd87 # v2026.38.3
        with:
          aspect-api-token: ${{ secrets.ASPECT_API_TOKEN }}
      - run: aspect ci warming --task:name warming -- //...

aspect ci runner-health-check: run only the health check.
aspect ci runner-metadata: print the runner’s cache paths and warming status.

​Options

​CI example

​Related

Options

CI example

Related