Harness Container Credentials

A containerized harness.run step receives only the credentials made available to its container. Dagu does not copy host login state into a container unless the DAG mounts the files or passes the environment variables required by the provider.

Environment Variables

Use container.env for API keys and provider tokens:

env:
  - PROVIDER_API_KEY: ${PROVIDER_API_KEY}

harnesses:
  your_provider:
    binary: your-provider
    prompt_mode: arg

steps:
  - id: review
    action: harness.run
    container:
      image: dagu-provider-runner:local
      pull_policy: never
      working_dir: /workspace
      volumes:
        - .:/workspace:ro
      env:
        - PROVIDER_API_KEY=${env.PROVIDER_API_KEY}
    with:
      provider: your_provider
      prompt: |
        Review this repository.

PROVIDER_API_KEY=${env.PROVIDER_API_KEY} is evaluated by Dagu before the container starts. The value must be available to the Dagu process that executes the run.

To load keys from a dotenv file instead, set container.env_file. The file must exist on the host that runs the step. See Environment Files.

Mounted Credential Directories

Some CLIs store login state in files. Mount the directory the CLI reads, then set the provider's home or config variable if that CLI supports one.

env:
  - PROVIDER_API_KEY: ${PROVIDER_API_KEY}

harnesses:
  your_provider:
    binary: your-provider
    prompt_mode: arg

steps:
  - id: review
    action: harness.run
    container:
      image: dagu-provider-runner:local
      pull_policy: never
      volumes:
        - ${HOME}/.provider:/provider-home
      env:
        - PROVIDER_HOME=/provider-home
    with:
      provider: your_provider
      prompt: |
        Review this repository.

In container.volumes, Dagu expands $VAR and ${VAR} only in the host-side source. In the example above, ${HOME}/.provider is resolved on the Dagu worker. /provider-home is passed to the container runtime as a literal container path.

Step-Level Visibility

Use a step-level container: when one harness attempt should receive a credential:

harnesses:
  your_provider:
    binary: your-provider
    prompt_mode: arg

steps:
  - id: review
    action: harness.run
    container:
      image: dagu-provider-runner:local
      pull_policy: never
      env:
        - PROVIDER_API_KEY=${env.PROVIDER_API_KEY}
    with:
      provider: your_provider
      prompt: |
        Review this repository.

Only that step receives PROVIDER_API_KEY through this container definition.

Root-Level Visibility

Use root-level container: only when every inherited step in the shared container may receive the same credential:

env:
  - PROVIDER_API_KEY: ${PROVIDER_API_KEY}

container:
  image: dagu-provider-runner:local
  pull_policy: never
  env:
    - PROVIDER_API_KEY=${env.PROVIDER_API_KEY}

harnesses:
  your_provider:
    binary: your-provider
    prompt_mode: arg

steps:
  - id: test
    run: npm test

  - id: review
    action: harness.run
    with:
      provider: your_provider
      prompt: |
        Review this repository.

Both test and review run inside the shared container and can read PROVIDER_API_KEY.

Provider-Specific Credential Shapes

• Codex
• Claude Code
• OpenCode