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Run OpenCode in a Container ​

This page describes action: harness.run with provider: opencode inside a Docker or Podman container.

The examples use an image named dagu-opencode-runner:local. Build that image before running the DAG examples.

Requirements ​

  • The Dagu process can reach Docker or Podman.
  • The runner image contains opencode in PATH.
  • The container can reach the network for real opencode run requests.
  • OpenCode has provider credentials inside the container.

OpenCode's current installation, CLI, and credential behavior is documented by OpenCode:

Build the Runner Image ​

OpenCode can be installed as a global npm package named opencode-ai.

dockerfile
FROM node:22-bookworm-slim

RUN apt-get update \
  && apt-get install -y --no-install-recommends \
    ca-certificates \
    git \
    bash \
  && rm -rf /var/lib/apt/lists/*

RUN npm install -g opencode-ai
RUN opencode --version

WORKDIR /workspace
ENTRYPOINT []
CMD ["bash"]

Build and verify the image:

sh
docker build -t dagu-opencode-runner:local -f Dockerfile .
docker run --rm dagu-opencode-runner:local opencode --version

Verify the Image Through Dagu ​

This DAG starts a container and calls opencode --version. It does not make a model request.

yaml
type: graph

harnesses:
  shell:
    binary: sh
    prefix_args:
      - -c
    prompt_mode: arg

steps:
  - id: opencode_version
    action: harness.run
    container:
      image: dagu-opencode-runner:local
      pull_policy: never
    with:
      provider: shell
      prompt: |
        set -eu
        opencode --version
        command -v opencode

The command must print the OpenCode version and the path to the opencode binary.

Step-Level Container ​

Use a step-level container when only the OpenCode step should receive the workspace mount and provider credentials.

yaml
steps:
  - id: review
    action: harness.run
    container:
      image: dagu-opencode-runner:local
      pull_policy: never
      working_dir: /workspace
      volumes:
        - .:/workspace:ro
        - ${HOME}/.local/share/opencode:/root/.local/share/opencode:ro
    with:
      provider: opencode
      prompt: |
        Review this repository and summarize the highest-risk issues.
      model: anthropic/claude-sonnet-4-5

provider: opencode invokes opencode run "<prompt>". OpenCode documents that opencode auth login stores provider credentials in ~/.local/share/opencode/auth.json. The mount above exposes the host OpenCode credentials to the root user inside this example image.

If the image runs as a non-root user, mount the credentials directory at that user's ~/.local/share/opencode path instead.

Root-Level Container ​

Use root-level container: when ordinary command steps and OpenCode should share the same container filesystem and toolchain.

yaml
type: graph

container:
  image: dagu-opencode-runner:local
  pull_policy: never
  working_dir: /workspace
  volumes:
    - .:/workspace
    - ${HOME}/.local/share/opencode:/root/.local/share/opencode:ro

harnesses:
  shell:
    binary: sh
    prefix_args:
      - -c
    prompt_mode: arg

steps:
  - id: test
    run: npm test

  - id: opencode_tools
    action: harness.run
    with:
      provider: shell
      prompt: |
        set -eu
        opencode --version
        command -v opencode

This example verifies the shared container path without making a model request. For a real OpenCode step, replace the shell provider with provider: opencode.

The mounted OpenCode credentials are readable by every inherited step inside the shared container.

Authentication ​

OpenCode can load provider credentials from:

  • ~/.local/share/opencode/auth.json
  • environment variables used by the selected provider
  • a project .env file

Use OpenCode's provider documentation for the exact variable names required by the selected model provider.

Mounted OpenCode credentials:

yaml
volumes:
  - ${HOME}/.local/share/opencode:/root/.local/share/opencode:ro

Provider environment variables:

yaml
env:
  - ANTHROPIC_API_KEY=${ANTHROPIC_API_KEY}

The ANTHROPIC_API_KEY example is only for an OpenCode configuration that uses Anthropic as the model provider. Use the variable required by the provider in the OpenCode model name.

In container.volumes, ${HOME} is expanded on the Dagu worker. /root/.local/share/opencode is the literal path inside the container.

Released under the MIT License.

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