Pre-build Dev Container

Pre-build Dev Container builds your .devcontainer/Dockerfile, pushes it to a container registry (GHCR by default), and optionally generates a prebuild/devcontainer.json so environments load instantly.

Quick Start

Copy this to .github/workflows/prebuild-devcontainer.yml:

name: 'Pre-build Dev Container'

on:
  push:
    tags:
      - 'v*'
      - '*-v*'
  workflow_dispatch:
    inputs:
      tag:
        description: 'Tag to build (e.g. v1.2.3 or main-v1.2.3)'
        required: true

jobs:
  build:
    runs-on: ubuntu-latest
    concurrency:
      group: ${{ github.workflow }}-${{ github.ref }}
      cancel-in-progress: true
    permissions:
      contents: write
      packages: write
    steps:
      - uses: actions/checkout@v4
      - uses: MiguelRodo/actions/prebuild-devcontainer@v2
        with:
          github_token: ${{ secrets.GITHUB_TOKEN }}
          tag: ${{ github.event.inputs.tag }}

Inputs

Input	Description	Required	Default
github_token	Token for logging into the container registry and pushing commits.	Yes	—
no_cache	Disable Docker cache during build (true/false).	No	false
create_prebuild_json	Generate and commit a prebuild/devcontainer.json (true/false).	No	true
devcontainer_path	Path to the .devcontainer directory, relative to the repo root.	No	.devcontainer
image_name	Full image name without tag (e.g. ghcr.io/myorg/myimage). Defaults to {registry}/{repo}-{branch}.	No	{registry}/{repo}-{branch}
tag	Git tag used as the primary container image tag. Auto-detected from GITHUB_REF on tag push; falls back to latest.	No	""
registry	Container registry URL.	No	ghcr.io
registry_username	Username for registry login.	No	Repository owner

SemVer Alias Tags

When the tag matches a semantic versioning pattern, the action automatically creates additional alias tags:

Tag format	Primary tag	Alias tags
vX.Y.Z (e.g. v1.2.3)	v1.2.3	v1.2, v1
{prefix}-vX.Y.Z (e.g. main-v1.2.3)	main-v1.2.3	main-v1.2, main-v1
Any other format (e.g. latest)	as-is	(none)

Examples

Custom image name

- uses: MiguelRodo/actions/prebuild-devcontainer@v2
  with:
    github_token: ${{ secrets.GITHUB_TOKEN }}
    image_name: 'ghcr.io/myorg/my-devcontainer'

Non-default devcontainer path

- uses: MiguelRodo/actions/prebuild-devcontainer@v2
  with:
    github_token: ${{ secrets.GITHUB_TOKEN }}
    devcontainer_path: 'src/.devcontainer'

Non-GitHub container registry

When using a custom image_name, the registry input is used only for login — it is not prepended to the image name automatically.

- uses: MiguelRodo/actions/prebuild-devcontainer@v2
  with:
    github_token: ${{ secrets.REGISTRY_TOKEN }}
    registry: 'registry.example.com'
    registry_username: 'my-username'
    image_name: 'registry.example.com/myorg/my-devcontainer'