Custom Dockerfile Devcontainer Example

This example demonstrates using a custom Dockerfile with Atmos devcontainers. The Dockerfile extends the Geodesic base image and pre-installs Atmos.

Files

• atmos.yaml - Configuration showing how to use devcontainers with Dockerfile builds
• devcontainer.json - Devcontainer configuration using build instead of image
• Dockerfile - Custom Dockerfile extending Geodesic with Atmos pre-installed

Configuration

The devcontainer.json uses the build section to specify how to build the container image:

{
  "build": {
    "dockerfile": "Dockerfile",
    "context": ".",
    "args": {
      "GEODESIC_VERSION": "latest"
    }
  }
}

Build Arguments

The Dockerfile accepts build arguments for customization:

• GEODESIC_VERSION - Version of Geodesic to use (default: latest)

Usage

Quick Start

# From this directory, build and launch the devcontainer
cd examples/devcontainer-build
atmos devcontainer shell geodesic

# Force rebuild (when Dockerfile changes)
atmos devcontainer shell geodesic --replace

Using with atmos.yaml

The included atmos.yaml shows two approaches:

Option 1: Include devcontainer.json file

devcontainer:
  geodesic:
    spec:
      - !include devcontainer.json

Option 2: Define build configuration inline

devcontainer:
  geodesic-inline:
    spec:
      name: "Geodesic with Atmos"
      build:
        dockerfile: "Dockerfile"
        context: "."
        args:
          GEODESIC_VERSION: "latest"
          ATMOS_VERSION: "latest"
      workspaceFolder: "/workspace"
      workspaceMount: "type=bind,source=${localWorkspaceFolder},target=/workspace"
      containerEnv:
        ATMOS_BASE_PATH: "/workspace"
      remoteUser: "root"

Launch the devcontainer

# Build and launch
atmos devcontainer shell geodesic

# Force rebuild (when Dockerfile changes)
atmos devcontainer shell geodesic --replace

# List available devcontainers
atmos devcontainer list

What's Included

Inside the container, you'll have:

• Geodesic - Full Geodesic shell environment
• Atmos - Pre-installed Atmos CLI (atmos version)
• Workspace - Your project mounted at /workspace
• Environment - ATMOS_BASE_PATH=/workspace pre-configured

Customization

You can customize the Dockerfile to:

• Install additional tools (terraform, kubectl, helm, etc.)
• Add custom scripts or configuration
• Set environment variables
• Install VS Code extensions
• Configure shell aliases

Example additions:

# Install additional tools
RUN apk add --no-cache \
    terraform \
    kubectl \
    helm

# Add custom shell configuration
COPY .bashrc /root/.bashrc

# Install VS Code extensions (if using VS Code)
RUN code-server --install-extension hashicorp.terraform

Build Process

When you run atmos devcontainer shell, Atmos will:

1. Build the image (if not already built or if changed)

   • Uses docker build or podman build
   • Passes build args from devcontainer.json
   • Tags the image as atmos-devcontainer-geodesic

2. Create the container from the built image

3. Start and attach to the container

Rebuilding

To rebuild the image after changing the Dockerfile:

# Rebuild the devcontainer
atmos devcontainer rebuild geodesic

# Or use --replace flag with shell command
atmos devcontainer shell geodesic --replace

Benefits of Custom Dockerfiles

• Reproducibility - Everyone gets the same tools and versions
• Speed - Tools are pre-installed, no setup time
• Consistency - Same environment across team members
• Customization - Add project-specific tools and configuration
• Version control - Dockerfile is versioned with your project