How to Customize the Base Ubuntu Version (e.g., noble, focal) in LabNow AI Builds

To customize the Ubuntu base version in LabNow AI builds, override the BASE_IMG build argument at build time, which defaults to ubuntu:noble in the docker_atom/Dockerfile.

The LabNow AI foundation repository (labnow-ai/lab-foundation) provides containerized environments built on Ubuntu Linux. When you need to customize the base Ubuntu version—whether switching from noble to focal, jammy, or another LTS release—the project exposes a configurable build argument that controls the entire image stack without requiring permanent Dockerfile modifications.

Understanding the Base Image Configuration

The root of the image hierarchy is defined in docker_atom/Dockerfile, where the base Ubuntu version is parameterized through the BASE_IMG build argument. According to the source code, this argument defaults to the latest LTS release:

# latest # default value: Latest LTS version of Ubuntu (https://hub.docker.com/_/ubuntu)

ARG BASE_IMG="ubuntu:noble"
FROM ${BASE_IMG}

This design pattern allows the entire LabNow AI stack to inherit from a single, configurable source image.

Local Build Customization

For local development or testing, you can override the default noble base by passing a specific Ubuntu tag during the Docker build process.

Overriding BASE_IMG with Docker Build

Use the --build-arg flag to inject your preferred Ubuntu version without editing source files:

# Switch to Ubuntu focal for local testing

docker build \
    --build-arg BASE_IMG=ubuntu:focal \
    -t labnow/atom:focal-custom \
    ./docker_atom

CI/CD and Automated Builds

The GitHub Actions workflow at .github/workflows/build-docker.yml supports dynamic base image selection through workflow inputs, enabling automated builds across different Ubuntu versions.

Configuring GitHub Actions Workflow Dispatch

The workflow accepts a base_image input parameter that forwards to the BASE_IMG build argument:

on:
  workflow_dispatch:
    inputs:
      base_image:
        description: 'Ubuntu base image (e.g. ubuntu:focal)'
        default: 'ubuntu:noble'
        required: false

When executed, the workflow passes this value to the Docker build command:

docker build \
  --build-arg BASE_IMG=${{ inputs.base_image || 'ubuntu:noble' }} \
  -t ${{ env.IMAGE_NAME }} .

This configuration supports matrix builds and compatibility testing across multiple Ubuntu LTS releases.

Propagation Across the Image Stack

The docker_atom image serves as the parent for downstream images including docker_core and docker_base. These child images reference the base through the pattern FROM ${BASE_NAMESPACE:+$BASE_NAMESPACE/}${BASE_IMG}, ensuring that modifying the BASE_IMG argument in the parent automatically propagates Ubuntu version changes throughout the entire LabNow AI container hierarchy.

Summary

• The BASE_IMG build argument in docker_atom/Dockerfile controls the Ubuntu base version, defaulting to ubuntu:noble.
• Override locally using docker build --build-arg BASE_IMG=ubuntu:focal for immediate testing without code changes.
• The GitHub Actions workflow at .github/workflows/build-docker.yml supports version selection via workflow_dispatch inputs.
• Child images inherit the base configuration automatically, maintaining consistency across the labnow-ai/lab-foundation stack.

Frequently Asked Questions

What is the default Ubuntu version in LabNow AI builds?

The default Ubuntu base version is ubuntu:noble (24.04 LTS), defined as the default value for the BASE_IMG argument in docker_atom/Dockerfile. You can verify this on lines 3-5 of the Dockerfile where ARG BASE_IMG="ubuntu:noble" is declared.

Can I use any Ubuntu tag with the BASE_IMG argument?

Yes, any valid Ubuntu Docker Hub tag will work, including specific point releases like ubuntu:22.04 or ubuntu:jammy. The build argument accepts any string that resolves to a valid base image reference, allowing you to pin to specific LTS versions or use rolling tags.

Do I need to modify multiple Dockerfiles to change the base version?

No, you only need to override the BASE_IMG argument when building the docker_atom image. Downstream images in docker_core, docker_base, and other directories automatically inherit this base through the ${BASE_IMG} reference pattern, ensuring single-point configuration for the entire stack.

How do I permanently change the default Ubuntu version?

To permanently change the default, edit line 4 of docker_atom/Dockerfile to modify the ARG BASE_IMG default value from "ubuntu:noble" to your preferred tag (e.g., "ubuntu:focal"), then commit and push the change. All subsequent builds will use the new default unless explicitly overridden at build time.

{
  "mcpServers": {
    "instagit": {
      "command": "npx",
      "args": ["-y", "instagit@latest"]
    }
  }
}