Refactor Dockerfile to use build argument for Ubuntu version and update README.md with detailed features and installation instructions

Dockerfile

@@ -1,7 +1,9 @@
-FROM ubuntu:24.04
+ARG UBUNTU_VERSION=24.04
+
+FROM ubuntu:${UBUNTU_VERSION}
 
 LABEL maintainer="thommyho"
-LABEL description="An Ubuntu 24.04 image with essential tools for git development and CI/CD pipelines."
+LABEL description="An Ubuntu image with essential tools for git development and CI/CD pipelines."
 
 ENV NVM_DIR=/usr/local/nvm \
     NODE_VERSION=24.11.1 \

README.md

@@ -1,11 +1,59 @@
-# Building the Docker Image
+# Docker Runner Gitea
 
-This command builds a Docker image for a Gitea runner environment with Node.js 24 on Ubuntu Noble.
+An Ubuntu-based Docker image with essential tools for Gitea CI/CD pipelines and development.
 
-**Usage:**
+## Features
 
-## Docker Runner Gitea
+- **Base OS:** Ubuntu 24.04 (Noble)
+- **Node.js:** v24.11.1 (managed via NVM)
+- **Build Tools:** Essential development utilities including git, curl, wget, build-essential
+- **Package Managers:** pip (Python 3), conan (C/C++ package manager)
+- **Additional Tools:** Python 3, ca-certificates
+
+## Prerequisites
+
+- Docker installed on your system
+- At least 2GB of free disk space
+- Internet connection (for downloading base image and dependencies)
+
+## Installation
+
+### Building the Image
+
+Clone or download this repository, then build the Docker image:
 
 ```sh
 docker build -t docker-runner-gitea:noble-node-24 .
 ```
+
+To specify a different Ubuntu version:
+
+```sh
+docker build --build-arg UBUNTU_VERSION=22.04 -t docker-runner-gitea:jammy-node-24 .
+```
+
+### Running a Container
+
+```sh
+docker run -it docker-runner-gitea:noble-node-24 /bin/bash
+```
+
+### Using as a Gitea Runner
+
+Configure this image in your Gitea instance for CI/CD pipelines by specifying the image name in your runner configuration.
+
+## Installed Packages
+
+| Package         | Version | Purpose               |
+|-----------------|---------|-----------------------|
+| Node.js         | 24.11.1 | JavaScript runtime    |
+| Python          | 3.x     | Scripting and tools   |
+| Conan           | Latest  | C/C++ package manager |
+| Git             | Latest  | Version control       |
+| build-essential | Latest  | Compilation tools     |
+
+Notes
+
+- The image uses NVM (Node Version Manager) for flexible Node.js version management
+- Pip packages are installed with --break-system-packages flag for Python 3
+- All apt cache is cleaned to minimize image size