Pack CLI

Build Apps with Cloud Native Buildpacks

The Pack CLI is a command-line interface tool designed for building applications using Cloud Native Buildpacks. It simplifies the process of creating container images from your source code without needing to write Dockerfiles. This tool is essential for developers looking to adopt modern, cloud-native practices for application packaging and deployment.

Key Pack CLI Commands

Here are some fundamental commands to get you started with the Pack CLI:

Suggesting Builders

Before building, it's often useful to see which builders are available and recommended for your project. The pack builder suggest command helps you discover suitable builders.

# List recommended builders
pack builder suggest

Building Container Images

The core functionality of the Pack CLI is to build container images. You use the pack build command, specifying the desired image name and the builder to use.

# Use a builder to build an image 
pack build <image-name> --builder <builder-to-use>

Example: Building a Node.js Application

This example demonstrates how to build a simple Node.js web server application into a container image using the Pack CLI. First, create a basic Node.js application file (e.g., app.js):

// app.js
var http = require('http');
http.createServer(function (request, response) {
   response.writeHead(200, {'Content-Type': 'text/plain'});
   response.end('Hello world!');
}).listen(8080);

Now, use the Pack CLI to build the image. We'll use the paketobuildpacks/builder:base builder for this example:

# Build a node app
pack build testbuild --builder paketobuildpacks/builder:base

After the build process completes successfully, you can run the containerized application:

# Run the built image
docker run --rm -p 8080:8080 testbuild

You can then test your application by sending a request to the specified port:

# Test the application
curl http://127.0.0.1:8080

This will output Hello world!, confirming that your application was built and is running correctly within the container.

Benefits of Using Pack CLI and Buildpacks

Cloud Native Buildpacks, powered by tools like the Pack CLI, offer several advantages:

Dockerfile-Free Builds: Automate image creation without manual Dockerfile maintenance.
Security: Build images with up-to-date base layers and dependencies, reducing vulnerability exposure.
Reproducibility: Ensure consistent builds across different environments.
Developer Productivity: Focus on writing code rather than managing container build processes.

Pack CLI - Build Apps with Cloud Native Buildpacks