Automation with Hashicorp Packer #8: File Provisioner

Introduction

This tutorial will guide you through the process of using File Provisioners in Hashicorp Packer. File Provisioners are essential for copying files onto your images, enabling you to set up prebuilt content, such as HTML files, directly onto your server images. Understanding this feature enhances your ability to automate image creation across various platforms like AWS, Azure, and more.

Step 1: Set Up Your Packer Template

Before using File Provisioners, you need a basic Packer template. This template defines the configuration for the image you want to create.

1. Create a Packer Template File

   • Use JSON or HCL format for your template.
   • Include the necessary builders and provisioners.

2. Example Template Structure

   {
     "builders": [
       {
         "type": "amazon-ebs",
         "access_key": "YOUR_AWS_ACCESS_KEY",
         "secret_key": "YOUR_AWS_SECRET_KEY",
         "region": "us-east-1",
         "source_ami": "ami-12345678",
         "instance_type": "t2.micro",
         "ssh_username": "ec2-user",
         "ami_name": "my-custom-image {{timestamp}}"
       }
     ],
     "provisioners": []
   }
   

Step 2: Add File Provisioner to Your Template

Now that you have a basic template, it’s time to add a File Provisioner to copy your files.

1. Define the File Provisioner

   • Add a new entry under the "provisioners" section in your template.

2. Example File Provisioner Configuration

   {
     "type": "file",
     "source": "./path/to/your/file.html",
     "destination": "/tmp/file.html"
   }
   

3. Complete Template Example

   {
     "builders": [
       {
         "type": "amazon-ebs",
         "access_key": "YOUR_AWS_ACCESS_KEY",
         "secret_key": "YOUR_AWS_SECRET_KEY",
         "region": "us-east-1",
         "source_ami": "ami-12345678",
         "instance_type": "t2.micro",
         "ssh_username": "ec2-user",
         "ami_name": "my-custom-image {{timestamp}}"
       }
     ],
     "provisioners": [
       {
         "type": "file",
         "source": "./path/to/your/file.html",
         "destination": "/tmp/file.html"
       }
     ]
   }
   

Step 3: Build the Image with Packer

After configuring your Packer template with the File Provisioner, you can build your image.

1. Run the Packer Build Command

   • Open your terminal and navigate to the directory containing your template file.
   • Execute the following command:

   packer build your-template-file.json
   

2. Monitor the Build Process

   • Watch the terminal output for any errors or messages indicating the progress of the image creation.

Step 4: Verify the Copied File in the Image

After the build process completes, it’s important to verify that your file was copied correctly.

1. Access the Created Image

   • Use the appropriate tools or services (like AWS Console) to access the created image.

2. SSH into the Instance

   • Launch an instance from your created image.
   • Use the SSH command to log in:

   ssh -i "your-key.pem" ec2-user@your-instance-ip
   

3. Check the File Location

   • Run the following command to verify the file:

   ls /tmp/file.html
   

Conclusion

In this tutorial, you learned how to utilize File Provisioners in Hashicorp Packer to copy files onto images. By setting up a Packer template, adding a File Provisioner, and building your image, you can efficiently automate the process of preparing customized images. Next steps may include experimenting with different file types or exploring other provisioners to extend your automation capabilities further.