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      How to Use the Linode Packer Builder


      Updated by Linode Contributed by Linode

      What is Packer?

      Packer is a HashiCorp maintained open source tool that is used to create machine images. A machine image provides the operating system, applications, application configurations, and data files that a virtual machine instance will run once it’s deployed. Using a single source configuration, you can generate identical machine images. Packer can be used in conjunction with common configuration management tools like Chef, Puppet, or Ansible to install software to your Linode and include those configurations into your image.

      In this guide you will complete the following steps:

      Before You Begin

      1. Ensure you have access to cURL on your computer.

      2. Generate a Linode API v4 access token with permission to read and write Linodes. You can follow the Get an Access Token section of the Getting Started with the Linode API guide if you do not already have one.

        Note

        The example cURL commands in this guide will refer to a $TOKEN environment variable. For example:

        curl -H "Authorization: Bearer $TOKEN" 
            https://api.linode.com/v4/images
        

        To set this variable up in your terminal, run:

        export TOKEN='<your-Linode-APIv4-token>'
        

        If you do not do this, you will need to alter these commands so that your API token is inserted wherever $TOKEN appears.

      3. Create an SSH authentication key-pair if your computer does not already have one. Your SSH public key will be added to your image via an Ansible module.

      4. Install Ansible on your computer and familiarize yourself with basic Ansible concepts (optional). Using the Getting Started With Ansible – Basic Installation and Setup guide, follow the steps in the Install Ansible section.

      The Linode Packer Builder

      In Packer’s ecosystem, builders are responsible for deploying machine instances and generating redeployable images from them. The Linode Packer builder can be used to create a Linode image that can be redeployed to other Linodes. You can share your image template across your team to ensure everyone is using a uniform development and testing environment. This process will help your team maintain an immutable infrastructure within your continuous delivery pipeline.

      The Linode Packer builder works in the following way:

      • You create a template to define the type of image you want Packer to build.
      • Packer uses the template to build the image on a temporary Linode.
      • A snapshot of the built image is taken and stored as a private Linode image.
      • The temporary Linode is deleted.
      • You can then reuse the private Linode image as desired, for example, by using your image to create Linode instances with Terraform.

      Install Packer

      The following instructions will install Packer on Ubuntu 18.04 from a downloaded binary. For more installation methods, including installing on other operating systems or compiling from source, see Packer’s official documentation.

      1. Make a Packer project directory in your home directory and then navigate to it:

        mkdir ~/packer
        cd ~/packer
        
      2. Download the precompiled binary for your system from the Packer website. Example wget commands are listed using the latest version available at time of publishing (1.4.4). You should inspect the links on the download page to see if a newer version is available and update the wget commands to use those URLs instead:

        • The 64-bit Linux .zip archive

          wget https://releases.hashicorp.com/packer/1.4.4/packer_1.4.4_linux_amd64.zip
          
        • The SHA256 checksums file

          wget https://releases.hashicorp.com/packer/1.4.4/packer_1.4.4_SHA256SUMS
          
        • The checksum signature file

          wget https://releases.hashicorp.com/packer/1.4.4/packer_1.4.4_SHA256SUMS.sig
          

      Verify the Download

      1. Import the HashiCorp Security GPG key (listed on the HashiCorp Security page under Secure Communications):

        gpg --recv-keys 51852D87348FFC4C
        

        The output should show that the key was imported:

          
        gpg: keybox '/home/user/.gnupg/pubring.kbx' created
        gpg: key 51852D87348FFC4C: 17 signatures not checked due to missing keys
        gpg: /home/user/.gnupg/trustdb.gpg: trustdb created
        gpg: key 51852D87348FFC4C: public key "HashiCorp Security " imported
        gpg: no ultimately trusted keys found
        gpg: Total number processed: 1
        gpg:               imported: 1
        
        
      2. Verify the checksum file’s GPG signature:

        gpg --verify packer*.sig packer*SHA256SUMS
        

        The output should contain the Good signature from "HashiCorp Security <[email protected]>" confirmation message:

          
        gpg: Signature made Tue 01 Oct 2019 06:30:17 PM UTC
        gpg:                using RSA key 91A6E7F85D05C65630BEF18951852D87348FFC4C
        gpg: Good signature from "HashiCorp Security " [unknown]
        gpg: WARNING: This key is not certified with a trusted signature!
        gpg:          There is no indication that the signature belongs to the owner.
        Primary key fingerprint: 91A6 E7F8 5D05 C656 30BE  F189 5185 2D87 348F FC4C
              
        
      3. Verify that the fingerprint output matches the fingerprint listed in the Secure Communications section of the HashiCorp Security page.

      4. Verify the .zip archive’s checksum:

        sha256sum -c packer*SHA256SUMS 2>&1 | grep OK
        

        The output should show the file’s name as given in the packer*SHA256SUMS file:

          
        packer_1.4.4_linux_amd64.zip: OK
              
        

      Configure the Packer Environment

      1. Unzip packer_*_linux_amd64.zip to your ~/packer directory:

        unzip packer_*_linux_amd64.zip
        

        Note

        If you receive an error that indicates unzip is missing from your system, install the unzip package and try again.

      2. Edit your ~./profile shell configuration file to include the ~/packer directory in your PATH. Then, reload the Bash profile:

        echo 'export PATH="$PATH:$HOME/packer"' >> ~/.profile
        source ~/.profile
        

        Note

        If you use a different shell, your shell configuration may have a different file name.

      3. Verify Packer can run by calling it with no options or arguments:

        packer
        
          
        Usage: packer [--version] [--help]  []
        
        Available commands are:
            build       build image(s) from template
            console     creates a console for testing variable interpolation
            fix         fixes templates from old versions of packer
            inspect     see components of a template
            validate    check that a template is valid
            version     Prints the Packer version
            
        

      Use the Linode Packer Builder

      Now that Packer is installed on your local system, you can create a Packer template. A template is a JSON formatted file that contains the configurations needed to build a machine image.

      In this section you will create a template that uses the Linode Packer builder to create an image using Debian 9 as its base distribution. The template will also configure your system image with a new limited user account, and a public SSH key from your local computer. The additional system configuration will be completed using Packer’s Ansible provisioner and an example Ansible Playbook. A Packer provisioner is a built-in third-party integration that further configures a machine instance during the boot process and prior to taking the machine’s snapshot.

      Note

      The steps in this section will incur charges related to deploying a 1GB Nanode. The Linode will only be deployed for the duration of the time needed to create and snapshot your image and will then be deleted. See our Billing and Payments guide for details about hourly billing.

      Access Linode and Private Images

      The Linode Packer Builder requires a Linode Image ID to deploy a disk from. This guide’s example will use the image linode/debian9, but you can replace it with any other image you prefer. To list the official Linode images and your account’s private images, you can curl the Linode API:

      curl -H "Authorization: Bearer $TOKEN" 
          https://api.linode.com/v4/images
      

      Create Your Template

      Note

      The Packer builder does not manage images. Once it creates an image, it will be stored on your Linode account and can be accessed and used as needed from the Linode Cloud Manager, via Linode’s API v4, or using third-party tools like Terraform. Linode Images are limited to 2GB per Image and 3 Images per account.

      Create a file named example.json with the following content:

      ~/packer/example.json
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      {
        "variables": {
          "my_linode_token": ""
        },
        "builders": [{
          "type": "linode",
          "image": "linode/debian9",
          "linode_token": "{{user `my_linode_token` }}",
          "region": "us-east",
          "instance_type": "g6-nanode-1",
          "instance_label": "temp-linode-packer",
          "image_label": "my-private-packer-image",
          "image_description": "My private packer image",
          "ssh_username": "root"
        }],
        "provisioners": [
          {
            "type": "ansible",
            "playbook_file": "./limited_user_account.yml"
          }
        ]
      }

      If you would rather not use a provisioner in your Packer template, you can use the example file below:

      ~/packer/example.json
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      {
        "variables": {
          "my_linode_token": ""
        },
        "builders": [{
          "type": "linode",
          "image": "linode/debian9",
          "linode_token": "{{user `my_linode_token` }}",
          "region": "us-east",
          "instance_type": "g6-nanode-1",
          "instance_label": "temp-linode-packer",
          "image_label": "my-private-packer-image",
          "image_description": "My private packer image",
          "ssh_username": "root"
        }]
      }

      There are three sections to the Packer template file:

      • variables: This section allows you to further configure your template with command-line variables, environment variables, Vault, or variable files. In the section that follows, you will use a command line variable to pass your Linode account’s API token to the template.
      • builders: The builder section contains the definition for the machine image that will be created. In the example template, you use a single builder –the Linode builder. The builder uses the linode/debian9 image as its base and will assign the image a label of my-private-packer-image. It will deploy a 1GB Nanode, take a snapshot, and create a reusable Linode Image. Refer to Packer’s official documentation for a complete Linode Builder configuration reference.

        Note

        You can use multiple builders in a single template file. This process is known as a parallel build which allows you to create multiple images for multiple platforms from a single template.
      • provisioners: (optional) with a provisioner you can further configure your system by completing common system administration tasks, like adding users, installing and configuring software, and more. The example uses Packer’s built-in Ansible provider and executes the tasks defined in the local limited_user_account.yml playbook. This means your Linode image will also contain anything executed by the playbook on your Nanode. Packer supports several other provisioners, like Chef, Salt, and shell scripts.

      Create your Ansible Playbook (Optional)

      In the previous section you created a Packer template that makes use of an Ansible Playbook to add system configurations to your image. Prior to building your image, you will need to create the referenced limited_user_account.yml Playbook. You will complete those steps in this section. If you chose not to use the Ansible provider, you can skip this section.

      1. The example Ansible Playbook makes use of Ansible’s user module. This module requires that a hashed value be used for its password parameter. Use the mkpasswd utility to generate a hashed password that you will use in the next step.

        mkpasswd --method=sha-512
        

        You will be prompted to enter a plain-text password and the utility will return a hash of the password.

          
        Password:
        $6$aISRzCJH4$nNJ/9ywhnH/raHuVCRu/unE7lX.L9ragpWgvD0rknlkbAw0pkLAwkZqlY.ahjj/AAIKo071LUB0BONl.YMsbb0
                  
        
      2. In your packer directory, create a file with the following content. Ensure you replace the value of the password parameter with your own hashed password:

        ~/packer/limited_user_account.yml
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        ---
        - hosts: all
          remote_user: root
          vars:
            NORMAL_USER_NAME: 'my-user-name'
          tasks:
            - name: "Create a secondary, non-root user"
              user: name={{ NORMAL_USER_NAME }}
                    password='$6$eebkauNy4h$peyyL1MTN7F4JKG44R27TTmbXlloDUsjPir/ATJue2bL0u8FBk0VuUvrpsMq6rSSOCm8VSip0QHN8bDaD/M/k/'
                    shell=/bin/bash
            - name: Add remote authorized key to allow future passwordless logins
              authorized_key: user={{ NORMAL_USER_NAME }} key="{{ lookup('file', '~/.ssh/id_rsa.pub') }}"
            - name: Add normal user to sudoers
              lineinfile: dest=/etc/sudoers
                          regexp="{{ NORMAL_USER_NAME }} ALL"
                          line="{{ NORMAL_USER_NAME }}"
        • This Playbook will created a limited user account named my-user-name. You can replace my-user-name, the value of the variable NORMAL_USER_NAME, with any system username you’d like to create. It will then add a public SSH key stored on your local computer. If the public key you’d like to use is stored in a location other than ~/.ssh/id_rsa.pub, you can update that value. Finally, the Playbook adds the new system user to the sudoers file.

      Create your Linode Image

      You should now have your completed template file and your Ansible Playbook file (optional) and can validate the template and finally, build your image.

      1. Validate the template before building your image. Replace the value of my_linode_token with your own Linode API v4 token.

        packer validate -var 'my_linode_token=myL0ngT0kenStr1ng' example.json
        

        If successful, you will see the following:

          
        Template validated successfully.
              
        

        Note

        To learn how to securely store and use your API v4 token, see the Vault Variables section of Packer’s documentation.
      2. You can now build your final image. Replace the value of my_linode_token with your own Linode API v4 token. This process may take a few minutes to complete.

        packer build -var 'my_linode_token=myL0ngT0kenStr1ng' example.json
        
          
        linode output will be in this color.
        
        ==> linode: Running builder ...
        ==> linode: Creating temporary SSH key for instance...
        ==> linode: Creating Linode...
        ==> linode: Using ssh communicator to connect: 192.0.2.0
        ==> linode: Waiting for SSH to become available...
        ==> linode: Connected to SSH!
        ==> linode: Provisioning with Ansible...
        ==> linode: Executing Ansible: ansible-playbook --extra-vars packer_build_name=linode packer_builder_type=linode -o IdentitiesOnly=yes -i /tmp/packer-provisioner-ansible136766862 /home/user/packer/limited_user_account.yml -e ansible_ssh_private_key_file=/tmp/ansible-key642969643
            linode:
            linode: PLAY [all] *********************************************************************
            linode:
            linode: TASK [Gathering Facts] *********************************************************
            linode: ok: [default]
            linode:
            linode: TASK [Create a secondary, non-root user] ***************************************
            linode: changed: [default]
            linode:
            linode: TASK [Add remote authorized key to allow future passwordless logins] ***********
            linode: changed: [default]
            linode:
            linode: TASK [Add normal user to sudoers] **********************************************
            linode: changed: [default]
            linode:
            linode: PLAY RECAP *********************************************************************
            linode: default                    : ok=4    changed=3    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0
            linode:
        ==> linode: Shutting down Linode...
        ==> linode: Creating image...
        Build 'linode' finished.
        
        ==> Builds finished. The artifacts of successful builds are:
        --> linode: Linode image: my-private-packer-image (private/7550080)
              
        

        The output will provide you with your new private image’s ID. In the example output the image ID is private/7550080. This image is now available on your Linode account to use as you desire. As an example, in the next section you will use this newly created image to deploy a new 1 GB Nanode using Linode’s API v4.

      Deploy a Linode with your New Image

      1. Issue the following curl command to deploy a 1GB Nanode to the us-east data center using your new Image to your Linode account. Ensure you replace private/7550080 with your own Linode Image’s ID and assign your own root_pass and label.

        curl -H "Content-Type: application/json" 
          -H "Authorization: Bearer $TOKEN" 
          -X POST -d '{
            "image": "private/7550080",
            "root_pass": "[email protected]",
            "booted": true,
            "label": "my-example-label",
            "type": "g6-nanode-1",
            "region": "us-east"
          }' 
          https://api.linode.com/v4/linode/instances
        

        You should receive a similar response from the API:

          
        {"id": 17882092, "created": "2019-10-23T22:47:47", "group": "", "specs": {"gpus": 0, "transfer": 1000, "memory": 1024, "disk": 25600, "vcpus": 1}, "label": "my-example-linode", "updated": "2019-10-23T22:47:47", "watchdog_enabled": true, "image": null, "ipv4": ["192.0.2.0"], "ipv6": "2600:3c03::f03c:92ff:fe98:6d9a/64", "status": "provisioning", "tags": [], "region": "us-east", "backups": {"enabled": false, "schedule": {"window": null, "day": null}}, "hypervisor": "kvm", "type": "g6-nanode-1", "alerts": {"cpu": 90, "network_in": 10, "transfer_quota": 80, "io": 10000, "network_out": 10}}%
            
        
      2. If you used the Ansible provisioner, once your Linode is deployed, you should be able to SSH into your newly deployed Linode using the limited user account you created with the Ansible playbook and your public SSH key. Your Linode’s IPv4 address will be available in the API response returned after creating the Linode.

        ssh [email protected]
        

      Next Steps

      If you’d like to learn how to use Terraform to deploy Linodes using your Packer created image, you can follow our Terraform guides to get started:

      Find answers, ask questions, and help others.

      This guide is published under a CC BY-ND 4.0 license.



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