Help Center> Image Management Service> Best Practices> Creating a Private Image Using Packer
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Creating a Private Image Using Packer

Packer is an open-source tool that can be used to create custom images. It consists of three components, builder, provisioner, and post-processor. The components can be flexibly combined using a JSON template to automatically create image files. Packer simplifies private image creation by changing the image creation process to a form in which management code can be configured. In this way, users can flexibly customize images and switch images between different cloud platforms.

This section describes how to create a Ubuntu 16.04 Server 64-bit private image from a CentOS 7.4 64-bit ECS using Packer and upload the created image to the public cloud platform.

Constraints

Full-ECS images cannot be used to create private images using Packer.

Procedure

Installing Packer

  1. Log in to the management console, create an ECS (for example, an ECS running CentOS 7.4 64-bit), and bind an EIP to the ECS.
  2. Log in to the ECSs.
  3. On the Packer download page, select the Packer version corresponding to the ECS OS and architecture type. You are advised to select a version ranging from 1.2.3 to 1.4.2.
  4. Run the following command to install Packer (packer_1.4.2_linux_amd64.zip is used as an example):

    wget --no-check-certificate https://releases.hashicorp.com/packer/1.4.2/packer_1.4.2_linux_amd64.zip

    • You need to bind an EIP to the ECS in advance so that the ECS can access the Internet.
    • If message "command not found" is displayed, the wget tool is not installed. Run the yum install wget command to install the wget tool.
  5. Run the following command to decompress the Packer installation package:

    unzip packer_1.4.2_linux_amd64.zip

  6. Run the following command to move the Packer installation package to the /usr/local/bin directory:
    mv packer /usr/local/bin

    The /usr/local/bin directory has been added to environment variables. You can also move the Packer installation package to another directory that has been added to environment variables.

  7. Run the following command to query the Packer version number and check whether Packer is installed successfully:

    packer -v

    • If the command output contains the Packer version number, Packer is installed successfully.
    • If "command not found" is displayed, the Packer installation fails. Check whether the directory where Packer resides has been added to environment variables.

      Run the env | grep PATH command to print environment variables and check whether the environment variable PATH contains the Packer installation directory.

      If the PATH does not contain the Packer installation directory, run the following commands to add the Packer installation directory to PATH:

      1. Run the following command to open the profile file:

        vim /etc/profile

      2. Press i to enter editing mode and add export PATH=$PATH:/usr/local/bin to the end of the file.

        Replace /usr/local/bin with the actual directory where Packer is installed.

      3. Press Esc to exit editing mode. Enter :wq and press Enter to save the changes and exit.
      4. Run the following command to make the change take effect:

        source /etc/profile

Creating a Packer Template

To create an image using Packer, you need a template in JSON format. You need to specify a builder, provisioner, and post-processor in the template. In the Builder, you can specify any operation on the source image, specify the installation software, and modify configuration. In this example, a post-processor is used to redirect the output path of manifest. If your Packer template has multiple builders, you can locate the ID of the image created from each builder based on the manifest output. For details about the builder, provisioner, and post-processor, see the official Packer documents.

This section uses the Shell provisioner as an example.

  1. Run the following command to create the hwcloud.json file:

    touch hwcloud.json

  2. Run the following command to open the hwcloud.json file:

    vim hwcloud.json

  3. Press i to enter editing mode and edit the template based on the site requirements. The following content is for reference only. For the parameter descriptions, see Table 1. 
    {
  "builders": [{
    "type": "openstack",
    "identity_endpoint": "https://iam.xxx.com/v3",
    "tenant_name": "xxx",
    "domain_name": "domain_name", 
    "username": "username",
    "password": "password",
    "ssh_username": "root",
    "region": "xxx",
    "image_name": "Ubuntu-image-updating-powered-by-Packer",
    "instance_name": "Ubuntu-image-updating-powered-by-Packer",
    "source_image": "f1dd2272-7041-479e-9663-646632b6ac00",
    "availability_zone": "xxx",
    "flavor": "s3.medium.2",
    "use_blockstorage_volume": true,
    "networks": ["11d661c4-e41f-487f-a6f6-9b88d623dd5d"],
    "floating_ip": "8f686f9a-3408-4fdd-be75-ea768065800c"
  }],
  "provisioners": [{
    "inline": [
      "apt-get update -y"
    ],
    "inline_shebang": "/bin/sh -x",
    "type": "shell",
    "skip_clean": true
  }],
  "post-processors": [{
    "strip_path": true,
    "output": "packer-template-ubuntu-updating-result.log",
    "type": "manifest"
  }]
}

    In Table 1, tenant_name, region, availability_zone, flavor, networks, and floating_ip are the attributes of the ECS used to create the private image.

    Table 1 Packer template parameters

    Parameter

    Description

    Mandatory

    type

    Specifies the type. Retain the default value openstack.

    Yes

    identity_endpoint

    Specifies the address of the identity authentication node. The format is https://IAM endpoint/v3.

    Obtain the IAM endpoint from Regions and Endpoints.

    Yes

    tenant_name

    Specifies the project name. To obtain the project name, perform the following operations:

    1. On the management console, move the cursor to the username in the upper right corner and choose My Credentials.
    2. On the API Credentials page, obtain the project name (value in the Project Name column).

    Yes

    domain_name

    Specifies the domain name. To obtain the domain name, perform the following operations:

    1. On the management console, move the cursor to the username in the upper right corner and choose My Credentials.
    2. On the API Credentials page, obtain the domain name.

    Yes

    username

    Specifies the IAM username. To obtain the IAM username, perform the following operations:

    1. On the management console, move the cursor to the username in the upper right corner and choose My Credentials.
    2. On the API Credentials page, obtain the IAM username.
    NOTE:

    If you use an account to log in to the HUAWEI CLOUD console, the IAM username and account name are the same.

    Yes

    password

    Specifies the password for logging in to the management console.

    Yes

    ssh_username

    Specifies the SSH login username of the private image to be created.

    Yes

    region

    Specifies the region name. Obtain the region name from Regions and Endpoints.

    Yes

    image_name

    Specifies the name of the private image to be created.

    Yes

    instance_name

    Specifies the name of the temporary instance generated during the private image creation. If you do not set this parameter, the system uses a random value.

    No

    source_image

    Specifies the ID of the source image, which can be obtained from the public image list on the IMS console. If you already have a Ubuntu 16.04 Server 64-bit private image and want to reconstruct the image using Packer, you can enter the ID of the private image.

    Yes

    availability_zone

    Specifies the AZ. Obtain the AZ from Regions and Endpoints.

    Yes

    flavor

    Specifies the ECS flavor.

    Yes

    use_blockstorage_volume

    Specifies whether the system disk rather than the whole ECS is used to create an image.

    Yes. The value must be true.

    networks

    Specifies the ID of the VPC subnet.

    Yes

    floating_ip

    Specifies the EIP ID.

    This parameter is mandatory if the image instance created using Packer needs to access the Internet.

    provisioners

    Specifies the type of the Packer provisioner used to create the private image. For details, see Packer Provisioners.

    Yes

    post-processors

    Specifies the type of the Packer post-processor used to create the private image.

    No

Creating a Private Image Using Packer

  1. After the Packer template is created, run the following command to create an image:

    packer build hwcloud.json

    The command output is as follows:

    openstack output will be in this color.

==> openstack: Loading flavor: s3.small.1
    openstack: Verified flavor. ID: s3.small.1
==> openstack: Creating temporary keypair: packer_5be8d358-2cc6-66a4-f1b5-31e8587c7bfa ...
==> openstack: Created temporary keypair: packer_5be8d358-2cc6-66a4-f1b5-31e8587c7bfa
==> openstack: Launching server...
==> openstack: Launching server...
    openstack: Server ID: fcf2014e-2f70-46c5-80d5-870ae0d1e659
==> openstack: Waiting for server to become ready...
    openstack: Selected floating IP: '8f686f9a-3408-4fdd-be75-ea768065800c' (119.3.67.11)
==> openstack: Associating floating IP '8f686f9a-3408-4fdd-be75-ea768065800c' (119.3.67.11) with instance port...
    openstack: Added floating IP '8f686f9a-3408-4fdd-be75-ea768065800c' (119.3.67.11) to instance!
==> openstack: Using ssh communicator to connect: 119.3.67.11
==> openstack: Waiting for SSH to become available...
==> openstack: Connected to SSH!
==> openstack: Provisioning with shell script: /tmp/packer-shell133419321
    openstack: + apt-get update -y
    openstack: Hit:1 http://archive.ubuntu.com/ubuntu xenial InRelease
           ......
    openstack: Fetched 7,088 kB in 9s (778 kB/s)
    openstack: Reading package lists...
==> openstack: Stopping server: fcf2014e-2f70-46c5-80d5-870ae0d1e659 ...
    openstack: Waiting for server to stop: fcf2014e-2f70-46c5-80d5-870ae0d1e659 ...
==> openstack: Creating the image: CentOS-image-updating-powered-by-Packer
    openstack: Image: 9eccbb17-9aed-4beb-bf44-1e8c80448ba3
==> openstack: Waiting for image CentOS-image-updating-powered-by-Packer (image id: 9eccbb17-9aed-4beb-bf44-1e8c80448ba3) to become ready...
==> openstack: Terminating the source server: fcf2014e-2f70-46c5-80d5-870ae0d1e659 ...
==> openstack: Deleting temporary keypair: packer_5be8d358-2cc6-66a4-f1b5-31e8587c7bfa ...
==> openstack: Running post-processor: manifest
Build 'openstack' finished.

==> Builds finished. The artifacts of successful builds are:
--> openstack: An image was created: 9eccbb17-9aed-4beb-bf44-1e8c80448ba3
--> openstack:
  2. Log in to the management console and click Image Management Service under Computing.
  3. Click the Private Images tab and view the image created using Packer. Figure 1 shows the created image.
    Figure 1 Viewing the private image created using Packer

Helpful Links

Packer official guide: https://www.packer.io/intro/getting-started/install.html