»Packer Plugins

»Create a required_plugins block

1. Add a required_plugins block to your packer block. Each block will tell Packer what version(s) of a particular plugin can be installed. Make sure to set a valid version constraint string.

Here is an example required_plugins block:

packer {
  required_plugins {
    myawesomecloud = {
      version = ">= 2.7.0"
      source = "github.com/azr/myawesomecloud"
    }
    happycloud = {
      version = ">= 1.1.3"
      source = "github.com/azr/happycloud"
    }
  }
}

packer {  required_plugins {    myawesomecloud = {      version = ">= 2.7.0"      source = "github.com/azr/myawesomecloud"    }    happycloud = {      version = ">= 1.1.3"      source = "github.com/azr/happycloud"    }  }}

2. Run packer init from your project directory (the directory containing your Packer templates) to install all missing plugin binaries. Given the above example, Packer will try to look for a GitHub repository owned by user or organization azr named packer-plugin-myawesomecloud and packer-plugin-happycloud.

»Names and Addresses

Each plugin has two identifiers:

• A source address, which is only necessary when requiring a plugin outside the HashiCorp domain.
• A unique local name, which is used everywhere else in a Packer configuration.

»Local Names

Local names allow you to access the components of a plugin and must be unique per configuration.

This is best explained using an example. In the above required_plugins block, we declared the local name "myawesomecloud" for the plugin azr/myawesomecloud. If the "myawesomecloud" plugin contains both an "ebs" builder and an "import" post-processor, then the builder will be accessed in a source block by using:

source "myawesomecloud-ebs" "example" {
  // builder configuration...
}

source "myawesomecloud-ebs" "example" {  // builder configuration...}

similarly, the import post-processor would be accessed by declaring the post-processor block:

post-processor "myawesomecloud-import" {
  // post-processor configuration...
}

post-processor "myawesomecloud-import" {  // post-processor configuration...}

If we change the required_plugins block to use a different local name "foo":

  required_plugins {
    foo = {
      version = ">= 2.7.0"
      source = "github.com/azr/myawesomecloud"
    }
  }

  required_plugins {    foo = {      version = ">= 2.7.0"      source = "github.com/azr/myawesomecloud"    }  }

Then we'd instead access that builder using the source:

source "foo-ebs" "example" {
  // builder configuration...
}

source "foo-ebs" "example" {  // builder configuration...}

»Source Addresses

A plugin's source address is its global identifier. It also tells Packer where to download it.

Source addresses consist of three parts delimited by slashes (/), as follows:

<HOSTNAME>/<NAMESPACE>/<TYPE>

• Hostname: The hostname of the location/service that distributes the plugin. Currently, the only valid "hostname" is github.com, but we plan to eventually support plugins downloaded from other domains.

• Namespace: An organizational namespace within the specified host. This often is the organization that publishes the plugin.

• Type: A short name for the platform or system the plugin manages. The type is usually the plugin's preferred local name.

For example, the fictional myawesomecloud plugin could belong to the hashicorp namespace on github.com, so its source could be github.com/hashicorp/myawesomecloud, Note: the actual repository that myawesomecloud comes from must always have the name format github.com/hashicorp/packer-plugin-myawesomecloud, but the required_plugins block omits the redundant packer-plugin- repository prefix for brevity.

The source address with all three components given explicitly is called the plugin's fully-qualified address. You will see fully-qualified address in various outputs, like error messages.

»Plugin location

Plugins will usually be located in the PACKER_HOME_DIR.

• packer init will install plugins in the last directory in the following numbered list.

• During the initialization of Packer, any plugin required in the required_plugins section will be looked up in all entries of the following list. First plugin found takes precedence. Two binaries of the same plugin with two different version will be considered as two different plugins. Highest found version matching required_plugins will be taken into consideration.

1. The directory where packer is, or the executable directory.
2. The current working directory. (".")
3. The PACKER_HOME_DIR/plugins directory. PACKER_HOME_DIR refers to Packer's home directory, if it could be found.
4. The director(y/ies) under the PACKER_PLUGIN_PATH env var, if PACKER_PLUGIN_PATH is set.

Using the following example :

    required_plugins {
      happycloud = {
        version = ">= 2.7.0"
        source = "github.com/azr/happycloud"
      }
    }

    required_plugins {      happycloud = {        version = ">= 2.7.0"        source = "github.com/azr/happycloud"      }    }

The plugin getter will then install the binaries in the following location for a system with no PACKER_PLUGIN_PATH env var set.

• PACKER_HOME_DIR/plugins/github.com/hashicorp/happycloud/

During initialization, on a darwin_amd64 system, Packer will look-up for the following files:

• PACKER_EXEC_DIR/github.com/azr/happycloud/packer-plugin-happycloud_*_x5.0_darwin_amd64
• ./github.com/azr/happycloud/packer-plugin-happycloud_*_x5.0_darwin_amd64
• PACKER_HOME_DIR/plugins/github.com/azr/happycloud/packer-plugin-happycloud_*_x5.0_darwin_amd64
• PACKER_PLUGIN_PATH/github.com/azr/happycloud/packer-plugin-happycloud_*_x5.0_darwin_amd64
• ./packer-plugin-happycloud

The first plugin-name/version files found will take precedence.

For plugins located under the github.com/azr/happycloud/ directory structure an accompanying SHA256SUM file will be required in order for packer init to ensure the plugin being loaded has not been tampered with. The SHA256SUM file will be automatically generated when a plugin is installed via packer init if the plugin was installed manually into PACKER_HOME_DIR/plugins/github.com/azr/happycloud/ then the file PACKER_HOME_DIR/plugins/github.com/azr/happycloud/packer-plugin-happycloud_*_x5.0_darwin_amd64_SHA256SUM must be generated manually as well.

»Implicit Github urls

Using the following example :

    required_plugins {
      happycloud = {
        version = ">= 2.7.0"
        source = "github.com/azr/happycloud"
      }
    }

    required_plugins {      happycloud = {        version = ">= 2.7.0"        source = "github.com/azr/happycloud"      }    }

The plugin getter will look for plugins located at:

• github.com/azr/packer-plugin-happycloud

Packer will error if you set the packer-plugin- prefix in a source. This will avoid conflicting with other plugins for other tools, like Terraform.