aws-greengrass-group-setup

Greengrass gg_group_setup is an example file-driven approach to the creation of an entire AWS Greengrass group.

This repository demonstrates how one might automate the following discrete steps, but if you're doing full, complex, deployment management of Greengrass Groups you will want to explore the new Greengrass CloudFormation support and read this blog post.

Usually the following discrete steps are necessary to setup and deploy a Greengrass group.

• create_thing
• create_core_definition
• create_device_definition
• create_function_definition
• create_logger_definition
• create_subscription_definition
• create_deployment

gg_group_setup provides functioning example code of how a Greengrass Group is created. It also provides a:

• gg_group_setup config file parser GroupConfigFile which can be sub-classed
• file-driven command line interface encapsulated in the GroupComnands class
  • The GroupCommands class is also an example implementation of the steps necessary to create a Greengrass Group.
• GroupType which can be sub-classed for more complex GroupCommands scenarios

gg_group_setup includes multiple commands: create, deploy, create-core, create-devices, clean-core, clean-devices, clean-file, and clean-all.

After installation you can use these commands from the Command Line Interface, or you can use them from within a program via the GroupCommands class.

Installation

The quickest way to get gg_group_setup is to install the latest stable version via pip.

pip install gg-group-setup

After installation, for command line help type:

gg_group_setup create -- --help
gg_group_setup deploy -- --help
gg_group_setup create-core -- --help
gg_group_setup create-devices -- --help
gg_group_setup clean-core -- --help
gg_group_setup clean-devices -- --help
gg_group_setup clean-file -- --help
gg_group_setup clean-all -- --help
gg_group_setup associate_devices -- --help

Quick Start

The high-level process to create a Greengrass group using gg_group_setup is as follows:

1. Execute $ gg_group_setup create-core <thing_name> <config_file> -- to create a Greengrass Core named thing_name
2. Execute $ gg_group_setup create-devices '[<device_thing_name_01>,<device_thing_name_02,...]' <config_file> -- to create things for use as devices in your Greengrass Group.
3. Create and alias your Lambda function(s)
4. Update the group <config_file>. Example: cfg.json
   1. update the lambda_functions section

      1. In the lambda_functions section of the configuration, replace <function_name> with the name of the Lambda function configured and aliased previously. Then for that function enter the arn and arn_qualifier of the function.

         "lambda_functions": {
           "<function_name>": {
             "arn": "<lambda_ARN>",
             "arn_qualifier": "<alias>"
             "environment_variables": {
               "<name>": "<value>",
             }
           }
         },

      2. For example, if the Lambda function is created in us-west-2, named MyFirstGreengrassLambda, and the alias named dev pointing to version 1, the lambda_functions section would contain these values.

         "lambda_functions": {
           "MyFirstGreengrassLambda": {
             "arn": "arn:aws:lambda:us-west-2:<account_id>:function:MyFirstGreengrassLambda:dev",
             "arn_qualifier": "dev"
             "environment_variables": {
               "SAY_HELLO_TO": "Miss. Mocking Bird",
             }
           }
         },

         • If you need more than one function in the group named MyFirstGreengrassLambda and MockDeviceLambda, the lambda_functions section would contain these values.

           "lambda_functions": {
             "MyFirstGreengrassLambda": {
               "arn": "arn:aws:lambda:us-west-2:<account_id>:function:MyFirstGreengrassLambda:dev",
               "arn_qualifier": "dev"
               "environment_variables": {
                 "SAY_HELLO_TO": "Miss. Mocking Bird",
               }
             },
             "MockDeviceLambda": {
               "arn": "arn:aws:lambda:us-west-2:<account_id>:function:MockDeviceLambda:dev",
               "arn_qualifier": "dev"
               "environment_variables": {
                 "SAY_GOODBYE_TO": "Mr. Sleepy Owl",
                 "SAY_GOODBYE_AT": "8:00 PM",
               }
             }
           },

   2. update the subscriptions section
      1. the subscriptions section should reflect the topics the Lambda functions and devices in the group use to communicate with each other and the cloud. For example, the MockDevice Lambda function expects to use the following subscriptions:

         "subscriptions": {
           "errors": "/errors",
           "telemetry": "/telemetry"
         }

5. Download the Greengrass software and follow these instructions to extract the software onto the Greengrass core.
6. Install the Greengrass core's certificates onto the core device
7. Start your Greengrass core
8. Execute $ gg_group_setup create <group_type> <config_file> -- to create the Greengrass group
9. Execute $ gg_group_setup deploy <config_file> -- to deploy the Greengrass group

Note: gg_group_setup also includes a Mock Device Lambda function you can use to get started.

Using gg_group_setup as a Library

After the Quick Start, you will probably want to configure your own unique Greengrass group with its own Lambda functions, devices, and subscription topology. To do this you will need to implement a sub-class of GroupType.

In the gg_group_setup folder you will see an example mock_device Lambda function and a mock_group.

After implementing a sub-class of GroupType called CustomGroupType, update the group <config_file> to reflect the custom group. The custom group can then be used in code as follows:

    config_file = "<filename>"  # filename of the group's <config_file>
    group_name = "<group_name>"  # if `None`, the group_type value will be used
    region = "<aws_region>"  # AWS region in which the group will be created
 
    gc = GroupCommands(group_types={
        CustomGroupType.CUSTOM_TYPE: CustomGroupType
    })
    gc.create(
        config_file, group_type=CustomGroupType.CUSTOM_TYPE, 
        group_name=group_name, region=region
    )

Entering an account_id

If you add your account ID to the config_file manually before running any commandsgg_group_setup will use the account ID to make a notch more restrictive Core and Device policies. Specifically, if you enter a value here:

  ...
  "misc": {
    "account_id": "<account_id_here>",
    "iot_endpoint": ""
  },...

These instructions show you how to find your AWS account ID.

Using the config_file manually

Although the helper commands create-core and create-devices will create things and store the proper information in the given config_file, you can also ignore those commands if you want to enter all the information manually. The create, deploy, and clean-all Greengrass group commands will use the config_file information as stored.

Projects using gg_group_setup

The aws-greengrass-mini-fulfillment repository creates and uses pretty complex custom group types.