Step 6: Receiving the configuration - AWS AppConfig

Step 6: Receiving the configuration

You must configure a client to receive configuration updates by integrating with the GetConfiguration API action. You can integrate using the AWS SDK. The following AWS CLI command demonstrates how to receive a configuration. This call includes the IDs of the AWS AppConfig application, the environment, the configuration profile, and a unique client ID. The configuration content is saved to the output filename.

Note

The client-id parameter in the following command is a unique, user-specified ID to identify the client for the configuration. This ID enables AWS AppConfig to deploy the configuration in intervals, as defined in the deployment strategy. 

aws appconfig get-configuration \
    --application application_name_or_ID \
    --environment environment_name_or_ID \
    --configuration configuration_profile_name_or_ID \
    --client-id client_ID \
output_filename

The system responds with information in the following format.

{
   "ConfigurationVersion":"configuration version",
   "ContentType":"content type"
}
Important

Note the following important details about the GetConfiguration API action:

  • The GetConfiguration response includes a Content section that shows the configuration data. The Content section only appears if the system finds new or updated configuration data. If the system doesn't find new or updated configuration data, then the Content section is not returned (Null).

  • AWS AppConfig uses the value of the ClientConfigurationVersion parameter to identify the configuration version on your clients. If you don’t send ClientConfigurationVersion with each call to GetConfiguration, your clients receive the current configuration. You are charged each time your clients receive a configuration.

  • To avoid excess charges, we recommend that you include the ClientConfigurationVersion value with every call to GetConfiguration. This value must be saved on your client. Subsequent calls to GetConfiguration must pass this value by using the ClientConfigurationVersion parameter, as shown here.

Sending ConfigurationVersion during subsequent polling for configuration updates is similar to the concept of HTTP ETags. 

aws appconfig get-configuration \
    --application application_name_or_ID \
    --environment environment_name_or_ID \
    --configuration configuration_profile_name_or_ID \
    --client-configuration-version previous_configuration_version_value \
    --client-id client_ID \
output_filename
Note

We recommend tuning the polling frequency of your GetConfiguration API calls based on your budget, the expected frequency of your configuration deployments, and the number of targets for a configuration.