AWS Management and Governance Tools Workshop > AWS AppConfig > Feature Toggle

Feature Toggle

In this section of the lab, we will modify our API Gateway Lambda to utilize the boolEnableLimitResults and intResultLimit properties of our configuration document to enable a new feature that will limit the number of results returned by API Gateway as well as utilize the value of intResultLimit to determine how many results to return.

The current state of our configuration document is as follows:

{
   "boolEnableLimitResults": false,
   "intResultLimit": 0
}

We will first need to modify our Lambda code to implement the limit feature, update our configuration document to turn on the feature and then redeploy our configuration profile to development.

Add Feature Toggle Code to Lambda to Enable Limiting

Next, we will update our Lambda application to implement the boolEnableLimitResults configuration value to turn on the limit results feature code block as well as utilize the value of intResultLimit to determine the number of results returned in the API response.

Use the following procedure to implement the limit feature toggle.

Visit the Lambda Console and select AppConfigLabAPIGatewayLambda from the functions list.
Select the Configuration tab and scroll down to the Function code section.
Locate the following line of code: // add result limit code here.
Replace this entire line with the code below. This block of code first evaluates if the value for boolEnableLimitResults is present and set to true. It then uses the value of intResultLimit to control the number of results returned.
```
if ( (parsedConfigData.boolEnableLimitResults) && parsedConfigData.intResultLimit ) {
  result = result.splice(0, parsedConfigData.intResultLimit);
}
```
Locate the line of code body: parsedConfigData and replace it with body: result such that the response constant reads as follows:
```
const response = {
  statusCode: 200,
  body: result,
};
```
Select Deploy.
Test the API Gateway by returning to the API Gateway Console and select AppConfigLabAPI from the list.
Select the GET method from the / root Resources.
Select Test and note that all the items in the array are returned.

Note that the limiting feature did not work because the value for boolEnableLimitResults is set to false. We need to update our hosted configuration by changing the value of boolEnableLimitResults to true to enable limiting as well as change the value of intResultLimit to 5 from 0 so that we get results. Then, we will need to redeploy AppConfig to our development environment to allow the API Gateway Lambda to access the updated configuration data.

Update & Deploy AppConfig Configuration Document

Use the following procedure to update the hosted configuration data and redeploy it to the development environment.

Visit the AppConfig Console and select the AppConfigLab application.
Select Configuration profiles tab.
Select the AppConfigLabHostedConfigurationProfile configuration profile.
In the Hosted configuration versions section, select Create to create a new version of our configuration JSON document.

Replace the contents of the JSON body with the content below.

{
  "boolEnableLimitResults": true,
  "intResultLimit": 5
}

Select Create hosted configuration version.
Select Start deployment.
Select AppConfigLabAPIGatewayDevelopment from the Environment dropdown list.
Select 2 from the Hosted configuration version dropdown list.
Select AppConfig.AllAtOnce (Quick) from the Deployment strategy dropdown list.
Enter Deploy limiting feature enabled in the Deployment description field.
Select Start deployment to being the deployment.
Observe the Percent complete and State until it reaches 100% and a state of Completed. Refresh the page after a couple of minutes to make sure the status updates.

With the updated configuration deployed, "boolEnableLimitResults": true and "intResultLimit": 5 are now both available for use by the API Gateway application.

Verify Feature Toggle in API Gateway

Next, we will verify that the limit feature is now in fact enabled.

Test the API Gateway by returning to the API Gateway Console and select AppConfigLabAPI from the list.
Select the GET method from the / root Resources.
Select Test and note that only five items returned within the API response. The response should resemble the following:

{
  "statusCode": 200,
  "body": [
    {
      "name": "AWS AppConfig"
    },
    {
      "name": "Amazon SageMaker Studio"
    },
    {
      "name": "Amazon Kendra"
    },
    {
      "name": "Amazon CodeGuru"
    },
    {
      "name": "Amazon Fraud Detector"
    }
  ]
}