Tutorial: Create a CloudFront function that includes key values

This tutorial shows you how to include key values with CloudFront function. Key values are part of a key-value pair. You include the name (from the key-value pair) in the function code. When the function runs, CloudFront replaces the name with the value.

Key-value pairs are variables that are stored in a key value store. When you use a key in your function (instead of hard-coded values), your function is more flexible. You can change the value of the key without having to deploy code changes. Key-value pairs can also reduce the size of your function. For more information, see Amazon CloudFront KeyValueStore.

Contents

• Prerequisites
• Create the key value store
• Add key-value pairs to the key value store
• Associate the key value store with the function
• Test and publish the function code

Prerequisites

If you're new to CloudFront Functions functions and the key value store, we recommend that you follow the tutorial in Tutorial: Create a simple function with CloudFront Functions.

After you complete that tutorial, you can follow this tutorial to extend the function that you created. For this tutorial, we recommend that you create the key value store first.

Create the key value store

First, create the key value store to use for your function.

To create the key value store

1. Plan the key-value pairs you want to include in the function. Make a note of key names. The key-value pairs that you want to use in a function must be in a single key value store.

2. Decide about the order of work. There are two ways to proceed:

   • Create a key value store, and add key-value pairs to the store. Then create (or modify) the function and incorporate the key names.

   • Or, create (or modify) the function and incorporate the key names you want to use. Then create a key value store, and add the key-value pairs.

3. Sign in to the AWS Management Console and open the CloudFront console at https://console.aws.amazon.com/cloudfront/v4/home.

4. In the navigation pane, choose Functions, and then choose the KeyValueStores tab.

5. Choose Create KeyValueStore and enter the following fields:

   • Enter a name and (optional) description for the store.

   • Leave S3 URI blank. In this tutorial you will enter the key-value pairs manually.

6. Choose Create. The details page for the new key value store appears. This page includes a Key value pairs section that is currently empty.

Add key-value pairs to the key value store

Next, manually add a list of key-value pairs to the key value store that you previously created.

To add key-value pairs to the key value store

1. In the Key value pairs section, choose Add key value pairs.

2. Choose Add pair and then enter a key and value. Choose the check mark to confirm your changes and repeat this step to add more.

3. When you're finished, choose Save changes to save the key-value pairs in the key value store. On the confirmation dialog, choose Done.

You now have a key value store that contains a group of key-value pairs.

Associate the key value store with the function

You have now created the key value store. And you have created or modified a function that includes the key names from the key value store. You can now associate the key value store and the function. You create that association from within the function.

To associate the key value store with the function

1. In the navigation pane, choose Functions. The Functions tab appears on top, by default.

2. Choose the function name and in the Associated KeyValueStore section, choose Associate Existing KeyValueStore.

3. Select the key value store and choose Associate KeyValueStore.

Note

You can associate only one key value store with each function.

Test and publish the function code

After you associate the key value store with your function, you can test and publish the function code. You should always test the function code every time you modify it, including when you do the following:

• Associate a key value store with the function.

• Modify the function and its key value store to include a new key-value pair.

• Change the value of a key-value pair.

To test and publish the function code

1. For information about how to test a function, see Test functions. Make sure that you choose to test the function in the DEVELOPMENT stage.

2. Publish the function when you're ready to use the function (with the new or revised key value pairs) in a LIVE environment.

   When you publish, CloudFront copies the version of the function from the DEVELOPMENT stage over to the live stage. The function has the new code and is associated with the key value store. (There is no need to perform the association again, in the live stage.)

   For information about how to publish the function, see Publish functions.