Fastly

This topic explains how to use the LaunchDarkly Fastly integration. This integration enables flag evaluation within Fastly Compute. The integration writes the latest flag data from the configured environment directly to Fastly Compute in your account. It also sends any change to a flag or segment configuration in your selected environment to Fastly Compute, ensuring your Fastly cache is always up to date. You can use the Fastly integration to bootstrap your application with the latest client-side feature flags. This eliminates the initial remote call to LaunchDarkly, providing zero-latency client-side feature flags with no flash of original content or shift in content layout. The Fastly integration also enables flag evaluations within Fastly Compute. This means you can use your LaunchDarkly flags without an added latency from network requests. For the Fastly integration to work, you need a Fastly account. Then, you need to:

• In Fastly, configure a Fastly KV store for LaunchDarkly.
• In LaunchDarkly, create a Fastly integration.
• In your application, use LaunchDarkly’s Fastly edge SDK to evaluate your feature flags.

This topic also describes how to manage your Fastly integration configurations in LaunchDarkly.

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Configure a Fastly KV store for LaunchDarkly

To configure a Fastly KV store for LaunchDarkly:

1. In Fastly, add a new KV store. We recommend naming this launchdarkly.
2. Connect this KV store with your Fastly Compute service.
3. Create a new Fastly Automation API Token. Give the token permission to read and write to the new KV store. We recommend the following settings:
   • Type: Automation token
   • Role: Engineer
   • Access: One or more services
4. Create a new Origin host on your Compute Service. We recommend naming this launchdarkly.
5. Configure this to have a host of events.launchdarkly.com and a TLS port of 443. This allows the LaunchDarkly Fastly SDK to send events back to LaunchDarkly.

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Create a Fastly integration

To create a new Fastly integration for your environment:

1. In LaunchDarkly, navigate to the Integrations page and find “Fastly.”
2. Click Add integration. The “Create Fastly configuration” panel appears.
3. Give the integration a human-readable Name.
4. Select a LaunchDarkly Environment. You cannot change this after you configure the integration.
5. In the KV Store ID field, enter the ID of the KV store to use for flag data. This is the store you created above.
6. Enter the API Token field, enter a Fastly API token with “Engineer” permissions. This is the API token you created above.
7. After reading the Integration Terms and Conditions, check the I have read and agree to the Integration Terms and Conditions checkbox.
8. Click Save configuration.

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Manage a Fastly integration

After you have created a Fastly integration, you can change its status, update it, or delete it. Here’s how:

1. In LaunchDarkly, navigate to the Integrations page and find “Fastly.”
2. Click the arrow menu to display the existing Fastly integrations.
3. Find your integration and click the pencil icon to edit. The “Edit Fastly configuration” panel appears.

Then complete one of the following actions:

• To change the status of an existing Fastly integration, toggle the Status to Off or On.
• To update an existing Fastly integration, edit the Name, KV Store ID, or API Token. Then click Save configuration.
• To delete an existing Fastly integration, click Delete.