Backblaze B2 / Fastly Compute@Edge Demo

Serve content from one of a set of B2 regions, depending on the edge server in use.

For more details about this demo, see the blog entry, Optimize Access to Backblaze B2 with Fastly Compute@Edge

Prerequisites

• Backblaze B2 accounts in each of the US and EU regions
• A bucket in each account, each containing the same set of resources
• An application key in each account with at least read access to the bucket

Configuration

Private Buckets

If you are using private buckets (the default), you will need to create an Edge Dictionary named bucket_auth with the following values for each region:

• <backend_name>_access_key_id - B2 application key ID
• <backend_name>_secret_access_key - B2 application key

If you use the 'Deploy to Fastly' button you will be prompted for these credentials and the Edge Dictionary will be created as part of the deployment process.

Note that the application is unable to access private buckets when run in the local test server (fastly compute serve), since Edge Dictionaries are not accessible.

Public Buckets

Comment out the last three lines of Cargo.toml to disable AWS signatures and use public buckets.

Origin Details

You must edit the EU_ORIGIN and US_ORIGIN structs in src/config.rs to match your environment:

• bucket_name: The name of the bucket in that region
• endpoint: The endpoint of the bucket, e.g. s3.eu-central-003.backblazeb2.com

Understanding the code

This demo is adapted from the Compute@Edge static content starter kit for Rust. When the application receives a request, it performs the following operations:

1. Discovers the three-letter abbreviation for the edge server ('pop') on which it is running, using the following mechanism:

• If the requested URL contains a pop query parameter, for example, https://three.interesting.words.edgecompute.app/image.png?pop=AMS than its value is used as the pop.
• Otherwise, if the application is running on the local test server rather than the Fastly Compute@Edge environment, use the default set in src/config.rs.
• Otherwise, use the value that Fastly exposes via the FASTLY_POP environment variable.

2. Selects the US or EU origin by looking up the pop in the POP_ORIGIN map defined in src/config.rs.
3. Removes query parameters, so that they do not interfere with Fastly caching resources.
4. Sets the request Host header according to the selected origin.
5. Applies an AWS V4 signature to the request.
6. Forwards the request to the origin's Fastly backend and returns the response.