Ways to Test Your Caching with cURL

Add the Fastly-Debug: True header to a request

Example: curl -svo /dev/null [url] -H "Fastly-Debug: true"
Purpose: provides more information about how the object is cached and handled by Fastly caches.
The following three headers are included in the object response:
Fastly-Debug-Path: which cache servers serve the request
Fastly-Debug-TTL: the TTL of the object in the queried server(s)
Fastly-Debug-Digest: the hash digest of the object.

Run a request through a specific cache node

Example: curl -svo /dev/null <url> -x <cache-node>.hosts.fastly.net:80
In the place of <cache-node>, you can insert any cache node that you usually see in the “X-Served-By” header on a response (ie cache-jfk1020, cache-lax1427, cache-fra1246, etc) running through Fastly.
Purpose: allows you to target your testing and make multiple calls to the same cache server. This can be useful for testing HIT/MISS, TTL values, or to check if the cache is correctly serving different versions of an object (for example if GZIP is enabled).

Add the Fastly-No-Shield: true header to a request

Example: curl -svo /dev/null [url] -H "Fastly-No-Shield: true"
Purpose: Disables clustering on the request. This may help you see what the request/response looks like when one cache server communicates directly with your origin.

Test a URL with a loop:

Examples:
for ((i=1;i<=10;i++)); do curl -svo /dev/null www.example.com; sleep 2; done
while true; do curl -svo /dev/null www.example.com; sleep 2; done
Purpose: this is convenient for seeing the results from numerous url calls and can also be helpful for testing logging output/performance.

To monitor for the presence of certain headers (Etag, Content-Type, etc) in a sample of responses:

for ((i=1;i<=1000;i++)); do curl -svo /dev/null www.example.com 2>&1 | grep Etag; sleep 1; done

while true; do curl -svo /dev/null www.example.com 2>&1 | grep Content-Type; sleep 1; done

Cassandra Dixon

October 19, 2015 16:47

You will want use --resolve in your curl command:

curl -svo /dev/null --resolve '<customer_hostname>:443:<ip address of cache node>' <https URL>

There are a few things you will need to confirm before running this command: * That you have TLS enabled with Fastly via a Shared Certificate or Hosted Cert * Determine the IP address of the cache node

For instance: host cache-lax1420.hosts.fastly.net cache-lax1420.hosts.fastly.net has address "199.27.79.20"

Note: If you have a hosted certificate, change the last octet to match your dedicated map

Then run your command:

Example:

curl -svo /dev/null --resolve 'www.example.com:443:199.27.79.20' https://www.example,com/some_file

Christoph

October 19, 2015 19:29

That's awesome, thanks so much @cassandra!

Rogier Mulhuijzen

October 19, 2015 19:45

Another tip is to use --compressed so that curl sends Accept-Encoding: deflate, gzip, to mimic browser behavior a little more closely.

And it's always a good idea to test both with and without --compressed to make sure that responses are compressed when they should be and aren't when they shouldn't. Content-Encoding: gzip in the response headers signifies that the response is compressed.

paolo mainardi

December 21, 2015 23:10

To test with a loop: watch -n [number] curl -svo /dev/null [url] -H "Fastly-Debug: true"

Where "number" is an integer.

Tom To

July 06, 2021 02:32

I see *.hosts.fastly.net doesnt have AAAA (ipv6) support. Is there some way to send a request through a specific cache node via ipv6?

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