Zstd

By enabling compression in Envoy you can save some network bandwidth, at the expense of increased processor usage.

Envoy supports compression and decompression for both requests and responses.

This sandbox provides an example of response compression served over HTTPS.

The sandbox covers two scenarios:

compression of files from an upstream server
compression of Envoy’s own statistics

Step 1: Start all of our containers

Change to the examples/zstd directory and bring up the docker composition.

$ pwd
envoy/examples/zstd
$ docker compose pull
$ docker compose up --build -d
$ docker compose ps
Name                 Command                        State   Ports
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
zstd_envoy-stats_1   /docker-entrypoint.sh /usr ... Up      0.0.0.0:10000->10000/tcp,:::10000->10000/tcp, 0.0.0.0:9901->9901/tcp,:::9901->9901/tcp, 0.0.0.0:9902->9902/tcp,:::9902->9902/tcp
zstd_service_1       python3 /code/service.py       Up

Step 2: Test Envoy’s compression of upstream files

The sandbox is configured with two endpoints on port 10000 for serving upstream files:

/file.txt
/file.json

Only /file.json is configured to be compressed.

Use curl to check that the response from requesting file.json contains the content-encoding: zstd header.

You will need to add an accept-encoding: zstd request header.

$ curl -ski -H "Accept-Encoding: zstd" https://localhost:10000/file.json | grep "content-encoding"
content-encoding: zstd

As only files with a content-type of application/json are configured to be compressed, the response from requesting file.txt should not contain the content-encoding: zstd header, and the file will not be compressed:

$ curl -ski -H "Accept-Encoding: zstd" https://localhost:10000/file.txt | grep "content-encoding"

Step 3: Test compression of Envoy’s statistics

The sandbox is configured with two ports serving Envoy’s admin and statistics interface:

9901 exposes the standard admin interface without tls
9902 exposes a compressed version of the admin interface with tls

Use curl to make a request for uncompressed statistics on port 9901, it should not contain the content-encoding header in the response:

$ curl -ski -H "Accept-Encoding: zstd" http://localhost:9901/stats/prometheus | grep "content-encoding"

Now, use curl to make a request for the compressed statistics:

$ curl -ski -H "Accept-Encoding: zstd" https://localhost:9902/stats/prometheus | grep "content-encoding"
content-encoding: zstd