Compression

Overview

This module improves the performance of your web applications by compressing HTTP response bodies returned by your upstream service.

If an HTTP request includes an Accept-Encoding header, HTTP responses will be automatically compressed and a Content-Encoding response header will be added. If the response was already compressed by your upstream service, ngrok takes no action.

Example Usage

Agent CLI

Loading…

Agent Config

Loading…

SSH

Loading…

Go

Loading…

Go Package Docs:

• https://pkg.go.dev/golang.ngrok.com/ngrok/config#WithCompression

Javascript

Loading…

Javascript SDK Docs:

• https://ngrok.github.io/ngrok-javascript/interfaces/Config.html#compression
• https://ngrok.github.io/ngrok-javascript/classes/HttpListenerBuilder.html#compression

Python

Loading…

Python SDK Docs:

• https://ngrok.github.io/ngrok-python/http_listener_builder.html#ngrok.HttpListenerBuilder.compression
• https://ngrok.github.io/ngrok-python/index.html#full-configuration

Rust

Loading…

Rust Crate Docs:

• https://docs.rs/ngrok/latest/ngrok/config/struct.HttpTunnelBuilder.html#method.compression

Kubernetes Controller

Loading…

Behavior

Streaming Compression

When ngrok performs compression, the response body is not buffered; the response body is compressed as it is streamed through the ngrok edge.

Algorithm Choice

If a request specifies Accept-Encoding but no requested values are supported, ngrok takes no action and the upstream response is returned without modification.

ngrok negotiates the encoding type as defined by the RFC for Accept-Encoding. It respects q-values and chooses the Accept-Encoding supported algorithm with the highest q-value.

ngrok supports the following compression algorithms in the Accept-Encoding header.

Algorithm	Supported
br	no
compress	no
deflate	yes
gzip	yes

Response Headers

When ngrok performs compression, the following changes are made to the HTTP response header:

• The Content-Length header is removed
• A Content-Encoding header is added with the negotiated algorithm
• A Vary: Accept-Encoding header is added

Compression Level

The compression level is a value which indicates whether the compression algorithm should prefer to save more space at the expense of being slower and using more compute. This value is not currently configurable. ngrok automatically chooses a value that provides a reasonable tradeoff.

Reference

Configuration

This module does not support any configuration. It is either enabled or disabled.

Upstream Headers

This module does not add any upstream headers.

Errors

This module does not return any errors.

Events

When this module is enabled, it populates the following fields in http_request_complete.v0 events.

Fields
compression.algorithm
compression.bytes_saved

Edges

Compression is an HTTPS Edge module which can be applied to Routes.

• Compression Edge Module API Resource

Pricing

This module is available on all plans.

Try it out

For testing purposes, create a directory with a file in it and then enter that directory.

Loading…

ngrok can serve files from any directory (just like Python's Simple HTTP Server) by forwarding to a file:// URL. We're going to use that capability for our compression testing.

First let's see what this looks like without using compression by running the following in your test-dir directory:

Loading…

Then in another terminal while ngrok is still running:

Loading…

• --compressed instructs curl to set the Accept-Encoding header to request compressed content
• -D - instructs curl to show the HTTP response headers

You should get a response that looks like:

Loading…

Now let's try it again with compression. Stop your ngrok agent and restart it by changing the command to:

Loading…

Rerun the same curl command:

Loading…

This time you should see that HTTP response headers include content-encoding: deflate indicating that the response was compressed.

Loading…