Introducing Unix Domain Socket Support

One of the headlining features of Insomnia 5.4.0 is support for UNIX Domain Sockets – a mechanism typically used for communication between processes running on the same host operating system. This post gives a brief introduction on connecting to a socket within Insomnia.

In order for Insomnia to distinguish socket requests, a slightly different URL syntax is required. The following syntax was borrowed from the popular NodeJS request library.

# Syntax for UNIX domain sockets
http://unix:$SOCKET:$PATH

Note: This feature provides same functionality as using the --unix-socket FILE flag with curl.

Example Using Docker Engine API

To demonstrate socket support, we'll issue a request to the /images endpoint that is exposed by the Docker Engine's socket API. Using the following URL in Insomnia will list the available Docker images on the host machine.

# Sample URL to communicate with Docker socket
http://unix:/var/run/docker.sock:/v1.24/images/json

This URL is specifying the path to the socket (/var/run/docker.sock) and the API endpoint path (/v1.24/images/json) using the previously mentioned URL syntax. Here's what it looks like within Insomnia.

Since the Docker socket communicates using HTTP and JSON, it looks indistinguishable from regular TCP/IP-based HTTP requests being made over the network.

And that's it! I can't wait to hear what you think!