readytalk/squirrel-server-go repository overview

⁠Squirrel Mac Server

The purpose of this project is to provide the server-side requirements of the Squirrel.Mac⁠ auto-update system. Note that this bears little-to-no relation to the Squirrel.Windows⁠ framework, which doesn't require an active server.

Squirrel.Mac is intended to be integrated with an application. It facilitates the process of checking for, downloading and installing updates.

⁠Update Process

The flow goes something like this:

• An application initializes Squirrel.Mac, gives it a url to hit to check for updates
• Squirrel requests this url
  • If it gets a "204 No Content" response, it assumes no update is required and reports as much to the application
  • Any other response is parsed as JSON, and the "url" field is extracted
• If an update is required, squirrel downloads the given URL, unzips it, and does various prepatatory steps
• Squirrel notifies the application an update is available
• The application presumably asks for user confirmation, then asks Squirrel to apply the update and then restart the application.

⁠Existing Server

There is an existing Squirrel.Server⁠, implemented in ruby. It wasn't sufficient for our case for the following reasons:

• It's inflexible, and only supports hosting updates for a single application
• It would require us to modify our deployment strategy to include restarting the server

⁠This Project

This server is dead simple. It sends a 204 response as appropriate, but otherwise just proxies json files hosted elsewhere It expects two parameters:

• url - the json url to request
• version (optional) - the version of the installed application

The server performs the following steps:

• Requests the url
• Parses the response as json (handling the various error cases)
• Extracts the version field from the json response (which is actually ignored by Squrrel.Mac)
• Compares that against the version query parameter
  • If they match, send 204 No Content
  • If not, send the data along

The server makes to attempt to do any caching, since load should be fairly low.

⁠Running

docker build -t squirrel-server-go .
docker run -d -p 3000:3000 squirrel-server-go