Middleware in Golang

This folder contains my notes and examples of how to write HTTP middleware in Go.

It uses the the standard net/http package, zap for logging, and Alice for easier chaining of middleware.

References:

• https://medium.com/@matryer/the-http-handler-wrapper-technique-in-golang-updated-bc7fbcffa702#.e4k81jxd3
• https://www.nicolasmerouze.com/middlewares-golang-best-practices-examples

Middleware

Currently there are three middleware methods:

• LogMiddleware - logs a start request and end request message.
• ResponseMesserMiddleware - prepends a naughty note to the body of the response by intercepting the ResponseWriter object and redirecting its writes.
• AddHeaderMiddleware - adds an arbitrary header value to the response. This was interesting because I wanted to make the method generic while still making it compatible with Alice, so I actually had to write a method that returned the method expected by Alice's New method.

Testing

All three middlewares have unit tests, which are written in the style of "black-box" tests (i.e. they are written using only the public interfaces of the package). See this GitHub issue and the linked StackOverflow answer for more details on this pattern.

Additionally, you can see some integration testing of the implementations of the middleware in the API in the api/integration folder.