Middleware
Overview
Middleware is a function chained in the HTTP request-response cycle with accessto Echo#Context
which it uses to perform a specific action, for example, loggingevery request or limiting the number of requests.
Handler is processed in the end after all middleware are finished executing.
Middleware registed using Echo#Use()
is only executed for paths which areregistered after Echo#Use()
has been called.
Levels
Root Level (Before router)
Echo#Pre()
can be used to register a middleware which is executed before routerprocesses the request. It is helpful to make any changes to the request properties,for example, adding or removing a trailing slash from the path so it matches theroute.
The following built-in middleware should be registered at this level:
- HTTPSRedirect
- HTTPSWWWRedirect
- WWWRedirect
- NonWWWRedirect
- AddTrailingSlash
- RemoveTrailingSlash
- MethodOverride
- Rewrite
As router has not processed the request, middleware at this level won’thave access to any path related API from
echo.Context
.
Root Level (After router)
Most of the time you will register a middleware at this level using Echo#Use()
.This middleware is executed after router processes the request and has full accessto echo.Context
API.
The following built-in middleware should be registered at this level:
- BodyLimit
- Logger
- Gzip
- Recover
- BasicAuth
- JWTAuth
- Secure
- CORS
- Static
Group Level
When creating a new group, you can register middleware just for that group. Forexample, you can have an admin group which is secured by registering a BasicAuthmiddleware for it.
Usage
e := echo.New()
admin := e.Group("/admin", middleware.BasicAuth())
You can also add a middleware after creating a group via admin.Use()
.
Route Level
When defining a new route, you can optionally register middleware just for it.
Usage
e := echo.New()
e.GET("/", <Handler>, <Middleware...>)
Skipping Middleware
There are cases when you would like to skip a middleware based on some condition,for that each middleware has an option to define a function Skipper func(c echo.Context) bool
.
Usage
e := echo.New()
e.Use(middleware.LoggerWithConfig(middleware.LoggerConfig{
Skipper: func(c echo.Context) bool {
if strings.HasPrefix(c.Request().Host, "localhost") {
return true
}
return false
},
}))
Example above skips Logger middleware when request host starts with localhost.