Proxy middleware docs update to include retry config

website/content/middleware/proxy.md

@@ -43,32 +43,64 @@ e.Use(middleware.ProxyWithConfig(middleware.ProxyConfig{}))
 
 ```go
 // ProxyConfig defines the config for Proxy middleware.
-  ProxyConfig struct {
-    // Skipper defines a function to skip middleware.
-    Skipper Skipper
-
-    // Balancer defines a load balancing technique.
-    // Required.
-    Balancer ProxyBalancer
-
-    // Rewrite defines URL path rewrite rules. The values captured in asterisk can be
-    // retrieved by index e.g. $1, $2 and so on.
-    Rewrite map[string]string
-
-    // RegexRewrite defines rewrite rules using regexp.Rexexp with captures
-    // Every capture group in the values can be retrieved by index e.g. $1, $2 and so on.
-    RegexRewrite map[*regexp.Regexp]string
-
-    // Context key to store selected ProxyTarget into context.
-    // Optional. Default value "target".
-    ContextKey string
-
-    // To customize the transport to remote.
-    // Examples: If custom TLS certificates are required.
-    Transport http.RoundTripper
-
-    // ModifyResponse defines function to modify response from ProxyTarget.
-    ModifyResponse func(*http.Response) error
+ProxyConfig struct {
+
+  // Skipper defines a function to skip middleware.
+  Skipper Skipper
+
+  // Balancer defines a load balancing technique.
+  // Required.
+  Balancer ProxyBalancer
+
+  // RetryCount defines the number of times a failed proxied request should be
+  // retried using the next available ProxyTarget. Defaults to 0, meaning
+  // requests are never retried.
+  RetryCount int
+
+  // RetryFilter defines a function used to determine if a failed request to a
+  // ProxyTarget should be retried. The RetryFilter will only be called when the
+  // number of previous retries is less than RetryCount. If the function returns
+  // true, the request will be retried. The provided error indicates the reason
+  // for the request failure. When the ProxyTarget is unavailable, the error will
+  // be an instance of echo.HTTPError with a Code of http.StatusBadGateway. In all
+  // other cases, the error will indicate an internal error in the Proxy middleware.
+  // When a RetryFilter is not specified, all requests that fail with
+  // http.StatusBadGateway will be retried. A custom RetryFilter can be provided to
+  // only retry specific requests. Note that RetryFilter is only called when the
+  // request to the target fails, or an internal error in the Proxy middleware has
+  // occurred. Successful requests that return a non-200 response code cannot be
+  // retried.
+  RetryFilter func(c echo.Context, e error) bool
+
+  // ErrorHandler defines a function which can be used to return custom errors from
+  // the Proxy middleware. ErrorHandler is only invoked when there has been either
+  // an internal error in the Proxy middleware or the ProxyTarget is unavailable.
+  // Due to the way requests are proxied, ErrorHandler is not invoked when a
+  // ProxyTarget returns a non-200 response. In these cases, the response is already
+  // written so errors cannot be modified. ErrorHandler is only invoked after all
+  // retry attempts have been exhausted.
+  ErrorHandler func(c echo.Context, err error) error
+
+  // Rewrite defines URL path rewrite rules. The values captured in asterisk can be
+  // retrieved by index e.g. $1, $2 and so on.
+  Rewrite map[string]string
+
+  // RegexRewrite defines rewrite rules using regexp.Rexexp with captures
+  // Every capture group in the values can be retrieved by index e.g. $1, $2 and
+  // so on.
+  RegexRewrite map[*regexp.Regexp]string
+
+  // Context key to store selected ProxyTarget into context.
+  // Optional. Default value "target".
+  ContextKey string
+
+  // To customize the transport to remote.
+  // Examples: If custom TLS certificates are required.
+  Transport http.RoundTripper
+
+  // ModifyResponse defines function to modify response from ProxyTarget.
+  ModifyResponse func(*http.Response) error
+}
 ```
 
 Default Configuration:
@@ -77,6 +109,7 @@ Default Configuration:
 | ---------- | -------------- |
 | Skipper    | DefaultSkipper |
 | ContextKey | `target`       |
+| RetryCount | 0              |
 
 ### Regex-based Rules