Feature: Exponential Backoff in Retry Middleware

docs/content/middlewares/retry.md

@@ -9,17 +9,19 @@ TODO: add schema
 
 The Retry middleware is in charge of reissuing a request a given number of times to a backend server if that server does not reply.
 To be clear, as soon as the server answers, the middleware stops retrying, regardless of the response status.
+The Retry middleware has an optional configuration for exponential backoff.
 
 ## Configuration Examples
 
 ```yaml tab="Docker"
-# Retry to send request 4 times
+# Retry to send request 4 times with exponential backoff
 labels:
   - "traefik.http.middlewares.test-retry.retry.attempts=4"
+  - "traefik.http.middlewares.test-retry.retry.initialinterval=100ms"
 ```
 
 ```yaml tab="Kubernetes"
-# Retry to send request 4 times
+# Retry to send request 4 times with exponential backoff
 apiVersion: traefik.containo.us/v1alpha1
 kind: Middleware
 metadata:
@@ -27,45 +29,55 @@ metadata:
 spec:
   retry:
     attempts: 4
+    initialInterval: 100ms
 ```
 
 ```yaml tab="Consul Catalog"
-# Retry to send request 4 times
+# Retry to send request 4 times with exponential backoff
 - "traefik.http.middlewares.test-retry.retry.attempts=4"
+- "traefik.http.middlewares.test-retry.retry.initialinterval=100ms"
 ```
 
 ```json tab="Marathon"
 "labels": {
-  "traefik.http.middlewares.test-retry.retry.attempts": "4"
+  "traefik.http.middlewares.test-retry.retry.attempts": "4",
+  "traefik.http.middlewares.test-retry.retry.initialinterval": "100ms",
 }
 ```
 
 ```yaml tab="Rancher"
-# Retry to send request 4 times
+# Retry to send request 4 times with exponential backoff
 labels:
   - "traefik.http.middlewares.test-retry.retry.attempts=4"
+  - "traefik.http.middlewares.test-retry.retry.initialinterval=100ms"
 ```
 
 ```toml tab="File (TOML)"
 # Retry to send request 4 times
 [http.middlewares]
   [http.middlewares.test-retry.retry]
-     attempts = 4
+    attempts = 4
+    initialInterval = "100ms"
 ```
 
 ```yaml tab="File (YAML)"
-# Retry to send request 4 times
+# Retry to send request 4 times with exponential backoff
 http:
   middlewares:
     test-retry:
       retry:
-       attempts: 4
+        attempts: 4
+        initialInterval: 100ms
 ```
 
 ## Configuration Options
 
-### `attempts` 
+### `attempts`
 
 _mandatory_
 
 The `attempts` option defines how many times the request should be retried.
+
+### `initialInterval`
+
+The `initialInterval` option defines the first wait time in the exponential backoff series (provided in seconds or as a valid duration format, see [time.ParseDuration](https://golang.org/pkg/time/#ParseDuration)). The maximum interval is calculated as twice the `initialInterval`. If unspecified, requests will be retried immediately.

docs/content/reference/dynamic-configuration/docker-labels.yml

@@ -112,6 +112,7 @@
 - "traefik.http.middlewares.middleware19.replacepathregex.regex=foobar"
 - "traefik.http.middlewares.middleware19.replacepathregex.replacement=foobar"
 - "traefik.http.middlewares.middleware20.retry.attempts=42"
+- "traefik.http.middlewares.middleware20.retry.initialinterval=42"
 - "traefik.http.middlewares.middleware21.stripprefix.forceslash=true"
 - "traefik.http.middlewares.middleware21.stripprefix.prefixes=foobar, foobar"
 - "traefik.http.middlewares.middleware22.stripprefixregex.regex=foobar, foobar"

docs/content/reference/dynamic-configuration/file.toml

@@ -261,6 +261,7 @@
     [http.middlewares.Middleware20]
       [http.middlewares.Middleware20.retry]
         attempts = 42
+        initialInterval = 42
     [http.middlewares.Middleware21]
       [http.middlewares.Middleware21.stripPrefix]
         prefixes = ["foobar", "foobar"]

docs/content/reference/dynamic-configuration/file.yaml

@@ -298,6 +298,7 @@ http:
     Middleware20:
       retry:
         attempts: 42
+        initialInterval: 42
     Middleware21:
       stripPrefix:
         prefixes:

docs/content/reference/dynamic-configuration/kv-ref.md

@@ -129,6 +129,7 @@
 | `traefik/http/middlewares/Middleware19/replacePathRegex/regex` | `foobar` |
 | `traefik/http/middlewares/Middleware19/replacePathRegex/replacement` | `foobar` |
 | `traefik/http/middlewares/Middleware20/retry/attempts` | `42` |
+| `traefik/http/middlewares/Middleware20/retry/initialInterval` | `42` |
 | `traefik/http/middlewares/Middleware21/stripPrefix/forceSlash` | `true` |
 | `traefik/http/middlewares/Middleware21/stripPrefix/prefixes/0` | `foobar` |
 | `traefik/http/middlewares/Middleware21/stripPrefix/prefixes/1` | `foobar` |

docs/content/reference/dynamic-configuration/marathon-labels.json

@@ -111,6 +111,7 @@
 "traefik.http.middlewares.middleware19.replacepathregex.regex": "foobar",
 "traefik.http.middlewares.middleware19.replacepathregex.replacement": "foobar",
 "traefik.http.middlewares.middleware20.retry.attempts": "42",
+"traefik.http.middlewares.middleware20.retry.initialinterval": "42",
 "traefik.http.middlewares.middleware21.stripprefix.forceslash": "true",
 "traefik.http.middlewares.middleware21.stripprefix.prefixes": "foobar, foobar",
 "traefik.http.middlewares.middleware22.stripprefixregex.regex": "foobar, foobar",