Feature: Exponential Backoff in Retry Middleware

integration/fixtures/retry/backoff.toml

@@ -0,0 +1,45 @@
+[global]
+  checkNewVersion = false
+  sendAnonymousUsage = false
+
+[log]
+  level = "DEBUG"
+
+[entryPoints]
+  [entryPoints.web]
+    address = ":8000"
+
+[api]
+  insecure = true
+
+[providers.file]
+  filename = "{{ .SelfFilename }}"
+
+## dynamic configuration ##
+
+[http.routers]
+  [http.routers.router1]
+    service = "service1"
+    middlewares = [ "retry" ]
+    rule = "PathPrefix(`/`)"
+
+[http.middlewares.retry.retry]
+  attempts = 4
+  initialInterval = "500ms"
+
+
+[http.services]
+  [http.services.service1]
+    [http.services.service1.loadBalancer]
+
+      [[http.services.service1.loadBalancer.servers]]
+        url = "http://{{.WhoamiEndpoint}}:8080"
+
+      [[http.services.service1.loadBalancer.servers]]
+        url = "http://{{.WhoamiEndpoint}}:8081"
+
+      [[http.services.service1.loadBalancer.servers]]
+        url = "http://{{.WhoamiEndpoint}}:8082"
+
+      [[http.services.service1.loadBalancer.servers]]
+        url = "http://{{.WhoamiEndpoint}}:80"

integration/retry_test.go

@@ -34,10 +34,41 @@ func (s *RetrySuite) TestRetry(c *check.C) {
 	err = try.GetRequest("http://127.0.0.1:8080/api/rawdata", 60*time.Second, try.BodyContains("PathPrefix(`/`)"))
 	c.Assert(err, checker.IsNil)
 
+	start := time.Now()
 	// This simulates a DialTimeout when connecting to the backend server.
 	response, err := http.Get("http://127.0.0.1:8000/")
+	duration, allowed := time.Since(start), time.Millisecond*250
 	c.Assert(err, checker.IsNil)
 	c.Assert(response.StatusCode, checker.Equals, http.StatusOK)
+	c.Assert(int64(duration), checker.LessThan, int64(allowed))
+}
+
+func (s *RetrySuite) TestRetryBackoff(c *check.C) {
+	whoamiEndpoint := s.composeProject.Container(c, "whoami").NetworkSettings.IPAddress
+	file := s.adaptFile(c, "fixtures/retry/backoff.toml", struct {
+		WhoamiEndpoint string
+	}{whoamiEndpoint})
+	defer os.Remove(file)
+
+	cmd, display := s.traefikCmd(withConfigFile(file))
+	defer display(c)
+	err := cmd.Start()
+	c.Assert(err, checker.IsNil)
+	defer s.killCmd(cmd)
+
+	err = try.GetRequest("http://127.0.0.1:8080/api/rawdata", 60*time.Second, try.BodyContains("PathPrefix(`/`)"))
+	c.Assert(err, checker.IsNil)
+
+	start := time.Now()
+	// This simulates a DialTimeout when connecting to the backend server.
+	response, err := http.Get("http://127.0.0.1:8000/")
+	duration := time.Since(start)
+	// test case delays: 500 + 700 + 1000ms with randomization.  It should be safely > 1500ms
+	minAllowed := time.Millisecond * 1500
+
+	c.Assert(err, checker.IsNil)
+	c.Assert(response.StatusCode, checker.Equals, http.StatusOK)
+	c.Assert(int64(duration), checker.GreaterThan, int64(minAllowed))
 }
 
 func (s *RetrySuite) TestRetryWebsocket(c *check.C) {