http/tcp checks: fix long timeout behavior to default to user-configured value

agent/checks/check.go

@@ -343,15 +343,10 @@ func (c *CheckHTTP) Start() {
 			Timeout:   10 * time.Second,
 			Transport: trans,
 		}
-
-		// For long (>10s) interval checks the http timeout is 10s, otherwise the
-		// timeout is the interval. This means that a check *should* return
-		// before the next check begins.
-		if c.Timeout > 0 && c.Timeout < c.Interval {
+		if c.Timeout > 0 {
 			c.httpClient.Timeout = c.Timeout
-		} else if c.Interval < 10*time.Second {
-			c.httpClient.Timeout = c.Interval
 		}
+
 		if c.OutputMaxSize < 1 {
 			c.OutputMaxSize = DefaultBufSize
 		}
@@ -482,15 +477,12 @@ func (c *CheckTCP) Start() {
 
 	if c.dialer == nil {
 		// Create the socket dialer
-		c.dialer = &net.Dialer{DualStack: true}
-
-		// For long (>10s) interval checks the socket timeout is 10s, otherwise
-		// the timeout is the interval. This means that a check *should* return
-		// before the next check begins.
-		if c.Timeout > 0 && c.Timeout < c.Interval {
+		c.dialer = &net.Dialer{
+			Timeout:   10 * time.Second,
+			DualStack: true,
+		}
+		if c.Timeout > 0 {
 			c.dialer.Timeout = c.Timeout
-		} else if c.Interval < 10*time.Second {
-			c.dialer.Timeout = c.Interval
 		}
 	}
 

agent/checks/check_test.go

@@ -328,6 +328,69 @@ func TestCheckHTTP(t *testing.T) {
 	}
 }
 
+func TestCheckHTTPTCP_BigTimeout(t *testing.T) {
+	testCases := []struct {
+		timeoutIn, intervalIn, timeoutWant time.Duration
+	}{
+		{
+			timeoutIn:   31 * time.Second,
+			intervalIn:  30 * time.Second,
+			timeoutWant: 31 * time.Second,
+		},
+		{
+			timeoutIn:   30 * time.Second,
+			intervalIn:  30 * time.Second,
+			timeoutWant: 30 * time.Second,
+		},
+		{
+			timeoutIn:   29 * time.Second,
+			intervalIn:  30 * time.Second,
+			timeoutWant: 29 * time.Second,
+		},
+		{
+			timeoutIn:   0 * time.Second,
+			intervalIn:  10 * time.Second,
+			timeoutWant: 10 * time.Second,
+		},
+		{
+			timeoutIn:   0 * time.Second,
+			intervalIn:  30 * time.Second,
+			timeoutWant: 10 * time.Second,
+		},
+		{
+			timeoutIn:   -1 * time.Second,
+			intervalIn:  10 * time.Second,
+			timeoutWant: 10 * time.Second,
+		},
+	}
+
+	for _, tc := range testCases {
+		desc := fmt.Sprintf("timeoutIn: %v, intervalIn: %v", tc.timeoutIn, tc.intervalIn)
+		t.Run(desc, func(t *testing.T) {
+			checkHTTP := &CheckHTTP{
+				Timeout:  tc.timeoutIn,
+				Interval: tc.intervalIn,
+			}
+			checkHTTP.Start()
+			defer checkHTTP.Stop()
+			if checkHTTP.httpClient.Timeout != tc.timeoutWant {
+				t.Fatalf("expected HTTP timeout to be %v, got %v", tc.timeoutWant, checkHTTP.httpClient.Timeout)
+			}
+
+			checkTCP := &CheckTCP{
+				Timeout:  tc.timeoutIn,
+				Interval: tc.intervalIn,
+			}
+			checkTCP.Start()
+			defer checkTCP.Stop()
+			if checkTCP.dialer.Timeout != tc.timeoutWant {
+				t.Fatalf("expected TCP timeout to be %v, got %v", tc.timeoutWant, checkTCP.dialer.Timeout)
+			}
+		})
+
+	}
+}
+
 func TestCheckMaxOutputSize(t *testing.T) {
 	t.Parallel()
 	timeout := 5 * time.Millisecond

website/source/docs/agent/checks.html.md

@@ -51,8 +51,8 @@ There are several different kinds of checks:
   unless the `method` field specifies a different method. Additional header
   fields can be set through the `header` field which is a map of lists of
   strings, e.g. `{"x-foo": ["bar", "baz"]}`. By default, HTTP checks will be
-  configured with a request timeout equal to the check interval, with a max of
-  10 seconds. It is possible to configure a custom HTTP check timeout value by
+  configured with a request timeout equal to 10 seconds.
+  It is possible to configure a custom HTTP check timeout value by
   specifying the `timeout` field in the check definition. The output of the
   check is limited to roughly 4KB. Responses larger than this will be truncated.
   HTTP checks also support TLS. By default, a valid TLS certificate is expected.
@@ -69,10 +69,9 @@ There are several different kinds of checks:
   addresses, and the first successful connection attempt will result in a
   successful check. This type of check should be preferred over a script that
   uses `netcat` or another external process to check a simple socket operation.
-  By default, TCP checks will be configured with a request timeout equal to the
-  check interval, with a max of 10 seconds. It is possible to configure a custom
-  TCP check timeout value by specifying the `timeout` field in the check
-  definition.
+  By default, TCP checks will be configured with a request timeout of 10 seconds. 
+  It is possible to configure a custom TCP check timeout value by specifying the 
+  `timeout` field in the check definition.
 
 * <a name="TTL"></a>Time to Live (TTL) - These checks retain their last known
   state for a given TTL.  The state of the check must be updated periodically