fix header comparison causing spurious http checks

check.go

@@ -136,7 +136,7 @@ func (c *CheckRunner) updateCheckHTTP(
 		httpCheck, httpCheckExists := c.checksHTTP.Load(checkHash)
 		if httpCheckExists &&
 			httpCheck.HTTP == http.HTTP &&
-			reflect.DeepEqual(httpCheck.Header, http.Header) &&
+			headersAlmostEqual(httpCheck.Header, http.Header) &&
 			httpCheck.Method == http.Method &&
 			httpCheck.TLSClientConfig.InsecureSkipVerify == http.TLSClientConfig.InsecureSkipVerify &&
 			httpCheck.TLSClientConfig.ServerName == http.TLSClientConfig.ServerName &&
@@ -172,6 +172,22 @@ func (c *CheckRunner) updateCheckHTTP(
 	return true
 }
 
+// Compares headers, skipping ones automatically added by Consul
+// in consul/agent/checks/check.go
+func headersAlmostEqual(h1, h2 map[string][]string) bool {
+	skip := map[string]bool{"User-Agent": true, "Accept": true}
+	for k1, v1 := range h1 {
+		if skip[k1] {
+			continue
+		}
+		v2 := h2[k1]
+		if !reflect.DeepEqual(v1, v2) {
+			return false
+		}
+	}
+	return true
+}
+
 func (c *CheckRunner) updateCheckTCP(
 	latestCheck *api.HealthCheck, checkHash types.CheckID,
 	definition *api.HealthCheckDefinition, updated, added checkIDSet,

check_test.go

@@ -423,3 +423,50 @@ func TestCheck_NoFlapping(t *testing.T) {
 	assert.Equal(t, 1, currentCheck.successCounter)
 	assert.Equal(t, api.HealthCritical, currentCheck.Status)
 }
+
+func TestHeadersAlmostEqual(t *testing.T) {
+	type headers map[string][]string
+	type testCase struct {
+		h1, h2 headers
+		equal  bool
+	}
+	testCases := []testCase{
+		{
+			h1:    headers{},
+			h2:    headers{},
+			equal: true,
+		},
+		{
+			h1:    headers{"foo": {"foo"}},
+			h2:    headers{"bar": {"bar"}},
+			equal: false,
+		},
+		{
+			h1:    headers{"User-Agent": {"foo"}},
+			h2:    headers{"Accept": {"bar"}},
+			equal: true,
+		},
+		{
+			h1:    headers{"foo": {"foo"}, "User-Agent": {"foo"}},
+			h2:    headers{"Accept": {"bar"}},
+			equal: false,
+		},
+		{
+			h1:    headers{"foo": {"foo"}, "User-Agent": {"foo"}},
+			h2:    headers{"foo": {"foo"}, "Accept": {"bar"}},
+			equal: true,
+		},
+	}
+	for _, tc := range testCases {
+		switch eq := headersAlmostEqual(tc.h1, tc.h2); tc.equal {
+		case true:
+			if !eq {
+				t.Error("headers should be equal", tc.h1, tc.h2)
+			}
+		case false:
+			if eq {
+				t.Error("headers should NOT be equal", tc.h1, tc.h2)
+			}
+		}
+	}
+}