agent: Allow custom HTTP headers and method for checks (#3106)

This patch adds support for custom headers and
method for HTTP checks.

Fixes #2474
Fixes #2657
Fixes #3106

api/agent.go

@@ -67,17 +67,19 @@ type AgentCheckRegistration struct {
 
 // AgentServiceCheck is used to define a node or service level check
 type AgentServiceCheck struct {
-	Script            string `json:",omitempty"`
-	DockerContainerID string `json:",omitempty"`
-	Shell             string `json:",omitempty"` // Only supported for Docker.
-	Interval          string `json:",omitempty"`
-	Timeout           string `json:",omitempty"`
-	TTL               string `json:",omitempty"`
-	HTTP              string `json:",omitempty"`
-	TCP               string `json:",omitempty"`
-	Status            string `json:",omitempty"`
-	Notes             string `json:",omitempty"`
-	TLSSkipVerify     bool   `json:",omitempty"`
+	Script            string              `json:",omitempty"`
+	DockerContainerID string              `json:",omitempty"`
+	Shell             string              `json:",omitempty"` // Only supported for Docker.
+	Interval          string              `json:",omitempty"`
+	Timeout           string              `json:",omitempty"`
+	TTL               string              `json:",omitempty"`
+	HTTP              string              `json:",omitempty"`
+	Header            map[string][]string `json:",omitempty"`
+	Method            string              `json:",omitempty"`
+	TCP               string              `json:",omitempty"`
+	Status            string              `json:",omitempty"`
+	Notes             string              `json:",omitempty"`
+	TLSSkipVerify     bool                `json:",omitempty"`
 
 	// In Consul 0.7 and later, checks that are associated with a service
 	// may also contain this optional DeregisterCriticalServiceAfter field,

command/agent/agent.go

@@ -1575,6 +1575,8 @@ func (a *Agent) AddCheck(check *structs.HealthCheck, chkType *CheckType, persist
 				Notify:        &a.state,
 				CheckID:       check.CheckID,
 				HTTP:          chkType.HTTP,
+				Header:        chkType.Header,
+				Method:        chkType.Method,
 				Interval:      chkType.Interval,
 				Timeout:       chkType.Timeout,
 				Logger:        a.logger,

command/agent/check.go

@@ -57,6 +57,8 @@ type CheckType struct {
 
 	Script            string
 	HTTP              string
+	Header            map[string][]string
+	Method            string
 	TCP               string
 	Interval          time.Duration
 	DockerContainerID string
@@ -347,6 +349,8 @@ type CheckHTTP struct {
 	Notify        CheckNotifier
 	CheckID       types.CheckID
 	HTTP          string
+	Header        map[string][]string
+	Method        string
 	Interval      time.Duration
 	Timeout       time.Duration
 	Logger        *log.Logger
@@ -429,15 +433,25 @@ func (c *CheckHTTP) run() {
 
 // check is invoked periodically to perform the HTTP check
 func (c *CheckHTTP) check() {
-	req, err := http.NewRequest("GET", c.HTTP, nil)
+	method := c.Method
+	if method == "" {
+		method = "GET"
+	}
+
+	req, err := http.NewRequest(method, c.HTTP, nil)
 	if err != nil {
 		c.Logger.Printf("[WARN] agent: http request failed '%s': %s", c.HTTP, err)
 		c.Notify.UpdateCheck(c.CheckID, api.HealthCritical, err.Error())
 		return
 	}
 
-	req.Header.Set("User-Agent", UserAgent)
-	req.Header.Set("Accept", "text/plain, text/*, */*")
+	req.Header = http.Header(c.Header)
+	if req.Header.Get("User-Agent") == "" {
+		req.Header.Set("User-Agent", UserAgent)
+	}
+	if req.Header.Get("Accept") == "" {
+		req.Header.Set("Accept", "text/plain, text/*, */*")
+	}
 
 	resp, err := c.httpClient.Do(req)
 	if err != nil {

command/agent/config.go

@@ -1437,6 +1437,20 @@ func FixupCheckType(raw interface{}) error {
 		case "service_id":
 			rawMap["serviceid"] = v
 			delete(rawMap, k)
+		case "header":
+			vm, ok := v.(map[string]interface{})
+			if ok {
+				m := map[string][]string{}
+				for k, vv := range vm {
+					vs, ok := vv.([]interface{})
+					if ok {
+						for _, s := range vs {
+							m[k] = append(m[k], s.(string))
+						}
+					}
+				}
+				rawMap["header"] = m
+			}
 		case "docker_container_id":
 			rawMap["DockerContainerID"] = v
 			delete(rawMap, k)

command/agent/config_test.go

@@ -1429,6 +1429,17 @@ func TestDecodeConfig_Checks(t *testing.T) {
 				"timeout": "100ms",
 				"service_id": "insecure-sslservice",
 				"tls_skip_verify": true
+			},
+			{
+				"id": "chk7",
+				"name": "service:insecure-sslservice",
+				"HTTP": "https://insecure-sslservice/status",
+				"Header": {"a":["b"], "c":["d", "e"]},
+				"Method": "PUT",
+				"interval": "10s",
+				"timeout": "100ms",
+				"service_id": "insecure-sslservice",
+				"tls_skip_verify": true
 			}
 		]
 	}`
@@ -1485,6 +1496,17 @@ func TestDecodeConfig_Checks(t *testing.T) {
 				Timeout:       100 * time.Millisecond,
 				TLSSkipVerify: true,
 			},
+			&CheckDefinition{
+				ID:            "chk7",
+				Name:          "service:insecure-sslservice",
+				ServiceID:     "insecure-sslservice",
+				HTTP:          "https://insecure-sslservice/status",
+				Header:        map[string][]string{"a": []string{"b"}, "c": []string{"d", "e"}},
+				Method:        "PUT",
+				Interval:      10 * time.Second,
+				Timeout:       100 * time.Millisecond,
+				TLSSkipVerify: true,
+			},
 		},
 	}
 	verify.Values(t, "", got, want)

command/agent/structs.go

@@ -62,6 +62,8 @@ type CheckDefinition struct {
 	//
 	Script                         string
 	HTTP                           string
+	Header                         map[string][]string
+	Method                         string
 	TCP                            string
 	Interval                       time.Duration
 	DockerContainerID              string