Add -docker-container-name to signal we should exec varnishstat in a …

…container with 'docker exec <container-name>'.

CHANGELOG.md

@@ -1,3 +1,7 @@
+1.4.1
+=====
+* `-docker-container-name` to signal that `varnishstat` should be ran in a docker container with `docker exec <container-name>` .
+
 1.4
 ===
 * Standard non Varnish prometheus metrics need to now be enabled with `-with-go-metrics`. Before they were included by default. Now dropped to export less clutter that majority of users will never need (@nipuntalukdar).

main.go

@@ -34,11 +34,12 @@ var (
 )
 
 type startParams struct {
-	ListenAddress  string
-	Path           string
-	HealthPath     string
-	VarnishstatExe string
-	Params         *varnishstatParams
+	ListenAddress          string
+	Path                   string
+	HealthPath             string
+	VarnishstatExe         string
+	VarnishDockerContainer string
+	Params                 *varnishstatParams
 
 	Verbose       bool
 	NoExit        bool
@@ -79,6 +80,9 @@ func init() {
 	flag.StringVar(&StartParams.Params.Instance, "n", StartParams.Params.Instance, "varnishstat -n value.")
 	flag.StringVar(&StartParams.Params.VSM, "N", StartParams.Params.VSM, "varnishstat -N value.")
 
+	// docker
+	flag.StringVar(&StartParams.VarnishDockerContainer, "docker-container-name", StartParams.VarnishDockerContainer, "Docker container name to exec varnishstat in.")
+
 	// modes
 	version := false
 	flag.BoolVar(&version, "version", version, "Print version and exit")

test/docker-compose.yml

@@ -0,0 +1,25 @@
+version: "2"
+services:
+  varnish:
+    image: eeacms/varnish
+    ports:
+    - "5081:6081"
+    - "5085:6085"
+    depends_on:
+    - hello_world
+    environment:
+      BACKENDS: "hello_world"
+      BACKENDS_PORT: "5090"
+      DNS_ENABLED: "true"
+      BACKENDS_PROBE_INTERVAL: "3s"
+      BACKENDS_PROBE_TIMEOUT: "1s"
+      BACKENDS_PROBE_WINDOW: "3"
+      BACKENDS_PROBE_THRESHOLD: "2"
+      DASHBOARD_USER: "admin"
+      DASHBOARD_PASSWORD: "admin"
+      DASHBOARD_SERVERS: "varnish"
+      DASHBOARD_DNS_ENABLED: "true"
+  hello_world:
+    image: eeacms/hello
+    environment:
+      PORT: "5090"

varnish.go

@@ -169,7 +169,12 @@ func ScrapeVarnishFrom(buf []byte, ch chan<- prometheus.Metric) ([]byte, error)
 // Returns the result of 'varnishtat' with optional command line params.
 func executeVarnishstat(varnishstatExe string, params ...string) (*bytes.Buffer, error) {
 	buf := &bytes.Buffer{}
-	cmd := exec.Command(varnishstatExe, params...)
+	var cmd *exec.Cmd
+	if len(StartParams.VarnishDockerContainer) == 0 {
+		cmd = exec.Command(varnishstatExe, params...)
+	} else {
+		cmd = exec.Command("docker", append([]string{"exec", "-t", StartParams.VarnishDockerContainer, varnishstatExe}, params...)...)
+	}
 	cmd.Stdout = buf
 	cmd.Stderr = buf
 	return buf, cmd.Run()