feat: enables healthcheck via cli for containerized deployments

cmd/app/health.go

@@ -0,0 +1,60 @@
+package main
+
+import (
+	"context"
+	"crypto/tls"
+	"net"
+	"net/http"
+	"os"
+	"strconv"
+	"time"
+)
+
+const healthProbeTimeout = 5 * time.Second
+
+// runHealthCheck probes the local health endpoint and exits with 0 on
+// HTTP 2xx, 1 otherwise.
+func runHealthCheck() {
+	os.Exit(probeHealth())
+}
+
+func probeHealth() int {
+	port := os.Getenv("HTTP_PORT")
+	if port == "" {
+		port = "8181"
+	}
+
+	scheme := "https"
+	if v, err := strconv.ParseBool(os.Getenv("HTTP_TLS_ENABLED")); err == nil && !v {
+		scheme = "http"
+	}
+
+	client := &http.Client{
+		Timeout: healthProbeTimeout,
+		Transport: &http.Transport{
+			TLSClientConfig: &tls.Config{InsecureSkipVerify: true}, //nolint:gosec // self-signed local probe
+		},
+	}
+	// Local probe targeting the loopback address on a fixed path.
+	url := scheme + "://" + net.JoinHostPort("127.0.0.1", port) + "/healthz"
+
+	ctx, cancel := context.WithTimeout(context.Background(), healthProbeTimeout)
+	defer cancel()
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, http.NoBody) //nolint:gosec // G107: trusted loopback URL built from env-validated port
+	if err != nil {
+		return 1
+	}
+
+	resp, err := client.Do(req) //nolint:gosec // G704: trusted loopback URL built from env-validated port
+	if err != nil {
+		return 1
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
+		return 1
+	}
+
+	return 0
+}

cmd/app/main.go

@@ -35,6 +35,10 @@ var (
 )
 
 func main() {
+	if len(os.Args) > 1 && (os.Args[1] == "--health" || os.Args[1] == "-health") {
+		runHealthCheck()
+	}
+
 	cfg, err := initializeConfigFunc()
 	if err != nil {
 		log.Fatalf("Config error: %s", err)