Initial revisin of healthchecker, inspired by HAProxy

internal/prober/tcp.go

@@ -0,0 +1,76 @@
+package prober
+
+import (
+	"context"
+	"crypto/tls"
+	"net"
+	"strconv"
+	"time"
+
+	"git.ipng.ch/ipng/vpp-maglev/internal/health"
+)
+
+// TCPProbe performs a TCP connect to cfg.Target:cfg.Port inside the healthcheck
+// netns. If cfg.TCP.SSL is true a TLS handshake is performed after connect,
+// making this an L6 check (useful for smtps, imaps, etc.).
+// Plain connect returns L4OK/L4TOUT/L4CON.
+// TLS handshake returns L6OK/L6TOUT/L6RSP (on top of an L4OK connect).
+func TCPProbe(ctx context.Context, cfg ProbeConfig) health.ProbeResult {
+	port := cfg.Port
+	if port == 0 {
+		port = 80
+	}
+	addr := net.JoinHostPort(cfg.Target.String(), strconv.Itoa(int(port)))
+
+	doTLS := cfg.TCP != nil && cfg.TCP.SSL
+	var serverName string
+	var insecureSkipVerify bool
+	if cfg.TCP != nil {
+		serverName = cfg.TCP.ServerName
+		insecureSkipVerify = cfg.TCP.InsecureSkipVerify
+	}
+
+	var result health.ProbeResult
+	err := inNetns(cfg.HealthCheckNetns, func() error {
+		dialer := &net.Dialer{Timeout: cfg.Timeout}
+		if cfg.ProbeSrc != nil {
+			dialer.LocalAddr = &net.TCPAddr{IP: cfg.ProbeSrc}
+		}
+		conn, err := dialer.DialContext(ctx, "tcp", addr)
+		if err != nil {
+			if isTimeout(err) {
+				result = health.ProbeResult{OK: false, Layer: health.LayerL4, Code: "L4TOUT", Detail: err.Error()}
+			} else {
+				result = health.ProbeResult{OK: false, Layer: health.LayerL4, Code: "L4CON", Detail: err.Error()}
+			}
+			return nil
+		}
+
+		if !doTLS {
+			conn.Close()
+			result = health.ProbeResult{OK: true, Layer: health.LayerL4, Code: "L4OK"}
+			return nil
+		}
+
+		// TLS handshake.
+		tlsConn := tls.Client(conn, tlsConfig(serverName, insecureSkipVerify))
+		tlsConn.SetDeadline(time.Now().Add(cfg.Timeout)) //nolint:errcheck
+		if err := tlsConn.HandshakeContext(ctx); err != nil {
+			tlsConn.Close()
+			if isTimeout(err) {
+				result = health.ProbeResult{OK: false, Layer: health.LayerL6, Code: "L6TOUT", Detail: err.Error()}
+			} else {
+				result = health.ProbeResult{OK: false, Layer: health.LayerL6, Code: "L6RSP", Detail: err.Error()}
+			}
+			return nil
+		}
+		tlsConn.Close()
+		result = health.ProbeResult{OK: true, Layer: health.LayerL6, Code: "L6OK"}
+		return nil
+	})
+
+	if err != nil {
+		return health.ProbeResult{OK: false, Layer: health.LayerL4, Code: "L4CON", Detail: err.Error()}
+	}
+	return result
+}