allow specification of source address for probes (http, grpc)

CONFIGURATION.md

@@ -153,6 +153,9 @@ modules:
   [ preferred_ip_protocol: <string> | default = "ip6" ]
   [ ip_protocol_fallback: <boolean> | default = true ]
 
+  # The source IP address.
+  [ source_ip_address: <string> ]
+
   # The body of the HTTP request used in probe.
   [ body: <string> ]
 
@@ -310,6 +313,9 @@ validate_additional_rrs:
 [ preferred_ip_protocol: <string> ]
 [ ip_protocol_fallback: <boolean> | default = true ]
 
+# The source IP address.
+[ source_ip_address: <string> ]
+
 # Whether to connect to the endpoint with TLS.
 [ tls: <boolean | default = false> ]
 

config/config.go

@@ -208,6 +208,7 @@ type HTTPProbe struct {
 	ValidHTTPVersions            []string                `yaml:"valid_http_versions,omitempty"`
 	IPProtocol                   string                  `yaml:"preferred_ip_protocol,omitempty"`
 	IPProtocolFallback           bool                    `yaml:"ip_protocol_fallback,omitempty"`
+	SourceIPAddress              string                  `yaml:"source_ip_address,omitempty"`
 	SkipResolvePhaseWithProxy    bool                    `yaml:"skip_resolve_phase_with_proxy,omitempty"`
 	NoFollowRedirects            *bool                   `yaml:"no_follow_redirects,omitempty"`
 	FailIfSSL                    bool                    `yaml:"fail_if_ssl,omitempty"`
@@ -230,6 +231,7 @@ type GRPCProbe struct {
 	TLS                 bool             `yaml:"tls,omitempty"`
 	TLSConfig           config.TLSConfig `yaml:"tls_config,omitempty"`
 	IPProtocolFallback  bool             `yaml:"ip_protocol_fallback,omitempty"`
+	SourceIPAddress     string           `yaml:"source_ip_address,omitempty"`
 	PreferredIPProtocol string           `yaml:"preferred_ip_protocol,omitempty"`
 }
 

prober/grpc.go

@@ -15,6 +15,11 @@ package prober
 
 import (
 	"context"
+	"net"
+	"net/url"
+	"strings"
+	"time"
+
 	"github.com/go-kit/log"
 	"github.com/go-kit/log/level"
 	"github.com/prometheus/blackbox_exporter/config"
@@ -27,10 +32,6 @@ import (
 	"google.golang.org/grpc/health/grpc_health_v1"
 	"google.golang.org/grpc/peer"
 	"google.golang.org/grpc/status"
-	"net"
-	"net/url"
-	"strings"
-	"time"
 )
 
 type GRPCHealthCheck interface {
@@ -182,6 +183,21 @@ func ProbeGRPC(ctx context.Context, target string, module config.Module, registr
 		}
 	}
 
+	// Use configured SourceIPAddress.
+	if len(module.GRPC.SourceIPAddress) > 0 {
+		srcIP := net.ParseIP(module.GRPC.SourceIPAddress)
+		if srcIP == nil {
+			level.Error(logger).Log("msg", "Error parsing source ip address", "srcIP", module.GRPC.SourceIPAddress)
+			return false
+		}
+		level.Info(logger).Log("msg", "Using local address", "srcIP", srcIP)
+		opts = append(opts, grpc.WithContextDialer(func(ctx context.Context, addr string) (net.Conn, error) {
+			return (&net.Dialer{
+				LocalAddr: &net.IPAddr{IP: srcIP},
+			}).DialContext(ctx, "tcp", addr)
+		}))
+	}
+
 	conn, err := grpc.Dial(target, opts...)
 
 	if err != nil {

prober/http.go

@@ -353,6 +353,23 @@ func ProbeHTTP(ctx context.Context, target string, module config.Module, registr
 		level.Error(logger).Log("msg", "Error generating HTTP client", "err", err)
 		return false
 	}
+	// Use configured SourceIPAddress.
+	if len(module.HTTP.SourceIPAddress) > 0 {
+		srcIP := net.ParseIP(module.HTTP.SourceIPAddress)
+		if srcIP == nil {
+			level.Error(logger).Log("msg", "Error parsing source ip address", "srcIP", module.HTTP.SourceIPAddress)
+			return false
+		}
+		level.Info(logger).Log("msg", "Using local address", "srcIP", srcIP)
+		client, err = pconfig.NewClientFromConfig(httpClientConfig, "http_probe", pconfig.WithKeepAlivesDisabled(),
+			pconfig.WithDialContextFunc((&net.Dialer{
+				LocalAddr: &net.IPAddr{IP: srcIP},
+			}).DialContext))
+		if err != nil {
+			level.Error(logger).Log("msg", "Error generating HTTP client", "err", err)
+			return false
+		}
+	}
 
 	httpClientConfig.TLSConfig.ServerName = ""
 	noServerName, err := pconfig.NewRoundTripperFromConfig(httpClientConfig, "http_probe", pconfig.WithKeepAlivesDisabled())