Add gRPC MaxConnectionAge config. (#5311)

This allows servers to tell clients to go away after some period of time, which triggers the clients to re-resolve DNS.

Per grpc/grpc#12295, this is the preferred way to do this.

Related: #5307.

cmd/config.go

@@ -269,6 +269,12 @@ type GRPCServerConfig struct {
 	// (SANs). The server will reject clients that do not present a certificate
 	// with a SAN present on the `ClientNames` list.
 	ClientNames []string `json:"clientNames"`
+	// MaxConnectionAge specifies how long a connection may live before the server sends a GoAway to the
+	// client. Because gRPC connections re-resolve DNS after a connection close,
+	// this controls how long it takes before a client learns about changes to its
+	// backends.
+	// https://pkg.go.dev/google.golang.org/grpc/keepalive#ServerParameters
+	MaxConnectionAge ConfigDuration
 }
 
 // PortConfig specifies what ports the VA should call to on the remote

grpc/server.go

@@ -5,12 +5,13 @@ import (
 	"errors"
 	"net"
 
-	"github.com/grpc-ecosystem/go-grpc-prometheus"
+	grpc_prometheus "github.com/grpc-ecosystem/go-grpc-prometheus"
 	"github.com/jmhodges/clock"
 	"github.com/letsencrypt/boulder/cmd"
 	bcreds "github.com/letsencrypt/boulder/grpc/creds"
 	"github.com/prometheus/client_golang/prometheus"
 	"google.golang.org/grpc"
+	"google.golang.org/grpc/keepalive"
 )
 
 // CodedError is a alias required to appease go vet
@@ -42,10 +43,17 @@ func NewServer(c *cmd.GRPCServerConfig, tlsConfig *tls.Config, metrics serverMet
 	}
 
 	si := newServerInterceptor(metrics, clk)
-	return grpc.NewServer(
+	options := []grpc.ServerOption{
 		grpc.Creds(creds),
 		grpc.UnaryInterceptor(si.intercept),
-	), l, nil
+	}
+	if c.MaxConnectionAge.Duration > 0 {
+		options = append(options,
+			grpc.KeepaliveParams(keepalive.ServerParameters{
+				MaxConnectionAge: c.MaxConnectionAge.Duration,
+			}))
+	}
+	return grpc.NewServer(options...), l, nil
 }
 
 // serverMetrics is a struct type used to return a few registered metrics from

test/config-next/akamai-purger.json

@@ -14,6 +14,7 @@
     },
     "grpc": {
       "address": ":9099",
+      "maxConnectionAge": "30s",
       "clientNames": [
         "health-checker.boulder",
         "ra.boulder"

test/config-next/ca-a.json

@@ -8,6 +8,7 @@
     },
     "hostnamePolicyFile": "test/hostname-policy.yaml",
     "grpcCA": {
+      "maxConnectionAge": "30s",
       "address": ":9093",
       "clientNames": [
         "health-checker.boulder",
@@ -15,6 +16,7 @@
       ]
     },
     "grpcOCSPGenerator": {
+      "maxConnectionAge": "30s",
       "address": ":9096",
       "clientNames": [
         "health-checker.boulder",

test/config-next/ca-b.json

@@ -8,6 +8,7 @@
     },
     "hostnamePolicyFile": "test/hostname-policy.yaml",
     "grpcCA": {
+      "maxConnectionAge": "30s",
       "address": ":9093",
       "clientNames": [
         "health-checker.boulder",
@@ -15,6 +16,7 @@
       ]
     },
     "grpcOCSPGenerator": {
+      "maxConnectionAge": "30s",
       "address": ":9096",
       "clientNames": [
         "health-checker.boulder",

test/config-next/nonce.json

@@ -8,6 +8,7 @@
         },
         "debugAddr": ":8111",
         "grpc": {
+            "maxConnectionAge": "30s",
             "address": ":9101",
             "clientNames": [
                 "health-checker.boulder",

test/config-next/publisher.json

@@ -4,6 +4,7 @@
     "blockProfileRate": 1000000000,
     "debugAddr": ":8009",
     "grpc": {
+      "maxConnectionAge": "30s",
       "address": ":9091",
       "clientNames": [
         "health-checker.boulder",

test/config-next/ra.json

@@ -42,6 +42,7 @@
       "timeout": "15s"
     },
     "grpc": {
+      "maxConnectionAge": "30s",
       "address": ":9094",
       "clientNames": [
         "admin-revoker.boulder",

test/config-next/sa.json

@@ -12,6 +12,7 @@
       "keyFile": "test/grpc-creds/sa.boulder/key.pem"
     },
     "grpc": {
+      "maxConnectionAge": "30s",
       "address": ":9095",
       "clientNames": [
         "admin-revoker.boulder",

test/config-next/va-remote-a.json

@@ -19,6 +19,7 @@
       "keyFile": "test/grpc-creds/va.boulder/key.pem"
     },
     "grpc": {
+      "maxConnectionAge": "30s",
       "address": ":9097",
       "clientNames": [
         "health-checker.boulder",

test/config-next/va-remote-b.json

@@ -19,6 +19,7 @@
       "keyFile": "test/grpc-creds/va.boulder/key.pem"
     },
     "grpc": {
+      "maxConnectionAge": "30s",
       "address": ":9098",
       "clientNames": [
         "health-checker.boulder",

test/config-next/va.json

@@ -19,6 +19,7 @@
       "keyFile": "test/grpc-creds/va.boulder/key.pem"
     },
     "grpc": {
+      "maxConnectionAge": "30s",
       "address": ":9092",
       "clientNames": [
         "health-checker.boulder",