tunnel: introduce custom Duration for time fields

All Tunnel timeout values are based on seconds however, there isn't a great way
to do this in a flexible way with Go due to `time.Duration` not having
marshal/unmarshal support in Go 1[1]. Instead, we introduce a custom
`TunnelDuration` value here and ensure it always converts durations into
seconds without impacting other users of `time.Duration`.

[1]: golang/go#10275

.changelog/1303.txt

@@ -0,0 +1,3 @@
+```release-note:breaking-change
+tunnel: swap `ConnectTimeout`, `TLSTimeout`, `TCPKeepAlive` and `KeepAliveTimeout` to `TunnelDuration` instead of `time.Duration`
+```

tunnel.go

@@ -6,9 +6,34 @@ import (
 	"errors"
 	"fmt"
 	"net/http"
+	"strconv"
 	"time"
 )
 
+// A TunnelDuration is a Duration that has custom serialization for JSON.
+// JSON in Javascript assumes that int fields are 32 bits and Duration fields
+// are deserialized assuming that numbers are in nanoseconds, which in 32bit
+// integers limits to just 2 seconds. This type assumes that when
+// serializing/deserializing from JSON, that the number is in seconds, while it
+// maintains the YAML serde assumptions.
+type TunnelDuration struct {
+	time.Duration
+}
+
+func (s TunnelDuration) MarshalJSON() ([]byte, error) {
+	return json.Marshal(s.Duration.Seconds())
+}
+
+func (s *TunnelDuration) UnmarshalJSON(data []byte) error {
+	seconds, err := strconv.ParseInt(string(data), 10, 64)
+	if err != nil {
+		return err
+	}
+
+	s.Duration = time.Duration(seconds * int64(time.Second))
+	return nil
+}
+
 // ErrMissingTunnelID is for when a required tunnel ID is missing from the
 // parameters.
 var ErrMissingTunnelID = errors.New("required missing tunnel ID")
@@ -118,17 +143,17 @@ type UnvalidatedIngressRule struct {
 // config.
 type OriginRequestConfig struct {
 	// HTTP proxy timeout for establishing a new connection
-	ConnectTimeout *time.Duration `json:"connectTimeout,omitempty"`
+	ConnectTimeout *TunnelDuration `json:"connectTimeout,omitempty"`
 	// HTTP proxy timeout for completing a TLS handshake
-	TLSTimeout *time.Duration `json:"tlsTimeout,omitempty"`
+	TLSTimeout *TunnelDuration `json:"tlsTimeout,omitempty"`
 	// HTTP proxy TCP keepalive duration
-	TCPKeepAlive *time.Duration `json:"tcpKeepAlive,omitempty"`
+	TCPKeepAlive *TunnelDuration `json:"tcpKeepAlive,omitempty"`
 	// HTTP proxy should disable "happy eyeballs" for IPv4/v6 fallback
 	NoHappyEyeballs *bool `json:"noHappyEyeballs,omitempty"`
 	// HTTP proxy maximum keepalive connection pool size
 	KeepAliveConnections *int `json:"keepAliveConnections,omitempty"`
 	// HTTP proxy timeout for closing an idle connection
-	KeepAliveTimeout *time.Duration `json:"keepAliveTimeout,omitempty"`
+	KeepAliveTimeout *TunnelDuration `json:"keepAliveTimeout,omitempty"`
 	// Sets the HTTP Host header for the local webserver.
 	HTTPHostHeader *string `json:"httpHostHeader,omitempty"`
 	// Hostname on the origin server certificate.

tunnel_test.go

@@ -210,7 +210,7 @@ func TestUpdateTunnelConfiguration(t *testing.T) {
 				Enabled: true,
 			},
 			OriginRequest: OriginRequestConfig{
-				ConnectTimeout: DurationPtr(10),
+				ConnectTimeout: &TunnelDuration{10},
 			},
 		}}
 
@@ -233,7 +233,7 @@ func TestUpdateTunnelConfiguration(t *testing.T) {
 				Enabled: true,
 			},
 			OriginRequest: OriginRequestConfig{
-				ConnectTimeout: DurationPtr(10 * time.Second),
+				ConnectTimeout: &TunnelDuration{10},
 			},
 		},
 	})
@@ -275,7 +275,7 @@ func TestGetTunnelConfiguration(t *testing.T) {
 				Enabled: true,
 			},
 			OriginRequest: OriginRequestConfig{
-				ConnectTimeout: DurationPtr(10),
+				ConnectTimeout: &TunnelDuration{10},
 			},
 		}}