Add cache-control header and config entry to manage it, closes #71

README.md

@@ -105,6 +105,11 @@ openssl req  -nodes -new -x509  -keyout server.key -out server.crt
 ```
 
 ```toml
+# Cache control configuration. TTL is time in seconds to request
+# that responses be cached by any downstream caching services.
+# Zero means no cache control header will be set.
+CacheTTL = 60
+
 # Advertise URLs relative to this server name
 # default is to looke this up from incoming request headers
 # UrlBase = "http://yourserver.com/"

config/pg_tileserv.toml.example

@@ -27,9 +27,16 @@
 
 # HTTPS configuration - TLS server certificate full chain and key
 # If you do not specify these, the TLS server will not be started
+# To generate self-signed key pair for testing,
+#  openssl req  -nodes -new -x509  -keyout server.key -out server.crt
 # TlsServerCertificateFile = "server.crt"
 # TlsServerPrivateKeyFile = "server.key"
 
+# Cache control configuration. TTL is time in seconds to request
+# that responses be cached by any downstream caching services.
+# Zero means no cache control header will be set.
+# CacheTTL = 0
+
 # Advertise URLs relative to this server name
 # default is to look this up from incoming request headers
 # UrlBase = "http://localhost/"

main.go

@@ -52,6 +52,10 @@ var globalPostGISVersion int = 0
 // which tiles are constructed
 var globalServerBounds *Bounds = nil
 
+// timeToLive is the Cache-Control timeout value that will be advertised
+// in the response headers
+var globalTimeToLive = -1
+
 /******************************************************************************/
 
 func init() {
@@ -75,6 +79,7 @@ func init() {
 	viper.SetDefault("DbTimeout", 10)
 	viper.SetDefault("CORSOrigins", []string{"*"})
 	viper.SetDefault("BasePath", "/")
+	viper.SetDefault("CacheTTL", 0) // cache timeout in seconds
 
 	viper.SetDefault("CoordinateSystem.SRID", 3857)
 	// XMin, YMin, XMax, YMax, must be square
@@ -385,9 +390,13 @@ func (fn tileAppHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 
 /******************************************************************************/
 
-func SetCacheControl(next http.Handler) http.Handler {
+func setCacheControl(next http.Handler) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		w.Header().Set("Cache-Control", "*")
+		ttl := getTTL()
+		if ttl > 0 {
+			ccVal := fmt.Sprintf("max-age=%d", ttl)
+			w.Header().Set("Cache-Control", ccVal)
+		}
 		next.ServeHTTP(w, r)
 	})
 }
@@ -439,7 +448,7 @@ func handleRequests() {
 		ReadTimeout:  1 * time.Second,
 		WriteTimeout: writeTimeout,
 		Addr:         fmt.Sprintf("%s:%d", viper.GetString("HttpHost"), viper.GetInt("HttpPort")),
-		Handler:      handlers.CompressHandler(handlers.CORS(corsOpt)(r)),
+		Handler:      setCacheControl(handlers.CompressHandler(handlers.CORS(corsOpt)(r))),
 	}
 
 	// start http service
@@ -468,7 +477,7 @@ func handleRequests() {
 			ReadTimeout:  1 * time.Second,
 			WriteTimeout: writeTimeout,
 			Addr:         fmt.Sprintf("%s:%d", viper.GetString("HttpHost"), viper.GetInt("HttpsPort")),
-			Handler:      handlers.CompressHandler(handlers.CORS(corsOpt)(r)),
+			Handler:      setCacheControl(handlers.CompressHandler(handlers.CORS(corsOpt)(r))),
 			TLSConfig: &tls.Config{
 				MinVersion: tls.VersionTLS12, // Secure TLS versions only
 			},

util.go

@@ -159,3 +159,10 @@ func getServerBounds() (b *Bounds, e error) {
 	globalServerBounds = &Bounds{srid, xmin, ymin, xmax, ymax}
 	return globalServerBounds, nil
 }
+
+func getTTL() (ttl int) {
+	if globalTimeToLive < 0 {
+		globalTimeToLive = viper.GetInt("CacheTTL")
+	}
+	return globalTimeToLive
+}