feat: support compression

This commit adds the ability to enable compression for websockets.
The compression is disabled by default due to the fact that it is marked
as experimental in gorilla/websocket and there have been issues with
compression whenever Safari is enabled.
This commit partially addresses #30.

CHANGELOG.md

@@ -7,6 +7,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 ### Added
+- Support for websocket compression - disabled by default (#40)
 ### Changed
 ### Fixed
 ### Docs

config.sample.yaml

@@ -6,6 +6,7 @@ webserver:
   domains_only_url: "/domains-only"
   cert_path: ""
   cert_key_path: ""
+  compression_enabled: false
 
 prometheus:
   enabled: true

internal/config/config.go

@@ -27,10 +27,11 @@ type ServerConfig struct {
 
 type Config struct {
 	Webserver struct {
-		ServerConfig   `yaml:",inline"`
-		FullURL        string `yaml:"full_url"`
-		LiteURL        string `yaml:"lite_url"`
-		DomainsOnlyURL string `yaml:"domains_only_url"`
+		ServerConfig       `yaml:",inline"`
+		FullURL            string `yaml:"full_url"`
+		LiteURL            string `yaml:"lite_url"`
+		DomainsOnlyURL     string `yaml:"domains_only_url"`
+		CompressionEnabled *bool  `yaml:"compression_enabled,omitempty"`
 	}
 	Prometheus struct {
 		ServerConfig        `yaml:",inline"`
@@ -134,6 +135,17 @@ func validateConfig(config Config) bool {
 		return false
 	}
 
+	if config.Webserver.CompressionEnabled == nil {
+		// On one hand the Calidog certstream server does support compression by default, however
+		// the gorilla/websocket library has had issues with Safari clients.
+		// See: https://github.com/gorilla/websocket/issues/731
+		// Moreover according to gorilla/weboscket documentation, the support is experimental
+		// See: https://pkg.go.dev/github.com/gorilla/websocket#hdr-Compression_EXPERIMENTAL
+		// Thus lets default to false - i.e. disable compression by default
+		CompressionEnabled := false
+		config.Webserver.CompressionEnabled = &CompressionEnabled
+	}
+
 	if config.Webserver.FullURL == "" || !URLRegex.MatchString(config.Webserver.FullURL) {
 		log.Println("Webhook full URL is not set or does not match pattern '/...'")
 		config.Webserver.FullURL = "/full-stream"

internal/web/server.go

@@ -20,7 +20,7 @@ import (
 
 var (
 	ClientHandler = BroadcastManager{}
-	upgrader      = websocket.Upgrader{} // use default options
+	upgrader      websocket.Upgrader
 )
 
 type WebServer struct {
@@ -248,7 +248,8 @@ func NewMetricsServer(networkIf string, port int, certPath, keyPath string) *Web
 }
 
 // NewWebsocketServer starts a new webserver and initialized it with the necessary routes.
-// It also starts the broadcaster in ClientHandler as a background job.
+// It also starts the broadcaster in ClientHandler as a background job and takes care of
+// setting up websocket.Upgrader.
 func NewWebsocketServer(networkIf string, port int, certPath, keyPath string) *WebServer {
 	server := &WebServer{
 		networkIf: networkIf,
@@ -258,6 +259,10 @@ func NewWebsocketServer(networkIf string, port int, certPath, keyPath string) *W
 		keyPath:   keyPath,
 	}
 
+	upgrader = websocket.Upgrader{
+		EnableCompression: *config.AppConfig.Webserver.CompressionEnabled,
+	}
+
 	if config.AppConfig.Webserver.RealIP {
 		server.routes.Use(middleware.RealIP)
 	}