chore: consolidate all CLI configuration (#233)

This is a port of GoogleCloudPlatform/cloud-sql-proxy#1563.

cmd/root.go

@@ -82,30 +82,10 @@ func Execute() {
 // Command represents an invocation of the AlloyDB Auth Proxy.
 type Command struct {
 	*cobra.Command
-	conf   *proxy.Config
-	logger alloydb.Logger
-	dialer alloydb.Dialer
-
-	cleanup                    func() error
-	disableTraces              bool
-	telemetryTracingSampleRate int
-	disableMetrics             bool
-	telemetryProject           string
-	telemetryPrefix            string
-	prometheus                 bool
-	prometheusNamespace        string
-	healthCheck                bool
-	httpAddress                string
-	httpPort                   string
-	quiet                      bool
-	otherUserAgents            string
-
-	// impersonationChain is a comma separated list of one or more service
-	// accounts. The first entry in the chain is the impersonation target. Any
-	// additional service accounts after the target are delegates. The
-	// roles/iam.serviceAccountTokenCreator must be configured for each account
-	// that will be impersonated.
-	impersonationChain string
+	conf    *proxy.Config
+	logger  alloydb.Logger
+	dialer  alloydb.Dialer
+	cleanup func() error
 }
 
 // Option is a function that configures a Command.
@@ -337,7 +317,7 @@ func NewCommand(opts ...Option) *Command {
 		if c.conf.StructuredLogs {
 			c.logger, c.cleanup = log.NewStructuredLogger()
 		}
-		if c.quiet {
+		if c.conf.Quiet {
 			c.logger = log.NewStdLogger(io.Discard, os.Stderr)
 		}
 		err := parseConfig(c, c.conf, args)
@@ -356,7 +336,7 @@ func NewCommand(opts ...Option) *Command {
 	pflags := cmd.PersistentFlags()
 
 	// Global-only flags
-	pflags.StringVar(&c.otherUserAgents, "user-agent", "",
+	pflags.StringVar(&c.conf.OtherUserAgents, "user-agent", "",
 		"Space separated list of additional user agents, e.g. cloud-sql-proxy-operator/0.0.1")
 	pflags.StringVarP(&c.conf.Token, "token", "t", "",
 		"Bearer token used for authorization.")
@@ -384,30 +364,30 @@ the maximum time has passed. Defaults to 0s.`)
 	pflags.StringVar(&c.conf.FUSETempDir, "fuse-tmp-dir",
 		filepath.Join(os.TempDir(), "alloydb-tmp"),
 		"Temp dir for Unix sockets created with FUSE")
-	pflags.StringVar(&c.impersonationChain, "impersonate-service-account", "",
+	pflags.StringVar(&c.conf.ImpersonationChain, "impersonate-service-account", "",
 		`Comma separated list of service accounts to impersonate. Last value
 +is the target account.`)
-	cmd.PersistentFlags().BoolVar(&c.quiet, "quiet", false, "Log error messages only")
+	cmd.PersistentFlags().BoolVar(&c.conf.Quiet, "quiet", false, "Log error messages only")
 
-	pflags.StringVar(&c.telemetryProject, "telemetry-project", "",
+	pflags.StringVar(&c.conf.TelemetryProject, "telemetry-project", "",
 		"Enable Cloud Monitoring and Cloud Trace integration with the provided project ID.")
-	pflags.BoolVar(&c.disableTraces, "disable-traces", false,
+	pflags.BoolVar(&c.conf.DisableTraces, "disable-traces", false,
 		"Disable Cloud Trace integration (used with telemetry-project)")
-	pflags.IntVar(&c.telemetryTracingSampleRate, "telemetry-sample-rate", 10_000,
+	pflags.IntVar(&c.conf.TelemetryTracingSampleRate, "telemetry-sample-rate", 10_000,
 		"Configure the denominator of the probabilistic sample rate of traces sent to Cloud Trace\n(e.g., 10,000 traces 1/10,000 calls).")
-	pflags.BoolVar(&c.disableMetrics, "disable-metrics", false,
+	pflags.BoolVar(&c.conf.DisableMetrics, "disable-metrics", false,
 		"Disable Cloud Monitoring integration (used with telemetry-project)")
-	pflags.StringVar(&c.telemetryPrefix, "telemetry-prefix", "",
+	pflags.StringVar(&c.conf.TelemetryPrefix, "telemetry-prefix", "",
 		"Prefix to use for Cloud Monitoring metrics.")
-	pflags.BoolVar(&c.prometheus, "prometheus", false,
+	pflags.BoolVar(&c.conf.Prometheus, "prometheus", false,
 		"Enable Prometheus HTTP endpoint /metrics")
-	pflags.StringVar(&c.prometheusNamespace, "prometheus-namespace", "",
+	pflags.StringVar(&c.conf.PrometheusNamespace, "prometheus-namespace", "",
 		"Use the provided Prometheus namespace for metrics")
-	pflags.StringVar(&c.httpAddress, "http-address", "localhost",
+	pflags.StringVar(&c.conf.HTTPAddress, "http-address", "localhost",
 		"Address for Prometheus and health check server")
-	pflags.StringVar(&c.httpPort, "http-port", "9090",
+	pflags.StringVar(&c.conf.HTTPPort, "http-port", "9090",
 		"Port for the Prometheus server to use")
-	pflags.BoolVar(&c.healthCheck, "health-check", false,
+	pflags.BoolVar(&c.conf.HealthCheck, "health-check", false,
 		`Enables HTTP endpoints /startup, /liveness, and /readiness
 that report on the proxy's health. Endpoints are available on localhost
 only. Uses the port specified by the http-port flag.`)
@@ -521,23 +501,10 @@ func parseConfig(cmd *Command, conf *proxy.Config, args []string) error {
 	}
 
 	if userHasSet("user-agent") {
-		defaultUserAgent += " " + cmd.otherUserAgents
+		defaultUserAgent += " " + cmd.conf.OtherUserAgents
 		conf.UserAgent = defaultUserAgent
 	}
 
-	if cmd.impersonationChain != "" {
-		accts := strings.Split(cmd.impersonationChain, ",")
-		conf.ImpersonateTarget = accts[0]
-		// Assign delegates if the chain is more than one account. Delegation
-		// goes from last back towards target, e.g., With sa1,sa2,sa3, sa3
-		// delegates to sa2, which impersonates the target sa1.
-		if l := len(accts); l > 1 {
-			for i := l - 1; i > 0; i-- {
-				conf.ImpersonateDelegates = append(conf.ImpersonateDelegates, accts[i])
-			}
-		}
-	}
-
 	var ics []proxy.InstanceConnConfig
 	for _, a := range args {
 		// split into instance uri and query parameters
@@ -615,12 +582,12 @@ func runSignalWrapper(cmd *Command) error {
 
 	// Configure collectors before the proxy has started to ensure we are
 	// collecting metrics before *ANY* AlloyDB Admin API calls are made.
-	enableMetrics := !cmd.disableMetrics
-	enableTraces := !cmd.disableTraces
-	if cmd.telemetryProject != "" && (enableMetrics || enableTraces) {
+	enableMetrics := !cmd.conf.DisableMetrics
+	enableTraces := !cmd.conf.DisableTraces
+	if cmd.conf.TelemetryProject != "" && (enableMetrics || enableTraces) {
 		sd, err := stackdriver.NewExporter(stackdriver.Options{
-			ProjectID:    cmd.telemetryProject,
-			MetricPrefix: cmd.telemetryPrefix,
+			ProjectID:    cmd.conf.TelemetryProject,
+			MetricPrefix: cmd.conf.TelemetryPrefix,
 		})
 		if err != nil {
 			return err
@@ -632,7 +599,7 @@ func runSignalWrapper(cmd *Command) error {
 			}
 		}
 		if enableTraces {
-			s := trace.ProbabilitySampler(1 / float64(cmd.telemetryTracingSampleRate))
+			s := trace.ProbabilitySampler(1 / float64(cmd.conf.TelemetryTracingSampleRate))
 			trace.ApplyConfig(trace.Config{DefaultSampler: s})
 			trace.RegisterExporter(sd)
 		}
@@ -646,10 +613,10 @@ func runSignalWrapper(cmd *Command) error {
 		needsHTTPServer bool
 		mux             = http.NewServeMux()
 	)
-	if cmd.prometheus {
+	if cmd.conf.Prometheus {
 		needsHTTPServer = true
 		e, err := prometheus.NewExporter(prometheus.Options{
-			Namespace: cmd.prometheusNamespace,
+			Namespace: cmd.conf.PrometheusNamespace,
 		})
 		if err != nil {
 			return err
@@ -704,10 +671,10 @@ func runSignalWrapper(cmd *Command) error {
 	}()
 
 	notify := func() {}
-	if cmd.healthCheck {
+	if cmd.conf.HealthCheck {
 		needsHTTPServer = true
 		cmd.logger.Infof("Starting health check server at %s",
-			net.JoinHostPort(cmd.httpAddress, cmd.httpPort))
+			net.JoinHostPort(cmd.conf.HTTPAddress, cmd.conf.HTTPPort))
 		hc := healthcheck.NewCheck(p, cmd.logger)
 		mux.HandleFunc("/startup", hc.HandleStartup)
 		mux.HandleFunc("/readiness", hc.HandleReadiness)
@@ -718,7 +685,7 @@ func runSignalWrapper(cmd *Command) error {
 	// Start the HTTP server if anything requiring HTTP is specified.
 	if needsHTTPServer {
 		server := &http.Server{
-			Addr:    net.JoinHostPort(cmd.httpAddress, cmd.httpPort),
+			Addr:    net.JoinHostPort(cmd.conf.HTTPAddress, cmd.conf.HTTPPort),
 			Handler: mux,
 		}
 		// Start the HTTP server.