plugins: standardize server API and errors

plugins/cmd/chainlink-median/main.go

@@ -14,7 +14,7 @@ const (
 )
 
 func main() {
-	s := plugins.StartServer(loggerName)
+	s := plugins.MustNewStartedServer(loggerName)
 	defer s.Stop()
 
 	p := median.NewPlugin(s.Logger)

plugins/cmd/chainlink-solana/main.go

@@ -21,7 +21,7 @@ const (
 )
 
 func main() {
-	s := plugins.StartServer(loggerName)
+	s := plugins.MustNewStartedServer(loggerName)
 	defer s.Stop()
 
 	p := &pluginRelayer{Base: plugins.Base{Logger: s.Logger}}

plugins/cmd/chainlink-starknet/main.go

@@ -21,7 +21,7 @@ const (
 )
 
 func main() {
-	s := plugins.StartServer(loggerName)
+	s := plugins.MustNewStartedServer(loggerName)
 	defer s.Stop()
 
 	p := &pluginRelayer{Base: plugins.Base{Logger: s.Logger}}

plugins/server.go

@@ -9,47 +9,78 @@ import (
 	"github.com/smartcontractkit/chainlink/v2/core/services"
 )
 
-// StartServer returns a started Server.
+// NewStartedServer returns a started Server.
 // The caller is responsible for calling Server.Stop().
-func StartServer(loggerName string) *Server {
-	s := Server{
+func NewStartedServer(loggerName string) (*Server, error) {
+	s, err := newServer(loggerName)
+	if err != nil {
+		return nil, err
+	}
+	err = s.start()
+	if err != nil {
+		return nil, err
+	}
+
+	return s, nil
+}
+
+// MustNewStartedServer returns a new started Server like NewStartedServer, but logs and exits in the event of error.
+// The caller is responsible for calling Server.Stop().
+func MustNewStartedServer(loggerName string) *Server {
+	s, err := newServer(loggerName)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Failed to start server: %s\n", err)
+		os.Exit(1)
+	}
+	err = s.start()
+	if err != nil {
+		s.Logger.Fatalf("Failed to start server: %s", err)
+	}
+
+	return s
+}
+
+// Server holds common plugin server fields.
+type Server struct {
+	loop.GRPCOpts
+	Logger logger.SugaredLogger
+	*PromServer
+	services.Checker
+}
+
+func newServer(loggerName string) (*Server, error) {
+	s := &Server{
 		// default prometheus.Registerer
 		GRPCOpts: loop.SetupTelemetry(nil),
 	}
 
 	lggr, err := loop.NewLogger()
 	if err != nil {
-		fmt.Fprintf(os.Stderr, "Failed to create logger: %s\n", err)
-		os.Exit(1)
+		return nil, fmt.Errorf("error creating logger: %s", err)
 	}
 	lggr = logger.Named(lggr, loggerName)
 	s.Logger = logger.Sugared(lggr)
+	return s, nil
+}
 
+func (s *Server) start() error {
 	envCfg, err := GetEnvConfig()
 	if err != nil {
-		lggr.Fatalf("Failed to get environment configuration: %s\n", err)
+		return fmt.Errorf("error getting environment configuration: %w", err)
 	}
-	s.PromServer = NewPromServer(envCfg.PrometheusPort(), lggr)
+	s.PromServer = NewPromServer(envCfg.PrometheusPort(), s.lggr)
 	err = s.PromServer.Start()
 	if err != nil {
-		lggr.Fatalf("Unrecoverable error starting prometheus server: %s", err)
+		return fmt.Errorf("error starting prometheus server: %w", err)
 	}
 
 	s.Checker = services.NewChecker()
 	err = s.Checker.Start()
 	if err != nil {
-		lggr.Fatalf("Failed to start health checker: %v", err)
+		return fmt.Errorf("error starting health checker: %w", err)
 	}
 
-	return &s
-}
-
-// Server holds common plugin server fields.
-type Server struct {
-	loop.GRPCOpts
-	Logger logger.SugaredLogger
-	*PromServer
-	services.Checker
+	return nil
 }
 
 // MustRegister registers the Checkable with services.Checker, or exits upon failure.
@@ -62,7 +93,7 @@ func (s *Server) MustRegister(c services.Checkable) {
 // Stop closes resources and flushes logs.
 func (s *Server) Stop() {
 	s.Logger.ErrorIfFn(s.Checker.Close, "Failed to close health checker")
-	s.Logger.ErrorIfFn(s.PromServer.Close, "error closing prometheus server")
+	s.Logger.ErrorIfFn(s.PromServer.Close, "Failed to close prometheus server")
 	if err := s.Logger.Sync(); err != nil {
 		fmt.Println("Failed to sync logger:", err)
 	}