Add support for json formatted logs (#1245)

api/server/server.go

@@ -48,6 +48,9 @@ const (
 	// forcing usage through WithXxx configuration methods and documenting there vs.
 	// expecting users to use os.SetEnv(EnvLogLevel, "debug") // why ?
 
+	// EnvLogFormat sets the stderr logging format, text or json only
+	EnvLogFormat = "FN_LOG_FORMAT"
+
 	// EnvLogLevel sets the stderr logging level
 	EnvLogLevel = "FN_LOG_LEVEL"
 
@@ -116,6 +119,9 @@ const (
 	// EnvMaxRequestSize sets the limit in bytes for any API request's length.
 	EnvMaxRequestSize = "FN_MAX_REQUEST_SIZE"
 
+	// DefaultLogFormat is text
+	DefaultLogFormat = "text"
+
 	// DefaultLogLevel is info
 	DefaultLogLevel = "info"
 
@@ -246,6 +252,7 @@ func NewFromEnv(ctx context.Context, opts ...Option) *Server {
 	}
 	opts = append(opts, WithWebPort(getEnvInt(EnvPort, DefaultPort)))
 	opts = append(opts, WithGRPCPort(getEnvInt(EnvGRPCPort, DefaultGRPCPort)))
+	opts = append(opts, WithLogFormat(getEnv(EnvLogFormat, DefaultLogFormat)))
 	opts = append(opts, WithLogLevel(getEnv(EnvLogLevel, DefaultLogLevel)))
 	opts = append(opts, WithLogDest(getEnv(EnvLogDest, DefaultLogDest), getEnv(EnvLogPrefix, "")))
 	opts = append(opts, WithZipkin(getEnv(EnvZipkinURL, "")))
@@ -309,6 +316,14 @@ func WithGRPCPort(port int) Option {
 	}
 }
 
+// WithLogFormat maps EnvLogFormat
+func WithLogFormat(format string) Option {
+	return func(ctx context.Context, s *Server) error {
+		common.SetLogFormat(format)
+		return nil
+	}
+}
+
 // WithLogLevel maps EnvLogLevel
 func WithLogLevel(ll string) Option {
 	return func(ctx context.Context, s *Server) error {

api/server/server_test.go

@@ -19,6 +19,7 @@ import (
 
 func testServer(ds models.Datastore, mq models.MessageQueue, logDB models.LogStore, rnr agent.Agent, nodeType NodeType, opts ...Option) *Server {
 	return New(context.Background(), append(opts,
+		WithLogFormat("text"),
 		WithLogLevel("debug"),
 		WithDatastore(ds),
 		WithMQ(mq),