Merge pull request #8 from go-flexible/feature/custom-logger-support

feat: allow passing in custom logger

flexmetrics.go

@@ -2,7 +2,6 @@ package flexmetrics
 
 import (
 	"context"
-	"log"
 	"net"
 	"net/http"
 	"net/http/pprof"
@@ -62,6 +61,18 @@ func WithServer(server *http.Server) Option {
 	}
 }
 
+// Logger defines any logger able to call Printf.
+type Logger interface {
+	Printf(format string, v ...interface{})
+}
+
+// WithLogger allows you to set a logger for the server.
+func WithLogger(l Logger) Option {
+	return func(s *Server) {
+		s.logger = l
+	}
+}
+
 // New creates a new default metrics server.
 func New(options ...Option) *Server {
 	path := os.Getenv("METRICS_PROMETHEUS_PATH")
@@ -94,8 +105,9 @@ func New(options ...Option) *Server {
 
 // Server represents a prometheus metrics server.
 type Server struct {
-	Path   string
+	logger Logger
 	Server *http.Server
+	Path   string
 }
 
 // Run will start the metrics server.
@@ -114,12 +126,12 @@ func (s *Server) Run(_ context.Context) error {
 	mux.HandleFunc("/debug/pprof/trace", pprof.Trace)
 
 	s.Server.Handler = mux
-	log.Printf("serving profiling and prometheus metrics over http on http://%s%s", s.Server.Addr, s.Path)
+	s.logger.Printf("serving profiling and prometheus metrics over http on http://%s%s", s.Server.Addr, s.Path)
 	return s.Server.Serve(lis)
 }
 
 // Halt will attempt to gracefully shut down the server.
 func (s *Server) Halt(ctx context.Context) error {
-	log.Printf("stopping serving profiling and prometheus metrics over http on http://%s...", s.Server.Addr)
+	s.logger.Printf("stopping serving profiling and prometheus metrics over http on http://%s...", s.Server.Addr)
 	return s.Server.Shutdown(ctx)
 }

flexmetrics_test.go

@@ -1,9 +1,13 @@
 package flexmetrics_test
 
 import (
+	"bytes"
 	"context"
+	"io"
+	"log"
 	"net/http"
 	"os"
+	"strings"
 	"testing"
 
 	"github.com/go-flexible/flexmetrics"
@@ -84,3 +88,30 @@ func TestOption_WithServer(t *testing.T) {
 		t.Error("WithServer option should set the provided http server")
 	}
 }
+
+func TestOption_WithLogger(t *testing.T) {
+	var buf bytes.Buffer
+
+	w := io.MultiWriter(&buf, os.Stderr)     // so we get console output.
+	logger := log.New(w, "TEST_LOGGER: ", 0) // so we get consistent output.
+
+	metrics := flexmetrics.New(
+		flexmetrics.WithAddr("127.0.0.1:"),
+		flexmetrics.WithLogger(logger),
+	)
+
+	ctx, cancel := context.WithCancel(context.Background())
+	cancel()
+
+	go func() {
+		_ = metrics.Run(ctx)
+	}()
+	_ = metrics.Halt(ctx)
+
+	t.Log(buf.String())
+
+	// ugly? yes, but, it will do.
+	if !strings.Contains(buf.String(), "TEST_LOGGER: ") {
+		t.Fatal("expected log message to contain prefix")
+	}
+}

go.mod

@@ -13,5 +13,6 @@ require (
 	github.com/prometheus/common v0.26.0 // indirect
 	github.com/prometheus/procfs v0.6.0 // indirect
 	golang.org/x/sys v0.0.0-20210603081109-ebe580a85c40 // indirect
+	golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 // indirect
 	google.golang.org/protobuf v1.26.0-rc.1 // indirect
 )

go.sum

@@ -117,8 +117,9 @@ golang.org/x/sys v0.0.0-20210603081109-ebe580a85c40/go.mod h1:oPkhp1MJrh7nUepCBc
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.2/go.mod h1:bEr9sfX3Q8Zfm5fL9x+3itogRgK3+ptLWKqgva+5dAk=
 golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
-golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 h1:E7g+9GITq07hpfrRu66IVDexMakfv52eLZ2CXBWiKr4=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 h1:go1bK/D/BFZV2I8cIQd1NKEZ+0owSTG1fDTci4IqFcE=
+golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 google.golang.org/appengine v1.4.0/go.mod h1:xpcJRLb0r/rnEns0DIKYYv+WjYCduHsrkT7/EB5XEv4=
 google.golang.org/protobuf v0.0.0-20200109180630-ec00e32a8dfd/go.mod h1:DFci5gLYBciE7Vtevhsrf46CRTquxDuWsQurQQe4oz8=
 google.golang.org/protobuf v0.0.0-20200221191635-4d8936d0db64/go.mod h1:kwYJMbMJ01Woi6D6+Kah6886xMZcty6N08ah7+eCXa0=