verbose output

cmd/oci-image-tool/create.go

@@ -19,6 +19,7 @@ import (
 	"strings"
 
 	"github.com/opencontainers/image-tools/image"
+	"github.com/opencontainers/image-tools/logger"
 	"github.com/urfave/cli"
 )
 
@@ -74,7 +75,7 @@ func createHandle(context *cli.Context) error {
 	}
 
 	if err != nil {
-		fmt.Printf("creating failed: %v\n", err)
+		logger.G(globalCtx).WithError(err).Infof("creating failed")
 	}
 
 	return err

cmd/oci-image-tool/main.go

@@ -18,11 +18,13 @@ import (
 	"fmt"
 	"os"
 
-	"github.com/Sirupsen/logrus"
+	"github.com/opencontainers/image-tools/logger"
 	"github.com/opencontainers/image-tools/version"
 	"github.com/urfave/cli"
 )
 
+var globalCtx = logger.WithLogger(logger.Background(), logger.LogEntry)
+
 // gitCommit will be the hash that the binary was built from
 // and will be populated by the Makefile
 var gitCommit = ""
@@ -43,9 +45,7 @@ func main() {
 		},
 	}
 	app.Before = func(c *cli.Context) error {
-		if c.GlobalBool("debug") {
-			logrus.SetLevel(logrus.DebugLevel)
-		}
+		logger.EnableDebugMode(c.GlobalBool("debug"))
 		return nil
 	}
 	app.Commands = []cli.Command{
@@ -55,6 +55,6 @@ func main() {
 	}
 
 	if err := app.Run(os.Args); err != nil {
-		logrus.Fatal(err)
+		os.Exit(1)
 	}
 }

cmd/oci-image-tool/unpack.go

@@ -19,6 +19,7 @@ import (
 	"strings"
 
 	"github.com/opencontainers/image-tools/image"
+	"github.com/opencontainers/image-tools/logger"
 	"github.com/urfave/cli"
 )
 
@@ -67,7 +68,7 @@ func unpackHandle(context *cli.Context) error {
 	}
 
 	if err != nil {
-		fmt.Printf("unpacking failed: %v\n", err)
+		logger.G(globalCtx).WithError(err).Errorf("unpacking failed")
 	}
 	return err
 }

cmd/oci-image-tool/validate.go

@@ -16,12 +16,12 @@ package main
 
 import (
 	"fmt"
-	"log"
 	"os"
 	"strings"
 
 	"github.com/opencontainers/image-spec/schema"
 	"github.com/opencontainers/image-tools/image"
+	"github.com/opencontainers/image-tools/logger"
 	"github.com/pkg/errors"
 	"github.com/urfave/cli"
 )
@@ -36,9 +36,8 @@ var validateTypes = []string{
 }
 
 type validateCmd struct {
-	stdout *log.Logger
-	typ    string // the type to validate, can be empty string
-	refs   []string
+	typ  string // the type to validate, can be empty string
+	refs []string
 }
 
 var v validateCmd
@@ -58,10 +57,11 @@ func validateHandler(context *cli.Context) error {
 
 	var errs []string
 	for _, arg := range context.Args() {
+		var ctx = logger.WithLogger(globalCtx, logger.G(globalCtx).WithField("target", arg))
 		err := validatePath(arg)
 
 		if err == nil {
-			fmt.Printf("%s: OK\n", arg)
+			logger.G(ctx).Infof("OK")
 			continue
 		}
 
@@ -78,9 +78,12 @@ func validateHandler(context *cli.Context) error {
 	}
 
 	if len(errs) > 0 {
-		return fmt.Errorf("%d errors detected: \n%s", len(errs), strings.Join(errs, "\n"))
+		err := fmt.Errorf("%d errors detected: \n%s", len(errs), strings.Join(errs, "\n"))
+		logger.G(globalCtx).WithError(err).Infof("validation failed")
+		return err
 	}
-	fmt.Println("Validation succeeded")
+
+	logger.G(globalCtx).Infof("Validation succeeded")
 	return nil
 }
 
@@ -98,13 +101,13 @@ func validatePath(name string) error {
 
 	switch typ {
 	case image.TypeImageLayout:
-		return image.ValidateLayout(name, v.refs, v.stdout)
+		return image.ValidateLayout(globalCtx, name, v.refs)
 	case image.TypeImage:
-		return image.ValidateFile(name, v.refs, v.stdout)
+		return image.ValidateFile(globalCtx, name, v.refs)
 	}
 
 	if len(v.refs) != 0 {
-		fmt.Printf("WARNING: type %q does not support refs, which are only appropriate if type is image or imageLayout.\n", typ)
+		logger.G(globalCtx).Warnf("type %q does not support refs, which are only appropriate if type is image or imageLayout.", typ)
 	}
 
 	f, err := os.Open(name)

image/image.go

@@ -18,55 +18,52 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
-	"log"
 	"os"
 	"path/filepath"
 
 	"github.com/opencontainers/image-spec/specs-go/v1"
+	"github.com/opencontainers/image-tools/logger"
 	"github.com/pkg/errors"
 )
 
 // ValidateLayout walks through the given file tree and validates the manifest
 // pointed to by the given refs or returns an error if the validation failed.
-func ValidateLayout(src string, refs []string, out *log.Logger) error {
-	return validate(newPathWalker(src), refs, out)
+func ValidateLayout(ctx logger.Context, src string, refs []string) error {
+	return validate(ctx, newPathWalker(src), refs)
 }
 
 // ValidateFile opens the tar file given by the filename, then calls ValidateReader
-func ValidateFile(tarFile string, refs []string, out *log.Logger) error {
+func ValidateFile(ctx logger.Context, tarFile string, refs []string) error {
 	f, err := os.Open(tarFile)
 	if err != nil {
 		return errors.Wrap(err, "unable to open file")
 	}
 	defer f.Close()
 
-	return Validate(f, refs, out)
+	return Validate(ctx, f, refs)
 }
 
 // Validate walks through a tar stream and validates the manifest.
 // * Check that all refs point to extant blobs
 // * Checks that all referred blobs are valid
 // * Checks that mime-types are correct
 // returns error on validation failure
-func Validate(r io.ReadSeeker, refs []string, out *log.Logger) error {
-	return validate(newTarWalker(r), refs, out)
+func Validate(ctx logger.Context, r io.ReadSeeker, refs []string) error {
+	return validate(ctx, newTarWalker(r), refs)
 }
 
 var validRefMediaTypes = []string{
 	v1.MediaTypeImageManifest,
 	v1.MediaTypeImageIndex,
 }
 
-func validate(w walker, refs []string, out *log.Logger) error {
+func validate(ctx logger.Context, w walker, refs []string) error {
 	ds, err := listReferences(w)
 	if err != nil {
 		return err
 	}
 	if len(refs) == 0 && len(ds) == 0 {
-		// TODO(runcom): ugly, we'll need a better way and library
-		// to express log levels.
-		// see https://github.com/opencontainers/image-spec/issues/288
-		out.Print("WARNING: no descriptors found")
+		logger.G(ctx).Warnf("no descriptors found")
 	}
 
 	if len(refs) == 0 {
@@ -96,9 +93,7 @@ func validate(w walker, refs []string, out *log.Logger) error {
 		if err := m.validate(w); err != nil {
 			return err
 		}
-		if out != nil {
-			out.Printf("reference %q: OK", ref)
-		}
+		logger.G(ctx).WithField("reference", ref).Infof("validate OK")
 	}
 	return nil
 }

image/image_test.go

@@ -28,6 +28,7 @@ import (
 
 	"github.com/opencontainers/go-digest"
 	"github.com/opencontainers/image-spec/specs-go/v1"
+	"github.com/opencontainers/image-tools/logger"
 )
 
 const (
@@ -150,7 +151,7 @@ func TestValidateLayout(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	err = ValidateLayout(root, []string{refTag}, nil)
+	err = ValidateLayout(logger.Background(), root, []string{refTag})
 	if err != nil {
 		t.Fatal(err)
 	}

logger/context.go

@@ -0,0 +1,31 @@
+// Copyright 2016 The Linux Foundation
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package logger
+
+import (
+	"context"
+)
+
+// Context is a copy of Context from the stdlib context package.
+type Context interface {
+	context.Context
+}
+
+// Background returns a non-nil, empty Context. The background context
+// provides a single key, "instance.id" that is globally unique to the
+// process.
+func Background() context.Context {
+	return context.Background()
+}

logger/logger.go

@@ -0,0 +1,69 @@
+// Copyright 2016 The Linux Foundation
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package logger
+
+import (
+	// TODO(xiekeyang): The adaptation should be checked for openSUSE
+	// on non-x86_64 architectures. If encounting problem, the golang
+	// version should be updated accordingly.
+	"context"
+	"os"
+
+	"github.com/Sirupsen/logrus"
+)
+
+var (
+	// G is an alias for GetLogger.
+	//
+	// We may want to define this locally to a package to get package tagged log
+	// messages.
+	G = GetLogger
+
+	// LogEntry provides a public and standard logger instance.
+	LogEntry = logrus.NewEntry(logrus.StandardLogger())
+)
+
+type (
+	loggerKey struct{}
+)
+
+// WithLogger returns a new context with the provided logger. Use in
+// combination with logger.WithField(s) for great effect.
+func WithLogger(ctx context.Context, logger *logrus.Entry) context.Context {
+	return context.WithValue(ctx, loggerKey{}, logger)
+}
+
+// GetLogger retrieves the current logger from the context. If no logger is
+// available, the default logger is returned.
+func GetLogger(ctx context.Context) *logrus.Entry {
+	logger := ctx.Value(loggerKey{})
+
+	if logger == nil {
+		return LogEntry
+	}
+
+	return logger.(*logrus.Entry)
+}
+
+// EnableDebugMode enables a selectable debug mode.
+func EnableDebugMode(debug bool) {
+	if debug {
+		LogEntry.Logger.Level = logrus.DebugLevel
+	}
+}
+
+func init() {
+	LogEntry.Logger.Out = os.Stderr
+}

man/oci-image-tool.1.md

@@ -35,6 +35,8 @@ oci-image-tool is a collection of tools for working with the [OCI image specific
   Create an OCI runtime bundle
   See **oci-image-tool-create**(1) for full documentation on the **create** command.
 
+During command run, the output stream will be sent to `OS stderr`.
+
 # SEE ALSO
 **oci-image-tool-validate**(1), **oci-image-tool-unpack**(1), **oci-image-tool-create**(1)