config.go

/*
 * umoci: Umoci Modifies Open Containers' Images
 * Copyright (C) 2016, 2017 SUSE LLC.
 *
 * 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 main

import (
	"strings"
	"time"

	"github.com/apex/log"
	"github.com/openSUSE/umoci/mutate"
	"github.com/openSUSE/umoci/oci/cas"
	igen "github.com/openSUSE/umoci/oci/generate"
	ispec "github.com/opencontainers/image-spec/specs-go/v1"
	"github.com/pkg/errors"
	"github.com/urfave/cli"
	"golang.org/x/net/context"
)

// FIXME: We should also implement a raw mode that just does modifications of
//        JSON blobs (allowing this all to be used outside of our build setup).
var configCommand = uxHistory(uxTag(cli.Command{
	Name:  "config",
	Usage: "modifies the image configuration of an OCI image",
	ArgsUsage: `--image <image-path>[:<tag>] [--tag <new-tag>]

Where "<image-path>" is the path to the OCI image, and "<tag>" is the name of
the tagged image from which the config modifications will be based (if not
specified, it defaults to "latest"). "<new-tag>" is the new reference name to
save the new image as, if this is not specified then umoci will replace the old
image.`,

	// config modifies a particular image manifest.
	Category: "image",

	// Verify the metadata.
	Before: func(ctx *cli.Context) error {
		if _, ok := ctx.App.Metadata["--image-path"]; !ok {
			return errors.Errorf("missing mandatory argument: --image")
		}
		if _, ok := ctx.App.Metadata["--image-tag"]; !ok {
			return errors.Errorf("missing mandatory argument: --image")
		}
		return nil
	},

	Flags: []cli.Flag{
		cli.StringFlag{Name: "config.user"},
		cli.StringSliceFlag{Name: "config.exposedports"},
		cli.StringSliceFlag{Name: "config.env"},
		cli.StringSliceFlag{Name: "config.entrypoint"}, // FIXME: This interface is weird.
		cli.StringSliceFlag{Name: "config.cmd"},        // FIXME: This interface is weird.
		cli.StringSliceFlag{Name: "config.volume"},
		cli.StringSliceFlag{Name: "config.label"},
		cli.StringFlag{Name: "config.workingdir"},
		cli.StringFlag{Name: "created"}, // FIXME: Implement TimeFlag.
		cli.StringFlag{Name: "author"},
		cli.StringFlag{Name: "architecture"},
		cli.StringFlag{Name: "os"},
		cli.StringSliceFlag{Name: "manifest.annotation"},
		cli.StringSliceFlag{Name: "clear"},
	},

	Action: config,
}))

func toImage(config ispec.ImageConfig, meta mutate.Meta) ispec.Image {
	return ispec.Image{
		Config:       config,
		Created:      meta.Created,
		Author:       meta.Author,
		Architecture: meta.Architecture,
		OS:           meta.OS,
	}
}

func fromImage(image ispec.Image) (ispec.ImageConfig, mutate.Meta) {
	return image.Config, mutate.Meta{
		Created:      image.Created,
		Author:       image.Author,
		Architecture: image.Architecture,
		OS:           image.OS,
	}
}

// parseEnv splits a given environment variable (of the form name=value) into
// (name, value). An error is returned if there is no "=" in the line or if the
// name is empty.
func parseEnv(env string) (string, string, error) {
	parts := strings.SplitN(env, "=", 2)
	if len(parts) != 2 {
		return "", "", errors.Errorf("environment variable must contain '=': %s", env)
	}

	name, value := parts[0], parts[1]
	if name == "" {
		return "", "", errors.Errorf("environment variable must have non-empty name: %s", env)
	}
	return name, value, nil
}

func config(ctx *cli.Context) error {
	imagePath := ctx.App.Metadata["--image-path"].(string)
	fromName := ctx.App.Metadata["--image-tag"].(string)

	// By default we clobber the old tag.
	tagName := fromName
	if val, ok := ctx.App.Metadata["--tag"]; ok {
		tagName = val.(string)
	}

	// Get a reference to the CAS.
	engine, err := cas.Open(imagePath)
	if err != nil {
		return errors.Wrap(err, "open CAS")
	}
	defer engine.Close()

	fromDescriptor, err := engine.GetReference(context.Background(), fromName)
	if err != nil {
		return errors.Wrap(err, "get from reference")
	}

	mutator, err := mutate.New(engine, *fromDescriptor)
	if err != nil {
		return errors.Wrap(err, "create mutator for manifest")
	}

	imageConfig, err := mutator.Config(context.Background())
	if err != nil {
		return errors.Wrap(err, "get base config")
	}

	imageMeta, err := mutator.Meta(context.Background())
	if err != nil {
		return errors.Wrap(err, "get base metadata")
	}

	annotations, err := mutator.Annotations(context.Background())
	if err != nil {
		return errors.Wrap(err, "get base annotations")
	}

	g, err := igen.NewFromImage(toImage(imageConfig, imageMeta))
	if err != nil {
		return errors.Wrap(err, "create new generator")
	}

	if ctx.IsSet("clear") {
		for _, key := range ctx.StringSlice("clear") {
			switch key {
			case "config.labels":
				g.ClearConfigLabels()
			case "manifest.annotations":
				annotations = nil
			case "config.exposedports":
				g.ClearConfigExposedPorts()
			case "config.env":
				g.ClearConfigEnv()
			case "config.volume":
				g.ClearConfigVolumes()
			case "rootfs.diffids":
				//g.ClearRootfsDiffIDs()
				return errors.Errorf("--clear=rootfs.diffids is not safe")
			default:
				return errors.Errorf("unknown key to --clear: %s", key)
			}
		}
	}

	if ctx.IsSet("created") {
		// How do we handle other formats?
		created, err := time.Parse(igen.ISO8601, ctx.String("created"))
		if err != nil {
			return errors.Wrap(err, "parse --created")
		}
		g.SetCreated(created)
	}
	if ctx.IsSet("author") {
		g.SetAuthor(ctx.String("author"))
	}
	if ctx.IsSet("architecture") {
		g.SetArchitecture(ctx.String("architecture"))
	}
	if ctx.IsSet("os") {
		g.SetOS(ctx.String("os"))
	}
	if ctx.IsSet("config.user") {
		g.SetConfigUser(ctx.String("config.user"))
	}
	if ctx.IsSet("config.workingdir") {
		g.SetConfigWorkingDir(ctx.String("config.workingdir"))
	}
	if ctx.IsSet("config.exposedports") {
		for _, port := range ctx.StringSlice("config.exposedports") {
			g.AddConfigExposedPort(port)
		}
	}
	if ctx.IsSet("config.env") {
		for _, env := range ctx.StringSlice("config.env") {
			name, value, err := parseEnv(env)
			if err != nil {
				return err
			}
			g.AddConfigEnv(name, value)
		}
	}
	// FIXME: This interface is weird.
	if ctx.IsSet("config.entrypoint") {
		g.SetConfigEntrypoint(ctx.StringSlice("config.entrypoint"))
	}
	// FIXME: This interface is weird.
	if ctx.IsSet("config.cmd") {
		g.SetConfigCmd(ctx.StringSlice("config.cmd"))
	}
	if ctx.IsSet("config.volume") {
		for _, volume := range ctx.StringSlice("config.volume") {
			g.AddConfigVolume(volume)
		}
	}
	if ctx.IsSet("config.label") {
		for _, label := range ctx.StringSlice("config.label") {
			parts := strings.SplitN(label, "=", 2)
			g.AddConfigLabel(parts[0], parts[1])
		}
	}
	if ctx.IsSet("manifest.annotation") {
		if annotations == nil {
			annotations = map[string]string{}
		}
		for _, label := range ctx.StringSlice("manifest.annotation") {
			parts := strings.SplitN(label, "=", 2)
			annotations[parts[0]] = parts[1]
		}
	}

	history := ispec.History{
		Author:     g.Author(),
		Comment:    "",
		Created:    time.Now().Format(igen.ISO8601),
		CreatedBy:  "umoci config",
		EmptyLayer: true,
	}

	if val, ok := ctx.App.Metadata["--history.author"]; ok {
		history.Author = val.(string)
	}
	if val, ok := ctx.App.Metadata["--history.comment"]; ok {
		history.Comment = val.(string)
	}
	if val, ok := ctx.App.Metadata["--history.created"]; ok {
		history.Created = val.(string)
	}
	if val, ok := ctx.App.Metadata["--history.created_by"]; ok {
		history.CreatedBy = val.(string)
	}

	newConfig, newMeta := fromImage(g.Image())
	if err := mutator.Set(context.Background(), newConfig, newMeta, annotations, history); err != nil {
		return errors.Wrap(err, "set modified configuration")
	}

	newDescriptor, err := mutator.Commit(context.Background())
	if err != nil {
		return errors.Wrap(err, "commit mutated image")
	}

	log.Infof("new image manifest created: %s", newDescriptor.Digest)

	err = engine.PutReference(context.Background(), tagName, &newDescriptor)
	if err == cas.ErrClobber {
		// We have to clobber a tag.
		log.Warnf("clobbering existing tag: %s", tagName)

		// Delete the old tag.
		if err := engine.DeleteReference(context.Background(), tagName); err != nil {
			return errors.Wrap(err, "delete old tag")
		}
		err = engine.PutReference(context.Background(), tagName, &newDescriptor)
	}
	if err != nil {
		return errors.Wrap(err, "add new tag")
	}

	log.Infof("created new tag for image manifest: %s", tagName)
	return nil
}