132 lines
		
	
	
		
			3.3 KiB
		
	
	
	
		
			Go
		
	
	
	
	
	
			
		
		
	
	
			132 lines
		
	
	
		
			3.3 KiB
		
	
	
	
		
			Go
		
	
	
	
	
	
/*
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   Copyright The containerd Authors.
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   Licensed under the Apache License, Version 2.0 (the "License");
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   you may not use this file except in compliance with the License.
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   You may obtain a copy of the License at
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       http://www.apache.org/licenses/LICENSE-2.0
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   Unless required by applicable law or agreed to in writing, software
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   distributed under the License is distributed on an "AS IS" BASIS,
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   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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   See the License for the specific language governing permissions and
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   limitations under the License.
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*/
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package apply
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import (
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	"context"
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	"fmt"
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	"io"
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	"time"
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	"github.com/containerd/containerd/content"
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	"github.com/containerd/containerd/diff"
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	"github.com/containerd/containerd/mount"
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	"github.com/containerd/log"
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	digest "github.com/opencontainers/go-digest"
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	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
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)
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// NewFileSystemApplier returns an applier which simply mounts
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// and applies diff onto the mounted filesystem.
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func NewFileSystemApplier(cs content.Provider) diff.Applier {
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	return &fsApplier{
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		store: cs,
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	}
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}
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type fsApplier struct {
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	store content.Provider
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}
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var emptyDesc = ocispec.Descriptor{}
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// Apply applies the content associated with the provided digests onto the
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// provided mounts. Archive content will be extracted and decompressed if
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// necessary.
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func (s *fsApplier) Apply(ctx context.Context, desc ocispec.Descriptor, mounts []mount.Mount, opts ...diff.ApplyOpt) (d ocispec.Descriptor, err error) {
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	t1 := time.Now()
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	defer func() {
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		if err == nil {
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			log.G(ctx).WithFields(log.Fields{
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				"d":      time.Since(t1),
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				"digest": desc.Digest,
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				"size":   desc.Size,
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				"media":  desc.MediaType,
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			}).Debugf("diff applied")
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		}
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	}()
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	var config diff.ApplyConfig
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	for _, o := range opts {
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		if err := o(ctx, desc, &config); err != nil {
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			return emptyDesc, fmt.Errorf("failed to apply config opt: %w", err)
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		}
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	}
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	ra, err := s.store.ReaderAt(ctx, desc)
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	if err != nil {
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		return emptyDesc, fmt.Errorf("failed to get reader from content store: %w", err)
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	}
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	defer ra.Close()
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	var processors []diff.StreamProcessor
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	processor := diff.NewProcessorChain(desc.MediaType, content.NewReader(ra))
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	processors = append(processors, processor)
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	for {
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		if processor, err = diff.GetProcessor(ctx, processor, config.ProcessorPayloads); err != nil {
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			return emptyDesc, fmt.Errorf("failed to get stream processor for %s: %w", desc.MediaType, err)
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		}
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		processors = append(processors, processor)
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		if processor.MediaType() == ocispec.MediaTypeImageLayer {
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			break
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		}
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	}
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	defer processor.Close()
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	digester := digest.Canonical.Digester()
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	rc := &readCounter{
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		r: io.TeeReader(processor, digester.Hash()),
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	}
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	if err := apply(ctx, mounts, rc); err != nil {
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		return emptyDesc, err
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	}
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	// Read any trailing data
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	if _, err := io.Copy(io.Discard, rc); err != nil {
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		return emptyDesc, err
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	}
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	for _, p := range processors {
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		if ep, ok := p.(interface {
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			Err() error
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		}); ok {
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			if err := ep.Err(); err != nil {
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				return emptyDesc, err
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			}
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		}
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	}
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	return ocispec.Descriptor{
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		MediaType: ocispec.MediaTypeImageLayer,
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		Size:      rc.c,
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		Digest:    digester.Digest(),
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	}, nil
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}
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type readCounter struct {
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	r io.Reader
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	c int64
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}
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func (rc *readCounter) Read(p []byte) (n int, err error) {
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	n, err = rc.r.Read(p)
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	if n > 0 {
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		rc.c += int64(n)
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	}
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	return
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}
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