860b28c5b9
To simplify the vendoring story for the client, we have now removed the requirement for `logrus` and the forked `context` package (usually imported as `dcontext`). We inject the logger via the metrics tracker for the blob cache and via options on the token handler. We preserve logs on the proxy cache for that case. Clients expecting these log messages may need to be updated accordingly. Signed-off-by: Stephen J Day <stephen.day@docker.com>
121 lines
3 KiB
Go
121 lines
3 KiB
Go
package cache
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import (
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"context"
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"github.com/docker/distribution"
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"github.com/opencontainers/go-digest"
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)
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// Metrics is used to hold metric counters
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// related to the number of times a cache was
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// hit or missed.
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type Metrics struct {
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Requests uint64
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Hits uint64
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Misses uint64
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}
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// Logger can be provided on the MetricsTracker to log errors.
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//
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// Usually, this is just a proxy to dcontext.GetLogger.
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type Logger interface {
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Errorf(format string, args ...interface{})
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}
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// MetricsTracker represents a metric tracker
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// which simply counts the number of hits and misses.
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type MetricsTracker interface {
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Hit()
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Miss()
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Metrics() Metrics
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Logger(context.Context) Logger
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}
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type cachedBlobStatter struct {
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cache distribution.BlobDescriptorService
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backend distribution.BlobDescriptorService
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tracker MetricsTracker
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}
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// NewCachedBlobStatter creates a new statter which prefers a cache and
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// falls back to a backend.
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func NewCachedBlobStatter(cache distribution.BlobDescriptorService, backend distribution.BlobDescriptorService) distribution.BlobDescriptorService {
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return &cachedBlobStatter{
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cache: cache,
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backend: backend,
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}
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}
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// NewCachedBlobStatterWithMetrics creates a new statter which prefers a cache and
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// falls back to a backend. Hits and misses will send to the tracker.
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func NewCachedBlobStatterWithMetrics(cache distribution.BlobDescriptorService, backend distribution.BlobDescriptorService, tracker MetricsTracker) distribution.BlobStatter {
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return &cachedBlobStatter{
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cache: cache,
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backend: backend,
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tracker: tracker,
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}
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}
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func (cbds *cachedBlobStatter) Stat(ctx context.Context, dgst digest.Digest) (distribution.Descriptor, error) {
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desc, err := cbds.cache.Stat(ctx, dgst)
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if err != nil {
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if err != distribution.ErrBlobUnknown {
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logErrorf(ctx, cbds.tracker, "error retrieving descriptor from cache: %v", err)
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}
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goto fallback
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}
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if cbds.tracker != nil {
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cbds.tracker.Hit()
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}
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return desc, nil
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fallback:
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if cbds.tracker != nil {
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cbds.tracker.Miss()
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}
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desc, err = cbds.backend.Stat(ctx, dgst)
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if err != nil {
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return desc, err
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}
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if err := cbds.cache.SetDescriptor(ctx, dgst, desc); err != nil {
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logErrorf(ctx, cbds.tracker, "error adding descriptor %v to cache: %v", desc.Digest, err)
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}
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return desc, err
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}
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func (cbds *cachedBlobStatter) Clear(ctx context.Context, dgst digest.Digest) error {
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err := cbds.cache.Clear(ctx, dgst)
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if err != nil {
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return err
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}
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err = cbds.backend.Clear(ctx, dgst)
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if err != nil {
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return err
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}
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return nil
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}
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func (cbds *cachedBlobStatter) SetDescriptor(ctx context.Context, dgst digest.Digest, desc distribution.Descriptor) error {
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if err := cbds.cache.SetDescriptor(ctx, dgst, desc); err != nil {
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logErrorf(ctx, cbds.tracker, "error adding descriptor %v to cache: %v", desc.Digest, err)
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}
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return nil
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}
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func logErrorf(ctx context.Context, tracker MetricsTracker, format string, args ...interface{}) {
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if tracker == nil {
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return
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}
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logger := tracker.Logger(ctx)
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if logger == nil {
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return
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}
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logger.Errorf(format, args...)
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}
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