package redis import ( "context" "fmt" "github.com/docker/distribution/registry/storage/cache/metrics" "github.com/docker/distribution" "github.com/docker/distribution/reference" "github.com/docker/distribution/registry/storage/cache" "github.com/garyburd/redigo/redis" "github.com/opencontainers/go-digest" ) // redisBlobStatService provides an implementation of // BlobDescriptorCacheProvider based on redis. Blob descriptors are stored in // two parts. The first provide fast access to repository membership through a // redis set for each repo. The second is a redis hash keyed by the digest of // the layer, providing path, length and mediatype information. There is also // a per-repository redis hash of the blob descriptor, allowing override of // data. This is currently used to override the mediatype on a per-repository // basis. // // Note that there is no implied relationship between these two caches. The // layer may exist in one, both or none and the code must be written this way. type redisBlobDescriptorService struct { pool *redis.Pool // TODO(stevvooe): We use a pool because we don't have great control over // the cache lifecycle to manage connections. A new connection if fetched // for each operation. Once we have better lifecycle management of the // request objects, we can change this to a connection. } // NewRedisBlobDescriptorCacheProvider returns a new redis-based // BlobDescriptorCacheProvider using the provided redis connection pool. func NewRedisBlobDescriptorCacheProvider(pool *redis.Pool) cache.BlobDescriptorCacheProvider { return metrics.NewPrometheusCacheProvider( &redisBlobDescriptorService{ pool: pool, }, "cache_redis", "Number of seconds taken by redis", ) } // RepositoryScoped returns the scoped cache. func (rbds *redisBlobDescriptorService) RepositoryScoped(repo string) (distribution.BlobDescriptorService, error) { if _, err := reference.ParseNormalizedNamed(repo); err != nil { return nil, err } return &repositoryScopedRedisBlobDescriptorService{ repo: repo, upstream: rbds, }, nil } // Stat retrieves the descriptor data from the redis hash entry. func (rbds *redisBlobDescriptorService) Stat(ctx context.Context, dgst digest.Digest) (distribution.Descriptor, error) { if err := dgst.Validate(); err != nil { return distribution.Descriptor{}, err } conn := rbds.pool.Get() defer conn.Close() return rbds.stat(ctx, conn, dgst) } func (rbds *redisBlobDescriptorService) Clear(ctx context.Context, dgst digest.Digest) error { if err := dgst.Validate(); err != nil { return err } conn := rbds.pool.Get() defer conn.Close() // Not atomic in redis <= 2.3 reply, err := conn.Do("HDEL", rbds.blobDescriptorHashKey(dgst), "digest", "size", "mediatype") if err != nil { return err } if reply == 0 { return distribution.ErrBlobUnknown } return nil } // stat provides an internal stat call that takes a connection parameter. This // allows some internal management of the connection scope. func (rbds *redisBlobDescriptorService) stat(ctx context.Context, conn redis.Conn, dgst digest.Digest) (distribution.Descriptor, error) { reply, err := redis.Values(conn.Do("HMGET", rbds.blobDescriptorHashKey(dgst), "digest", "size", "mediatype")) if err != nil { return distribution.Descriptor{}, err } // NOTE(stevvooe): The "size" field used to be "length". We treat a // missing "size" field here as an unknown blob, which causes a cache // miss, effectively migrating the field. if len(reply) < 3 || reply[0] == nil || reply[1] == nil { // don't care if mediatype is nil return distribution.Descriptor{}, distribution.ErrBlobUnknown } var desc distribution.Descriptor if _, err := redis.Scan(reply, &desc.Digest, &desc.Size, &desc.MediaType); err != nil { return distribution.Descriptor{}, err } return desc, nil } // SetDescriptor sets the descriptor data for the given digest using a redis // hash. A hash is used here since we may store unrelated fields about a layer // in the future. func (rbds *redisBlobDescriptorService) SetDescriptor(ctx context.Context, dgst digest.Digest, desc distribution.Descriptor) error { if err := dgst.Validate(); err != nil { return err } if err := cache.ValidateDescriptor(desc); err != nil { return err } conn := rbds.pool.Get() defer conn.Close() return rbds.setDescriptor(ctx, conn, dgst, desc) } func (rbds *redisBlobDescriptorService) setDescriptor(ctx context.Context, conn redis.Conn, dgst digest.Digest, desc distribution.Descriptor) error { if _, err := conn.Do("HMSET", rbds.blobDescriptorHashKey(dgst), "digest", desc.Digest, "size", desc.Size); err != nil { return err } // Only set mediatype if not already set. if _, err := conn.Do("HSETNX", rbds.blobDescriptorHashKey(dgst), "mediatype", desc.MediaType); err != nil { return err } return nil } func (rbds *redisBlobDescriptorService) blobDescriptorHashKey(dgst digest.Digest) string { return "blobs::" + dgst.String() } type repositoryScopedRedisBlobDescriptorService struct { repo string upstream *redisBlobDescriptorService } var _ distribution.BlobDescriptorService = &repositoryScopedRedisBlobDescriptorService{} // Stat ensures that the digest is a member of the specified repository and // forwards the descriptor request to the global blob store. If the media type // differs for the repository, we override it. func (rsrbds *repositoryScopedRedisBlobDescriptorService) Stat(ctx context.Context, dgst digest.Digest) (distribution.Descriptor, error) { if err := dgst.Validate(); err != nil { return distribution.Descriptor{}, err } conn := rsrbds.upstream.pool.Get() defer conn.Close() // Check membership to repository first member, err := redis.Bool(conn.Do("SISMEMBER", rsrbds.repositoryBlobSetKey(rsrbds.repo), dgst)) if err != nil { return distribution.Descriptor{}, err } if !member { return distribution.Descriptor{}, distribution.ErrBlobUnknown } upstream, err := rsrbds.upstream.stat(ctx, conn, dgst) if err != nil { return distribution.Descriptor{}, err } // We allow a per repository mediatype, let's look it up here. mediatype, err := redis.String(conn.Do("HGET", rsrbds.blobDescriptorHashKey(dgst), "mediatype")) if err != nil { return distribution.Descriptor{}, err } if mediatype != "" { upstream.MediaType = mediatype } return upstream, nil } // Clear removes the descriptor from the cache and forwards to the upstream descriptor store func (rsrbds *repositoryScopedRedisBlobDescriptorService) Clear(ctx context.Context, dgst digest.Digest) error { if err := dgst.Validate(); err != nil { return err } conn := rsrbds.upstream.pool.Get() defer conn.Close() // Check membership to repository first member, err := redis.Bool(conn.Do("SISMEMBER", rsrbds.repositoryBlobSetKey(rsrbds.repo), dgst)) if err != nil { return err } if !member { return distribution.ErrBlobUnknown } return rsrbds.upstream.Clear(ctx, dgst) } func (rsrbds *repositoryScopedRedisBlobDescriptorService) SetDescriptor(ctx context.Context, dgst digest.Digest, desc distribution.Descriptor) error { if err := dgst.Validate(); err != nil { return err } if err := cache.ValidateDescriptor(desc); err != nil { return err } if dgst != desc.Digest { if dgst.Algorithm() == desc.Digest.Algorithm() { return fmt.Errorf("redis cache: digest for descriptors differ but algorithm does not: %q != %q", dgst, desc.Digest) } } conn := rsrbds.upstream.pool.Get() defer conn.Close() return rsrbds.setDescriptor(ctx, conn, dgst, desc) } func (rsrbds *repositoryScopedRedisBlobDescriptorService) setDescriptor(ctx context.Context, conn redis.Conn, dgst digest.Digest, desc distribution.Descriptor) error { if _, err := conn.Do("SADD", rsrbds.repositoryBlobSetKey(rsrbds.repo), dgst); err != nil { return err } if err := rsrbds.upstream.setDescriptor(ctx, conn, dgst, desc); err != nil { return err } // Override repository mediatype. if _, err := conn.Do("HSET", rsrbds.blobDescriptorHashKey(dgst), "mediatype", desc.MediaType); err != nil { return err } // Also set the values for the primary descriptor, if they differ by // algorithm (ie sha256 vs sha512). if desc.Digest != "" && dgst != desc.Digest && dgst.Algorithm() != desc.Digest.Algorithm() { if err := rsrbds.setDescriptor(ctx, conn, desc.Digest, desc); err != nil { return err } } return nil } func (rsrbds *repositoryScopedRedisBlobDescriptorService) blobDescriptorHashKey(dgst digest.Digest) string { return "repository::" + rsrbds.repo + "::blobs::" + dgst.String() } func (rsrbds *repositoryScopedRedisBlobDescriptorService) repositoryBlobSetKey(repo string) string { return "repository::" + rsrbds.repo + "::blobs" }