DTR cache configuration reference

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This topic applies to Docker Enterprise.

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DTR caches are based on Docker Registry, and use the same configuration file format. Learn more about the configuration options.

The DTR cache extends the Docker Registry configuration file format by introducing a new middleware called downstream that has three configuration options: blobttl, upstreams, and cas:

# Settings that you would include in a
# Docker Registry configuration file followed by

      - name: downstream
          blobttl: 24h
            - <Externally-reachable address for upstream registry or content cache in format scheme://host:port>
            - <Absolute path to next-hop upstream registry or content cache CA certificate in the container's filesystem>

Below you can find the description for each parameter, specific to DTR caches.

Parameter Required Description
blobttl no A positive integer and an optional unit of time suffix to determine the TTL (Time to Live) value for blobs in the cache. If blobttl is configured, storage.delete.enabled must be set to true. Acceptable units of time are:
  • ns (nanoseconds)
  • us (microseconds)
  • ms (milliseconds)
  • s (seconds)
  • m (minutes)
  • h (hours)
If you omit the suffix, the system interprets the value as nanoseconds.
cas no An optional list of absolute paths to PEM-encoded CA certificates of upstream registries or content caches.
upstreams yes A list of externally-reachable addresses for upstream registries of content caches. If more than one host is specified, it will pull from registries in round-robin order.
DTR, cache