Read snapshot

GET /{bucket}/{stream}/snapshot/{offset} returns the snapshot blob at a specific offset. To read the latest snapshot, take its offset from the Stream-Snapshot-Offset header of HEAD.

bucketpathstringrequired

Bucket ID.

streampathstringrequired

Stream ID.

offsetpathstringrequired

Snapshot offset: the 20-character zero-padded decimal token returned by previous reads or Stream-Snapshot-Offset headers.

Stream-Incarnationheaderstring

Optional precondition: the stream's incarnation token, as a previous response's Stream-Incarnation header returned it. The read is answered only if the stream that serves it is still that incarnation; otherwise it answers 412. Without the header, the request behaves exactly as described here. A malformed value answers 400. See Stream-Incarnation.

Rangeheaderstring

Optional: one byte range of the snapshot, bytes=a-b, bytes=a- or bytes=-n. The answer is 206 with only those bytes and Content-Range: bytes a-b/total. Several ranges, a value that does not parse, or a request that also carries If-Range get the whole snapshot as 200. A body in the cold tier is read only where the range needs it.

Status	Meaning
`200`	Snapshot blob returned.
`206`	The requested byte range returned.
`304`	`If-None-Match` named the snapshot's `ETag`. The headers are those of the `200`.
`307`	In a cluster, this node is not the stream's group leader. `Location` is the same request on the leader.
`400`	The request carries `incarnation`, which immutable reads carry in the path instead.
`404`	Stream, snapshot, or offset not found. When the stream exists and the snapshot is not its latest, `Stream-Incarnation` is the stream's token.
`412`	`Stream-Incarnation` did not match. The response's `Stream-Incarnation` is the current token.
`416`	The range starts at or past the end of the snapshot. `Content-Range: bytes */total` names its size, and `Stream-Incarnation` the stream's token.
`502`	The snapshot body is in the cold tier and could not be read.
`503`	The group has no known leader, or the leader could not confirm its leadership in time. Retry after `Retry-After`.

Response headers include Content-Type, Content-Length, Accept-Ranges: bytes, ETag (the snapshot digest in quotes), Stream-Next-Offset, Stream-Snapshot-Offset, Stream-Snapshot-Digest, Stream-Incarnation, and Stream-Up-To-Date: true when the snapshot offset is the stream's tail. They describe the whole snapshot on a 206 too: the digest always covers the whole body. A 404 comes before the range is looked at, then 416, then 412. A revalidation with If-None-Match ignores the range and answers 412 or 304. To read a snapshot through a cache, use immutable reads. A body stored in the cold tier is streamed from it. Snapshot answers are never compressed.

curl 'http://127.0.0.1:4437/demo/hello/snapshot/00000000000000000042'

curl -H 'Range: bytes=0-55' \
  'http://127.0.0.1:4437/demo/hello/snapshot/00000000000000000042'

Snapshot reads are served by the group's leader after it confirms with a majority of voters that it still leads, so the read reflects every snapshot publish acknowledged before the request. A follower answers 307 to the leader; follow the redirect. See Durability and consistency.

See snapshots for the snapshot lifecycle.