S3: Support specifying S3 storage class

[juanrh]

• I added CHANGELOG entry for this change.
• Change is not relevant to the end user.

Changes

Changes

For thanos-io/thanos#5663, enable specifying S3 storage class by specifying it in config.put_user_metadata. For example launching the sidecar with a --objstore.config-file as follows stores all S3 files with storage class of STANDARD_IA

type: S3
prefix: thanos-test-standard-ia
config:
  endpoint: s3.us-east-1.amazonaws.com
  region: us-east-1
  bucket: MY_BUCKET
  put_user_metadata:
    X-Amz-Storage-Class: STANDARD_IA
  trace:
    enable: true

while using the following config file uses the default storage class of STANDARD

type: S3
prefix: thanos-test-standard-ia
config:
  endpoint: s3.us-east-1.amazonaws.com
  region: us-east-1
  bucket: MY_BUCKET
  trace:
    enable: true

Verification

Added unit tests.

Manual tests launching the sidecar with the two configurations listed above, doing rm ${PROM_ROOT}/data/thanos.shipper.json before that to force uploading files, and with a prometheus instance with small block duration to force upload.

${PROM_ROOT}/prometheus --config.file=${PROM_ROOT}/prometheus.yml \
  --storage.tsdb.min-block-duration=1m \
  --storage.tsdb.max-block-duration=1m

[bwplotka]

Thanks! Proposed some changes, otherwise LGTM (:

[bwplotka]

Suggested change

	- [#25](https://github.com/thanos-io/objstore/pull/25) Thanos Objstore S3: Support specifying S3 storage class.
	- [#25](https://github.com/thanos-io/objstore/pull/25) S3: Support specifying S3 storage class.