google-cloud-storage

Hi. First of all, kudos to you for the VFS cache - it's really brilliant. I have one request though.

For a little background, as of now I'm using the following settings:

--vfs-cache-mode full \
  --vfs-cache-max-size 500G \
  --vfs-cache-max-age 5000h \
  --vfs-cache-poll-interval 5m \
  --vfs-read-ahead 2G \
  --bwlimit-file 32M \
  --vfs-read-chunk-size=64M \
  --vfs-read-chunk-s

From code https://github.com/thanos-io/thanos/blob/main/pkg/queryfrontend/roundtrip.go#L123, we are compiling the regex every time to match strings. This can be optimized by only compiling the regex once and checking if the string matches.

			matched, err := regexp.MatchString("/api/v1/label/.+/values$", r.URL.Path)
			if err == nil && matched {
				return labelValuesOp
			}

webui/src/lib/api/index.js

I see no documentation for the .kopiaignore format. A search in https://kopia.io/docs/ finds no matches (which looks like a bug in the docs search engine, since .kopiaignore is mentioned, but not described, in the documentation).

#773 suggests that .kopiaignore now behave similarly to .gitignore, but this is not mentioned in the documentation, and presumably there are some differences s

https://github.com/googleapis/google-cloud-cpp/blob/472f20a660310973191fcb99b7fbca81ec843a47/google/cloud/grpc_options.h#L38-L47

This option only applies in certain libraries (the handwritten ones). We should make this clear.

This means documenting the option:

@note This option only applies to a few libraries. Check the service's `*Connection` documentation for details.

... and

Thanks a bunch for this library, I've been trying to make use of it with an s3-emulating service that is not 100% bit-for-bit compliant and I've run into issues in a couple places.
Specifically I've noticed that in S3Client._remove, you assert for response==204, the clone-service I'm using responds with a 200 when you successfully delete instead.
I'd love to submit a PR to fix this but I need so