Allow a user to determine if they are logged into the BSR.

[zachgersh]

Feature

In my local workflow, I want to double check that a user has a netrc with credentials in it so they can be authenticated to the BSR. I use this check to make sure that a docker build does not fail on their machine since we are mounting their netrc in as a secret to do client downloads from BSR.

Change I'd like to see

The buf cli could probably have something like buf registry auth status or some similar commands that could tell you that you are logged in or not. The message that it prints isn't really important (could print the auth json) the more important part would be that it exits 0 if auth'ed and exits 1 if not auth'ed.

What does my bash code look like without this feature?

echo "Checking Buf Schema Registry login..."
bsr_auth_http_code=$(curl -o /dev/null -s -w "%{http_code}" -L -n {bsr_module_url}/@v/list)
if [ "$bsr_auth_http_code" -eq 200 ]; then
    echo "Successfully logged into BSR"
else
    echo "Please auth with the buf cli"
    exit 1
fi
echo -e "Done!\n"

buf curl could also work for this.

[zachgersh]

happy to put a PR in for this feature as well as long as we agree on what the command is and the spec above.