Create `safekeeper_pg_io_bytes_total` metric to track total amount of
bytes written/read in a postgres connections to safekeepers. This metric
has the following labels:
- `client_az` – availability zone of the connection initiator, or
`"unknown"`
- `sk_az` – availability zone of the safekeeper, or `"unknown"`
- `app_name` – `application_name` of the postgres client
- `dir` – data direction, either `"read"` or `"write"`
- `same_az` – `"true"`, `"false"` or `"unknown"`. Can be derived from
`client_az` and `sk_az`, exists purely for convenience.
This is implemented by passing availability zone in the connection
string, like this: `-c tenant_id=AAA timeline_id=BBB
availability-zone=AZ-1`.
Update ansible deployment scripts to add availability_zone argument
to safekeeper and pageserver in systemd service files.
Added basic instrumentation to integrate sentry with the proxy, pageserver, and safekeeper processes.
Currently in sentry there are three projects, one for each process. Sentry url is sent to all three processes separately via cli args.
