Refactors Compute::prepare_and_run. It's split into subroutines
differently, to make it easier to attach tracing spans to the
different stages. The high-level logic for waiting for Postgres to
exit is moved to the caller.
Replace 'env_logger' with 'tracing', and add `#instrument` directives
to different stages fo the startup process. This is a fairly
mechanical change, except for the changes in 'spec.rs'. 'spec.rs'
contained some complicated formatting, where parts of log messages
were printed directly to stdout with `print`s. That was a bit messed
up because the log normally goes to stderr, but those lines were
printed to stdout. In our docker images, stderr and stdout both go to
the same place so you wouldn't notice, but I don't think it was
intentional.
This changes the log format to the default
'tracing_subscriber::format' format. It's different from the Postgres
log format, however, and because both compute_tools and Postgres print
to the same log, it's now a mix of two different formats. I'm not
sure how the Grafana log parsing pipeline can handle that. If it's a
problem, we can build custom formatter to change the compute_tools log
format to be the same as Postgres's, like it was before this commit,
or we can change the Postgres log format to match tracing_formatter's,
or we can start printing compute_tool's log output to a different
destination than Postgres
We passed the pageserver's libpq endpoint URL as the 'compute_ctl
--connstr' argument, but that was bogus: the --connstr URL is supposed
to be the URL to the *Postgres* instance that compute_ctl launches and
monitors, not to the pageserver. compute_ctl does need the pageserver
URL too, but it is read from the cluster spec JSON, not --connstr.
That was pretty confusing, as you got a lot of "unknown command"
errors in the pageserver log, when compute_tools tries to run regular
SQL commands on the pageserver. The test still passed, however, as it
doesn't require the SQL commands to succeed. But to make this less
confusing, use an invalid hostname instead, so that the queries will
fail to even connect.
