## Problem
It took me a while to understand the purpose of all the tasks spawned in
the main functions.
## Summary of changes
Utilising the type system and less macros, plus much more comments,
document the shutdown procedure of each task in detail
## Problem
#4528
## Summary of changes
Add a 60 seconds default timeout to the reqwest client
Add retries for up to 3 times to call into the metric consumption
endpoint
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Co-authored-by: Christian Schwarz <christian@neon.tech>
It fixes the miscalculation of the metric for projects that use multiple
branches for the same endpoint.
We were under billing users with such projects. So we need to
communicate the change in Release Notes.
Since we allow switching endpoints between different branches, it is important to use composite key.
Otherwise, we may try to calculate delta between metric values for two different branches.
On the surface, this doesn't add much, but there are some benefits:
* We can do graceful shutdowns and thus record more code coverage data.
* We now have a foundation for the more interesting behaviors, e.g. "stop
accepting new connections after SIGTERM but keep serving the existing ones".
* We give the otel machinery a chance to flush trace events before
finally shutting down.
This commit sets up OpenTelemetry tracing and exporter, so that they
can be exported as OpenTelemetry traces as well.
All outgoing HTTP requests will be traced. A separate (child)
span is created for each outgoing HTTP request, and the tracing
context is also propagated to the server in the HTTP headers.
If tracing is enabled in the control plane and compute node too, you
can now get an end-to-end distributed trace of what happens when a new
connection is established, starting from the handshake with the
client, creating the 'start_compute' operation in the control plane,
starting the compute node, all the way to down to fetching the base
backup and the availability checks in compute_ctl.
Co-authored-by: Dmitry Ivanov <dima@neon.tech>
