Add support for OpenTelemetry tracing via OTLP

[saschagrunert]

What type of PR is this?

/kind feature

What this PR does / why we need it:

This allows using the GRPC endpoint of an OTLP exporter to export span-based telemetry data directly from conmon-rs.

Which issue(s) this PR fixes:

Fixes tokio-rs/tracing#481

Special notes for your reviewer:

Demo:

For usage with the current CRI-O main we have to manually force-enable tracing:

diff --git a/conmon-rs/server/src/config.rs b/conmon-rs/server/src/config.rs
index 98f99ed..f2b5ff2 100644
--- a/conmon-rs/server/src/config.rs
+++ b/conmon-rs/server/src/config.rs
@@ -113,6 +113,7 @@ pub struct Config {
         env(concat!(prefix!(), "ENABLE_TRACING")),
         long("enable-tracing"),
         short('e'),
+        default_value("true"),
     )]
     /// Enable OpenTelemetry tracing.
     enable_tracing: bool,

Then we can give it a try:

> cargo build
> cd contrib/tracing/ && docker-compose up
> cd /path/to/cri-o
> sudo crictl run test/testdata/container_redis.json test/testdata/sandbox_config.json && sudo crictl rmp -fa

Opening Jaeger UI on http://localhost:16686 does now show the conmonrs service:

And the spans contain the relevant information:

There seems to be a bug that spans are missing from the telemetry, which should be fixed before used in production:
open-telemetry/opentelemetry-rust#888, tokio-rs/tracing-opentelemetry#58

Does this PR introduce a user-facing change?

Added support for OpenTelemetry OTLP GRPC tracing via `--enable-tracing` and `--tracing-endpoint`.

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: saschagrunert

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• OWNERS [saschagrunert]

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[codecov-commenter]

Codecov Report

Merging #785 (d667c7f) into main (2521c24) will decrease coverage by 0.08%.
The diff coverage is 100.00%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     tokio-rs/tracing#785      +/-   ##
==========================================
- Coverage   31.35%   31.26%   -0.09%     
==========================================
  Files          13       13              
  Lines        1129     1129              
  Branches      429      427       -2     
==========================================
- Hits          354      353       -1     
- Misses        492      494       +2     
+ Partials      283      282       -1     

[saschagrunert]

Green CI, PTAL @haircommander @rphillips.

[rphillips]

/lgtm