Add OTLP HTTP Log Exporter example using tracing appender.

[lalitb]

Changes

• Update the existing OTLP HTTP exporter to export logs instrumented through tokio library, using tracing appender. This change could have suffered from infinite live-loop issue described in Need a way to suppress telemetry from SDKs own operation #1171, but the Hyper HTTP library emits tracing/debug logs only if the tracing feature (which is disabled by default) is enabled for this library, and Cargo.toml for this example doesn't enable it. Also, there are no errors reported from this library (which would also get routed to OpenTelemetry appender) if the steps in examples are executed properly. So only the logs, traces and metrics geerated from the example code are exported to the collector.

• Also for simplicity removed all-in-one jaeger exporter from the collector configuration, and instead used Debug Exporter which dumps all events to console.

• The infinite live-issue discussed in Need a way to suppress telemetry from SDKs own operation #1171 need to be investigated separately, one option could be to filter all such non-required events using event_enabled function by checking the target/module.

Please provide a brief description of the changes here.

Merge requirement checklist

• CONTRIBUTING guidelines followed
• Unit tests added/updated (if applicable)
• Appropriate CHANGELOG.md files updated for non-trivial, user-facing changes
• Changes in public API reviewed (if applicable)

[codecov]

Codecov Report

Attention: 7 lines in your changes are missing coverage. Please review.

Files	Coverage Δ
opentelemetry-sdk/src/metrics/view.rs	78.4% <89.2%> (+10.2%)	⬆️

... and 1 file with indirect coverage changes

📢 Thoughts on this report? Let us know!.

[shaun-cox]

Thanks for doing this. Just one nit which would be nice to address before merging...

[lalitb]

The CI is failing with:

error: package `regex-syntax v0.8.1` cannot be built because it requires rustc 1.65 or newer, while the currently active rustc version is 1.64.0 Error: Process completed with exit code 101.

Does it mean we should bump up msrv to 1.65.0 ?

[lalitb]

The CI is failing with:

error: package `regex-syntax v0.8.1` cannot be built because it requires rustc 1.65 or newer, while the currently active rustc version is 1.64.0 Error: Process completed with exit code 101.

Does it mean we should bump up msrv to 1.65.0 ?

@jtescher @TommyCpp Seems the PRs are blocked on this error. Should we raise a separate PR to bump the msrv version ?

[jtescher]

@lalitb We could do that, an alternative would be to swap the view regex impl to use a glob impl instead as suggested in #1262, which would drop the need for the dependency entirely