feat: Add datadog tracing to http middleware

[f0ssel]

No description provided.

[codecov]

Codecov Report

Merging #530 (8e2f954) into main (9485fd6) will increase coverage by 0.30%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #530      +/-   ##
==========================================
+ Coverage   63.56%   63.86%   +0.30%     
==========================================
  Files         197      114      -83     
  Lines       11524    10654     -870     
  Branches       85        0      -85     
==========================================
- Hits         7325     6804     -521     
+ Misses       3419     3091     -328     
+ Partials      780      759      -21     

Flag	Coverage Δ
unittest-go-	63.06% <100.00%> (+0.45%)	⬆️
unittest-go-macos-latest	58.78% <100.00%> (+0.32%)	⬆️
unittest-go-ubuntu-latest	61.36% <100.00%> (-0.07%)	⬇️
unittest-go-windows-2022	57.76% <100.00%> (+0.01%)	⬆️
unittest-js	?

Impacted Files	Coverage Δ
cli/start.go	66.15% <100.00%> (+2.35%)	⬆️
coderd/coderd.go	96.47% <100.00%> (+0.02%)	⬆️
peerbroker/dial.go	75.43% <0.00%> (-7.02%)	⬇️
provisionersdk/transport.go	74.46% <0.00%> (-6.39%)	⬇️
peer/conn.go	77.15% <0.00%> (-3.30%)	⬇️
provisioner/terraform/provision.go	72.29% <0.00%> (-1.37%)	⬇️
provisioner/terraform/serve.go	50.00% <0.00%> (ø)
site/src/components/SignIn/Welcome.tsx
site/src/components/Workspace/Workspace.tsx
site/src/components/Form/FormSection.tsx
... and 87 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 9485fd6...8e2f954. Read the comment docs.

[kylecarbs]

Two minor things, but LGTM!

[kylecarbs]

The failing check on here will be fixed if you merge in main!

[f0ssel]

Moved the ddtracer into a thin wrapper package tracer in 9ce5328. I wanted a place to write comments, have the code be more clearly self documenting, and give us a seam to use if we add more tracing things in the future.

[kylecarbs]

Let's add a thin-test to call start and stop with goleak. Then we can ensure no goroutines are leaked!

Apart from my one structural comment, this is awesome! Thoughts on adding a CLI flag to enable/disable tracing with the DATADOG_TOKEN? I'd rather this not be implicit, just in case customers want to disable it.

We can add that to coder.env too. That's used by our systems service in our dogfood deployment! Tracing in dogfood😎

[kylecarbs]

@f0ssel it appears the tunnel default to true broke from the flag PR. Since this is about to merge, could you investigate that? (assuming it's a simple fix)

[f0ssel]

@f0ssel it appears the tunnel default to true broke from the flag PR. Since this is about to merge, could you investigate that? (assuming it's a simple fix)

I'll do this in a separate PR to keep things clean