feat: add express plugin #666

[vmarchaud]

TODO:

• add http.route in the http server span
• add options to disable span for specific middlewares/router

[codecov-io]

Codecov Report

Merging #685 into master will increase coverage by 3.46%.
The diff coverage is 98.7%.

@@            Coverage Diff             @@
##           master     #685      +/-   ##
==========================================
+ Coverage   91.11%   94.57%   +3.46%     
==========================================
  Files         232      217      -15     
  Lines       10444     9981     -463     
  Branches      958      857     -101     
==========================================
- Hits         9516     9440      -76     
+ Misses        928      541     -387

Impacted Files	Coverage Δ
packages/opentelemetry-plugin-http/src/http.ts	97.72% <ø> (ø)	⬆️
...es/opentelemetry-plugin-express/test/utils.test.ts	100% <100%> (ø)
...ckages/opentelemetry-plugin-express/src/version.ts	100% <100%> (ø)
packages/opentelemetry-plugin-http/src/utils.ts	97.4% <100%> (+0.14%)	⬆️
...lemetry-plugin-http/test/functionals/utils.test.ts	99.4% <100%> (+0.03%)	⬆️
packages/opentelemetry-plugin-express/src/types.ts	100% <100%> (ø)
packages/opentelemetry-plugin-express/src/utils.ts	95.45% <95.45%> (ø)
...ckages/opentelemetry-plugin-express/src/express.ts	98.85% <98.85%> (ø)
.../opentelemetry-plugin-express/test/express.test.ts	99.14% <99.14%> (ø)
...ages/opentelemetry-plugin-http/test/utils/utils.ts	33.33% <0%> (-26.67%)	⬇️
... and 73 more

[OlivierAlbertini]

First pass, added few comments. Good job!

[obecny]

I added few comments, and have some questions too.
Last thing: could you please add some screenshots how the spans look like (for example from zipkin or something relevant etc.) ?

[dyladan]

Overall this looks ok, but I am very wary of the use of a mutilated request object. In my mind this not only has the chance to break a user's application (in the unlikely event they also try to set/modify a property with the same name), but makes the express plugin an implicit dependency of the http plugin. If someone unaware of this behavior modifies this plugin in the future and changes this property, it has the chance of breaking a seemingly unrelated non-dependent plugin.

[mayurkale22]

Somehow getting 500 (Server Error) on codecov report.

[dyladan]

@OlivierAlbertini since you had a lot of comments I would appreciate your review here before merge

[obecny]

I just miss some screenshots to show how the spans will look like when using this plugin, other than that lgtm

[vmarchaud]

@obecny i will add examples in a seperate PRs and include screenshot in there

[dyladan]

@vmarchaud I agree with mayur we should not have broken links in the readmes. We can add a link when there is an example to link to

@mayurkale22 once he does that I think we should merge this. seems like @OlivierAlbertini is busy

[OlivierAlbertini]

Sorry for the delay, I will test with some internal apps this week-end. I will give feedback if needed.
@vmarchaud good job!

[OlivierAlbertini]

👍

[vmarchaud]

@dyladan I've rebased the PR and removed the link from the readme