ENG-1670 - improve proxyd metrics, support local rate limiter

[mslipper]

This PR improves proxyd metrics, and removes the requirement to use Redis with the rate limiter.

New metrics

rpc_backend_http_response_codes_total{"auth", "backend_name", "method_name", "status_code"} - This counter tracks HTTP error codes returned from each proxy backend. It's maintained as a separate metric from rpc_errors_total since rpc_errors_total keeps track of errors found in the JSON-RPC response body.

http_response_codes_total - This counter tracks HTTP response codes returned to the client. Usually, this will be 200 except in a couple of exceptional cases:

• 503 when there are no backends available.
• 400 when the request payload is inavlid.
• 401 when a bad auth token is provided.
• 404 when a path can't be found.

Other errors will return either a 500, or a 200 with a JSON-RPC response code. HTTP error codes other than 400s are not proxied from the upstream because they are inconsistent among different infrastructure providers.

Rate limiting

Redis is no longer required to apply rate limiting. If the [redis] stanza is not provided in the config, then proxyd will use an in-memory rate limiter instead. To remove rate limiting from an endpoint altogether, remove Redis from the config and set the RPS and concurrency limits to zero.

User agent logging

The user agent is now logged. It looks like this:

INFO [11-18|09:00:59.516] received RPC request                     req_id=eb133e436364c84a179e auth=foobar user_agent="Paw/3.3.1 (Macintosh; OS X/11.4.0) GCDHTTPRequest"
INFO [11-18|09:00:59.622] forwarded RPC request                    method=eth_chainId auth=foobar req_id=eb133e436364c84a179e

You can use the req_id to correlate subsequent log lines with the user agent.

[changeset-bot]

🦋 Changeset detected

Latest commit: da6138f

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@eth-optimism/proxyd	Minor

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[tynes]

Can you add a changeset?

[tynes]

Spacing is off here, mixed tabs + spaces

[codecov-commenter]

Codecov Report

Merging #1782 (ea6db40) into develop (d59341a) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff            @@
##           develop    #1782   +/-   ##
========================================
  Coverage    71.81%   71.81%           
========================================
  Files           69       69           
  Lines         2303     2303           
  Branches       344      344           
========================================
  Hits          1654     1654           
  Misses         649      649           

Flag	Coverage Δ
batch-submitter	61.56% <ø> (ø)
contracts	87.96% <ø> (ø)
core-utils	56.53% <ø> (ø)
data-transport-layer	38.23% <ø> (ø)
message-relayer	70.86% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...ontracts/contracts/L1/verification/BondManager.sol	100.00% <0.00%> (ø)
...tracts/contracts/L1/messaging/L1StandardBridge.sol	97.05% <0.00%> (ø)
...racts/contracts/L1/rollup/StateCommitmentChain.sol	87.50% <0.00%> (ø)
...acts/contracts/L1/rollup/ChainStorageContainer.sol	70.00% <0.00%> (ø)
.../contracts/L1/messaging/L1CrossDomainMessenger.sol	96.77% <0.00%> (ø)
.../contracts/L1/rollup/CanonicalTransactionChain.sol	86.66% <0.00%> (ø)
.../contracts/libraries/bridge/CrossDomainEnabled.sol	100.00% <0.00%> (ø)

---

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 d59341a...ea6db40. Read the comment docs.