op-service, op-batcher, op-proposer: Active sequencer follow mode

[EvanJRichard]

Description

This PR proposes to add dial.ActiveL2EndpointProvider and dial.ActiveL2RollupProvider. These endpoint providers will check that they are pointing to the active sequencer before providing rollup clients and l2 ethClients to callers. They are enabled by passing a comma-separated list as the rollup/l2 ethclient URL string. Additionally, this PR adds infrastructure for unit testing these structs, such as testutils.MockRollupClient.

Tests
See new unit test file, op-service/dial/active_l2_provider_test.go, about half the changeset is that file. Most unit tests follow the pattern where an ActiveL2RollupProvider/ActiveL2EndpointProvider is pointing at an active sequencer, "notices" that the sequencer goes inactive, and then dials a new sequencer that reports it is active.

This also successfully failed over in a devnet-like test run locally on my machine. It has also been tested to work on our internal cloud devnet during a ZDD.

Metadata

• Requires and builds on top of op-service, op-proposer, op-batcher: Add L2EndpointProvider and its first struct, StaticL2EndpointProvider. #8580
• Fixes https://github.com/ethereum-optimism/client-pod/issues/166

[semgrep-app]

Semgrep found 1 nil-check-after-call finding:

• op-node/p2p/node.go: L74-167

Potential p2pmetrics nil dereference when NewBandwidthCounter is called

_{Ignore this finding from nil-check-after-call.}

[coderabbitai]

Walkthrough

Walkthrough

An update has been made across several files to support multiple URL configurations for L2 Ethereum RPC and Rollup RPC endpoints. This includes handling comma-separated lists and ensuring URL counts match. A new ActiveL2EndpointProvider and ActiveL2RollupProvider have been introduced to manage multiple endpoints and facilitate failover. The changes also include new validation logic, additional test cases, and the import of the strings package to handle string operations.

Changes

File Path	Summary
.../batcher/config.go .../proposer/service.go	Updated CLIConfig to allow comma-separated lists for L2EthRpc and RollupRpc, added validation for URL counts, and imported strings. Also, conditionally used NewActiveL2RollupProvider based on comma presence in cfg.RollupRpc.
.../batcher/service.go	Modified initRPCClients to handle multiple URLs for RPC clients.
.../dial/active_l2_provider.go .../dial/active_rollup_provider.go	Introduced new types and functions for managing multiple L2 and Rollup endpoints, including failover logic.
.../dial/active_l2_provider_test.go	Added new test cases for failover scenarios, active sequencer selection, and long check durations; modified test harness setup.

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[sebastianst]

Going in a good direction. Maybe we want to simplify further by not doing retries after having iterated over the whole list once. We then offload the retry driving to the callers. Might work well, should check.

[semgrep-app]

Semgrep found 1 import-text-template finding:

• op-bindings/gen/main.go: L14

When working with web applications that involve rendering user-generated content, it's important to properly escape any HTML content to prevent Cross-Site Scripting (XSS) attacks. In Go, the text/template package does not automatically escape HTML content, which can leave your application vulnerable to these types of attacks. To mitigate this risk, it's recommended to use the html/template package instead, which provides built-in functionality for HTML escaping. By using html/template to render your HTML content, you can help to ensure that your web application is more secure and less susceptible to XSS vulnerabilities.

_{Ignore this finding from import-text-template.}

Semgrep found 1 ifs-tampering finding:

• op-challenger/scripts/list_claims.sh: L17

The special variable IFS affects how splitting takes place when expanding unquoted variables. Don't set it globally. Prefer a dedicated utility such as 'cut' or 'awk' if you need to split input data. If you must use 'read', set IFS locally using e.g. 'IFS="," read -a my_array'.

_{Ignore this finding from ifs-tampering.}

[sebastianst]

I may be confused, don't we want to retry a new sequencer if dialing one fails?

We might need to add functionality to the test setup to let the dialers error on dial.

[sebastianst]

Should be good to go! There are some comments to fix in the regression test. Also proposed another 1-2 tests that we might have missed.

[sebastianst]

LGTM ✨