This directory is used to build a local erigon binary for the integration tests in op-e2e (and possibly for future use elsewhere).

The top level go mod has replace directives to use op-geth instead of vanilla go-ethereum, among other dependency replacements. These replacements are incompatible with erigon. Unfortunately, replace directives are global, and are irrespective of build tags or other hacks the only way to replace them is with a new go.mod. This directory simply contains a go.mod with replace directives pointing to the desired op-erigon version.

Go generally doesn't play very nicely with git submodules. In order to utilize a submodule, generally speaking, you need to either treat it exactly like you would an independent repository (e.g. executing commands only locally inside it), or you must utilize replace directives pointing to local paths.

As already pointed out, replace directives are often problematic, and they are ignored unless they belong to the top level go.mod. That means that if someone tries to build an op-erigon binary with a simple go build command pointing to a repository with sub-modules, this command is likely to fail in confusing ways.

Keeping this version aligned with the upstream version being tested is as simple as specifying the desired upstream tag or branch in the go.mod and running go mod tidy or, executing a go get with the appropriate version info. Checks to ensure the docker image and e2e versions are aligned should be added to CI and the make process if and when such enhancements are added.