Put config files for the trees you symlinked in /trees in here. The assumed default config (which can list multiple trees) is config.json.

A good starting point is probably tests/searchfox-config.json, noting that you probably want to increment the codesearch_port to start at port 8082 and keep incrementing from there. The tests repo uses port 8080 and searchfox uses 8081, so this avoids edge cases if you are switching between what is indexed.

You can then build the trees via make build-trees from /vagrant inside of your docker image if your config file is the default of config.json. If your config file is named something else, then you can set the CONFIG env variable by doing something like CONFIG=my-config.json make build-trees. Note that although make can accept variable assignments as part of its arguments, that's not how this is intended to work, and so maybe it won't work!