The roots.pem file contains the fallback trusted root certificates used by gRPC. Specifically, these are the roots used if the user doesn't explicitly configure roots and there are no roots found on the expected filesystem paths the gRPC process is running on. It is generated from the Chromium Root Store.
The roots.pem file includes full text descriptions of each certificate followed by the PEM block.
The roots.pem file was generated by fetching the source from the Chromium repository in base64 format and decoding it.
Example command to regenerate:
curl "https://chromium.googlesource.com/chromium/src/+/refs/heads/main/net/data/ssl/chrome_root_store/root_store.certs?format=TEXT" | base64 -d > etc/roots.pem