How to enable plugin caching without getting "Incomplete lock file information for providers" warning

It seems that enabling provider caching automatically triggers the “Incomplete lock file information for providers” warning when you run a terraform init. Why do I have to download the provider every time to “be safe?”

You don’t - it is safe to ignore the warning.

Further background information can be found at

and

In the forthcoming v1.4.0 release Terraform will construct a complete dependency lock file by default, so you can check that into your version control and avoid encountering this situation.

Even in current versions of Terraform (v1.3 and earlier) I would expect this message to appear only when Terraform adds a new entry to the lock file. Once you already have the file in your version control system you should not see the warning again until you next upgrade the provider, which will then of course regenerate the lock file entry and so you’ll once again have an incomplete entry that needs to be amended with checksums for other platforms.