keep the drive letter prefix in the path for windows

[alexrohozneanu]

Why the changes in this PR are needed?

Because i fixes issue #6910 and #4521. The windows like paths, prefixed with the drive letter are being stripped.

What are the changes in this PR?

Notes to assist PR review:

Further comments:

[johanfylling]

I'm afraid this PR constitutes a breaking change that might adversely affect users.

The way OPA separates prefix and file path with a : has an unfortunate syntactic overlap with how drive letters are specified in Windows paths.

On Windows, to specify an absolute path that includes a drive letter, the file:///c:/a/b/c format should be used.

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[johanfylling]

Nice and clean solution! 😃

[johanfylling]

I noticed an issue with these changes that we need to fix before this can be merged into main. Once loaded, the TLS cert, private key, and CA pool files are continually checked for changes on disk. Your changes unfortunately only accounts for the first load, and not subsequent reloads. You can test this by either changing one of the specified cert/key material files after starting the OPA server; or by additionally adding the --tls-cert-refresh-period flag, that'll force a periodic reload of the files (e.g. --tls-cert-refresh-period 5s for a 5 second reload period).

I think what needs to change to account for this is to also set the params.rt.CertificateFile, params.rt.CertificateKeyFile, and params.rt.CertPoolFile properties to the cleaned-up file paths here. It looks like these fields will then propagate to the reloading mechanism. Easiest is probably to move the fileurl.Clean() calls to initRuntime(), store the result in local variables that we then assign to the params.rt fields and pass to loadCertificate() and loadCertPool().

[johanfylling]

Thank you, great work!