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hashicorp / go-plugin

Golang plugin system over RPC.
Mozilla Public License 2.0
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Add `ProtocolVersionError` type with client/server versions #191

Closed bendrucker closed 2 years ago

bendrucker commented 2 years ago

This adds a ProtocolVersionError error type that is returned when encountering a client/server plugin API mismatch. This error exposes the ClientVersions and ServerVersions. The error string remains the same as it is currently.

This provides a mechanism for plugin authors to implement custom messaging around version mismatches. For example, if the plugin server version is greater than the offered client versions, you could tell the user "upgrade the client or downgrade the plugin."

See https://github.com/terraform-linters/tflint/issues/1341 for an example of the issues that come up when protocol iterations are semi-frequent. And https://github.com/terraform-linters/tflint/blob/bf80af29756b3de976871360d3574879f5eddec0/plugin/discovery.go#L137-L156 for a hack that was put in place to try to wrap this error.

Since the code is so simple I figured I'd offer this. Happy to work on other approaches as well.

bendrucker commented 2 years ago

Closing based on the lack of activity, if there's any interest in this in the future let me know