• follow-up to Update and validation of generated files #44697
• relates to generate plugin clients via template #13835
• relates to Add timeouts for volume plugin ops #35441
• addresses / fixes Add make target (and verify step) to regenerate protobufs #40176

While working on some changes, I noticed that a file I was editing was a generated file;

However, the header didn't have the correct format for generated files so didn't warn me about this, so I thought: "let me update the template to have the right comment". To verify my changes, I ran make generated-files, which didn't complain, but did not update the generated file. When I tried to manually go generate the file, the file did change, but also generated very different code.

So, looking at the file's history (perhaps I used the wrong command for generating the file?), I found various manual changes were made to this file in the past, but CI never complained about this 🤔

In short: this PR is the result of one of those "down the rabbit-hole" cases:

• Update the template to actually generate the expected code.
• Update the template to have a correctly formatted "this is a generated file" comment.
• Fix the make generated-files target to also include this file (fun fact: it was generating the file, but not copying it out, and because of that, was not validating it for changes).
• And finally: update the template with some of the changes I was about to make manually, and to make the code slightly more iodiomatic.

. Looking at the history of the file, I then noticed that the file was manually updated a few times in the past.

pkg/plugins: pluginrpc-gen: fix go generate for volume driver

The volume driver plugin generated code was manually updated in
b15f8d2, so generating the code
would no longer produce the same output.

This patch updates the generator code to allow regenerating the volume
driver plugin.

• update buildImports to allow additional imports to be passed
• add a conditional block to the template for volumeDriver
• add a conditional block to set the right timeout, depending on what
  method we're generating code for.
• slightly adjust the template to make the output format match the
  existing code.

Some of this is a bit quirky, so we should look for a more generic option,
but I tried to preserve the ability to generate this code, so that it
can evolve if things change.

To verify the generated code:

GO111MODULE=off go install ./pkg/plugins/pluginrpc-gen
GO111MODULE=off go generate ./volume/drivers

hack: generate-files.Dockerfile: validate volume/drivers

Maybe this was left out on purpose in 7daaa00,
because the pluginrpc-gen generator was broken for this code, but now
that the generator works correctly, we can enable generating this package,
and validate it in CI.

The Dockerfile was actually building pluginrpc-gen and generating the
plugin (volume/drivers), but was not copying the result, and as a result
also not validating the results.

hack: generate-files.Dockerfile: simplify pluginrpc-gen install

pluginrpc-gen is also "go install"-able (if there's a go.mod), so let's
use it :)

pkg/plugins: pluginrpc-gen: fix "generated code" header to be detected

Update the comment to match the format defined by Golang, otherwise
it won't be detected by IDEs and linters.

With this change, my IDE properly picks up that the file is generated:

pkg/plugins: pluginrpc-gen: use struct-literals in generated code

Makes the generated code slightly nicer :)

pkg/plugins: pluginrpc-gen: use early return on error

Don't assign output variables if an error occurred.

pkg/plugins: pluginrpc-gen: assert interface

Make sure the generated code matches the interface, and produce a
compile-time error otherwise.

pkg/plugins: pluginrpc-gen: fix generating logger plugin

Make the generator work for generating daemon/logger/logPluginProxy.

(removed this commit)

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