Proposal: Update truss to generate .pb.go files even when gRPC service is not defined.

[adamryman]

If I have a .proto file that contains messages that I would like to use in multiple services:

$ cat shared.proto
syntax = "proto3";

package shared;

message SharedRequest {
  string In = 1;
}

And if truss is run on this file, I propose that truss generates a corresponding .pb.go file.

In the case of shared.proto the generated shared.pb.go would look like this.

Currently, truss panics because it cannot find the service name. (This used to have a nice error, guess this needs to have a test as well)

$ truss shared.proto
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x64568f]

To implement:

• Review and merge Remove --pbout, ensure .pb.go are generated next to .proto #239
• fix panic caused here parsesvcdef.go:66, return error no Service or Service.Name
• cmd/truss/main.go, function parseInput() needs to
  • handle the error from parsesvcname.FromPaths
  • warn that no service is defined
  • info that .pb.go files will be generated
  • be wired up to execprotoc.GeneratePBDotGo() to actually generate the .pb.go files.

This is a step to fix #241

[adamryman]

Fixed by #246.

Thanks again @eriktate and welcome to being a contributor!