Should not require socket path to be set in both firecracker.Config and firecracker.VMCommandBuilder

[samuelkarp]

The SDK currently requires the socket path to be set in two places, and for it to be set to the same thing:

• firecracker.Config
• firecracker.VMCommandBuilder

firecracker.VMCommandBuilder is used for building the command to start the firecracker binary. Specifying the socket path here adds the --api-sock command-line argument that tells Firecracker to open the socket in a particular location.

firecracker.Config is used in the API client so that the client knows how to talk to the Firecracker API.

In order to both start a VM and communicate with it, a user of this SDK is required to specify the socket path in both places. If the user is intending to start a VM and immediately control it (which I think is the most common case), we should make it simpler to do so and allow the field to be specified only once.

[kzys]

If a customer is using NewMachine, he/she doesn't have to specify the socket path twice, because of

firecracker-go-sdk/machine.go

Line 319 in 6237a44

WithSocketPath(cfg.SocketPath).

I think that covers most of use cases.

Do we want to improve UX even further for customers who use NewClient() directly?