Rework standalone API

[wbrowne]

What this PR does / why we need it:
This PR attempts to simplify how the standalone package works by refactor into a client/server pattern. I found it quite difficult to navigate as we historically have combined both standalone and locator functionality in the same code path, which makes it tricky to know what information is needed and where.

Compatibility changes:

# github.com/grafana/grafana-plugin-sdk-go/backend
## incompatible changes
GracefulStandaloneServe: changed from func(ServeOpts, github.com/grafana/grafana-plugin-sdk-go/internal/standalone.Args) error to func(ServeOpts, github.com/grafana/grafana-plugin-sdk-go/internal/standalone.ServerSettings) error
StandaloneServe: removed

Special notes for your reviewer:

• This PR removes the need for a -debug flag as standalone/server mode will now always generate a standalone.txt and pid.txt.
• GF_PLUGIN_GRPC_ADDRESS_<PLUGIN_ID> is an existing env var, but now both client and server will use this as the primary source of truth for creating or connecting to the standalone server. The pre-existing generation of the address and reading from file still exists, but are treated as fallbacks in their respective modes.

[andresmgot]

I tried this PR and was not able to run a plugin with vscode debugger. I have also set the variable GF_PLUGIN_GRPC_STANDALONE_<PLUGIN_ID>="true", which I don't know if it's needded.

There is no error in the plugin logs though:

with this changes:

Detaching and terminating target process
dlv dap (37840) exited with code: 0
Starting: /home/andres/go/bin/dlv dap --listen=127.0.0.1:39521 --log-dest=3 from .../pkg
DAP server listening at: 127.0.0.1:39521
Type 'dlv help' for list of commands.
{"@level":"debug","@message":"Profiler","@timestamp":"2023-06-14T13:33:17.341648+02:00","enabled":false}
{"@level":"debug","@message":"Tracing","@timestamp":"2023-06-14T13:33:17.341701+02:00","enabled":false,"propagation":""}
{"@level":"debug","@message":"Standalone plugin server","@timestamp":"2023-06-14T13:33:17.342686+02:00","capabilities":["diagnostics","resources","data","stream"]}

This is using main:

Detaching and terminating target process
connection error: Error: read ECONNRESET
dlv dap (41046) exited with code: 0
Starting: /home/andres/go/bin/dlv dap --listen=127.0.0.1:40495 --log-dest=3 from .../pkg
DAP server listening at: 127.0.0.1:40495
Type 'dlv help' for list of commands.
{"@level":"debug","@message":"Profiler","@timestamp":"2023-06-14T13:41:10.963160+02:00","enabled":false}
{"@level":"debug","@message":"Tracing","@timestamp":"2023-06-14T13:41:10.963222+02:00","enabled":false,"propagation":""}
{"@level":"info","@message":"Creating standalone address and pid files","@timestamp":"2023-06-14T13:41:14.229516+02:00"}
2023/06/14 13:41:14 Killing process: 39246
{"@level":"debug","@message":"Standalone plugin server","@timestamp":"2023-06-14T13:41:14.241631+02:00","capabilities":["diagnostics","resources","data","stream"]}

Is there something that I am missing?

[wbrowne]

I tried this PR and was not able to run a plugin with vscode debugger. I have also set the variable GF_PLUGIN_GRPC_STANDALONE_<PLUGIN_ID>="true", which I don't know if it's needded.

There is no error in the plugin logs though:

with this changes:

Detaching and terminating target process
dlv dap (37840) exited with code: 0
Starting: /home/andres/go/bin/dlv dap --listen=127.0.0.1:39521 --log-dest=3 from .../pkg
DAP server listening at: 127.0.0.1:39521
Type 'dlv help' for list of commands.
{"@level":"debug","@message":"Profiler","@timestamp":"2023-06-14T13:33:17.341648+02:00","enabled":false}
{"@level":"debug","@message":"Tracing","@timestamp":"2023-06-14T13:33:17.341701+02:00","enabled":false,"propagation":""}
{"@level":"debug","@message":"Standalone plugin server","@timestamp":"2023-06-14T13:33:17.342686+02:00","capabilities":["diagnostics","resources","data","stream"]}

This is using main:

Detaching and terminating target process
connection error: Error: read ECONNRESET
dlv dap (41046) exited with code: 0
Starting: /home/andres/go/bin/dlv dap --listen=127.0.0.1:40495 --log-dest=3 from .../pkg
DAP server listening at: 127.0.0.1:40495
Type 'dlv help' for list of commands.
{"@level":"debug","@message":"Profiler","@timestamp":"2023-06-14T13:41:10.963160+02:00","enabled":false}
{"@level":"debug","@message":"Tracing","@timestamp":"2023-06-14T13:41:10.963222+02:00","enabled":false,"propagation":""}
{"@level":"info","@message":"Creating standalone address and pid files","@timestamp":"2023-06-14T13:41:14.229516+02:00"}
2023/06/14 13:41:14 Killing process: 39246
{"@level":"debug","@message":"Standalone plugin server","@timestamp":"2023-06-14T13:41:14.241631+02:00","capabilities":["diagnostics","resources","data","stream"]}

Is there something that I am missing?

Should be okay now @andresmgot - thanks for checking. Had fudged the paths a bit, but should be okay now

[marefr]

What kind of tests do you have in mind, manual or unit/integration tests? Trying to understand why this is needed, sorry if I'm stupid/tired 😄

[andresmgot]

FWIW it works fine for me now

[wbrowne]

What kind of tests do you have in mind, manual or unit/integration tests? Trying to understand why this is needed, sorry if I'm stupid/tired 😄

No longer relevant for now @marefr. This PR is just a refactoring. Let me know if it makes things clearer

[marefr]

LGTM

[xnyo]

Amazing work 🙏!! Love this. I took it for a spin and it works perfectly.

I only have left a couple of optional nits in case you want to address them.

We also have to update the docs for "other ide" section:
https://grafana.com/docs/grafana/latest/developers/plugins/development-with-local-grafana/#other-ides

because the -debug flag is technically not required anymore.

🎉