09c01dd942
This change adds basic support for discovering, loading, binding to, and invoking RPC methods on, resource provider plugins. In a nutshell, we add a new context object that will share cached state such as loaded plugins and connections to them. It will be a policy decision in server scenarios how much state to share and between whom. This context also controls per-resource context allocation, which in the future will allow us to perform structured cancellation and teardown amongst entire groups of requests. Plugins are loaded based on their name, and can be found in one of two ways: either simply by having them on your path (with a name of "mu-ressrv-<pkg>", where "<pkg>" is the resource package name with any "/"s replaced with "_"s); or by placing them in the standard library installation location, which need not be on the path for this to work (since we know precisely where to look). If we find a protocol, we will load it as a child process. The protocol for plugins is that they will choose a port on their own -- to eliminate races that'd be involved should Mu attempt to pre-pick one for them -- and then write that out as the first line to STDOUT (terminated by a "\n"). This is the only STDERR/STDOUT that Mu cares about; from there, the plugin is free to write all it pleases (e.g., for logging, debugging purposes, etc). Afterwards, we then bind our gRPC connection to that port, and create a typed resource provider client. The CRUD operations that get driven by plan application are then simple wrappers atop the underlying gRPC calls. For now, we interpret all errors as catastrophic; in the near future, we will probably want to introduce a "structured error" mechanism in the gRPC interface for "transactional errors"; that is, errors for which the server was able to recover to a safe checkpoint, which can be interpreted as ResourceOK rather than ResourceUnknown. |
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| go/pkg/murpc | ||
| js/src/murpc | ||
| proto | ||
| README.md | ||
sdk
The SDK directory contains language packages for the various supported languages.
These packages are real language packages and not MuPackages. Therefore, they can contain I/O, asynchronous code, and anything else necessary for building runtime code, resource providers, and other helpful Mu tooling and abstractions.