Resource Provider Interface

Note that the resource provider interface is still in development.

The interface between a resource provider and NixOps consist of expectations about:

• The Nix expression that builds the provider and its output
• The process that runs the provider
• A JSON-lines protocol between the provider and NixOps

Nix Expression

TODO

Process

NixOps launches the resource provider process built in the previous step.

It communicates with the provider over the standard input and output streams using a JSON-lines protocol. Standard error is used for logging, and is line-buffered.

TODO: exit behaviors

Protocol

JSON-lines is a textual protocol where each line is a JSON value that is rendered without line breaks. Each line must contain a single JSON value, and be terminated with a newline character.

We will refer to the JSON value that takes the line as a message.

Messages going from NixOps to the provider are requests, and messages going from the provider to NixOps are responses.

The content of the messages is specified in resource-provider-schema.json.