Using `openapi-cli` during API design: part two

Part one showed the basics of using openapi-cli for a single-definition project. Let’s see how it works for multi-definition projects.

#Multi-what?

By multi-definition project I mean a project with several OpenAPI description documents. For example, it can be useful if you want to keep contracts for all services in one place. Then, you can reuse common schemas between definitions.

Another use case is keeping parts of your APIs hidden from the final description document (internal and external APIs). This approach will mostly work only if separation is on path-level (see more here).

#Configuration

In our small Stargate API example we are splitting gates and addresses APIs into two description docs (commit). Next step is to change configuration file, so that openapi-cli would know that we have two definitions (commit).

apiDefinitions:
  gates: openapi/gates.yaml
  addresses: openapi/addresses.yaml

But now we need to fix our scripts in the package.json so that we could work with both definitions!

#Preview

If you simply run openapi preview-docs as we did before, it will start server only for the first definition in config file (in our case: gates). To preview a specific definition, you need to pass a definition label from configuration file: openapi preview-docs addresses.

But what if we want to preview both definitions? The simple fix will be adding separate scripts to run each definition on different ports:

"scripts": {
	"preview:gates": "openapi preview-docs -p 8080 gates",
	"preview:addresses": "openapi preview-docs -p 8081 addresses",
	...
}

Then, run both commands (either setting them to background processes or in the different terminals).

#Linting

Nothing to change here! openapi lint without any definition labels will check all of them.

#Bundling

Remember how we had to use -o dist/openapi to properly generate bundled desciption doc for single-definition project? Now we should simply leave it as -o dist. This will generate dist/gates.yaml and dist/addresses.yaml based on definitions labels.

#Generating reference docs

To generate static reference docs we should split npm run docs into separate scripts to target each definition:

"scripts": {
	...
	"docs:gates": "node plugins/prepareOptions.js && redoc-cli bundle dist/gates.yaml -o dist/redoc-gates.html --options .redoc.json",
	"docs:addresses": "node plugins/prepareOptions.js && redoc-cli bundle dist/addresses.yaml -o dist/redoc-addresses.html --options .redoc.json",
	"docs": "npm run docs:gates && npm run docs:addresses",
	...
}

There is no need to run prepareOptions.js twice, but I’m keeping it in case I’d want to generate only one reference doc.

The final working package.json is here. As you can see, we have to manually manage some building processes, but the most important pieces (linting & bundling) are quite transparent.

In the next article we’re gonna finally see juicy linting magic!

Using openapi-cli during API design: part two