API開発のためのOpenAPI CLIの使用

I use this term akin to exploratory testing. You can search for works of Cem Kaner, James Bach, Michael Bolton, Elisabeth Hendrickson, James Whittaker, but beware, that’s a nice little serpentarium of a field.

In the simplest words, it is a process of learning something about API I don’t know or have a limited information about. That’s it. The main contexts for this activity are:

• Necessity. I want to use some API.
• Curiosity. Just looking at how other APIs are done.
• Assessment. I need to check APIs for certain characteristics.

There are many ways to perform exploration, countless tools and sources to use. In this article I’ll be looking only at OpenAPI description documents, because that’s where openapi-cli comes handy.

Note: When exploring unknown APIs, I run a globally installed package: npm i -g @redocly/openapi-cli . Then it is accessible in the terminal as openapi <args> .

Gathers some basic statistics for an OpenAPI description document. Can be in “stylish” format (as in the example below) or in JSON.

➜ openapi stats http://localhost:8888/api/v1/swagger.json
Document: http://localhost:8888/api/v1/swagger.json stats:

🚗 References: 12 
📦 External Documents: 0 
📈 Schemas: 12 
👉 Parameters: 9 
🔗 Links: 0 
➡️ Path Items: 4 
👷 Operations: 7 
🔖 Tags: 1 

Nothing useful for me at the moment. The only use case that comes to mind is when you have a bunch of documents for an assessment and you’re not sure where to start. Then, you can check stats for each doc and proceed with the smallest one.

This command is the primary reason I have openapi-cli installed as a global package: I use it all the time. The command accepts path or link to the existing OpenAPI description document and starts a local HTTP server with the generated Redoc reference doc.

➜ openapi preview-docs http://localhost/api/v1/swagger.json
Using Redoc community edition.
Login with openapi-cli login or use an enterprise license key to preview with the premium docs.

🔎 Preview server running at http://127.0.0.1:8080

👀 Watching http://localhost/api/v1/swagger.json and all related resources for changes

Bundling...

Created a bundle for http://localhost/api/v1/swagger.json successfully

Why you’d want that?

First, sometimes there is just an OpenAPI description document and nothing else. No documentation whatsoever. Rare, but I do stumble upon this with internal APIs.

The second reason is when there are some reference docs, but they don’t fit you.

For example, it’s a SwaggerUI, and you don’t like it, or the description doc has advanced features like oneOf or discriminator . In such case, SwaggerUI cannot generate fancy form-based presentation, so you have to read bare model definitions.

Reading a big OpenAPI description doc is cumbersome. Especially when you need to jump back and forth between references.