Command to generate swagger/openapi schema from @fastify/swagger

[segevfiner]

Prerequisites

• I have written a descriptive issue title
• I have searched existing issues to ensure the feature has not already been requested

🚀 Feature Proposal

It would be cool to have a CLI command to generate the swagger/openapi schema that @fastify/swagger generates to a file.

Motivation

So that I won't have to start the server or eject and write a custom script to achieve this.

(Could make sense as a plugin for fastify-cli itself, but I don't think fastify-cli supports plugins supplying custom commands)

Example

fastify generate-swagger server.js > openapi.json

Which will essentially call fastify.swagger() and print it out. Of course, output file flags, flag to generate yaml, etc. Are also welcome.

[mcollina]

We have some code for doing this in Platformatic: https://github.com/platformatic/platformatic/blob/main/packages/db/lib/gen-schema.mjs

I don't think this should be part of fastify-cli as having an OpenAPI definition is likely too opinionated.

[segevfiner]

As just a subcommand, or as a plugin to fastify-cli itself? Or an external command that uses some the same code that fastify-cli uses to import the app (Which might not be exported ATM)?

[mcollina]

The problem is that this does not bundle @fastify/swagger, so how would you add this plugin to the CLI?

[segevfiner]

Conditionally at runtime, the user will have to install it in his app, we will only check if it exists on the app instance rather than try to use our own copy.

[mcollina]

I would love to see how you'd implement this. However I'm not sure this would land.