Converting a Swagger YAML file to JSON from the command line

Question

I'd like to convert a Swagger YAML file to JSON from the command line. The plan is to use this command line during a CI job. I've searched on google and found many solutions, but most of them use Python or Ruby, which I'd prefer not to use. For example: http://www.commandlinefu.com/commands/view/12218/convert-yaml-to-json

I'd like to do this without using Python or Ruby, and I'd also like to be able to control the leading whitespace when formatting the JSON to match exactly the JSON that is output from Swagger's editor.swagger.io editor, when you choose File -> Download JSON

All this means is that I'd like the whitespace padding to be four spaces, like so:

{     "swagger": "2.0",     "info": {         "title": "API TITLE", 

I haven't tried the Python method in the link above, but the Ruby method uses two space whitespace padding. Perhaps there is a way to control that, but I don't want to use Ruby or Python in this solution anyway.

I'm sure that there are many "correct" answers to this question. I am looking for the solution that is most elegant with the least number of dependencies. Ideally, a diff of the resulting JSON file against a JSON file generated by the editor.swagger.io should be empty.

Answer 1

I think that you are looking for the swagger-codegen (now OpenApi-generator) functionality:

Running

swagger-codegen generate -i swagger.yaml -l swagger

will out put a swagger.json in the same location.

Update For CI: If you can install it on your build machine- good for you. If you can't - the github page has a link to a docker image with a nodejs server is available (to convert using a curl command as suggested in a different answer).

Update For Docker: If you use Docker, try swaggerapi/swagger-codegen-cli, there is an example for docker-compose that might help a few answers down by Fabian & ckeeney.

Update about OpenApi:

This question is about swagger, and a few years old. If you're just starting to use Swagger you should switch to OpenApi instead, and if you have existing swagger files, i suggest migrating.

Answer 2

Using yamljs:

yaml2json swagger.yaml -p -i4 

The output from this command diff'd against the JSON output from editor.swagger.io produces an empty diff.

This is indeed what I'm looking for, but it brings in a huge dependency (node). I'm hoping for something even lighter, yet equally as elegant as this.