Honor variable defaults from servers declaration during OpenAPI3 import

[develohpanda]

This PR adds functionality to honor variable defaults from the servers declaration during an OpenAPI3 spec import.

The openapi-2-kong package already does this, the functionality is simply adapted for insomnia-importers.

The openapi3 importer honors variable defaults, but if a variable exists in the URL and is missing in server.variables, an error is thrown and presented to the user.

Example spec

openapi: 3.0.2
info:
  description: This API is for administrating files and file storages.
  license:
    name: Some license
  title: File and Storage API
  version: 0.1.0
servers:
  - description: Devserver
    url: '{protocol}://{host}:{port}/{basePath}'
    variables:
      port:
        default: 8080
      host:
        default: localhost
      basePath:
        default: filemanagement
paths:
  /files:
    get:
      operationId: find_files

Insomnia Core

Insomnia Designer
Doesn't do anything during design -> debug navigation, silently swallows any errors caused by parsing an invalid spec. This is existing behavior, which we should improve.

Closes #1640

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[gschier]

Curious why you used a different approach than openapi-2-kong does. Is it so you could replace vars with a default value if they don't have one defined? If so, can we make sure the fixture defined handles the case where there is no default?

insomnia/packages/openapi-2-kong/src/common.js

Line 121 in d6998ad

export function fillServerVariables(server: OA3Server): string {

[develohpanda]

There are two approaches (there should be a unified one) to fill server variables in openapi-2-kong:

1. iterates over server.variables, throws if default missing, and replaces items in the url
2. iterates over variables in the url, searches for a default in server.variables, defaults to http or .* if missing

I used a hybrid approach for the openapi3 importer, for several reasons:

• To successfully parse the URL, we need a valid, resolved URL, and smart defaults are much more involved,
• A truly valid OpenAPI spec should have variable defaults defined for a server url
• o2k (kubernetes) can handle missing defaults (as per the requirements) using .* fallback

The openapi3 importer honors variable defaults, but if a variable exists in the URL and is missing in server.variables, an error is thrown and presented to the user.

@gschier

[gschier]