It'll be nice to make it more restrictive with regexp pattern.

I guess we can improve regexp at methodPathPattern so it's:

const methodPathPattern = new RegExp(
  `^(\\*|(?:${Array.from(allowedMethods).join('|')}))( .+)?$`,
  'i'
);

And define property with regexp setting

Also having that, it'll be nice to simplify validation logic in resolveConfiguration, as over there we may blindly assume that format is respected. So we should cover only cases which are not handled by schema

@medikoo, noted, will update accordingly :)
One last thing on that matter : some error messages lose in clarity
Suppose you define for a function hello the httpApi attribute equals to the string myPath, the following error messages are displayed :

• before schema validation : Invalid "<method> <path>" route in function hello for httpApi event in serverless.yml
• after schema validation : Configuration error at 'functions.hello.events[0].httpApi': should pass "regexp" keyword validation

One way to compensate would be to define custom JSON Schema error messages based on validation keywords. WDYT ?

@fredericbarthelet that's a very good point.

In light of that I think we should improve messaging of regex keyword errors. It easily can be done here:

Let's replace the message, with e.g. doesn't match expected format (if you feel you can come up with something better, please propose :)

@medikoo, I added a custom message for regexp keyword : value '${error.data}' does not satisfy pattern ${error.schema}. The resulting error message in the scenario described above, now much clearer, is :

Configuration error at 'functions.hello.events[0].httpApi': value "myPath" does not satisfy pattern /^(?:*|(GET|POST|PUT|PATCH|OPTIONS|HEAD|DELETE) (/\S*))$/i

WDYT ?

Looks good. I wonder whether listing pattern, won't be too noisy, but it's definitely very informative, so I'd say it's great!