Correct path for non-custom endpoints

[bsdkurt]

Non-custom domain endpoints (e.g. https://xyz.execute-api.region.amazonws.com/{stage}) strip off {stage} in event.path, but event.requestContext.path is correct for all cases I believe. Also should fix #35.

[dougmoscrop]

Thanks for this!

[dougmoscrop]

Hey, @bsdkurt I have to revert this, it doesn't seem to work as expected.

Now that I think about it, I don't think we want the path to contain the stage.

[bsdkurt]

@dougmoscrop What use case broke?

[bsdkurt]

@dougmoscrop Ok I see the bug reports. There does seem to be two use cases that would need to adjust for this change:

• offline since the path is now obtained from event.requestContext.path vs event.path
• users using non-custom domain endpoints (e.g. https://xyz.execute-api.region.amazonws.com/{stage}) since the path exposed to them will have a change and include the {stage} part

I do think this is the correct path to expose since for non-custom domain endpoints what is exposed now is incorrect (e.g. #35) and also would require the developer to make changes to the routing to account for the additional path segment if the same code is migrated to a custom domain with a basepath.

Due to the need for adjustments for the two cases above, perhaps this change is better suited for a 1.6 or 2.0 release with upgrade instructions for the two cases?

[dougmoscrop]

I'm not sure if it's correct to expose it.

The application routing logic won't match when the stage is exposed. You write app routers as "relative" to some assumed baseUrl (which is empty).

[bsdkurt]

Let's take three cases for a GET at the root where lambda attaches:

• Custom Domain With Basepath

GET https://api.mydomain.com/mybasepath
event.path === event.requestContext.path === '/mybasepath'

• Custom Domain Without Basepath (e.g. basepath === '')

GET https://api.mydomain.com
event.path === event.requestContext.path === '/'

• Amazon Endpoint - stage 'dev'

GET https://xxxxx.execute-api.us-east-1.amazonaws.com/dev/
event.path !== event.requestContext.path
event.path === '/'
event.requestContext.path === '/dev'

I believe express expects to know the full path as can be seen in #35. That's why I think event.requestContext.path is the correct path to expose out.

[dougmoscrop]

If you app.use(/foo) are you saying express understands /dev/foo?

[dougmoscrop]

(baseUrl is a separate concept)

I think we want to set baseUrl to rc.path.replace(event.path, '')

[dougmoscrop]

Yeah bunch of people had to mount their app under the stage name which isn't ideal

[XuluWarrior]

@bsdkurt Did you try my PR #36?
It seems you and I are trying to fix similar issues and I tested my PR with a number of scenarios including

• non-custom domains
• custom domains
• custom domains with base path
• serverless-offline

If you have a use case that is missing and breaks then I'm sure that between the three of us, we can square the wheel.

[XuluWarrior]

It has been my intention for far too long now to create a sample project that demonstrates the different configurations but I have to admit that it still remains on my todo list. And I'm off on holiday tomorrow morning so it will have to wait a while longer.

[dougmoscrop]

If you could, add them to the integration test. I run it before publish.

…

On Wed, Mar 28, 2018, 5:33 PM XuluWarrior ***@***.***> wrote: It has been my intention for far too long now to create a sample project that demonstrates the different configurations but I have to admit that it still remains on my todo list. And I'm off on holiday tomorrow morning so it will have to wait a while longer. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#42 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAjzFOj6uDNUKi06jx3kF9_MW9_sDwdDks5tjAG5gaJpZM4S6ili> .

[bsdkurt]

@dougmoscrop Sorry for disrupting the userbase with the PR. I think I'm not doing a very good job explaining why I think the change is correct.

Suppose we were running express or koa in node (not with AWS API GW). Is there a scenario where the user types this url in the browser http://www.mydomain.com/pathsegment1/ where express or koa would receive a request object from the listener where request.url is '/'? or would it always get '/pathsegement1/?

If it is correct to say that express and koa expect the request.url to include /pathsegment1/ from the listener always, then I would make a case that since AWS forces the stage on its endpoints, that it should be there for express or koa to see. If I was planning on using AWS endpoints I would have the following setup:

const router = express.Router();
router.get('/', rootget);
...
app.use('/' + process.env.STAGE_NAME, router);

For custom domains with basepaths, I would use the same solution but use process.env.BASE_PATH.

@XuluWarrior I didn't try #36 because I didn't think it was the correct fix. baseUrl is an express request object extension, koa doesn't support baseUrl on the request object. baseUrl is also set by express route.js. I thought from code inspection that it may be replaced with express's idea of what baseUrl should be, although I didn't test that to see if I can break it.

[dougmoscrop]

I certainly think there is a gap here! I'm just not sure where it is or what the best fix it. API Gateway is mounting the application in a non-transparent way only in certain scenarios.

[XuluWarrior]

I've finally created a demo repository (https://github.com/XuluWarrior/serverless-http-tests) that demonstrates the issue as I understand it.

It has three branches

master
This is a simple express server that uses the current version of serverless-http and serves a static index.html from /static.
It is live at
https://vjbhf8sye8.execute-api.us-east-1.amazonaws.com/dev/serverless-http-tests and
https://api.xuluwarrior.org/serverless-http-tests

The issue that started me looking at this is that when you visit
https://vjbhf8sye8.execute-api.us-east-1.amazonaws.com/dev/serverless-http-tests/static it redirects to
https://vjbhf8sye8.execute-api.us-east-1.amazonaws.com/serverless-http-tests/static/ rather than
https://vjbhf8sye8.execute-api.us-east-1.amazonaws.com/dev/serverless-http-tests/static/

This is because express.static depends on baseUrl to determine the full redirect url.

https://api.xuluwarrior.org/serverless-http-tests/static redirects as expected

set-baseurl
This branch uses my PR and sets both baseUrl and originalUrl so that the correct redirect can be calculated.
It is live at
https://lnm600m566.execute-api.us-east-1.amazonaws.com/dev/serverless-http-tests-use-baseurl and
https://api.xuluwarrior.org/serverless-http-tests-use-baseurl

koa
This is my attempt to set up a similar koa server (I am not familiar with koa). The static server doesn't behave the same as the express on and so is not a good example. But what is of interest is the properties on the context object. It includes originalUrl which would be of use to get the full url of the request.

However, the koa code sets originalUrl from req.url rather than req.originalUrl. So even though my PR sets req.originalUrl it is not copied onto the context object.

I have added a hacky middleware function that does the copy.

I have done this not to suggest that it is the correct solution but just to show possibilities.

The koa server is live at
https://api.xuluwarrior.org/serverless-http-tests-koa and
http://localhost:3000/serverless-http-tests-koa/

[dougmoscrop]

thanks! need to think about what the best course of action is so not to upend all libraries for the sake of one, or collide with fields that are used differently between libraries.

[dougmoscrop]

Thought: One way to figure this out might be to check if the Host: header contains the execute-api.blahblah and then we know we should add the stage name to the originalUrl/url.