AWS AppSync
AWS AppSync, simply said API Gateway for GraphQL since it allows you to connect your GraphQL schema to different data source...
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Thank you for the article, mostly for the point number 5 as most of the people here in the comments ;)
I have one comment though:
that's no longer true. If in the subscription response mapping template your are returning something, eg
$util.toJson($context.result)then it might block you from starting the connection. Changing it to$util.toJson(null)helped me to mitigate that issue.Great Article..
Almost these all are not in the documentation.
If this is the case in 5th point. How the feature Enhanced Filters will work not able to find working of enhanced fitlers. Can anyone know this
Hi there,
the article was written before existence of Enhanced Filters, so I'm not sure how exactly it behaves at the moment.
Maybe somebody else will be able to help. 🙂
Thank you very much, great article!
Thanks, happy it helped! 🙌 😊
Great article!
I learned all these the hard way too :)
I did not know about 5, I had never tried it. I also wonder if you can invoke a DynamoDB resolver too (I don't see why it would not work).
Apart from authorization, I think maybe a use case for that could be to log subscription requests or do something with them, if you wanted to do that for some reason.
Thanks for the feedback @bboure ! 🙂
Yes, the 5th point was quite important for us, because we were trying to figure out how to handle authorization for the subscriptions.
I got this case where the mutation response is in nested structure but the arguments is flat.
Mutation Response:
The Subscription:
Filip, do you do anything special in your CDK stack file to enable graphQL subscription annotations? I'm kind of stuck, probably something stupid, but for me, the subscription never fires.
stackoverflow.com/questions/702773...
Hi Dmitry, I don't use CDK for this so I can't tell you. But since the schema is being given to CloudFormation in a raw form [1] it should work out of the box. But maybe the CDK construct has some special (broken) inner mechanism for schema validation or something like that.
[1] docs.aws.amazon.com/AWSCloudFormat...
I spent a couple of days wondering why my EventBridge rule wasn't triggering the AppSync mutation before I found out that while the documentation says "The AWS AppSync API must support IAM authorization to be used as an EventBridge target", what isn't clear is that IAM must be the primary authorisation mode, not an additional mode.
Nice article @filippyrek , it's great that you put it together!
I would be curious if you have any in-depth article or reference on how you solved this problem of subscriptions being tightly coupled to the mutations by making use of local resolvers, like you're hinting in the beginning of the article:
Has anyone ever ran into an issue where they have a frontend that subscribes successfully, receiving the startAck, but cannot ever receive data messages. The subscription works perfectly in the AWS console, but it's just silence in my app.
Number 5 is no longer true - at some point during late summer 2022 it must have been patched by AWS.
We set up a resolver to throw an exception if authorization failed. It worked for a month or two, but at some point the behavior changed such that the connection is established even when the exception is thrown.
After some more testing, it seems that the behavior changed when we enabled advanced filtering. After disabling advanced filtering, the resolver can once again be used to block access as the blog post describes.
So there's a gotcha - don't enable advanced filtering if you plan on using tip number 5.
Hey Filip, beautifully put across. I was stuck on the 3rd and 4th point and learnt about it the hard way. This definitely helps out developers who are trying it for the first time.
Thank you!
great article