apollo-server-redis SET method called with ttl 0

[raduachim]

Hi,

I am trying to understand how to use apollo-server-redis for caching calls to a REST api.
For me it's a bit confusing from the docs how the flow would work.

For the graphql server I am using:

• "apollo-datasource-rest": "^2.0.0-rc.6",
• "apollo-server-lambda": "^2.0.0-rc.6",
• "apollo-server-redis": "^2.0.0-rc.6",

I have a simple Redis inside a container and have configured my apollo server with:

cache: new RedisCache({
    host: '127.0.0.1'
  })

On my type in the schema I have added a @cacheControl(maxAge: 600) and then I tried my query only to receive the error: "message": "ERR invalid expire time in set",

Digging a bit in the apollo-server-redis code I see that the set method is called with options that has a key ttl with value 0.

After some more experimenting I see that I need to set in my REST api in the response header the header cache-control: max-age=1337. Might be a stupid question, but why do I need to do this?

And after configured my REST api to return this cache-control header, the set method in the apollo-server-redis is being called with a float value, not 1337 but rather 1336.24 or something similar.
Which also breaks when trying to set something in Redis. So it seems to need some parseInt

[clarencenpy]

Hi @raduachim! If you are using the Datasources API on top of a REST API that already has standard cache-control headers set, these will be passed through directly to apollo-server-redis. That is one of the cool benefits of wrapping REST with datasources, and there is no need to specify @cacheControl(maxAge: 600).

I suspect there are some rounding issues with converting milliseconds to seconds while parsing the cache-control header, will look into that!

[raduachim]

Thanks for the response @clarencenpy

So just to make sure I understand this correctly - this works only if the REST API has the cache-control headers set?

When the headers are not set I can see that the redis set method is called with ttl: 0

[raduachim]

Hi

I think I understand now how it should work.
The REST API should reply with the cache-control header.

I've looked a bit in the code and what I can tell is that the age function from http-cache-semantics is returning the float value.

A parseInt on let ttl = policy.timeToLive() / 1000; inside the HTTPCache from apollo-datasource-rest should fix it. I tried looking if I can create a PR for it but it seems a bit difficult to test it since time is mocked and I am unsure if it should be fixed by this package or in that external dependency?

[clarencenpy]

Hi @raduachim, thanks for digging in on this! It seems like the easiest fix would be to parseInt on policy.timeToLive(). If that one line change fixes up your issue nicely, I think merging it in as a PR would be not be a problem at all (since changes are minimal).

[raduachim]

@clarencenpy Thanks. I realized it should be a Math.round rather than a parseInt.
I hope I've created the PR to the correct branch.

[clarencenpy]

PR merged, closing issue. Thanks @raduachim for working on this!