AWS lambda invoke not calling another lambda function – Node.js

Note

I will denote by executor the lambda that executes the second lambda.

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Why Timeout?

Since the executor is “locked” behind a VPC – all internet communications are blocked.

That results in any http(s) calls to be timed out as they request packet never gets to the destination.

That is why all actions done by aws-sdk result in a timeout.

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Simple Solution

If the executor does not have to be in a VPC – just put it out of it, a lambda can work as well without a VPC.

Locating the lambda in a VPC is required when the lambda calls resources inside the VPC.

Real Solution

From the above said, it follows that any resource located inside a VPC cannot access the internet – that is not correct – just few configurations need to be made.

1. Create a VPC.
2. Create 2 Subnets, let one be denoted as private and the second public (these terms are explained ahead, keep reading).
3. Create an Internet Gateway – this is a virtual router that connects a VPC to the internet.
4. Create a NAT Gateway – pick the public subnet and create a new elastic IP for it (this IP is local to your VPC) – this component will pipe communications to the internet-gateway.

5. Create 2 Routing Tables – one named public and the second private.

   1. In the public routing table, go to Routes and add a new route:

   Destination: 0.0.0.0/0

   Target: the ID of the internet-gateway

   2. In the private routing table, go to Routes and add a new route:

   Destination: 0.0.0.0/0

   Target: the ID of the nat-gateway

   • A private subnet is a subnet that in its routing table – there is no route to an internet-gateway.

   • A public subnet is a subnet that in its routing table – there exists a route to an internet-gateway

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What we had here?

We created something like this:

This, what allows resources in private subnets to call out the internet.
You can find more documentation here.