esp-v2 VS nodejs-pubsub

Moreover, integrating rate limiting can thwart DDoS attacks, and schema validation can prevent malformed requests, ensuring only legitimate and well-formed traffic reaches your serverless functions. Tools like Amazon API Gateway, Azure API Management, and Google Cloud Endpoints offer these capabilities, allowing you to set up custom authorization workflows and request validation rules that align with your security requirements.

AFAIK, API Gateway is just managed Cloud Endpoints, which are just ESPv2 containers. Cloud Endpoints are still a thing but I would agree that they are a bit dead, as they don't support OpenAPI v3, which was released in 2016. See this support ticket from 2018: https://issuetracker.google.com/issues/78271318?pli=1

Cloud Endpoints: Cloud API gateway 🔗Link

We use the ESPv2 gateway (https://github.com/GoogleCloudPlatform/esp-v2) to transcode between REST/JSON and gRPC/protobuf for client-to-backend communication.

Secondly, Go is incredibly easy to learn and in my opinion, maintain. This means that if you're a growing company and expect to onboard new teams and team members, having Go as a basis for your systems should mean that new engineers can get up to speed quickly.  Below is a small sample application that can connect to Google PubSub, subscribe to a topic, send an event and then clean up. In total, its 82 lines of code including liberal line breaks. Even if you have never written or read a line of Go before, I hope you'll agree that it's quite clear and readable:

Pub/Sub

Google Cloud Pub/Sub is a fully-managed, globally scalable and secure queue provided by Google Cloud for asynchronous processing messages. Cloud Pub/Sub has many of the same advantages and disadvantages as SQS due to also being cloud hosted. It has a free and paid tier.

Cloud Pub/Sub: A global messaging service for event-driven architectures

Google Cloud Pub/Sub (*https://cloud.google.com/pubsub*)

Google Cloud Functions is a FaaS offering from Google Cloud Platform (GCP). It allows developers to run their code in response to events, such as changes in a database or the arrival of a message in a Pub/Sub topic. Like AWS Lambda, Google Cloud Functions can be used to build a variety of applications, including serverless websites, data processing pipelines, and real-time data streams.

that gets triggered when a Pub/Sub topic is fired (from the webhook function)

Maybe Pub/Sub from GCP?

I'm curious - given your limited knowledge, is there a reason you're looking to self host this in your own cluster rather than using a managed service like https://cloud.google.com/find-a-partner/partner/confluent-inc?redirect= or just native Google PubSub https://cloud.google.com/pubsub/ ?

Pub/Sub, the GCP managed service for message queuing, has two levels of services on standard and one Lite. Standard is the high availability version of it and Lite could be a zonal or regional service with infrastructure managed by the client. Obviously, the model pricing will be very different with a x10 between Standard and zonal Lite. However, the model pricing is the same is based on throughput for message publishing, message storage costs and egress for message distribution. Here, we totally break the similarity with a VM model (except on storage). Everything is drived on volumetry and performance of inbound and outbound messages.