GCP Cloud Run and gRPC Streaming Costs: A Comprehensive Guide

If you’re a developer or architect working with cloud-based applications, you’re likely no stranger to the world of Cloud Run and gRPC. These powerful technologies enable you to build scalable, high-performance applications that can handle massive amounts of data. But have you stopped to think about the costs associated with using these technologies, particularly when it comes to gRPC streaming?

What is gRPC Streaming?

Before we dive into the costs, let’s take a quick refresher on what gRPC streaming is. gRPC is a high-performance RPC framework that allows you to define service interfaces and generate client and server code. One of the key features of gRPC is its support for streaming, which enables you to send and receive large amounts of data in real-time.

syntax = "proto3";

package greet;

service Greeter {
  rpc SayHello(HelloRequest) returns (HelloResponse) {}
  rpc LotsOfReplies(HelloRequest) returns (stream HelloResponse) {}
  rpc LotsOfGreetings(stream HelloRequest) returns (HelloResponse) {}
  rpc BidiHello(stream HelloRequest) returns (stream HelloResponse) {}
}

In the example above, we define a gRPC service called `Greeter` that has four methods: `SayHello`, `LotsOfReplies`, `LotsOfGreetings`, and `BidiHello`. The last three methods demonstrate streaming in action. `LotsOfReplies` returns a stream of `HelloResponse` objects, while `LotsOfGreetings` accepts a stream of `HelloRequest` objects. `BidiHello` is a bidirectional streaming method that both sends and receives streams of data.

How Does gRPC Streaming Work in Cloud Run?

When you deploy a gRPC service to Cloud Run, you can configure it to handle streaming requests and responses. Cloud Run provides a containerized environment for your service, which means you can write your gRPC service in any language and framework you like. When a client sends a streaming request to your service, Cloud Run routes the request to an available container instance, which then handles the streaming request.

FROM golang:alpine

WORKDIR /app

COPY go.mod go.sum ./
RUN go mod download

COPY . .

RUN go build -o server main.go

EXPOSE 8080

CMD ["server"]

In the example above, we define a Dockerfile for a Go-based gRPC service. We expose port 8080, which is the default port for gRPC services in Cloud Run. When we deploy this service to Cloud Run, it will be containerized and scaled automatically based on incoming traffic.

Costs Associated with gRPC Streaming in Cloud Run

Now that we’ve covered the basics of gRPC streaming and how it works in Cloud Run, let’s talk about costs. There are several factors that influence the cost of gRPC streaming in Cloud Run, including:

• Instance Hours**: Cloud Run bills you for instance hours, which are the number of hours your container instances are running. If you have a high-volume gRPC service with many concurrent connections, you’ll need more instance hours to handle the load.
• Network Egress**: When you stream data in and out of your gRPC service, you incur network egress costs. These costs are based on the amount of data transferred out of Cloud Run.
• CPU and Memory Usage**: If your gRPC service is computationally intensive or requires a lot of memory, you’ll incur higher costs for CPU and memory usage.

 instance_hours = 1000 connections * 1 hour / 60 minutes * 1 minute / 60 seconds = 166.67 hours
 network_egress = 100MB/second * 60 seconds/minute * 60 minutes/hour * 1 hour = 36 GB
 cpu_usage = 1000 connections * 1 CPU-hour / 1000 connections = 1 CPU-hour
 memory_usage = 1000 connections * 1 GB-hour / 1000 connections = 1 GB-hour

 total_cost = (instance_hours * $0.000004) + (network_egress * $0.12) + (cpu_usage * $0.000004) + (memory_usage * $0.000004)
 total_cost = ($0.6667) + ($4.32) + ($0.000004) + ($0.000004)
 total_cost = $5.00