helloworld

Hello World

This directory contains files for building the "hello world" microservice, which consists of a "hello" service that calls a "world" service to complete its request. Configs for running these services in Kubernetes live in the k8s-daemonset/ directory.

Building

To build the buoyantio/helloworld Docker image, run:

$ docker build -t buoyantio/helloworld:<tag-name> .

Build Multi-Arch Images with Buildx

Create the builder instance:

$ docker run --rm --privileged multiarch/qemu-user-static --reset -p yes
$ docker buildx create --name=multiarch-builder --driver=docker-container --use
$ docker buildx inspect multiarch-builder --bootstrap

Build the images:

$ docker buildx build . \
    --platform linux/amd64,linux/arm64,linux/arm/v7 \
    --push \
    --tag buoyantio/helloworld:<tag-name>

Where <tag-name> is the tag of the image that you want to build.

To regenerate the protobuf gRPC bindings in the proto directory, run:

$ protoc -I ./proto/ ./proto/helloworld.proto --go_out=plugins=grpc:proto

Usage

The behavior of each server is controlled via command line flags and environment variables. The available command line flags are:

$ helloworld -help
Usage of helloworld:
  -addr string
      address to serve on (default ":7777")
  -failure-rate float
      rate of error responses to return
  -json
      return JSON instead of plaintext responses (HTTP only)
  -latency duration
      time to sleep before processing request
  -protocol string
      API protocol: http or grpc (default "http")
  -target string
      target service to call before returning
  -text string
      text to serve (default "Hello")

The server also reads a few environment variable that are set as part of our Kubernetes configs, as follows:

• POD_IP: If the service is running in a Kubernetes pod, setting this environment to the IP address of the pod will alter the response to include the IP after the text string, e.g. world! becomes world (1.2.3.4)!.

• TARGET_WORLD: If set, the value of this environment variable will be used as the text string, overriding the value of the -text flag, e.g. running TARGET_WORLD=foo helloworld -text bar will return foo!, not bar!.

To see a working example of the hello and world services configured to run in Kubernetes, see hello-world.yml.

Running locally

Here are brief examples to demonstrate how to run the hello world app locally.

HTTP

Follow the instructions below to bring up the hello service and the world service, communicating with each other via HTTP.

Start by starting the "world" service on port 7778:

$ go run main.go -addr :7778 -text world &
starting HTTP server on :7778

Next bring up the "hello" service on port 7777, and configure it to make an additional call to the "world" service running on port 7778:

$ go run main.go -addr :7777 -text Hello -target localhost:7778 &
starting HTTP server on :7777

Send traffic to the "hello" service with:

$ curl localhost:7777
Hello world!!

gRPC

Follow the instructions below to bring up the hello service and the world service, communicating with each other via gRPC.

Start by starting the "world" service on port 7778:

$ go run main.go -addr :7778 -text world -protocol grpc &
starting gRPC server on :7778

Next bring up the "hello" service on port 7777, and configure it to make an additional call to the "world" service running on port 7778:

$ go run main.go -addr :7777 -text Hello -target localhost:7778 -protocol grpc &
starting gRPC server on :7777

Send a unary gRPC request to the "hello" service with:

$ go run helloworld-client/main.go localhost:7777
Hello world!!

Or send a streaming gRPC request with:

$ go run helloworld-client/main.go -streaming localhost:7777
Hello world!!
Hello world!!
Hello world!!
Hello world!!
Hello world!!

Hello friend, nice to meet you.