Hello API

Hello API exposes a simple service over gRPC and OpenAPI to record visitors and visits.

Prerequisites

• gcloud CLI
• Docker
• Go 1.8

Development

Run make help or make

API

The API can be explored by pointing your browser to https://localhost:9999/#/Hello.

When using curl, an Accept header specifying application/json is required in order to hit the HTTP API. Otherwise, it is going to attempt to serve Swagger UI.

curl --insecure -H "Accept: application/json" https://localhost:9999/hello/camilo | jq .
curl --insecure -H "Accept: application/json" https://localhost:9999/counts | jq .
curl -v --insecure -X DELETE -H "Accept: application/json" https://localhost:9999/counts | jq .

Technical details

• I used gRPC and Open API to generate the service from hello.proto and implemented hello_service.go and hello_service_test.go
• I added Swagger UI to make it more convenient to explore the HTTP API.
• Third-party dependencies are kept to the minimum possible.
• The API also supports HTTP2 and TLS 1.2
• A very minimal Dockerfile was also added.
• Releasing a binary of the service was automated with Github Releases: https://github.com/c4milo/hello/releases
• Dependencies are vendored using govendor
• The total effort, including tests, docs and deployment was roughly 4 hours. Most of the time was spent dealing with GCP.

Deployment

A GKE cluster was created using GCP's web console, only 1 replica is launched as the service is managing state locally. In order to deploy changes follow these steps:

1. Increase version number in Makefile
2. Increase version number in deployment/hello.yaml accordingly.
3. Run make image-push
4. Run kubectl apply deployment/hello.yaml
5. Verify by visiting https://35.185.24.220/#/Hello

Things that can be improved further

• Manage state externally so the service can be scaled horizontally.
• Add compression
• Add rate limiting
• Add LetsEncrypt certificate and schedule K8S to periodically renew the certificate.
• Use domain name instead of IP address to access the service.

Issues I ran across

• I spent a good deal of time trying to fix an authentication issue with gcloud as I had a previous project configured before.
• K8s does not seem to be able to register service health checks in GCP's network load balancer