Showcasing gRPC, Rust and Kubernetes

This project is for demonstration purposes.

The project uses tonic for gRPC APIs, minikube for a local Kubernetes cluster, and Postgresql with diesel for the database.

Building the App

Since there are three cargo packages I provided a simple script to build Docker images for each sequentially.

Build images

./build_images.sh

Start Minikube

Start your Minikube cluster!

minikube start

Push locally built images to Minikube

Since built images are stored in whatever container runtime you are using, you need to push them to minikube to render them accessible.

minikube cache add clock_image:latest
minikube cache add numbers_image:latest
minikube cache add dbapi_image:latest

Create an SSL Certificate and Key

This step is needed since you need to terminate TLS at ingress-nginx level before routing to services. Although I provided a key and certificate for this occassion. I wouldn't do this in a real project of course...

openssl req -x509 -sha256 -nodes -days 365 -newkey rsa:2048 -keyout tls.key -out tls.crt -subj "/CN=smartmodels.local/O=smartmodels.local" -addext "subjectAltName = DNS:smartmodels.local"

Push SSL Certificate and Key to Minikube Secrets as a TLS secret

We send the certificate and the key, and configure the ingress so it can access it for secure connections.

kubectl create secret tls mkcert --key tls.key --cert tls.crt
minikube addons configure ingress
    -- Enter custom cert (format is "namespace/secret"): default/mkcert
minikube addons disable ingress
minikube addons enable ingress

Deploy the Minikube cluster declaratively

kubectl apply -f k8s_config/workload.yaml -f k8s_config/services.yaml -f k8s_config/ingress.yaml

Tunnel ingress to localhost if needed on a seperate shell

This is necessary for some working environments. I had to since I work on WSL2.

minikube tunnel

Add ingress hostname to /etc/hosts if you had to tunnel

Since you cannot use IP addresses for SSL, I just added my made up hostname to /etc/hosts, and routed it to 127.0.0.1 since I used tunnel.

echo "127.0.0.1       smartmodels.local" >> /etc/hosts

Open up the dashboard in another terminal if you'd like

For easier control over your Minikube cluster. And monitoring what's happening inside.

minikube addons enable dashboard
minikube dashboard

Testing the App

I used grpcurl for all my testings. I chose to use this tool instead of a tonic client since I wanted to keep it as simple and universal as possible. I provided the binary for grpcurl for convenience.

Clock SmartModel

./grpcurl -insecure -import-path ./proto -proto clock.proto -d '{"name": "Midge Ure"}' smartmodels.local:443 clock.Clock/SayHello
./grpcurl -insecure -import-path ./proto -proto clock.proto -d '{"name": "Robert Smith"}' smartmodels.local:443 clock.Clock/SayHelloAgain

Numbers SmartModel

./grpcurl -insecure -import-path ./proto -proto numbers.proto -d '{"lhs": 5, "rhs": 25}' smartmodels.local:443 numbers.Calculate/AddNumbers
./grpcurl -insecure -import-path ./proto -proto numbers.proto -d '{"lhs": 5, "rhs": 25}' smartmodels.local:443 numbers.Calculate/MultNumbers

The DB gRPC api

./grpcurl -insecure -import-path ./proto -proto dbapi.proto -d '{"name": "clock_tonic", "category": "wearable"}' smartmodels.local:443 dbapi.Database/InsertModel
./grpcurl -insecure -import-path ./proto -proto dbapi.proto -d '{"name": "numbers", "category": "wearable"}' smartmodels.local:443 dbapi.Database/InsertModel

./grpcurl -insecure -import-path ./proto -proto dbapi.proto -d '{"name": "clock_tonic"}' smartmodels.local:443 dbapi.Database/SelectModel
./grpcurl -insecure -import-path ./proto -proto dbapi.proto -d '{"category": "wearable"}' smartmodels.local:443 dbapi.Database/SelectModel
./grpcurl -insecure -import-path ./proto -proto dbapi.proto -d '{"name": "clock_tonic"}' smartmodels.local:443 dbapi.Database/SelectModel
./grpcurl -insecure -import-path ./proto -proto dbapi.proto -d '{"name": "numbers", "category": "wearable"}' smartmodels.local:443 dbapi.Database/SelectModel

./grpcurl -insecure -import-path ./proto -proto dbapi.proto -d '{"name": "say_hello", "category": "greeter", "model": "clock_tonic"}' smartmodels.local:443 dbapi.Database/InsertFeature
./grpcurl -insecure -import-path ./proto -proto dbapi.proto -d '{"name": "say_hello_again", "category": "greeter", "model": "clock_tonic"}' smartmodels.local:443 dbapi.Database/InsertFeature
./grpcurl -insecure -import-path ./proto -proto dbapi.proto -d '{"name": "add_numbers", "category": "calculator", "model": "numbers"}' smartmodels.local:443 dbapi.Database/InsertFeature
./grpcurl -insecure -import-path ./proto -proto dbapi.proto -d '{"name": "mult_numbers", "category": "calculator", "model": "numbers"}' smartmodels.local:443 dbapi.Database/InsertFeature

./grpcurl -insecure -import-path ./proto -proto dbapi.proto -d '{"model": "clock_tonic"}' smartmodels.local:443 dbapi.Database/SelectFeature
./grpcurl -insecure -import-path ./proto -proto dbapi.proto -d '{"name": "mult_numbers", "category": "calculator"}' smartmodels.local:443 dbapi.Database/SelectFeature