A gRPC based microservices implementation in Go, deployed in a kubernetes cluster and consisting of two microservices:

• Maths service
• REST API to expose the Maths service

The Maths microservice that:

• computes the Addition of two numbers
• computes the Average of an array of numbers
• computes the Maximum of an array of numbers
• computes the Minimum of an array of numbers
• computes the Summation of an array of numbers
• computes the Sorted form of an array of numbers

A REST API that responds to the client and routes them to the corresponding Maths compute

To start the application without deploying to kubernetes, we need to enter the downloaded project directory, and run the server and api in separate terminals respectively i.e.

• for the server, execute go run server/main.go
• for the api, execute go run api/main.go

Now test with integer 17, integer 18 and array [48, 96, 86, 68, 57, 82, 63, 70, 37, 34, 83, 27, 19, 97, 9, 17], via the sample api requests:

127.0.0.1:8080/add/17/18
127.0.0.1:8080/average/[48, 96, 86, 68, 57, 82, 63, 70, 37, 34, 83, 27, 19, 97, 9, 17]
127.0.0.1:8080/max/[48, 96, 86, 68, 57, 82, 63, 70, 37, 34, 83, 27, 19, 97, 9, 17]
127.0.0.1:8080/min/[48, 96, 86, 68, 57, 82, 63, 70, 37, 34, 83, 27, 19, 97, 9, 17]
127.0.0.1:8080/sum/[48, 96, 86, 68, 57, 82, 63, 70, 37, 34, 83, 27, 19, 97, 9, 17]
127.0.0.1:8080/sort/[48, 96, 86, 68, 57, 82, 63, 70, 37, 34, 83, 27, 19, 97, 9, 17]

To deploy and start the application in kubernetes, we need to make a few changes to ensure the api is able to communicate with the math-service server. These changes to be implemented from within the project directory are:

• start kubernetes by running minikube start
• ensure docker reuses the Docker deamon in minikube, by running eval $(minikube docker-env)
• update api/main.go by changing localhost:9090 to math-service:9090 on line 35
• rebuild api docker image by running docker build -t math-service-api -f Dockerfile.api .
• rebuild server docker image by running docker build -t math-service-server -f Dockerfile.server .
• clean-up previous kubernetes deployments, by running kubectl delete all --all
• deploy the api to kubernetes by running kubectl create -f api.yaml
• deploy the server to kubernetes by running kubectl create -f server.yaml
• copy the api's new kubernetes ip address after running minikube service api-service --url

Now test again with integer 17, integer 18 and array [48, 96, 86, 68, 57, 82, 63, 70, 37, 34, 83, 27, 19, 97, 9, 17], via the sample api requests:

<ip-address:port>/add/17/18
<ip-address:port>/average/[48, 96, 86, 68, 57, 82, 63, 70, 37, 34, 83, 27, 19, 97, 9, 17]
<ip-address:port>/max/[48, 96, 86, 68, 57, 82, 63, 70, 37, 34, 83, 27, 19, 97, 9, 17]
<ip-address:port>/min/[48, 96, 86, 68, 57, 82, 63, 70, 37, 34, 83, 27, 19, 97, 9, 17]
<ip-address:port>/sum/[48, 96, 86, 68, 57, 82, 63, 70, 37, 34, 83, 27, 19, 97, 9, 17]
<ip-address:port>/sort/[48, 96, 86, 68, 57, 82, 63, 70, 37, 34, 83, 27, 19, 97, 9, 17]

where <http://ip-address:port> represents the result of running minikube service api-service --url. For example, if <http://ip-address:port> was http://192.168.99.100:32348, then we can use the terminal to make the api request: curl http://192.168.99.100:32348/add/17/18. For the array: [48, 96, 86, 68, 57, 82, 63, 70, 37, 34, 83, 27, 19, 97, 9, 17] samples, simply copy/past the requests into a browser's address bar i.e. intead of using curl.

In both scenarios of runing the application (i.e. with or without kubernetes), the test examples should give us results numbers similar to:

Addition is:  35
================
Average is:  55.8125
================
Maximum element is:  97
================
Minimum element is:  9
================
Sum total of the elements is:  893
================
Sorted array is:  [9 17 19 27 34 37 48 57 63 68 70 82 83 86 96 97]
================