calc-server-gce

Google Container Engine Microservices based app

The application

• it's a web application with a microservice architecture to calculate the hypotenuse (ie. c side) of a right-angled triangle, using the Pythagorean theorem (ie. for a and b it returns sqrt( a^2 + b^2 ))
• each microservice takes care of only one arithmetic operation; they take the inputs from the URL query form and return the result or error message in JSON format
• calc_server_square calculates the square of a number; for the square of 1234 it is called with the URL http://example.com:8080/compute/square?a=1234
• calc_server_add sends its two arguments to the above calc_server_square server and adds whatever that returns; for the numbers 1234 and 5678 it is called with the URL http://example.com:8081/compute/add?a=1234&b=5678
• calc_server_sqrt sends its two arguments to the above calc_server_add server and computes the square root of whatever that returns; for the numbers 1234 and 5678 it is called with the URL http://example.com:8082/compute/sqrt?a=1234&b=5678
• in the Makefile there's a rudimentary example of spawning all of the services and connecting them, plus sending a test request

Environment

• the Go compiler (version v1.6.2) is installed and the go command is on the path
• make and anything else needed by the Makefile is installed and is on the path
• docker is on the path and the user running make is in the docker group
• a docker login was already performed so docker push just works
• kubectl is on the path
• a Kubernetes cluster is set up and the the default kubectl context points to that cluster

Build and Test

• Build images using make docker-images DOCKER_REPO=gcr.io/calc-server
• Create and test cluster using make kubernetes-test
• Clean up after testing using make kubernetes-clean