JUnit 4 Annotations

@Test		Identifies a method as a test method.

@Before		Executed before each test. It is used to prepare the test environment
		(e.g. read input data, initialize the class).

@After		Executed after test. It is used to cleanup the test environment. 
		It can also save memory by cleaning up expensive memory structures.

@BeforeClass	Executed once, before the start of all tests. Methods marked with
		this annotaion need to be defined as static to work with JUnit.

@AfterClass	Executed once, after all tests have been finished. 
		Methods annotated with this annotation need to be defined as static 
        	to work with JUnit.

@Ignore		Marks that the test should be disabled.

@Test(expected =	Fails if the method does not throw the named exception.
Exception.class)

@Test(timeout = 10)	Fails if the method takes longer than 100 millseconds.

                                 

Types of Services

 Cluster IP => Set up an easy-to-remember URL to access a pod. 

                   Only exposes pods in the cluster

Node Port => Makes a pod accessible from outside the cluster.

                   Usually only used for dev purposes

Load Balancer =>  Makes a pod accessible from outside the cluster. 

                         This is the right way to expose a pod to the outside world

External Name => Redirects an in-cluster request to a CNAME url...

_______________________________________________________________________________________

Load Balancer Service =>  Tells Kubernetes to reach out to its provider

                                   and provision a load balancer. 

                                  Gets traffic in to a single pod

Ingress or Ingress Controller => 

A pod with a set of routing rules to distribute traffic to other services

Kubernetes Config Files

 1. Thells Kubernetes about the different Deployments, Pods, and Services 
(referred to as 'Objects') that we want to create

 

2. Written in YAML syntax

3. Always store these files with our project source code - they are documentation!

4. We can create Objects without config files - do not do this. Config files 

provide a precise definition of what your cluster is running.

 Install MiniKube (https://kubernetes.io/docs/tasks/tools/install-minikube/)

minikube start

kubectl version

kubectl get all

kubectl apply -f first-pod.yaml

kubectl get all

minikube ip

kubectl describe pod webapp

kubectl exec webapp ls

kubectl -it exec webapp sh

wget http://localhost:80

cat index.html

kubernetes

 Kubernetes Cluster       => A collections of nodes + a master to manage them

 Node                        => A virtual machine that will run our containers

Pod                           => More or less a running container.

                                     Technically, a pod can run multiple containers

                                     (we won't do this)

Deployment                => Monitors a set of pods, make sure they are running

                                    and restarts them if they crash

Service                      => Provides an easy-to-remember URL to access 

                                    a running container

 

node js building docker

 FROM                  node:alpine       => Specify base image

 WORKDIR             /app                => Set the working directory to '/app' in the                                                                  container. All following commands will be 

                                                      issued relative to this dir

 COPY                   package.json ./   => Copy over only the package.json file

 RUN                    npm install        => Install all dependencies

 COPY                   ./ ./                 => Copy over all of our remaining source code

 CMD                    ["npm", "start"]  => Set the command to run when the container

                                                      starts up

Dockerfile

FROM node:alpine

WORKDIR /app

COPY package.json ./

RUN npm install

COPY ./ ./

CMD ["npm", "start"]

.dockerignore

node_modules

docker build .

Successfully built eb521ea6b7e6

docker run eb521ea6b7e6

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

docker build -t abcdefg/efgh .            => Build an image based on the dockerfile in the 

                                                        current directory. Tag it as 'abcdefg/efgh'

docker run [image id or image tag]     => Create and start a container based on the

                                                        provided image id or tag

docker run -it [image id or image tag] [cmd] => Create and start container, but also

                                                                override the default command

docker ps                                    => Print out information about all of the 

                                                      running containers

docker exec -it [container id] [cmd]    => Execute the given command in a running 

                                                      container

docker logs [container id]                => Print out logs from the given container