Towards micro-services architectures

Towards micro-services architectures

https://www.docker.com A Better Way to Build Apps

Let's get started - Docker for mac - Docker for windows

Dockerfile - Used by docker build - INSTRUCTION arguments - The first instruction must be `FROM` - FROM, RUN, CMD, COPY, ADD, - LABEL, ENV, WORKDIR, EXPOSE, … See https://github.com/docker-library/rails https://docs.docker.com/engine/reference/builder/

https://hub.docker.com You don’t have to reinvent the wheel (public vs private) 460K images

Monolithic vs Micro-services architectures Monolithic Microservices

What if I want to run multiple containers? Use docker-compose!
 You just need a docker-compose.yml

Towards micro-services architectures

https://kubernetes.io Kubernetes (k8s) is an open-source system for automating deployment, scaling, and management of containerized applications.
 
 It groups containers that make up an application into logical units for easy management and discovery. Kubernetes builds upon 15 years of experience of running production workloads at Google, combined with best-of-breed ideas and practices from the community. What is Kubernetes?

https://kubernetes.io Automatic binpacking Self-healing Horizontal scaling Service discovery and load balancing Automated rollouts and rollbacks Kubernetes Features

Kubernetes Master API UI CLI ETCD API SERVER SCHEDULER CONTROLLER The master is responsible for exposing the application program interface (API), scheduling the deployments and managing the overall cluster.

Kubernetes Master API UI CLI ETCD API SERVER SCHEDULER CONTROLLER The API server validates and configures data for the api objects which include pods, services, replication controllers, and others. The API Server services REST operations and provides the frontend to the cluster’s shared state through which all other components interact.

Kubernetes Master API UI CLI ETCD API SERVER SCHEDULER CONTROLLER The scheduler is a workload- specific function that significantly impacts availability, performance, and capacity. The scheduler needs to take into account individual and collective resource requirements, quality of service requirements, …

Kubernetes Master API UI CLI ETCD API SERVER SCHEDULER CONTROLLER The controller a controller is a control loop that watches the shared state of the cluster through the api server and makes changes attempting to move the current state towards the desired state.

Kubernetes Master API UI CLI ETCD API SERVER SCHEDULER CONTROLLER ETCD is a highly-available key value store which Kubernetes uses for persistent storage of all of its REST API objects.

Kubernetes Node POD POD POD POD ADDONS KUBELET DOCKER KUBE-PROXY FLUENTD POD

Kubernetes Components (simplified version)

https://kubernetes.io/docs/resources-reference/v1.5/#container-v1 Container name: nginx # Run the nginx:1.7.9 image image: nginx:1.7.9
 ports: - name: http containerPort: 8080 env: - name MY_ENV_VARIALBE value: my-value A simple container.*
 
 *Containers are only ever created within the context of a Pod. This is usually done using a Controller. See Controllers: Deployment, Job, or StatefulSet. or

https://kubernetes.io/docs/user-guide/pods/ Pod A Pod is a group of one or more containers that share the same hostname. Pod templates are pod specifications which are included in other objects, such as Replication Controllers, Jobs, and DaemonSets. Controllers use Pod Templates to make actual pods.

Labels and Selectors Labels are key/value pairs associated with kubernetes objects. They are used to query subsets of objects. Essential glue to associate one API object with other: - ReplicationController - Pods - Services - Pods - Pods - Nodes https://kubernetes.io/docs/user-guide/labels/ apiVersion: v1 kind: Pod metadata: name: nginx labels: type: frontend

https://kubernetes.io/docs/user-guide/replication-controller/ Replication Controller A ReplicationController ensures that a specified number of pod “replicas” are running at any one time. If there are too few, the ReplicationController will start more. Unlike manually created pods, the pods maintained by a ReplicationController are automatically replaced if they fail, get deleted, or are terminated. apiVersion: v1 kind: ReplicationController metadata: name: nginx spec: replicas: 3 selector: app: nginx template: metadata: name: nginx
 labels: app: nginx spec: containers: - name: nginx image: nginx:1.7.9 ports: - containerPort: 80

https://kubernetes.io/docs/user-guide/deployments/ Deployment A Deployment provides declarative updates for Pods and Replica Sets (the next- generation Replication Controller). You only need to describe the desired state in a Deployment object, and the Deployment controller will change the actual state to the desired state at a controlled rate for you. apiVersion: extensions/v1beta1 kind: Deployment metadata: name: nginx spec: replicas: 3 template: metadata: labels: app: nginx spec: containers: - name: nginx image: nginx:1.7.9 ports: - containerPort: 80

https://kubernetes.io/docs/user-guide/pods/ Pod, what’s the problem? Kubernetes Pods are mortal. They are born and when they die, they are not resurrected. While each pod gets its own IP address, even those IP addresses cannot be relied upon to be stable over time.

https://kubernetes.io/docs/user-guide/services/ Service A single pod or a replica set can be exposed to the internal or external consumers via Services. apiVersion: v1 kind: Service metadata: name: my-service spec:
 selector: name: nginx type: NodePort ports: - port: 8080 name: http

https://kubernetes.io/docs/user-guide/horizontal-pod-autoscaling/walkthrough/ Horizontal Pod Autoscaler Horizontal Pod Autoscaling (HPA) automatically scales the number of pods in a replication controller, deployment or replica set based on observed CPU utilization.

https://github.com/kubernetes/community/blob/master/contributors/design-proposals/horizontal-pod-autoscaler.md Horizontal Pod Autoscaler

https://github.com/kubernetes/minikube Minikube Minikube is a tool that makes it easy to run Kubernetes locally. Minikube runs a single-node Kubernetes cluster inside a VM on your laptop for users looking to try out Kubernetes or develop with it day-to-day.

https://github.com/kubernetes/dashboard Kubernetes Dashboard https://github.com/kubernetes/dashboard

References • Getting started with docker, the step by step tutorial with examples
 https://www.youtube.com/watch?v=Vyp5_F42NGs • Docker Containers and Kubernetes with Brian Dorsey
 https://www.youtube.com/watch?v=Fcb4aoSAZ98