chore: reorder the sections
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@ -18,7 +18,7 @@ data:
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You can apply the file:
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```bash
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$ kubectl apply -f 11-secrets/01-secrets.
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$ kubectl apply -f 10-secrets/01-secrets.yml
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secret "mysecret" created
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```
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@ -0,0 +1,32 @@
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apiVersion: apps/v1
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kind: StatefulSet
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metadata:
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name: web
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spec:
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selector:
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matchLabels:
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app: nginx # has to match .spec.template.metadata.labels
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serviceName: "nginx"
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replicas: 3
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template:
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metadata:
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labels:
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app: nginx # has to match .spec.selector.matchLabels
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spec:
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containers:
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- name: nginx
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image: k8s.gcr.io/nginx-slim:0.8
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ports:
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- containerPort: 80
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name: web
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volumeMounts:
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- name: www
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mountPath: /usr/share/nginx/html
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volumeClaimTemplates:
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- metadata:
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name: www
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spec:
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accessModes: [ "ReadWriteOnce" ]
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resources:
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requests:
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storage: 1Gi
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@ -0,0 +1,100 @@
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# Other topics
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## Introduction
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In this section you will get an overview of others k8s useful features, in order of complexity.
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## Namespace
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`Namespaces` is the way to support multiple virtual clusters in k8s.
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They are intended for use in environments with many users spread across multiple teams, or projects. For clusters with a few to tens of users, you should not need to create or think about `namespaces` at all. Start using `namespaces` when you need the features they provide.
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By default, all objects are in the `default` namespace. There is a "hidden" `namespace` where k8s runs services for itself.
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Try:
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```bash
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$ kubectl get namespace
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NAME STATUS AGE
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default Active 56d
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kube-public Active 56d
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kube-system Active 56d
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```
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```bash
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$ kubectl get all --namespace=kube-system
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[lot of stuff]
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```
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## `kubeval`
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It is a tool to validate your k8s YAML files: <https://github.com/garethr/kubeval>
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The easiest integration is with `docker run`, if you files are in the directory `kubernetes`
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```bash
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docker run -it -v `pwd`/kubernetes:/kubernetes garethr/kubeval kubernetes/**/*
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```
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## Helm
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It is a package manager for k8s: <https://helm.sh/>.
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It contains multiple, ready to use, k8s manifest for projects, for example [mysql](https://github.com/helm/charts/tree/master/stable/mysql)
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## Stateful Set
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Like a `Deployment`, a `StatefulSet` manages Pods that are based on an identical container spec. Unlike a `Deployment`, a `StatefulSet` maintains a sticky identity for each of their Pods. These pods are created from the same spec, but are not interchangeable: each has a persistent identifier that it maintains across any rescheduling.
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`StatefulSets` are valuable for applications that require one or more of the following.
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* Stable, unique network identifiers, ex: distributed system, like ElasticSearch
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* Stable, persistent storage, ex: MySQL
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* Ordered, graceful deployment and scaling
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* Ordered, automated rolling updates, ex: MySQL Master+Slave
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```yaml
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apiVersion: apps/v1
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kind: StatefulSet
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metadata:
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name: web
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spec:
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selector:
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matchLabels:
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app: nginx # has to match .spec.template.metadata.labels
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serviceName: "nginx"
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replicas: 3 # by default is 1
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template:
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metadata:
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labels:
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app: nginx # has to match .spec.selector.matchLabels
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spec:
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containers:
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- name: nginx
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image: k8s.gcr.io/nginx-slim:0.8
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ports:
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- containerPort: 80
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name: web
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volumeMounts:
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- name: www
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mountPath: /usr/share/nginx/html
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volumeClaimTemplates:
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- metadata:
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name: www
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spec:
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accessModes: [ "ReadWriteOnce" ]
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resources:
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requests:
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storage: 1Gi
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```
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## Exercises
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1. Install `helm`, and use it to install [`redis`](https://github.com/helm/charts/tree/master/stable/redis) in your minikube
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2. Configure a stateful set for nginx with a HPA at 1% CPU, in a namespace `staging`
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## Clean up
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```bash
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kubectl delete statefulset,deployment,service,pod --all
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```
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42
README.md
42
README.md
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@ -9,13 +9,15 @@
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1. [Deploying my first application: deployment](#deploying-my-first-application-deployment)
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1. [Accessing my first application: service](#accessing-my-first-application-service)
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1. [Running a background process: cronjob](#running-a-background-process-cronjob)
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1. [Running a stateful application: volumes](#running-a-stateful-application-volumes)
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1. [Secrets](#secrets)
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1. [Liveness and readiness probes, and how it impacts your pods](#liveness-and-readiness-probes,-and-how-it-impacts-your-pods)
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1. [Resources, and how it impacts the scheduling](#resources,-and-how-it-impacts-the-scheduling)
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1. [HPA, VPA](#hpa-vpa)
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1. [Affinity and anti-affinity](#affinity-and-anti-affinity)
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1. [Improve the availability of your application: affinity and anti-affinity](#affinity-and-anti-affinity)
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1. [Improve the availability of your application: pod disruptions budget](#pdb)
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1. [Improve the elasticiy of your applications: HPA, VPA](#hpa-vpa)
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1. [Sidecar containers: what, why, and how](#sidecar-containers-what,-why,-and-how)
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1. [Running a stateful application: volumes](#running-a-stateful-application-volumes)
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1. [Running a stateful application: stateful-sets](#running-a-stateful-application-stateful-sets)
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1. [Controllers: what, why, and how](#controllers-what,-why,-and-how)
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1. [Operators and CRDs: what, why, and how](#operators-and-crds-what,-why,-and-how)
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1. [RBAC](#rbac)
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@ -200,53 +202,57 @@ See the dedicated [README](08-service).
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See the dedicated [README](09-cronjob).
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## Running a stateful application: `volumes`
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See the dedicated [README](10-volumes).
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## Secrets
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See the dedicated [README](11-secrets).
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See the dedicated [README](10-secrets).
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## Liveness and readiness probes, and how it impacts your pods
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See the dedicated [README](12-probes).
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See the dedicated [README](11-probes).
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## Resources, and how it impacts the scheduling
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See the dedicated [README](13-resources).
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See the dedicated [README](12-resources).
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## Affinity and anti-affinity
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See the dedicated [README](14-affinity-anti-affinity).
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See the dedicated [README](13-affinity-anti-affinity).
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## PDB
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See the dedicated [README](15-pdb).
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See the dedicated [README](14-pdb).
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## HPA, VPA
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See the dedicated [README](16-hpa-vpa).
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See the dedicated [README](15-hpa-vpa).
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## Sidecar containers: what, why, and how
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See the dedicated [README](17-sidecar-containers).
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See the dedicated [README](16-sidecar-containers).
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## Running a stateful application: `volumes`
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See the dedicated [README](17-volumes).
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## Running a stateful application: `stateful sets`
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See the dedicated [README](18-stateful-sets).
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## Controllers: what, why, and how
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See the dedicated [README](18-controllers).
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See the dedicated [README](19-controllers).
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## Operators and CRDs: what, why, and how
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See the dedicated [README](19-operators).
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See the dedicated [README](20-operators).
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## RBAC
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See the dedicated [README](20-rbac).
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See the dedicated [README](21-rbac).
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## Good practices
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See the dedicated [README](21-good-practices).
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See the dedicated [README](99-good-practices).
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## Links
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