MARP - Markdown Presentations

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# Malmal and Kubernetes

by Lucas Meurer
https://malmal.io

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# Kubernetes Intro

> Kubernetes is a portable, extensible, open-source platform for managing containerized workloads and services, that facilitates both declarative configuration and automation.

https://kubernetes.io/docs/concepts/overview/what-is-kubernetes/

- Basically a very complex way to run docker containers


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# Main Components

- pods
 - group of one or more containers
 - temporary
- deployments
 - declare the desired state for a pod
 - scale pods
 - roll out new versions and pod updates
- services
 - define a logical set of pods
 - exposes them to other pods or the outside world

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# A sample Deployment


```yaml
apiVersion: apps/v1
kind: Deployment
metadata:
 name: nginx-deployment
 labels:
   app: nginx
spec:
 replicas: 3
 selector:
   matchLabels:
     app: nginx
 template:
   metadata:
     labels:
       app: nginx
   spec:
     containers:
     - name: nginx
       image: nginx:1.14.2
       ports:
       - containerPort: 80```
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# A sample Service

```yaml
apiVersion: v1
kind: Service
metadata:
 name: nginx-service
spec:
 selector:
   app: nginx
 ports:
   - name: http
     protocol: TCP
     port: 80
     targetPort: 80```
`curl http://my-service` should now work inside the cluster
- will be load balanced between pods

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# Digital Ocean Kuberntes (DOKS)

- managed k8s cluster on digitalocean
- malmal previously ran on google cloud
 - that was too expensive
 - when doks had the cluster-autoscaler I finally switched

https://www.digitalocean.com/products/kubernetes/

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# Helm

- package manager for kubernetes
- a package is called "chart"
- automatically creates deployments, services, etc..
- charts can have dependencies so an app chart could have a dependency to the postgres chart

```$ helm repo add bitnami https://charts.bitnami.com/bitnami
$ helm install my-rabbitmq bitnami/rabbitmq --values values.yaml```
values.yaml
```yaml
replicas: 1

resources:
 limits:
   cpu: 50m
   memory: 200Mi```
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# Deployment?

- in the beginning I managed all the kubernetes resources myself
- very tedious and a lot of copy & paste and `kubectl apply -f`


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# GitOps!

- infrastructure as code
- git is the single source of truth for infrastructure
- changes are automatically applied when a branch is merged


https://www.gitops.tech/


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# flux

> Flux is a tool for keeping Kubernetes clusters in sync with sources of configuration (like Git repositories), and automating updates to configuration when there is new code to deploy.

https://toolkit.fluxcd.io/

- dedicated infrastructure repo
- it "just works" (no complicated ci pipelines)
- can add things to the cluster from
 - other git repos
 - helm charts
 - kubernetes yaml files
- used to set up kubernetes tools like cert-manager

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# werf.io

Werf implements GitOps using helm templates

- werf
 - automatically builds and publishes docker images
 - applies the current helm chart
 - tracks the current deployment
 - allows quick rollbacks
 - works with GitLab CI, Github Actions and more
 - can easily spin up review environments

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#  Lets have a look at some of malmals infrastructure!