# Snippets for k3s * [Install k3s](#install-k3s) * [Disable Traefik-ingress](#disable-traefik-ingress) * [Enable NGINX-ingress](#enable-nginx-ingress) * [Installation](#install-nginx-ingress) * [Change service type from NodePort to LoadBalancer](#nginx-ingress-loadbalancer) * [Enable nginx-ingress tcp- and udp-services for apps other than http/s](#nginx-ingress-tcp-udp-enabled) * [Enable client-IP transparency and expose TCP-port 9000](#enable-client-ip-transp-expose-tcp-9000) * [Deploy my-nginx-service](#deploy-my-nginx-service) * [Stick the nginx-ingress controler and my-nginx app together](#stick-nginx-ingress-and-tcp-service) * [Test exposed app on TCP-port 9000](#test-nginx-ingress-and-tcp-service) * [Running postfix in kubernetes](#running-postfix-in-kuberentes) ## Install k3s https://k3s.io/: ``` curl -sfL https://get.k3s.io | sh - ``` ## Disable Traefik-ingress edit /etc/systemd/system/k3s.service: ``` [...] ExecStart=/usr/local/bin/k3s \ server --disable traefik \ [...] ``` Finally `systemctl daemon-reload` and `systemctl restart k3s` ## Enable NGINX-ingress ### Installation https://kubernetes.github.io/ingress-nginx/deploy/#bare-metal ### Change service type from NodePort to LoadBalancer `kubectl edit service -n ingress-nginx ingress-nginx-controller` and change `type: NodePort` to `type: LoadBalancer` Port 80 and 443 should listen now on an *External-IP* `kubectl get all --all-namespaces`: ``` [...] NAMESPACE NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE [...] ingress-nginx service/ingress-nginx-controller-admission ClusterIP 10.43.174.128 443/TCP 35m ingress-nginx service/ingress-nginx-controller LoadBalancer 10.43.237.255 10.62.94.246 80:30312/TCP,443:30366/TCP 35m [...] ``` Test: `curl -s http://` should return well known nginx-404-page: ``` dominik@muggler:~$ curl -s http://10.62.94.246 404 Not Found

404 Not Found

nginx/1.19.1 ``` ### Enable nginx-ingress tcp- and udp-services for apps other than http/s Docs: https://kubernetes.github.io/ingress-nginx/user-guide/exposing-tcp-udp-services/ `kubectl edit deployment -n ingress-nginx ingress-nginx-controller` and search for `spec:`/`template`/`spec`/`containers` section: ``` [...] spec: [...] template: metadata: creationTimestamp: null labels: app.kubernetes.io/component: controller app.kubernetes.io/instance: ingress-nginx app.kubernetes.io/name: ingress-nginx spec: containers: - args: - /nginx-ingress-controller - --election-id=ingress-controller-leader - --ingress-class=nginx - --configmap=ingress-nginx/ingress-nginx-controller - --validating-webhook=:8443 - --validating-webhook-certificate=/usr/local/certificates/cert - --validating-webhook-key=/usr/local/certificates/key >>> ADD - --tcp-services-configmap=ingress-nginx/tcp-services - --udp-services-configmap=ingress-nginx/udp-services <<< ADD env: [...] ``` ## Enable client-IP transparency and expose TCP-port 9000 Enable client-IP transparency (X-Original-Forwarded-For) and expose my-nginx app on nginx-ingress TCP-port 9000: `kubectl edit service -n ingress-nginx ingress-nginx-controller` Find the `ports:`-section of the `ingress-nginx-controller` service and *ADD* the definition for port 9000: ``` [...] spec: clusterIP: 10.43.237.255 >>> CHANGE externalTrafficPolicy from Cluster to Local if original client-IP is desirable externalTrafficPolicy: Local <<< CHANGE ports: - name: http nodePort: 30312 port: 80 protocol: TCP targetPort: http - name: https nodePort: 30366 port: 443 protocol: TCP targetPort: https >>> ADD - name: proxied-tcp-9000 port: 9000 protocol: TCP targetPort: 9000 <<< ADD [...] ``` Verify nginx-ingress is listening on port 9000 with `kubectl get all --all-namespaces`: ``` [...] NAMESPACE NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE [...] ingress-nginx service/ingress-nginx-controller LoadBalancer 10.43.237.255 10.62.94.246 80:30312/TCP,443:30366/TCP,9000:31460/TCP 71m [...] ``` ### Deploy my-nginx-service my-nginx-deployment.yml: ``` apiVersion: apps/v1 kind: Deployment metadata: name: my-nginx spec: selector: matchLabels: run: my-nginx replicas: 1 template: metadata: labels: run: my-nginx spec: containers: - name: my-nginx image: nginx:alpine ports: - containerPort: 80 --- apiVersion: v1 kind: Service metadata: name: my-nginx labels: run: my-nginx spec: ports: - port: 80 protocol: TCP selector: run: my-nginx ``` Apply with `kubectl apply -f my-nginx-deployment.yml`: ``` deployment.apps/my-nginx created service/my-nginx created ``` Test: `kubectl get all`: ``` [...] NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE [...] service/my-nginx ClusterIP 10.43.118.13 80/TCP 99s [...] ``` ## Stick the nginx-ingress controler and my-nginx app together Finally, the nginx-ingress controller needs a port-mapping pointing to the my-nginx app. This will be done with the config-map `tcp-services-config-map.yml`, referenced earlier in the nginx-ingress deployment definition: ``` --- apiVersion: v1 kind: ConfigMap metadata: name: tcp-services namespace: ingress-nginx data: "9000": default/my-nginx:80 ``` Apply with `kubectl apply -f tcp-services-config-map.yml`: ``` configmap/tcp-services created ``` Subsequently the config-map can be edited with `kubectl edit configmap tcp-services -n ingress-nginx` **Changes to config-maps do not take effect on running pods! A re-scale to 0 and back can solve this problem: https://stackoverflow.com/questions/37317003/restart-pods-when-configmap-updates-in-kubernetes** ## Test exposed app on TCP-port 9000 ``` dominik@muggler:~$ curl -s http://10.62.94.246:9000 Welcome to nginx!

Welcome to nginx!

If you see this page, the nginx web server is successfully installed and working. Further configuration is required.

For online documentation and support please refer to nginx.org.
Commercial support is available at nginx.com.

Thank you for using nginx.

``` Check logs of ingress-nginx-controller POD: ``` root@k3s-master:~# kubectl get pods --all-namespaces |grep ingress-nginx [...] ingress-nginx ingress-nginx-controller-d88d95c-khbv4 1/1 Running 0 4m36s [...] ``` ``` root@k3s-master:~# kubectl logs ingress-nginx-controller-d88d95c-khbv4 -f -n ingress-nginx [...] [10.62.94.1] [23/Aug/2020:16:38:33 +0000] TCP 200 850 81 0.001 [...] ``` Check logs of my-nginx POD: ``` root@k3s-master:/k3s# kubectl get pods NAME READY STATUS RESTARTS AGE my-nginx-65c68bbcdf-xkhqj 1/1 Running 0 90m ``` ``` kubectl logs my-nginx-65c68bbcdf-xkhqj -f [...] 10.42.0.18 - - [23/Aug/2020:16:38:33 +0000] "GET / HTTP/1.1" 200 612 "-" "curl/7.64.0" "-" [...] ``` # Running postfix in kubernetes https://www.tauceti.blog/post/run-postfix-in-kubernetes/ Important in term of Deployment(one node)/Daemonset(all nodes) * hostNetwork: true * dnsPolicy: ClusterFirstWithHostNet