daemonset

README.md

@@ -10,7 +10,7 @@
   * [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)
+* [Running DaemonSets on `hostPort`](#running-daemonsets)
 
 ## Install k3s <a name="install-k3s"></a>
 https://k3s.io/:
@@ -252,9 +252,58 @@ kubectl logs my-nginx-65c68bbcdf-xkhqj -f
 [...]
 ```
 
-# Running postfix in kubernetes <a name="running-postfix-in-kuberentes"></a>
-https://www.tauceti.blog/post/run-postfix-in-kubernetes/
+# Running DaemonSets on `hostPort` <a name="running-daemonsets"></a>
+Docs: https://kubernetes.io/docs/concepts/workloads/controllers/daemonset/
 
-Important in term of Deployment(one node)/Daemonset(all nodes)
-* hostNetwork: true
-* dnsPolicy: ClusterFirstWithHostNet
+In this case configuration of networking in context of services are not needed.
+
+```
+kind: DaemonSet
+apiVersion: apps/v1
+metadata:
+  name: netcat-daemonset
+  labels:
+    app: netcat-daemonset
+spec:                                                                     
+  selector:                                                    
+    matchLabels:                                               
+      app: netcat-daemonset                                             
+  template:                                                    
+    metadata:                                                  
+      labels:                                                  
+        app: netcat-daemonset                                           
+    spec:                                                                                                                                                                                     
+      containers:                                              
+      - command:                                               
+        - nc                                                   
+        - -lk                              
+        - -p                    
+        - "23456"                          
+        - -v                                                     
+        - -e                                                     
+        - /bin/true                                              
+        env:                                                     
+        - name: DEMO_GREETING                                    
+          value: Hello from the environment                      
+        image: dockreg-zdf.int.zwackl.de/alpine/latest/amd64:prod
+        imagePullPolicy: Always                                  
+        name: netcat-daemonset                                            
+        ports:                                                   
+        - containerPort: 23456 
+          hostPort: 23456
+          protocol: TCP                                          
+        resources:                                               
+          limits:                                                
+            cpu: 500m                                            
+            memory: 64Mi                                         
+          requests:                                              
+            cpu: 50m                                             
+            memory: 32Mi                                         
+      restartPolicy: Always                         
+      securityContext: {}                           
+      terminationGracePeriodSeconds: 30             
+  updateStrategy:                                   
+    rollingUpdate:                                  
+      maxUnavailable: 1                             
+    type: RollingUpdate
+```