PODMAN: How To Configure Podman Container Instance As System Unit Service To Autorestart When the Host OS Reboots

Please find the steps below for enabling the podman container instance to auto restart when the OS is rebooted.

1) list the podman instances to get the container ID and name. 

podman ps -a

For e.g. below output

# podman ps -a

CONTAINER ID  IMAGE           COMMAND   CREATED        STATUS     PORTS       NAMES

45782651b66d  localhost/ock-ostree:latest nginx -g daemon o...  2 minutes ago  Up 2 minutes           0.0.0.0:8080->80/tcp    ock-content-server

2) Configure the podman container instance as service and enable the service. 

For this use below steps.

2(a) Create systemd file for podman container instances. In below command replace the name with container ID and os-tree-podman.service with the service name of choice.

podman generate systemd --new --name 9596fff2a7b1>/etc/systemd/system/ostree-podman.service

Above command will create a file /etc/systemd/system/ostree-podman.service

2(b) Restart the system daemon

systemctl daemon-reload

2(c) Enable the newly created podman container system unit file.

systemctl enable ostree-podman.service

2(d) List the system unit files 

systemctl list-unit-files | grep -i podman

You should see the newly created podman container system unit file and it should be enabled. For e.g. below output

# systemctl list-unit-files | grep -i podman

ostree-podman.service  enabled  

3) Reboot the host and  validate that the podman container instances is auto restarted.

For veirfying this, run below command.

podman ps -a

Keywords

Configuring setting up setup autorestart auto-restart service unit files files containers instances operating system rebooting reboots reboot restart restarting restarts os

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KUBERNETES: Deploy Sample nginx Weblogic (from Docker.io) to Kubernetes Cluster For Testing

KUBERNETES: Deploy Sample nginx Weblogic (from Docker.io) to Kubernetes Cluster For Testing

1) Create nginx deployment yaml file. For e.g. nginx.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-webapp
spec:
  replicas: 3
  selector:
    matchLabels:
      app: my-webapp
  template:
    metadata:
      labels:
        app: my-webapp
    spec:
      containers:
      - name: my-webapp
        image: nginx:1.7.9
        ports:
        - containerPort: 80

2)Create nginx service yaml file to listen on the Nodeport. For e.g. nginx-service-nodeport.yaml

apiVersion: v1
kind: Service
metadata:
  name: my-webapp-service
spec:
  selector:
    app: my-webapp
  ports:
  - port: 80
    targetPort: 80
    nodePort: 30007
  type: NodePort

3) Deployment the nginx webapp and create service. 

kubectl apply -f nginx.yaml

kubectl apply -f nginx-service-nodeport.yaml

4) Check the deployment and service are created in default namespace.

For this run below command.

kubectl get all

Below is sample output.

NAME                             READY   STATUS    RESTARTS   AGE
pod/my-webapp-6c854bcc4c-256kh   1/1     Running   0          8m19s
pod/my-webapp-6c854bcc4c-ghnnv   1/1     Running   0          8m19s
pod/my-webapp-6c854bcc4c-v87jj   1/1     Running   0          8m19s

NAME                        TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)        AGE
service/kubernetes          ClusterIP   10.96.0.1       <none>        443/TCP        3d20h
service/my-webapp-service   NodePort    10.101.27.114   <none>        80:30007/TCP   6m50s

NAME                        READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/my-webapp   3/3     3            3           8m19s

NAME                                   DESIRED   CURRENT   READY   AGE
replicaset.apps/my-webapp-6c854bcc4c   3         3         3       8m19s

5) Acccess the nginx webapp using nodeport 30007 and Kubernetes machine IP where pod is running.

http://IP:30007

keywords

deploying install installing nginx example sample samples examples web app webapp application services

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LINUX: Netstat Command To Check the TCP Details - PacketLoss, Retransmits, Dropped, Aborted Connections Etc. For Troubleshooting

"netstat -s" command can be used for checking the TCP network details to check packetloss, retransmits, dropped, aborted connections etc. for troubleshooting.

Below is sample output.

#netstat -s | egrep -i "timeout|retransmit|segments|lost|TcpRetransSegs|drop"

    20 fragments dropped after timeout

    22297220 segments received

    22212157 segments sent out

    4461 segments retransmitted

    0 bad segments received

    Detected reordering 4 times using reno fast retransmit

    TCPLostRetransmit: 1281

    5 timeouts in loss state

    32 fast retransmits

    19 retransmits in slow start

    TCPTimeouts: 2531

    221 connections aborted due to timeout

    TcpTimeoutRehash: 1705

Keywords:

troubleshoot troubleshooting network networking issue issues problem problems debug debugging check checking bottleneck performance stall stalled packets transmit transmission 

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KUBERNETES: How to Check the Liveness and Readiness Probe for Kube apiserver?

Kube apiserver liveness and readiness probe settings can be checked inside /etc/kubernetes/manifests/kube-apiserver.yaml file on the Kubernetes nodes.

Keywords:

liveness liveliness ready readiness probe probes monitor monitoring check checking

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