Cloud DevOps Admin Guide

List all services

kubectl get services 
kubectl get svc

List everything

kubectl get all --all-namespaces

Describe service <name>

kubectl describe svc <name>

Get services sorted by name

kubectl get services –sort-by=.metadata.name

List all pods

kubectl get pods

Watch nodes continuously

kubectl get pods -w

Get version information

kubectl get version

Get cluster information

kubectl get cluster-info

Get the configuration

kubectl config view

Output information about a node

kubectl describe node <node-name>

List the replication controllers

kubectl get rc

List the replication controllers in specific <namespace>

kubectl get rc -n <namespace-name>

Describe replication controller <name>

kubectl describe rc <name>

Delete pod <name>

kubectl delete pod <name>

Delete replication controller <name>

kubectl delete rc <name>

Delete service <name>

kubectl delete svc <name>

Remove <node> from the cluster

kubectl delete node <name>

Show metrics for nodes

kubectl top nodes

Show metrics for pods

kubectl top pods

Watch the Kublet logs

watch -n 2 cat /var/log/kublet.log

Get logs from service <name>, optionally  selecting container <$container>

kubectl logs -f <name> [-c <$container>] 

execute <command> on <service>, optionally  selecting container <$container>

kubectl exec <service> <command> [-c <$container>]

Initialize your master node

kubeadm init

Join a node to your Kubernetes cluster

kubeadm join --token <token> <master-ip>:<master-port>

Create namespace <name>

kubectl create namespace <namespace>

Allow Kubernetes master nodes to run pods

kubectl taint nodes --all node-role.kubernetes.io/master

Reset current state

kubeadm reset

List all secrets

kubectl get secrets

Launch a pod called <name> ,using image <image-name>

kubectl run <name> --image=<image-name>

Create a service described in <manifest.yaml> file

kubectl create -f <manifest.yaml>

Validate yaml file with dry run

kubectl create --dry-run --validate -f sysaix.yaml

Scale replication controller

kubectl scale rc <name> --replicas=<count>

Stop all pods on specific pods

kubectl drain <n> --delete-local-data --force --ignore-deamonsets

Explain resource

kubectl explain pods
kubectl explain svc

Open a bash terminal in a pod

kubectl exec -it sysa'xpod sh

Check pod environment variables

kubectl exec sysaixpod env

Filter pods by label

kubectl get pods -l owner=emre

List statefulset

kubectl get sts

Scale statefulset

kubectl scale sts <stateful_set_name> --replicas=5

Delete statefulset only (not pods)

kubectl delete sts <stateful_set_name> --cascade=false

View all events

kubectl get events --all-namespaces

Install Dependencies

yum install bc sysstat jq moreutils

git clone https://github.com/OutsideIT/FireMotD.git

Blue

Red

Gray

What is EPEL

[root@cloud ~]# df -h /home/
 Filesystem            Size  Used Avail Use% Mounted on
 /dev/mapper/vg_cloud-LogVol00
                       12G   9.2G  1.9G  84%  /home

Step:1 Umount the file system

[root@cloud ~]# umount /home/

Step:2 check the file system for Errors using e2fsck command.

[root@cloud ~]# e2fsck -f /dev/mapper/vg_cloud-LogVol00
 e2fsck 1.41.12 (17-May-2010)
 Pass 1: Checking inodes, blocks, and sizes
 Pass 2: Checking directory structure
 Pass 3: Checking directory connectivity
 Pass 4: Checking reference counts
 Pass 5: Checking group summary information
 /dev/mapper/vg_cloud-LogVol00: 12/770640 files (0.0% non-contiguous), 2446686/3084288 blocks

Step:3 Reduce or Shrink the size of /home to desire size.

[root@cloud ~]# resize2fs /dev/mapper/vg_cloud-LogVol00 10G
 resize2fs 1.41.12 (17-May-2010)
 Resizing the filesystem on /dev/mapper/vg_cloud-LogVol00 to 2621440 (4k) blocks.
 The filesystem on /dev/mapper/vg_cloud-LogVol00 is now 2621440 blocks long.

Step:4 Now reduce the size using lvreduce command.

[root@cloud ~]# lvreduce -L 10G /dev/mapper/vg_cloud-LogVol00
 WARNING: Reducing active logical volume to 10.00 GiB
 THIS MAY DESTROY YOUR DATA (filesystem etc.)
 Do you really want to reduce LogVol00? [y/n]: y
 Reducing logical volume LogVol00 to 10.00 GiB
 Logical volume LogVol00 successfully resized

Step:5 (Optional) For the safer side, now check the reduced file system for errors

[root@cloud ~]# e2fsck -f /dev/mapper/vg_cloud-LogVol00
 e2fsck 1.41.12 (17-May-2010)
 Pass 1: Checking inodes, blocks, and sizes
 Pass 2: Checking directory structure
 Pass 3: Checking directory connectivity
 Pass 4: Checking reference counts
 Pass 5: Checking group summary information
 /dev/mapper/vg_cloud-LogVol00: 12/648960 files (0.0% non-contiguous), 2438425/2621440 blocks

Step:6 Mount the file system and verify its size.

[root@cloud ~]# mount /home/
 [root@cloud ~]# df -h /home/
 Filesystem            Size  Used Avail Use% Mounted on
 /dev/mapper/vg_cloud-LogVol00
                       9.9G  9.2G  208M  98% /home