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CKA
Certified Kubernetes Administrator: https://www.cncf.io/certification/cka/
Exam Curriculum (Topics): https://github.com/cncf/curriculum
Candidate Handbook: https://www.cncf.io/certification/candidate-handbook
Exam Tips: http://training.linuxfoundation.org/go//Important-Tips-CKA-CKAD
Manage, Plan, Schedule, Monitor Nodes
ETCD Cluster - Database
kube-scheduler - identify the write node to put the pod on.
Controller-Manager Node-Controller Replication-Controller
kube-apiserver
Standard: Open Container Initiative
- imagespec
- runtimespec
ETCD – Commands (Optional)
(Optional) Additional information about ETCDCTL UtilityETCDCTL is the CLI tool used to interact with ETCD.ETCDCTL can interact with ETCD Server using 2 API versions – Version 2 and Version 3. By default it’s set to use Version 2. Each version has different sets of commands.
For example, ETCDCTL version 2 supports the following commands:
etcdctl backup etcdctl cluster-health etcdctl mk etcdctl mkdir etcdctl set
Whereas the commands are different in version 3
etcdctl snapshot save etcdctl endpoint health etcdctl get etcdctl put
To set the right version of API set the environment variable ETCDCTL_API command
export ETCDCTL_API=3
When the API version is not set, it is assumed to be set to version 2. And version 3 commands listed above don’t work. When API version is set to version 3, version 2 commands listed above don’t work.
Apart from that, you must also specify the path to certificate files so that ETCDCTL can authenticate to the ETCD API Server. The certificate files are available in the etcd-master at the following path. We discuss more about certificates in the security section of this course. So don’t worry if this looks complex:
--cacert /etc/kubernetes/pki/etcd/ca.crt --cert /etc/kubernetes/pki/etcd/server.crt --key /etc/kubernetes/pki/etcd/server.key
So for the commands, I showed in the previous video to work you must specify the ETCDCTL API version and path to certificate files. Below is the final form:
kubectl exec etcd-controlplane -n kube-system -- sh -c "ETCDCTL_API=3 etcdctl get / --prefix --keys-only --limit=10 --cacert /etc/kubernetes/pki/etcd/ca.crt --cert /etc/kubernetes/pki/etcd/server.crt --key /etc/kubernetes/pki/etcd/server.key"