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{% assign concept="Pod" %}
{% capture what_is %} A pod is the vehicle for running containers in Kubernetes. A pod consists of:
- One or more containers
- An IP address that is unique within the cluster
- Optionally: Environment variables, storage volumes, and enterprise features (such as health checking)
Resources are shared amongst containers in the pod. Containers within a pod also share an IP address and port space, and can find each other via localhost, or interprocess communications (such as semaphores).
{: style="max-width: 25%" } {% comment %}https://drive.google.com/open?id=1pQe4-s76fqyrzB8f3xoJo4MPLNVoBlsE1tT9MyLNINg{% endcomment %}
{% endcapture %}
{% capture when_to_use %} Pods are used any time you need a container to be run. However, they are rarely created by a user, and are instead automatically created by controllers such as jobs, replication controllers, deployments, daemon set. The following table describes the strategy each controller uses to create pods.
Controller | Usage Strategy |
---|---|
Deployment | For running pods as a continuous and healthy application |
Replication Controller | Used for the same purpose as Deployments (superseded Replication Controllers) |
Jobs | For running pods "to completion" (which are then shut down) |
Daemon Set | Mainly for performing operations on any nodes that match given parameters |
{% endcapture %}
{% capture when_not_to_use %} Do not use pods directly. Pods should always be managed by a controller. {% endcapture %}
{% capture status %} To retrieve the status of a pod, run the following command:
kubectl get pod <name>
Return Value | Description |
---|---|
READY |
Describes the number of containers that are ready to receive traffic. |
STATUS |
A value from the PodPhase enum describing the current status of the pod. Can be Running , Pending , Succeeded , Failed , and Unknown . |
TODO: Link to refpage for kubectl get pod
To get a full description of a pod, including past events, run the following command:
kubectl describe pod <name>
TODO: Link to refpage for kubectl describe pod
Possible status results
Value | Description |
---|---|
Deployment | For running pods as a continuous and healthy application |
Replication Controller | Used for the same purpose as Deployments (superseded Replication Controllers) |
Jobs | For running pods "to completion" (which are then shut down) |
Daemon Set | Mainly for performing operations on any nodes that match given parameters |
{% endcapture %}
{% capture usage %}
Pods are defined when configuring the controller of your choice. In controller specifications,
the parts that define the contents of the pod are inside the template:
section.
YAML EXAMPLE HERE
{% endcapture %}
{% include templates/concept-overview.md %}