72 lines
2.9 KiB
Markdown
72 lines
2.9 KiB
Markdown
---
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title: "Introduction to kubectl"
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content_type: concept
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weight: 1
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---
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kubectl is the Kubernetes cli version of a swiss army knife, and can do many things.
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While this Book is focused on using kubectl to declaratively manage applications in Kubernetes, it
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also covers other kubectl functions.
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## Command Families
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Most kubectl commands typically fall into one of a few categories:
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| Type | Used For | Description |
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|----------------------------------------|----------------------------|----------------------------------------------------|
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| Declarative Resource Management | Deployment and operations (e.g. GitOps) | Declaratively manage Kubernetes workloads using resource configuration |
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| Imperative Resource Management | Development Only | Run commands to manage Kubernetes workloads using Command Line arguments and flags |
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| Printing Workload State | Debugging | Print information about workloads |
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| Interacting with Containers | Debugging | Exec, attach, cp, logs |
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| Cluster Management | Cluster operations | Drain and cordon Nodes |
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## Declarative Application Management
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The preferred approach for managing resources is through
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declarative files called resource configuration used with the kubectl *Apply* command.
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This command reads a local (or remote) file structure and modifies cluster state to
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reflect the declared intent.
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{{< alert color="success" title="Apply" >}}
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Apply is the preferred mechanism for managing resources in a Kubernetes cluster.
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{{< /alert >}}
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## Printing State about Workloads
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Users will need to view workload state.
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- Printing summarize state and information about resources
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- Printing complete state and information about resources
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- Printing specific fields from resources
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- Query resources matching labels
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## Debugging Workloads
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kubectl supports debugging by providing commands for:
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- Printing Container logs
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- Printing cluster events
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- Exec or attaching to a Container
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- Copying files from Containers in the cluster to a user's filesystem
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## Cluster Management
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On occasion, users may need to perform operations to the Nodes of cluster. kubectl supports
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commands to drain workloads from a Node so that it can be decommissioned or debugged.
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## Porcelain
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Users may find using resource configuration overly verbose for *development* and prefer to work with
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the cluster *imperatively* with a shell-like workflow. kubectl offers porcelain commands for
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generating and modifying resources.
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- Generating + creating resources such as Deployments, StatefulSets, Services, ConfigMaps, etc.
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- Setting fields on resources
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- Editing (live) resources in a text editor
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{{< alert color="warning" title="Porcelain for Dev Only" >}}
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Porcelain commands are time saving for experimenting with workloads in a dev cluster, but shouldn't
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be used for production.
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{{< /alert >}}
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