September 22, 2019

2602 words 13 mins read

derailed/k9s

Kubernetes CLI To Manage Your Clusters In Style!


repo name	derailed/k9s
repo link	https://github.com/derailed/k9s
homepage	https://k9scli.io
language	Go
size (curr.)	26158 kB
stars (curr.)	5468
created	2019-01-25
license	Other

K9s - Kubernetes CLI To Manage Your Clusters In Style!

K9s provides a terminal UI to interact with your Kubernetes clusters. The aim of this project is to make it easier to navigate, observe and manage your applications in the wild. K9s continually watches Kubernetes for changes and offers subsequent commands to interact with your observed resources.

Documentation

Please refer to our K9s documentation site for installation, usage, customization and tips.

Slack Channel

Wanna discuss K9s features with your fellow K9sers or simply show your support for this tool?

Channel: K9ersSlack
Invite: K9slackers Invite

Installation

K9s is available on Linux, macOS and Windows platforms.

Binaries for Linux, Windows and Mac are available as tarballs in the release page.
Via Homebrew or LinuxBrew for macOS and Linux
```
brew install derailed/k9s/k9s
```
Via MacPorts
```
sudo port install k9s
```
On Arch Linux
```
pacman -S k9s
```
Via Scoop for Windows
```
scoop install k9s
```
Building from source K9s was built using go 1.13 or above. In order to build K9 from source you must:
1. Clone the repo
2. Add the following command in your go.mod file
```
replace (
  github.com/derailed/k9s => MY_K9S_CLONED_GIT_REPO
)
```
3. Build and run the executable
```
go run main.go
```

PreFlight Checks

K9s uses 256 colors terminal mode. On `Nix system make sure TERM is set accordingly.
```
export TERM=xterm-256color
```

Screenshots

Pods
Logs
Deployments

Headers description

Pods view

Header	Description
NAME	Pod name
IMAGE	Image used
READY	Is pod ready ?
STATE	Pod state
INIT	Is an init pod ?
RS	Restart count
PROBES(L:R)	Liveness and Readiness probes
CPU	CPU used (millicores)
MEM	Memory used (Mb)
%CPU/R	% ratio of CPU used/requested
%MEM/R	% ratio of MEM used/requested
%CPU/L	% ratio of CPU used/limit
%MEM/L	% ratio of MEM used/limit
PORTS	Ports exposed
AGE	Pod age

Demo Videos/Recordings

The Command Line

# List all available CLI options
k9s help
# To get info about K9s runtime (logs, configs, etc..)
k9s info
# To run K9s in a given namespace
k9s -n mycoolns
# Start K9s in an existing KubeConfig context
k9s --context coolCtx
# Start K9s in readonly mode - with all modification commands disabled
k9s --readonly

Key Bindings

K9s uses aliases to navigate most K8s resources.

Command	Result	Example
`:dp`, `:deploy`	View deployments
`:no`, `:nodes`	View nodes
`:svc`, `:service`	View services
`:`alias`<ENTER>`	View a Kubernetes resource aliases	`:po<ENTER>`
`?`	Show keyboard shortcuts and help
`Ctrl-a`	Show all available resource alias	select+`<ENTER>` to view
`/`filter`ENTER`	Filter out a resource view given a filter	`/bumblebeetuna`
`/`-l label-selector`ENTER`	Filter resource view by labels	`/-l app=fred`
`<Esc>`	Bails out of view/command/filter mode
`d`,`v`, `e`, `l`,…	Key mapping to describe, view, edit, view logs,…	`d` (describes a resource)
`:`ctx`<ENTER>`	To view and switch to another Kubernetes context	`:`+`ctx`+`<ENTER>`
`:`ns`<ENTER>`	To view and switch to another Kubernetes namespace	`:`+`ns`+`<ENTER>`
`:screendump`, `:sd`	To view all saved resources
`Ctrl-d`	To delete a resource (TAB and ENTER to confirm)
`Ctrl-k`	To kill a resource (no confirmation dialog!)
`:q`, `Ctrl-c`	To bail out of K9s

K9s Configuration

K9s keeps its configurations in a .k9s directory in your home directory $HOME/.k9s/config.yml.

NOTE: This is still in flux and will change while in pre-release stage!

# config.yml
k9s:
  # Represents ui poll intervals.
  refreshRate: 2
  # Indicates whether modification commands like delete/kill/edit are disabled. Default is false
  readOnly: false
  # Indicates log view maximum buffer size. Default 1k lines.
  logBufferSize: 200
  # Indicates how many lines of logs to retrieve from the api-server. Default 200 lines.
  logRequestSize: 200
  # Indicates the current kube context. Defaults to current context
  currentContext: minikube
  # Indicates the current kube cluster. Defaults to current context cluster
  currentCluster: minikube
  # Persists per cluster preferences for favorite namespaces and view.
  clusters:
    cooln:
      namespace:
        active: coolio
        favorites:
        - cassandra
        - default
      view:
        active: po
    minikube:
      namespace:
        active: all
        favorites:
        - all
        - kube-system
        - default
      view:
        active: dp

Command Aliases

In K9s, you can define your very own command aliases (shortnames) to access your resources. In your $HOME/.k9s define a file called alias.yml. A K9s alias defines pairs of alias:gvr. A gvr (Group/Version/Resource) represents a fully qualified Kubernetes resource identifier. Here is an example of an alias file:

# $HOME/.k9s/alias.yml
alias:
  pp: v1/pods
  crb: rbac.authorization.k8s.io/v1/clusterrolebindings

Using this alias file, you can now type pp/crb to list pods or clusterrolebindings respectively.

HotKey Support

Entering the command mode and typing a resource name or alias, could be cumbersome for navigating thru often used resources. We’re introducing hotkeys that allows a user to define their own hotkeys to activate their favorite resource views. In order to enable hotkeys please follow these steps:

Create a file named $HOME/.k9s/hotkey.yml

Add the following to your hotkey.yml. You can use resource name/short name to specify a command ie same as typing it while in command mode.

# $HOME/.k9s/hotkey.yml
hotKey:
  # Hitting Shift-0 navigates to your pod view
  shift-0:
    shortCut:    Shift-0
    description: Viewing pods
    command:     pods
  # Hitting Shift-1 navigates to your deployments
  shift-1:
    shortCut:    Shift-1
    description: View deployments
    command:     dp
  # Hitting Shift-2 navigates to your xray deployments
  shift-2:
    shortCut:    Shift-2
    description: Xray Deployments
    command:     xray deploy

Not feeling so hot? Your custom hotkeys will be listed in the help view ?. Also your hotkey file will be automatically reloaded so you can readily use your hotkeys as you define them.

You can choose any keyboard shotcuts that make sense to you, provided they are not part of the standard K9s shortcuts list.

NOTE: This feature/configuration might change in future releases!

Plugins

K9s allows you to extend your command line and tooling by defining your very own cluster commands via plugins. K9s looks at $HOME/.k9s/plugin.yml to locate all available plugins. A plugin is defined as follows:

# $HOME/.k9s/plugin.yml
plugin:
  # Defines a plugin to provide a `Ctrl-l` shortcut to tail the logs while in pod view.
  fred:
    shortCut: Ctrl-L
    description: Pod logs
    scopes:
    - po
    command: kubectl
    background: false
    args:
    - logs
    - -f
    - $NAME
    - -n
    - $NAMESPACE
    - --context
    - $CONTEXT

This defines a plugin for viewing logs on a selected pod using Ctrl-l mnemonic while in the pods view.

Shortcut: the key a user must enter to activate the plugin.
Command: the shell commands the plugin runs upon activation.
Scopes: select the resources that can access the plugin command. Defines a collection of resource names/shortnames for which the plugin shortcut will be made available to the user. You can specify all to make a plugin available in all views.
Background: boolean to indicate whether to run the command in the background or not.
Description: a short description of the command that will be shown in the ui next to the action mnemonic.
Args: a collection of arguments for the given command.

K9s does provide additional environment variables for you to further customize your plugins. Currently, the available environment variables are as follows:

$NAMESPACE – the selected resource namespace
$NAME – the selected resource name
$CONTAINER – the current container if applicable
$FILTER – the current filter if any
$KUBECONFIG – the KubeConfig location.
$CLUSTER the active cluster name
$CONTEXT the active context name
$USER the active user
$GROUPS the active groups
$COL-<RESOURCE_COLUMN_NAME> use a given column name for a viewed resource. Must be prefixed by COL-!

NOTE: This is an experimental feature! Options and layout may change in future K9s releases as this feature solidifies.

Benchmark Your Applications

K9s integrates Hey from the brilliant and super talented Jaana Dogan. Hey is a CLI tool to benchmark HTTP endpoints similar to AB bench. This preliminary feature currently supports benchmarking port-forwards and services (Read the paint on this is way fresh!).

To setup a port-forward, you will need to navigate to the PodView, select a pod and a container that exposes a given port. Using SHIFT-F a dialog comes up to allow you to specify a local port to forward. Once acknowledged, you can navigate to the PortForward view (alias pf) listing out your active port-forwards. Selecting a port-forward and using CTRL-B will run a benchmark on that HTTP endpoint. To view the results of your benchmark runs, go to the Benchmarks view (alias be). You should now be able to select a benchmark and view the run stats details by pressing <ENTER>. NOTE: Port-forwards only last for the duration of the K9s session and will be terminated upon exit.

Initially, the benchmarks will run with the following defaults:

Concurrency Level: 1
Number of Requests: 200
HTTP Verb: GET
Path: /

The PortForward view is backed by a new K9s config file namely: $HOME/.k9s/bench-mycluster.yml. Each cluster you connect to will have its own bench config file. Changes to this file should automatically update the PortForward view to indicate how you want to run your benchmarks.

Here is a sample benchmarks.yml configuration. Please keep in mind this file will likely change in subsequent releases!

# This file resides in $HOME/.k9s/bench-mycluster.yml
benchmarks:
  # Indicates the default concurrency and number of requests setting if a container or service rule does not match.
  defaults:
    # One concurrent connection
    concurrency: 1
    # Number of requests that will be sent to an endpoint
    requests: 500
  containers:
    # Containers section allows you to configure your http container's endpoints and benchmarking settings.
    # NOTE: the container ID syntax uses namespace/pod-name:container-name
    default/nginx:nginx:
      # Benchmark a container named nginx using POST HTTP verb using http://localhost:port/bozo URL and headers.
      concurrency: 1
      requests: 10000
      http:
        path: /bozo
        method: POST
        body:
          {"fred":"blee"}
        header:
          Accept:
            - text/html
          Content-Type:
            - application/json
  services:
    # Similary you can Benchmark an HTTP service exposed either via nodeport, loadbalancer types.
    # Service ID is ns/svc-name
    default/nginx:
      # Set the concurrency level
      concurrency: 5
      # Number of requests to be sent
      requests: 500
      http:
        method: GET
        # This setting will depend on whether service is nodeport or loadbalancer. Nodeport may require vendor port tuneling setting.
        # Set this to a node if nodeport or LB if applicable. IP or dns name.
        host: A.B.C.D
        path: /bumblebeetuna
      auth:
        user: jean-baptiste-emmanuel
        password: Zorg!

K9s RBAC FU

On RBAC enabled clusters, you would need to give your users/groups capabilities so that they can use K9s to explore their Kubernetes cluster. K9s needs minimally read privileges at both the cluster and namespace level to display resources and metrics.

These rules below are just suggestions. You will need to customize them based on your environment policies. If you need to edit/delete resources extra Fu will be necessary.

NOTE! Cluster/Namespace access may change in the future as K9s evolves. NOTE! We expect K9s to keep running even in atrophied clusters/namespaces. Please file issues if this is not the case!

Cluster RBAC scope

---
# K9s Reader ClusterRole
kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: k9s
rules:
  # Grants RO access to cluster resources node and namespace
  - apiGroups: [""]
    resources: ["nodes", "namespaces"]
    verbs: ["get", "list", "watch"]
  # Grants RO access to RBAC resources
  - apiGroups: ["rbac.authorization.k8s.io"]
    resources: ["clusterroles", "roles", "clusterrolebindings", "rolebindings"]
    verbs: ["get", "list", "watch"]
  # Grants RO access to CRD resources
  - apiGroups: ["apiextensions.k8s.io"]
    resources: ["customresourcedefinitions"]
    verbs: ["get", "list", "watch"]
  # Grants RO access to metric server (if present)
  - apiGroups: ["metrics.k8s.io"]
    resources: ["nodes", "pods"]
    verbs: ["get", "list", "watch"]

---
# Sample K9s user ClusterRoleBinding
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: k9s
subjects:
  - kind: User
    name: fernand
    apiGroup: rbac.authorization.k8s.io
roleRef:
  kind: ClusterRole
  name: k9s
  apiGroup: rbac.authorization.k8s.io

Namespace RBAC scope

If your users are constrained to certain namespaces, K9s will need to following role to enable read access to namespaced resources.

---
# K9s Reader Role (default namespace)
kind: Role
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: k9s
  namespace: default
rules:
  # Grants RO access to most namespaced resources
  - apiGroups: ["", "apps", "autoscaling", "batch", "extensions"]
    resources: ["*"]
    verbs: ["get", "list", "watch"]
  # Grants RO access to metric server
  - apiGroups: ["metrics.k8s.io"]
    resources: ["pods", "nodes"]
    verbs:
      - get
      - list
      - watch

---
# Sample K9s user RoleBinding
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
  name: k9s
  namespace: default
subjects:
  - kind: User
    name: fernand
    apiGroup: rbac.authorization.k8s.io
roleRef:
  kind: Role
  name: k9s
  apiGroup: rbac.authorization.k8s.io

Skins

Example: Dracula Skin ;)

You can style K9s based on your own sense of look and style. Skins are YAML files, that enable a user to change the K9s presentation layer. K9s skins are loaded from $HOME/.k9s/skin.yml. If a skin file is detected then the skin would be loaded if not the current stock skin remains in effect.

You can also change K9s skins based on the cluster you are connecting too. In this case, you can specify the skin file name as $HOME/.k9s/mycluster_skin.yml Below is a sample skin file, more skins are available in the skins directory in this repo, just simply copy any of these in your user’s home dir as skin.yml.

Colors can be defined by name or uing an hex representation. Of recent, we’ve added a color named default to indicate a transparent background color to preserve your terminal background color settings if so desired.

NOTE: This is very much an experimental feature at this time, more will be added/modified if this feature has legs so thread accordingly!

# Skin InTheNavy...
k9s:
  # General K9s styles
  body:
    fgColor: dodgerblue
    bgColor: '#ffffff'
    logoColor: '#0000ff'
  # ClusterInfoView styles.
  info:
    fgColor: lightskyblue
    sectionColor: steelblue
  frame:
    # Borders styles.
    border:
      fgColor: dodgerblue
      focusColor: aliceblue
    # MenuView attributes and styles.
    menu:
      fgColor: darkblue
      keyColor: cornflowerblue
      # Used for favorite namespaces
      numKeyColor: cadetblue
    # CrumbView attributes for history navigation.
    crumbs:
      fgColor: white
      bgColor: steelblue
      activeColor: skyblue
    # Resource status and update styles
    status:
      newColor: '#00ff00'
      modifyColor: powderblue
      addColor: lightskyblue
      errorColor: indianred
      highlightcolor: royalblue
      killColor: slategray
      completedColor: gray
    # Border title styles.
    title:
      fgColor: aqua
      bgColor: white
      highlightColor: skyblue
      counterColor: slateblue
      filterColor: slategray
  views:
    # TableView attributes.
    table:
      fgColor: blue
      bgColor: darkblue
      cursorColor: aqua
      # Header row styles.
      header:
        fgColor: white
        bgColor: darkblue
        sorterColor: orange
    # YAML info styles.
    yaml:
      keyColor: steelblue
      colonColor: blue
      valueColor: royalblue
    # Logs styles.
    logs:
      fgColor: white
      bgColor: black

Here is a list of all available color names.

Color Names
black	maroon	green	olive	navy
purple	teal	silver	gray	red
lime	yellow	blue	fuchsia	aqua
white	aliceblue	antiquewhite	aquamarine	azure
beige	bisque	blanchedalmond	blueviolet	brown
burlywood	cadetblue	chartreuse	chocolate	coral
cornflowerblue	cornsilk	crimson	darkblue	darkcyan
darkgoldenrod	darkgray	darkgreen	darkkhaki	darkmagenta
darkolivegreen	darkorange	darkorchid	darkred	darksalmon
darkseagreen	darkslateblue	darkslategray	darkturquoise	darkviolet
deeppink	deepskyblue	dimgray	dodgerblue	firebrick
floralwhite	forestgreen	gainsboro	ghostwhite	gold
goldenrod	greenyellow	honeydew	hotpink	indianred
indigo	ivory	khaki	lavender	lavenderblush
lawngreen	lemonchiffon	lightblue	lightcoral	lightcyan
lightgoldenrodyellow	lightgray	lightgreen	lightpink	lightsalmon
lightseagreen	lightskyblue	lightslategray	lightsteelblue	lightyellow
limegreen	linen	mediumaquamarine	mediumblue	mediumorchid
mediumpurple	mediumseagreen	mediumslateblue	mediumspringgreen	mediumturquoise
mediumvioletred	midnightblue	mintcream	mistyrose	moccasin
navajowhite	oldlace	olivedrab	orange	orangered
orchid	palegoldenrod	palegreen	paleturquoise	palevioletred
papayawhip	peachpuff	peru	pink	plum
powderblue	rebeccapurple	rosybrown	royalblue	saddlebrown
salmon	sandybrown	seagreen	seashell	sienna
skyblue	slateblue	slategray	snow	springgreen
steelblue	tan	thistle	tomato	turquoise
violet	wheat	whitesmoke	yellowgreen	grey
dimgrey	darkgrey	darkslategrey	lightgrey	lightslategrey
slategrey

Known Issues

This is still work in progress! If something is broken or there’s a feature that you want, please open a PR or file a ticket.

K9s will most likely blow up if…

You’re running older versions of Kubernetes. K9s works best on Kubernetes latest.
You don’t have enough RBAC fu to manage your cluster.

ATTA Girls/Boys!

K9s sits on top of many open source projects and libraries. Our sincere appreciations to all the OSS contributors that work nights and weekends to make this project a reality!

Meet The Core Team!

Fernand Galiana
- fernand@imhotep.io
- @kitesurfer We always enjoy hearing from folks who benefit from our work.