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kube-capacity

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This is a simple CLI that provides an overview of the resource requests, limits, and utilization in a Kubernetes cluster. It attempts to combine the best parts of the output from kubectl top and kubectl describe into an easy to use CLI focused on cluster resources.

Installation

Go binaries are automatically built with each release by GoReleaser. These can be accessed on the GitHub releases page for this project.

Homebrew

This project can be installed with Homebrew:

brew tap robscott/tap
brew install robscott/tap/kube-capacity

Krew

This project can be installed with Krew:

kubectl krew install resource-capacity

Usage

By default, kube-capacity will output a list of nodes with the total CPU and Memory resource requests and limits for all the pods running on them. For clusters with more than one node, the first line will also include cluster wide totals. That output will look something like this:

kube-capacity

NODE              CPU REQUESTS    CPU LIMITS    MEMORY REQUESTS    MEMORY LIMITS
*                 560m (28%)      130m (7%)     572Mi (9%)         770Mi (13%)
example-node-1    220m (22%)      10m (1%)      192Mi (6%)         360Mi (12%)
example-node-2    340m (34%)      120m (12%)    380Mi (13%)        410Mi (14%)

Including Pods

For more detailed output, kube-capacity can include pods in the output. When -p or --pods are passed to kube-capacity, it will include pod specific output that looks like this:

kube-capacity --pods

NODE              NAMESPACE     POD                   CPU REQUESTS    CPU LIMITS    MEMORY REQUESTS    MEMORY LIMITS
*                 *             *                     560m (28%)      780m (38%)    572Mi (9%)         770Mi (13%)

example-node-1    *             *                     220m (22%)      320m (32%)    192Mi (6%)         360Mi (12%)
example-node-1    kube-system   metrics-server-lwc6z  100m (10%)      200m (20%)    100Mi (3%)         200Mi (7%)
example-node-1    kube-system   coredns-7b5bcb98f8    120m (12%)      120m (12%)    92Mi (3%)          160Mi (5%)

example-node-2    *             *                     340m (34%)      460m (46%)    380Mi (13%)        410Mi (14%)
example-node-2    kube-system   kube-proxy-3ki7       200m (20%)      280m (28%)    210Mi (7%)         210Mi (7%)
example-node-2    tiller        tiller-deploy         140m (14%)      180m (18%)    170Mi (5%)         200Mi (7%)

Including Utilization

To help understand how resource utilization compares to configured requests and limits, kube-capacity can include utilization metrics in the output. It's important to note that this output relies on metrics-server functioning correctly in your cluster. When -u or --util are passed to kube-capacity, it will include resource utilization information that looks like this:

kube-capacity --util

NODE              CPU REQUESTS    CPU LIMITS    CPU UTIL    MEMORY REQUESTS    MEMORY LIMITS   MEMORY UTIL
*                 560m (28%)      130m (7%)     40m (2%)    572Mi (9%)         770Mi (13%)     470Mi (8%)
example-node-1    220m (22%)      10m (1%)      10m (1%)    192Mi (6%)         360Mi (12%)     210Mi (7%)
example-node-2    340m (34%)      120m (12%)    30m (3%)    380Mi (13%)        410Mi (14%)     260Mi (9%)

Displaying Available Resources

To more clearly see the total available resources on the node it is possible to pass the --available option to kube-capacity, which will give output in the following format

kube-capacity --available

NODE              CPU REQUESTS    CPU LIMITS    MEMORY REQUESTS    MEMORY LIMITS
*                 560/2000m       130/2000m     572/5923Mi         770/5923Mi 
example-node-1    220/1000m       10/1000m      192/3200Mi         360/3200Mi 
example-node-2    340/1000m       120/1000m     380/2923Mi         410/2923Mi

Including Pods and Utilization

For more detailed output, kube-capacity can include both pods and resource utilization in the output. When --util and --pods are passed to kube-capacity, it will result in a wide output that looks like this:

kube-capacity --pods --util

NODE              NAMESPACE     POD                   CPU REQUESTS    CPU LIMITS   CPU UTIL     MEMORY REQUESTS    MEMORY LIMITS   MEMORY UTIL
*                 *             *                     560m (28%)      780m (38%)   340m (17%)   572Mi (9%)         770Mi (13%)     470Mi (8%)

example-node-1    *             *                     220m (22%)      320m (32%)   160m (16%)   192Mi (6%)         360Mi (12%)     210Mi (7%)
example-node-1    kube-system   metrics-server-lwc6z  100m (10%)      200m (20%)   70m (7%)     100Mi (3%)         200Mi (7%)      120Mi (4%)
example-node-1    kube-system   coredns-7b5bcb98f8    120m (12%)      120m (12%)   90m (9%)     92Mi (3%)          160Mi (5%)      90Mi (3%)

example-node-2    *             *                     340m (34%)      460m (46%)   180m (18%)   380Mi (13%)        410Mi (14%)     260Mi (9%)
example-node-2    kube-system   kube-proxy-3ki7       200m (20%)      280m (28%)   110m (11%)   210Mi (7%)         210Mi (7%)      120Mi (4%)
example-node-2    tiller        tiller-deploy         140m (14%)      180m (18%)   70m (7%)     170Mi (6%)         200Mi (7%)      140Mi (5%)

It's worth noting that utilization numbers from pods will likely not add up to the total node utilization numbers. Unlike request and limit numbers where node and cluster level numbers represent a sum of pod values, node metrics come directly from metrics-server and will likely include other forms of resource utilization.

Sorting

To highlight the nodes, pods, and containers with the highest metrics, you can sort by a variety of columns:

kube-capacity --util --sort cpu.util

NODE              CPU REQUESTS    CPU LIMITS    CPU UTIL    MEMORY REQUESTS    MEMORY LIMITS   MEMORY UTIL
*                 560m (28%)      130m (7%)     40m (2%)    572Mi (9%)         770Mi (13%)     470Mi (8%)
example-node-2    340m (34%)      120m (12%)    30m (3%)    380Mi (13%)        410Mi (14%)     260Mi (9%)
example-node-1    220m (22%)      10m (1%)      10m (1%)    192Mi (6%)         360Mi (12%)     210Mi (7%)

Filtering By Labels

For more advanced usage, kube-capacity also supports filtering by pod, namespace, and/or node labels. The following examples show how to use these filters:

kube-capacity --pod-labels app=nginx
kube-capacity --namespace default
kube-capacity --namespace-labels team=api
kube-capacity --node-labels kubernetes.io/role=node

JSON and YAML Output

By default, kube-capacity will provide output in a table format. To view this data in JSON or YAML format, the output flag can be used. Here are some sample commands:

kube-capacity --pods --output json
kube-capacity --pods --containers --util --output yaml

Flags Supported

  -c, --containers                includes containers in output
      --context string            context to use for Kubernetes config
  -h, --help                      help for kube-capacity
  -n, --namespace string          only include pods from this namespace
      --namespace-labels string   labels to filter namespaces with
      --node-labels string        labels to filter nodes with
  -o, --output string             output format for information
                                    (supports: [table json yaml])
                                    (default "table")
  -a, --available                 includes quantity available instead of percentage used
  -l, --pod-labels string         labels to filter pods with
  -p, --pods                      includes pods in output
      --sort string               attribute to sort results be (supports:
                                    [cpu.util cpu.request cpu.limit mem.util mem.request mem.limit name])
                                    (default "name")
  -u, --util                      includes resource utilization in output

Prerequisites

Any commands requesting cluster utilization are dependent on metrics-server running on your cluster. If it's not already installed, you can install it with the official helm chart.

Similar Projects

There are already some great projects out there that have similar goals.

  • kube-resource-report: generates HTML/CSS report for resource requests and limits across multiple clusters.
  • kubetop: a CLI similar to top for Kubernetes, focused on resource utilization (not requests and limits).

Contributors

Although this project was originally developed by robscott, there have been some great contributions from others:

License

Apache License 2.0

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A simple CLI that provides an overview of the resource requests, limits, and utilization in a Kubernetes cluster

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