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https://github.com/stackrox/kube-linter

KubeLinter is a static analysis tool that checks Kubernetes YAML files and Helm charts to ensure the applications represented in them adhere to best practices.
https://github.com/stackrox/kube-linter

hactoberfest helm-charts kubernetes static-analysis yaml-files

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KubeLinter is a static analysis tool that checks Kubernetes YAML files and Helm charts to ensure the applications represented in them adhere to best practices.

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README 

        


Static analysis for Kubernetes



[![Go Report Card](https://goreportcard.com/badge/github.com/stackrox/kube-linter)](https://goreportcard.com/report/github.com/stackrox/kube-linter)



# What is KubeLinter?



KubeLinter analyzes Kubernetes YAML files and Helm charts, and checks them against a variety of best practices, with a focus on production readiness and security.



KubeLinter runs sensible default checks, designed to give you useful information about your Kubernetes YAML files and Helm charts. This is to help teams check early and often for security misconfigurations and DevOps best practices. Some common examples of these include running containers as a non-root user, enforcing least privilege, and storing sensitive information only in secrets.



KubeLinter is configurable, so you can enable and disable checks, as well as create your own custom checks, depending on the policies you want to follow within your organization.



When a lint check fails, KubeLinter reports recommendations for how to resolve any potential issues and returns a non-zero exit code.



## Documentation

Visit https://docs.kubelinter.io for detailed documentation on installing, using and configuring KubeLinter.



## Installing KubeLinter



Kube-linter binaries could be found here: https://github.com/stackrox/kube-linter/releases/latest



### Using Go



To install using [Go](https://golang.org/), run the following command:



```bash

go install golang.stackrox.io/kube-linter/cmd/kube-linter@latest

```

Otherwise, download the latest binary from [Releases](https://github.com/stackrox/kube-linter/releases) and add it to your

PATH.



### Using Homebrew for macOS or LinuxBrew for Linux



To install using Homebrew or LinuxBrew, run the following command:



```bash

brew install kube-linter

```



### Using nix-shell



```

nix-shell -p kube-linter

```



### Using docker



```

docker pull stackrox/kube-linter:latest

```



## Development



### Prerequisites

- Make sure that you have [installed Go](https://golang.org/doc/install) prior to building from source.



### Building KubeLinter



Installing KubeLinter from source is as simple as following these steps:



1. First, clone the KubeLinter repository.



   ```bash

   git clone [email protected]:stackrox/kube-linter.git

   ```



1. Then, compile the source code. This will create the kube-linter binary files for each platform and places them in the `.gobin` folder.



   ```bash

   make build

   ```



1. Finally, you are ready to start using KubeLinter. Verify your version to ensure you've successfully installed KubeLinter.



   ```bash

   .gobin/kube-linter version

   ```



### Testing KubeLinter

There are several layers of testing. Each layer is expected to pass.



1. `go` unit tests:



   ```bash

   make test

   ```



2. end-to-end integration tests:



   ```bash

   make e2e-test

   ```



3. and finally, end-to-end integration tests using `bats-core`:



   ```bash

   make e2e-bats

   ```



## Verifying KubeLinter images



KubeLinter images are signed by [cosign](https://github.com/sigstore/cosign).

We recommend verifying the image before using it.



Once you've installed cosign, you can use the [KubeLinter public key](kubelinter-cosign.pub) to verify the KubeLinter image with:



```shell

cat kubelinter-cosign.pub

-----BEGIN PUBLIC KEY-----

MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEl0HCkCRzYv0qH5QiazoXeXe2qwFX

DmAszeH26g1s3OSsG/focPWkN88wEKQ5eiE95v+Z2snUQPl/mjPdvqpyjA==

-----END PUBLIC KEY-----



cosign verify --key kubelinter-cosign $IMAGE_NAME

```



KubeLinter also provides [cosign keyless signatures](https://github.com/sigstore/cosign/blob/623d50f9b77ee85886a166daac648455e65003ec/KEYLESS.md).



You can verify the KubeLinter image with:

```shell

# NOTE: Keyless signatures are NOT PRODUCTION ready.



COSIGN_EXPERIMENTAL=1 cosign verify $IMAGE_NAME

```



## Using KubeLinter



### Local YAML Linting



Running KubeLinter to Lint your YAML files only requires two steps in its most basic form.



1. Locate the YAML file you'd like to test for security and production readiness best practices:

1. Run the following command:



   ```bash

   kube-linter lint /path/to/your/yaml.yaml

   ```



### Example



Consider the following sample pod specification file `pod.yaml`. This file has two production readiness issues and one security issue:



**Security Issue:**

1. The container in this pod is not running as a read only file system, which could allow it to write to the root filesystem.



**Production readiness:**

1. The container's memory limits are not set, which could allow it to consume excessive memory



   ```yaml

   apiVersion: v1

   kind: Pod

   metadata:

     name: security-context-demo

   spec:

     securityContext:

       runAsUser: 1000

       runAsGroup: 3000

       fsGroup: 2000

     volumes:

     - name: sec-ctx-vol

       emptyDir: {}

     containers:

     - name: sec-ctx-demo

       image: busybox

       resources:

         requests:

           memory: "64Mi"

           cpu: "250m"

       command: [ "sh", "-c", "sleep 1h" ]

       volumeMounts:

       - name: sec-ctx-vol

         mountPath: /data/demo

       securityContext:

         allowPrivilegeEscalation: false

   ```



1. Copy the YAML above to pod.yaml and lint this file by running the following command:



   ```bash

   kube-linter lint pod.yaml

   ```

1. KubeLinter runs its default checks and reports recommendations. Below is the output from our previous command.



   ```

   pod.yaml: (object: /security-context-demo /v1, Kind=Pod) The container "sec-ctx-demo" is using an invalid container image, "busybox". Please use images that are not blocked by the `BlockList` criteria : [".*:(latest)$" "^[^:]*$" "(.*/[^:]+)$"] (check: latest-tag, remediation: Use a container image with a specific tag other than latest.)



   pod.yaml: (object: /security-context-demo /v1, Kind=Pod) container "sec-ctx-demo" does not have a read-only root file system (check: no-read-only-root-fs, remediation: Set readOnlyRootFilesystem to true in the container securityContext.)



   pod.yaml: (object: /security-context-demo /v1, Kind=Pod) container "sec-ctx-demo" has memory limit 0 (check: unset-memory-requirements, remediation: Set memory limits for your container based on its requirements. Refer to https://kubernetes.io/docs/concepts/configuration/manage-resources-containers/#requests-and-limits for details.)



   Error: found 3 lint errors

   ```

To learn more about using and configuring KubeLinter, visit the [documentation](./docs) page.



## Mentions/Tutorials



The following are tutorials on KubeLinter written by users. If you have one that you would like to add to this list, please send a PR!



* [Ensuring YAML best practices using KubeLinter](https://www.civo.com/learn/yaml-best-practices-using-kubelinter) at civo.com by Saiyam Pathak.

* [Analyze Kubernetes files for errors with KubeLinter](https://opensource.com/article/21/1/kubelinter) at opensource.com by Jessica Cherry.

* [How to add a new check in KubeLinter?](https://www.psaggu.com/upstream-contribution/2021/08/17/notes.html) by Priyanka Saggu.

* [Extending kube-linter To Build A Custom Template](https://github.com/garethahealy/kubelinter-extending-blog) by [Gareth Healy](https://github.com/garethahealy).



## Community



If you would like to engage with the KubeLinter community, including maintainers and other users, you can join the Slack workspace [here](https://join.slack.com/t/kube-linter/shared_invite/zt-kla9qvyo-Tk~wynTSbr9EE3AjHcv4BQ).



To contribute, check out our [contributing guide](./CONTRIBUTING.md).



As a reminder, all participation in the KubeLinter community is governed by our [code of conduct](./CODE_OF_CONDUCT.md).



## WARNING: Alpha release



KubeLinter is at an early stage of development. There may be breaking changes in

the future to the command usage, flags, and configuration file formats. However,

we encourage you to use KubeLinter to test your environment YAML files, see what

breaks, and [contribute](./CONTRIBUTING.md).



## LICENSE



KubeLinter is licensed under the [Apache License 2.0](./LICENSE).



## StackRox



KubeLinter is made with ❤️ by [StackRox](https://stackrox.com/).



If you're interested in KubeLinter, or in any of the other cool things we do, please know that we're hiring!

Check out our [open positions](https://www.stackrox.com/job-board/). We'd love to hear from you!