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https://github.com/blendle/kubecrt

Convert Helm charts to Kubernetes resources.
https://github.com/blendle/kubecrt

helm-charts helm-plugins kubernetes

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Convert Helm charts to Kubernetes resources.

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# kubecrt



Convert Helm charts to Kubernetes resources.



## Description



kubecrt allows you to define your application's Kubernetes infrastructure based

on a single configuration file.



The configuration file contains your application name, and namespace (both can

also be set using CLI arguments), and you provide a list of charts that you want

to install, optionally providing override values for those charts.



When running `kubecrt`, you provide it your project's configuration file, and in

turn, it returns you the parsed Kubernetes resource files generated by the

charts.



This allows you to use Helm Charts without actually using Helm, and instead

using regular `kubectl` to deploy and manage your resources.



The configuration file you feed into kubecrt will be processed using the epp

templating tool, allowing you to inject variables at runtime, based on your own

conditional logic (production vs staging, etc...).



## Installation



```

brew tap blendle/blendle

brew install kubecrt

```



## Usage



See `kubecrt --help`



```

kubecrt - convert Helm charts to Kubernetes resources



Given a charts.yml file, compile all the charts with

the provided template variables and return the

resulting Kubernetes resource files to STDOUT, or

write them to a provided file.



Doing this, you can use Kubernetes charts, without

having to use Helm locally, or Tiller on the server.



Usage:

  kubecrt [options] CHARTS_CONFIG

  kubecrt -h | --help

  kubecrt --version

  kubecrt --example-config



Where CHARTS_CONFIG is the location of the YAML file

containing the Kubernetes Charts configuration.



Arguments:

  CHARTS_CONFIG                    Charts configuration file



Options:

  -h, --help                       Show this screen

  --version                        Show version

  -n NS, --namespace=NS            Set the .Release.Namespace chart variable,

                                   used by charts during compilation

  -a NAME, --name=NAME             Set the .Release.Name chart variable, used by

                                   charts during compilation

  -o PATH, --output=PATH           Write output to a file, instead of STDOUT

  -r NAME=URL, --repo=NAME=URL,... List of NAME=URL pairs of repositories to add

                                   to the index before compiling charts config

  -p DIR, --partials-dir=DIR       Path from which to load partial templates

                                   [default: config/deploy/partials]

  -j, --json                       Print resources formatted as JSON instead of

                                   YAML. Each resource is printed on a single

                                   line.

  --example-config                 Print an example charts.yaml, including

                                   extended documentation on the tunables

```



## Charts Configuration File



See `kubecrt --example-config`



```yaml

# apiVersion defines the version of the charts.yaml structure. Currently,

# only "v1" is supported.

apiVersion: v1



# name is the .Release.Name template value that charts can use in their

# templates, which can be overridden by the "--name" CLI flag. If omitted,

# "--name" is required.

name: my-bundled-apps



# namespace is the .Release.Namespace template value that charts can use in

# their templates. Note that since kubecrt does not communicate with

# Kubernetes in any way, it is up to you to also use this namespace when

# doing kubectl apply [...]. Can be overridden using "--namespace".  If omitted,

# "--namespace" is required.

namespace: apps



# charts is an array of charts you want to compile into Kubernetes resource

# files.

#

# A single chart might be used to deploy something simple, like a memcached pod,

# or something complex, like a full web app stack with HTTP servers, databases,

# caches, and so on.

charts:



# A Chart can either be in the format REPO/NAME, or a PATH to a local chart.

#

# If using REPO/NAME, kubecrt knows by-default where to locate the "stable"

# repository, all other repositories require the "repo" configuration (see

# below).

- stable/factorio:

    # values is a map of key/value pairs used when compiling the chart. This

    # uses the same format as in regular chart "values.yaml" files.

    #

    # see: https://git.io/v9Tyr

    values:

      resources:

        requests:

          memory: 1024Mi

          cpu: 750m

      factorioServer:

        # charts.yaml supports the same templating as chart templates do,

        # using the "sprig" library.

        #

        # see: https://masterminds.github.io/sprig/

        name: >

          {{ env "MY_SERVER_NAME" | default "hello world!" }}



- stable/minecraft:

    # version is a semantic version constraint.

    #

    # see: https://github.com/Masterminds/semver#basic-comparisons

    version: ~> 0.1.0

    values:

      minecraftServer:

        difficulty: hard



- opsgoodness/prometheus-operator:

    # repo is the location of a repositry, if other than "stable". This is

    # the URL you would normally add using "helm repo add NAME URL".

    repo: http://charts.opsgoodness.com

    values:

      sendAnalytics: false



# For the above charts, see here for the default configurations:

#

#   * stable/factorio: https://git.io/v9Tyr

#   * stable/minecraft: https://git.io/v9Tya

#   * opsgoodness/prometheus-operator: https://git.io/v9SAY

```



## Partial Templates



You can optionally split your `charts.yml` file into multiple chunks, by using

_partial templates_. This works almost the same way as Helm's support for these

in charts. See the [Helm documentation][docs] for more details.



To use these partials, you have to set the `--partials-dir` flag when calling

`kubecrt`, pass it the path to your partials directory, and then use those

partials in your `charts.yml`.



Example:



**charts.yml**:



```yaml

apiVersion: v1

name: my-bundled-apps

namespace: apps

charts:

- stable/factorio:

    values:

      resources:

{{ include "factorio/resources" . | indent 8 }}

```



**partials/factorio/resources.yml**



```yaml

{{- define "factorio/resources" -}}

requests:

  memory: 1024Mi

  cpu: 750m

{{- end -}}

```



You can then run this as follows:



```

kubecrt --partials-dir ./partials charts.yml

```



And the result is a fully-parsed charts printed to stdout.



Some notes:



* you can use subfolders to organise your partials

* each named `define` has to be uniquely named, or risk being overwritten

* you can define multiple `define` blocks in a single file

* the files don't need to be yaml files, you can use any content you need



[docs]: https://github.com/kubernetes/helm/blob/master/docs/chart_template_guide/named_templates.md



## Releasing new version



```

make (major|minor|patch)

git push --tags

make dist

open _dist/

```



Next, go to the [GitHub releases](https://github.com/blendle/kubecrt/releases)

page, and edit the tag you just push:



* Release title: vx.x.x

* Describe this release: short description of important changes

* Attach binaries: drop the files created in `_dist` here



Click "Update release".



Don't forget to update the Homebrew formula, located at

[blendle/homebrew-blendle][tap].



[tap]: https://github.com/blendle/homebrew-blendle