Helm Plugin for Gradle

This is a simple plugin for interacting with Helm in gradle builds.

Why?

This plugin is different from the alternatives listed at the bottom.

• Focus on a single thing and do it good: build charts.
• Thus only limited support for uploads/publishing. Although chartmuseum and artifactory should work, I recommend to use different ways of helm chart publishing as there's no official spec on how to do it (Helm 3 has experimental support for publishing to OCI registries). For example use the artifactory gradle plugin if you're using artifactory.
• the only plugin which has a real notion of chart tests including some simple types of assertions and a junit compatible XML report.

What?

• zero config because of sane defaults
• ready for CI/CD, no dependencies to build environment (downloads appropriate Helm version automatically)
• provides task types:
  • HelmInitTask: client only helm init, usually done only once, skipped for v3+
  • HelmBuildTask: render the expansions, build deps and package the chart
  • HelmTestTask: test the packaged chart
    • executes helm lint with default values
    • for each test:
      • executes helm lint for test values
      • executes helm template for test values
      • runs any given assertions against rendered output
    • stores test XML report into .${buildDir}/helm/test/helm-junit-report.xml
  • HelmDeployTask: uploads the packaged chart
• preconfigures all tasks according to DSL (see below)

Tested with Gradle 6

Changelog

See releases.

Usage

Activate

plugins {
    id 'com.kiwigrid.helm' version '1.5.1'
}

Configure

// everything is optional
helm {
    version '3.0.0' // defaults to 2.17.0
    architecture 'amd64' // auto-detected if not given
    operatingSystem 'linux' // auto-detected if not given
    helmDownloadUrl 'https://example.com/helm.tar.gz' // defaults to 'https://get.helm.sh/helm-v${version}-${operatingSystem}-${architecture}.tar.gz'

    // will be added via: helm repo add <name> <url>, non-existent will be removed (but 'local' and 'stable')
    repositories {
        myHelmRepoName {
            url "https://example.com"
            user "happy-dev" // username used for basic auth (supported since helm v2.9.0-rc3)
            password "1234" // password used for basic auth (supported since helm v2.9.0-rc3)
            deployVia 'PUT' to 'https://example.de/' // also supports 'POST', filename will be appended if url ends with '/' and method is 'PUT'
			// shortcut if url is the same:
			// deployVia 'PUT' toFetchUrl()
        }
    }

    // expansions are replaced in the chart files if found in the form ${path.to.value}
    expansions = [
            helm: [
                    chartName:'my-chart',
                    chartVersion: project.version
            ],
            anotherParam: project.version,
            path: [
                    to: [
                            value: 'foobar'
                    ]
            ]
    ]

    // this will upload the chart to the respective repo using the appropriate deploy spec
    deployTo repositories.myHelmRepoName
}

helmChartBuild() {
    // source folder for the charts manifest files. just an example here, provide your own as needed
    // defaults to file('/src/main/helm')
    source = file(project.projectDir.getAbsolutePath() + '/helm') 
}

helmChartTest() {
    // source folder for the tests files. just an example here, provide your own as needed
    // defaults to file('/src/test/helm')
    tests = file(project.projectDir.getAbsolutePath() + "/helm/test")
}
// Optional. You need to register new pair of tasks for each additional helm chart in your project
// outputDirectory must be same in both tasks and differs from helm.outputDirectory
tasks.register("helmSecondChartBuild", HelmBuildTask.class) {
  dependsOn tasks.named("helmRepoSync")
  expansions = helm.expansions
  copyFrom helm
  
  // custom configuration
  // source folder for the charts manifest files. just an example here, provide your own as needed
  // defaults to file('/src/main/helm')
  source = file('src/main/secondchart')
  // output folder for the compiled charts manifest files. just an example here, provide your own as needed
  outputDirectory = file("$buildDir/helm/repo2")
}

tasks.register("helmSecondChartTest", HelmBuildTask.class) {
  dependsOn tasks.named("helmSecondChartBuild")
  copyFrom helm
  
  // custom configuration
  // source folder for the tests files. just an example here, provide your own as needed
  tests = file('src/test/secondchart')
  // output folder for the compiled charts manifest files. just an example here, provide your own as needed
  // defaults to file('/src/test/helm')
  outputDirectory = file("$buildDir/helm/repo2")
}

Author chart

<project folder>
|-- src/main/helm
|   |-- Chart.yml
|   `-- templates
|       `-- ...
`-- src/test/helm
    |-- test-suite01
    |   |-- values_test1.yaml
    |   `-- values_test2.yaml
    |-- value-config-1.yaml
    |-- value-config-2.yaml
    `-- value-config-3.yaml

Noteworthy:

• the plugin automatically applies the base plugin and attaches tasks as dependencies to the lifecycle tasks
• If you're using Helm >= 2.8.0 helmChartTest is locally rendering all templates for each test value file into build/helm/test/<value-file-name>/ so you can test drive how your templates react to values
• If you're using Helm >= 2.9.0-rc3
  • helmChartTest is linting once with default values and once per test so you can test drive various value combinations.
  • authenticated repositories are supported (using basic auth)

Author Tests

The structure of a test yaml file can take 2 different forms.

If on the top level the key title and values are found this is considered a structured test. Otherwise it's just a value test.

A tests name is determined by the relative path within src/test/helm.

Value Tests

Provides a sample value file. The test case is named like the file name. The value file is fed into helm template and helm lint. If both succeed with exit code 0 the test is considered successful.

Structured Tests

Create a yaml structure like this:

# a simple title for logging purposes
title: "Test title"

# everything under values is provided in a separate value file to helm
values: ~ 

# by default value files are expected to work, set succeed to false
# for negative testing (asserts are ignored in this case)
succeed: true  

# any assertions to be made on the rendered files
assert:
  - file: "<rendered file name relative to chart root>"
    test: "<name-of-test>"
    # ... test specific properties, see below
  - ...

If and only if title and values is present, a structured test is assumed.

Supported tests are:

• eq: property path is JSON-PATH'd out of file and has to equal propery value
• match: property path is JSON-PATH'd out of file as YAML and has to match the regular expression given in property pattern

Note:

• loading a manifest yaml is done such that it's always a list of yaml documents whereby the outermost list has to be respected in the path (e.g. $[*][data])
• file is a relative path to the chart (e.g. templates/configmap.yaml)
• pattern is a java regular expression which has to match the complete extracted fragment, you might want to use embedded modifiers (e.g. (?ms))

Further work:

• more tests
• provenance files
• certificate based authentication
• auto-detect at least local chart dependencies to improve up-to-date checks
• support for kube score

Alternatives

When the plugin has been created, there hasn't been an alternative. These days there are numerous alternatives:

• https://github.com/unbroken-dome/gradle-helm-plugin

  This one does it all but requires a locally installed helm

• https://github.com/rmee/gradle-plugins/tree/master/helm

  Comes integrated with a kubectl plugin and also allows remote release management.

• https://github.com/wfhartford/gradle-helm

  Extensive multi chart support.

• https://github.com/frantic777/helmplugin

  Yet another one.

• https://plugins.gradle.org/plugin/nl.surfsara.sda.buildplugin

  That one is also listed on the gradle plugin portal.