K3charts

This is an experimental project to automate system charts and adding overlays files on top of it.

Charts will have two categories:

1. Charts that Rancher created and maintained (Rancher original).

2. Charts that Rancher modified from upstream (Rancher modified).

Rancher original chart is created and maintained by Rancher Team, such as rancher-cis-benchmark, rancher-k3s-upgrader.

Rancher modified chart is modified from upstream chart, while there are customizations added into the upstream chart from rancher side.

For Rancher original charts, it should have the following tree structure

packages/${CHART_NAME}/
  charts/                   # regular helm chart directory
    templates/
    Chart.yaml
    values.yaml
  sha256sum.txt             # sha256 checksum of all files in helm directory

For Rancher modified charts, it should have the following tree structure

package/${CHART_NAME}/
  package.yaml              # metadata manifest containing upstream chart location, package version
  ${CHART_NAME}.patch       # patch file containing the diff between modified chart and upstream
  overlay/*                 # overlay files that needs to added on top of upstream, for example, questions.yaml
  sha256sum.txt             # sha256 checksum for all files included in the modified helm chart

A regular package.yaml will have the following content:

url: https://charts.bitnami.com/bitnami/external-dns-2.20.10.tgz # url to fetch upstream chart
packageVersion: 00 # packageVersion of modified charts, producing a $version-$packageVersion chart. For example, if istio 1.4.7 is modified with changes, rancher produces a 1.4.7-00 chart version that includes the modification rancher made on top of upstream charts.

Here is an example of upstream chart based on git repository

url: https://github.com/open-policy-agent/gatekeeper.git  # Url to fetch upstream chart from git
subdirectory: chart/gatekeeper-operator # Sub directory for helm charts in git repo
type: git # optinal, indicate that upstream chart is from git
commit: v3.1.0-beta.8 # the revision of git repo
packageVersion: 00 # package version

Workflow

Modifying Rancher original charts is the same workflow as modifying helm charts. First make changes into charts/ and commit changes. CI will automatically upload artifacts if file contents have been changed.

Modifying Rancher modified takes extra steps, as it requires modifications to be saved into patch files so that later it can retrieve the chart based on upstream chart and patch files.

The step includes:

1. Run make CHART={CHART_NAME} prepare

   This prepares charts with the current upstream chart and current patch.

2. Change the version in package.yaml. If upstream chart needs to be updated, update url to point the latest chart. packageVersion also needs to updated.

3. Make modification to your charts.

4. Run make CHART={CHART_NAME} patch

   This will compare your current chart with upstream chart and generate the correct patch.

5. Run make CHART={CHART_NAME} clean

   This will clean up the charts directory so that it won't committed.

This repo provides a workflow that automatically uploads patch files and tarball of charts. Commit will only need to update package/${chart-name}/charts and make sure patches are up-to-date with the latest chart. It also automatically build github pages to serve index.yaml and artifacts of charts.

Helm repo index

To add this repo as a helm repo, run

helm repo add https://strongmonkey.github.com/k3chart

Makefile

make bootstrap:

Download binaries that are needed for ci scripts.

make prepare:

Prepare the chart for modification. This will apply the upstream chart with the current patch. Use CHART=${NAME} for specific chart.

make charts:

Generate tarball for each charts. Use CHART=${NAME} for specific chart.

make patch:

Compare the current chart with upstream and generate patch file. Use CHART=${NAME} for specific chart.

make validate:

Validate if patch file can be applied.

make mirror:

Run image mirroring scripts.(Experimental)