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Enable templating within systemd unit files #351

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6 changes: 6 additions & 0 deletions CHANGELOG.md
Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,12 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0

## [Unreleased]

### Added

- Added support for `Service` section in custom systemd configuration
- Added support for `After`, `Requires`, `Wants` and `BindsTo` within unit section of custom systemd configuration
- Added support for passing Helm templating from provider chart values through to systemd unit templates

## [1.4.1] - 2024-09-23

### Fixed
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58 changes: 58 additions & 0 deletions README.md
Original file line number Diff line number Diff line change
Expand Up @@ -430,6 +430,64 @@ cluster:
- echo "workers command after kubeadm"
```

### Systemd unit templating

You can pass Helm templating syntax through from cluster-\<provider\> charts which will be rendered by the cluster chart. This is
written as plain text within the cluster-\<provider\> chart values under the `additionalFields` key. Consider the following:

```
global:
connectivity:
network:
staticRoutes:
- destination: 10.2.3.0/24
via: 10.9.8.7
- destination: 10.20.30.0/24
via: 10.9.8.7
cluster:
providerIntegration:
kubeadmConfig:
# ignition for both control plane and worker nodes
ignition:
containerLinuxConfig:
additionalConfig:
systemd:
units:
- contents:
install:
wantedBy:
- multi-user.target
service:
additionalFields: |-
{{- if $.global.connectivity.network.staticRoutes }}
{{- range $.global.connectivity.network.staticRoutes }}
ExecStart=/usr/bin/bash -cv 'ip route add {{ .destination }} via {{ .via }}'
{{- end }}
{{- end }}
unit:
requires:
- coreos-metadata.service
```

This results in the following unit:

```
[Unit]
Requires=coreos-metadata.service
[Service]
ExecStart=/usr/bin/bash -cv 'ip route add 10.2.3.0/24 via 10.9.8.7'
ExecStart=/usr/bin/bash -cv 'ip route add 10.20.30.0/24 via 10.9.8.7'
[Install]
WantedBy=multi-user.target
```

The Helm templating syntax is treated as plain text by the provider chart. The cluster chart's templating function has
access to the values under the provider chart's `.global` key so any values referenced in the template must exist
under `.global`.

Note that variable scoping is important here - the templating function does not have access to the root `$.Values` object,
so any variables under `.global` must be referenced as `$.global.some.var` (not `$.Values.global.some.var`).

## Workload cluster configuration

Workload clusters can be configured by setting Helm values in two top-level objects:
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48 changes: 48 additions & 0 deletions helm/cluster/README.md

Large diffs are not rendered by default.

3 changes: 2 additions & 1 deletion helm/cluster/templates/bastion/_helpers_flatcar.tpl
Original file line number Diff line number Diff line change
Expand Up @@ -3,8 +3,9 @@ containerLinuxConfig:
additionalConfig: |
systemd:
{{- if (((((($.Values.providerIntegration.bastion).kubeadmConfig).ignition).containerLinuxConfig).additionalConfig).systemd).units }}
{{- $systemdUnitValues := dict "global" $.Values.global "units" $.Values.providerIntegration.bastion.kubeadmConfig.ignition.containerLinuxConfig.additionalConfig.systemd.units }}
units:
{{- include "cluster.internal.kubeadm.ignition.containerLinuxConfig.additionalConfig.systemd.units" $.Values.providerIntegration.bastion.kubeadmConfig.ignition.containerLinuxConfig.additionalConfig.systemd.units | indent 6 }}
{{- include "cluster.internal.kubeadm.ignition.containerLinuxConfig.additionalConfig.systemd.units" $systemdUnitValues | indent 6 }}
{{- else }}
units: []
{{- end }}
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31 changes: 30 additions & 1 deletion helm/cluster/templates/clusterapi/_helpers_flatcar.tpl
Original file line number Diff line number Diff line change
Expand Up @@ -5,7 +5,7 @@
{{- end }}

{{- define "cluster.internal.kubeadm.ignition.containerLinuxConfig.additionalConfig.systemd.units" }}
{{- range . }}
{{- range .units }}
- name: {{ .name }}
{{- if hasKey . "enabled" }}
enabled: {{ .enabled }}
Expand All @@ -21,6 +21,35 @@
{{- if hasKey .contents.unit "defaultDependencies" }}
DefaultDependencies={{ if .contents.unit.defaultDependencies }}yes{{ else }}no{{ end }}
{{- end }}
{{- if .contents.unit.after }}
{{- range $after := .contents.unit.after }}
After={{ $after }}
{{- end }}
{{- end }}
{{- if .contents.unit.requires }}
{{- range $requires := .contents.unit.requires }}
Requires={{ $requires }}
{{- end }}
{{- end }}
{{- if .contents.unit.wants }}
{{- range $wants := .contents.unit.wants }}
Wants={{ $wants }}
{{- end }}
{{- end }}
{{- if .contents.unit.bindsTo }}
BindsTo={{ .contents.unit.bindsTo }}
{{- end }}
{{- end }}
{{- if .contents.service }}
[Service]
Type={{ .contents.service.type }}
RemainAfterExit={{ .contents.service.remainAfterExit }}
{{- if .contents.service.execStart }}
ExecStart={{ .contents.service.execStart }}
{{- end }}
{{- if .contents.service.additionalFields }}
{{ tpl .contents.service.additionalFields $ | nindent 4 }}
{{- end }}
{{- end }}
{{- if .contents.mount }}
[Mount]
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Original file line number Diff line number Diff line change
Expand Up @@ -19,10 +19,12 @@ containerLinuxConfig:

{{- define "cluster.internal.controlPlane.kubeadm.ignition.containerLinuxConfig.additionalConfig.systemd.units" }}
{{- if ((((($.Values.providerIntegration.kubeadmConfig).ignition).containerLinuxConfig).additionalConfig).systemd).units }}
{{- include "cluster.internal.kubeadm.ignition.containerLinuxConfig.additionalConfig.systemd.units" $.Values.providerIntegration.kubeadmConfig.ignition.containerLinuxConfig.additionalConfig.systemd.units }}
{{- $systemdUnitValues := dict "global" $.Values.global "units" $.Values.providerIntegration.kubeadmConfig.ignition.containerLinuxConfig.additionalConfig.systemd.units }}
{{- include "cluster.internal.kubeadm.ignition.containerLinuxConfig.additionalConfig.systemd.units" $systemdUnitValues }}
{{- end }}
{{- if (((((($.Values.providerIntegration.controlPlane).kubeadmConfig).ignition).containerLinuxConfig).additionalConfig).systemd).units }}
{{- include "cluster.internal.kubeadm.ignition.containerLinuxConfig.additionalConfig.systemd.units" $.Values.providerIntegration.controlPlane.kubeadmConfig.ignition.containerLinuxConfig.additionalConfig.systemd.units }}
{{- $systemdUnitValues := dict "global" $.Values.global "units" $.Values.providerIntegration.controlPlane.kubeadmConfig.ignition.containerLinuxConfig.additionalConfig.systemd.units }}
{{- include "cluster.internal.kubeadm.ignition.containerLinuxConfig.additionalConfig.systemd.units" $systemdUnitValues }}
{{- end }}
{{- end }}

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Original file line number Diff line number Diff line change
Expand Up @@ -16,10 +16,12 @@ containerLinuxConfig:

{{- define "cluster.internal.workers.kubeadm.ignition.containerLinuxConfig.additionalConfig.systemd.units" }}
{{- if ((((($.Values.providerIntegration.kubeadmConfig).ignition).containerLinuxConfig).additionalConfig).systemd).units }}
{{- include "cluster.internal.kubeadm.ignition.containerLinuxConfig.additionalConfig.systemd.units" $.Values.providerIntegration.kubeadmConfig.ignition.containerLinuxConfig.additionalConfig.systemd.units }}
{{- $systemdUnitValues := dict "global" $.Values.global "units" $.Values.providerIntegration.kubeadmConfig.ignition.containerLinuxConfig.additionalConfig.systemd.units }}
{{- include "cluster.internal.kubeadm.ignition.containerLinuxConfig.additionalConfig.systemd.units" $systemdUnitValues }}
{{- end }}
{{- if (((((($.Values.providerIntegration.workers).kubeadmConfig).ignition).containerLinuxConfig).additionalConfig).systemd).units }}
{{- include "cluster.internal.kubeadm.ignition.containerLinuxConfig.additionalConfig.systemd.units" $.Values.providerIntegration.workers.kubeadmConfig.ignition.containerLinuxConfig.additionalConfig.systemd.units }}
{{- $systemdUnitValues := dict "global" $.Values.global "units" $.Values.providerIntegration.workers.kubeadmConfig.ignition.containerLinuxConfig.additionalConfig.systemd.units }}
{{- include "cluster.internal.kubeadm.ignition.containerLinuxConfig.additionalConfig.systemd.units" $systemdUnitValues }}
{{- end }}
{{- end }}

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61 changes: 61 additions & 0 deletions helm/cluster/values.schema.json
Original file line number Diff line number Diff line change
Expand Up @@ -926,6 +926,38 @@
}
}
},
"service": {
"type": "object",
"title": "Service",
"description": "Configuration of the [Service] section.",
"required": [
"type",
"remainAfterExit"
],
"additionalProperties": false,
"properties": {
"type": {
"type": "string",
"title": "Type",
"description": "systemd service Type."
},
"additionalFields": {
"type": "string",
"title": "AdditionalFields",
"description": "any extra fields to add to the systemd [Service] section."
},
"execStart": {
"type": "string",
"title": "ExecStart",
"description": "systemd service ExecStart."
},
"remainAfterExit": {
"type": "string",
"title": "RemainAfterExit",
"description": "systemd service RemainAfterExit."
}
}
},
"unit": {
"type": "object",
"title": "Unit",
Expand All @@ -940,10 +972,39 @@
"title": "Description",
"description": "systemd unit description."
},
"after": {
"type": "array",
"title": "After",
"description": "systemd unit After.",
"items": {
"type": "string"
}
},
"bindsTo": {
"type": "string",
"title": "BindsTo",
"description": "systemd unit BindsTo."
},
"defaultDependencies": {
"type": "boolean",
"title": "DefaultDependencies",
"description": "Flag that indicates if this systemd unit should have the default systemd unit dependencies."
},
"requires": {
"type": "array",
"title": "Requires",
"description": "systemd unit Requires.",
"items": {
"type": "string"
}
},
"wants": {
"type": "array",
"title": "Wants",
"description": "systemd unit Wants.",
"items": {
"type": "string"
}
}
}
}
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