Enable templating within systemd unit files

[AverageMarcus]

What does this PR do?

Fixes giantswarm/roadmap#3691

• 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

What is the effect of this change to users?

N/A - allows for additional configuration from cluster charts

How does it look like?

N/A

Any background context you can provide?

Required by cluster-cloud-director to allow the customer to provide some custom values that will get added to the ignition

What is needed from the reviewers?

Do the docs need to be updated?

Should this change be mentioned in the release notes?

• CHANGELOG.md has been updated (if it exists)

[taylorbot]

Hey @AverageMarcus, a test pull request has been created for you in the cluster-aws repo! Go to pull request giantswarm/cluster-aws#872 in order to test your cluster chart changes on AWS.

[njuettner]

LGTM if tested

[glitchcrab]

i have no issues with this, so me likey

[glitchcrab]

following up to my review, i thought of a helpful addition. as we're making an interface to systemd units here, it would be helpful to have Wants as an option in the [Unit] section please 🙏

edit - i've made these changes but I haven't pushed them yet

[glitchcrab]

And a further thought - would it be possible to support multiple Unit ordering fields like we already do with WantedBy? e.g. we have some units which have multiple After dependencies

edit - i've made these changes but I haven't pushed them yet

[glitchcrab]

this was tested with the following provider values:

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

and the following systemd unit values:

                - contents:
                    install:
                      wantedBy:
                        - multi-user.target
                    service:
                      additionalFields: |-
                        ExecStart=/usr/bin/bash -cv 'echo "$("$(find /usr/bin /usr/share/oem -name vmtoolsd -type f -executable 2>/dev/null | head -n 1)" --cmd "info-get guestinfo.ignition.network")" > /opt/bin/set-networkd-units.sh'
                        ExecStart=/usr/bin/bash -cv 'chmod u+x /opt/bin/set-networkd-units.sh'
                        ExecStart=/opt/bin/set-networkd-units.sh
                        {{- if $.global.connectivity.network.staticRoutes }}
                        ExecStart=/usr/bin/bash -cv 'sleep 3'
                        {{- range $.global.connectivity.network.staticRoutes }}
                        ExecStart=/usr/bin/bash -cv 'ip route add {{ .destination }} via {{ .via }}'
                        {{- end }}
                        {{- end }}
                      remainAfterExit: "yes"
                      type: oneshot
                    unit:
                      after:
                        - set-hostname.service
                      description: Install the systemd-networkd unit files and add static routes
                      requires:
                        - coreos-metadata.service

which produced the following unit:

                - name: set-networkd-units.service
                  enabled: true
                  contents: |
                    [Unit]
                    Description=Install the systemd-networkd unit files and add static routes
                    After=set-hostname.service
                    Requires=coreos-metadata.service
                    [Service]
                    Type=oneshot
                    RemainAfterExit=yes

                    ExecStart=/usr/bin/bash -cv 'echo "$("$(find /usr/bin /usr/share/oem -name vmtoolsd -type f -executable 2>/dev/null | head -n 1)" --cmd "info-get guestinfo.ignition.network")" > /opt/bin/set-networkd-units.sh'
                    ExecStart=/usr/bin/bash -cv 'chmod u+x /opt/bin/set-networkd-units.sh'
                    ExecStart=/opt/bin/set-networkd-units.sh
                    ExecStart=/usr/bin/bash -cv 'sleep 3'
                    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

[AverageMarcus]

This is beautiful! 😍 (I can't approve it though as I opened the PR 🤦 )

@Gacko Mind giving this work of art a little ✅ ?

[github-actions]

There were no differences in the rendered Helm template.

Output

=== Differences when rendered with values file helm/cluster/ci/test-required-values.yaml ===

No difference


=== Differences when rendered with values file helm/cluster/ci/test-zot-mc-and-local-values.yaml ===

No difference


=== Differences when rendered with values file helm/cluster/ci/test-zot-mc-values.yaml ===

No difference


=== Differences when rendered with values file helm/cluster/ci/test-zot-only-local-values.yaml ===

No difference


=== No differences at all ===

[Gacko]

LGTM!