helm documentation hitachienergy#896

docs/home/howto/HELM.md

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+## Helm charts in repository
+
+
+System Helm charts are stored in the following location:
+
+`roles/helm_charts/files/system`
+
+There is also dedicated Helm charts location for users
+
+`roles/helm_charts/files/user`
+
+- Currently user part has no automation implemented. It will need some additional "options" via epi client but it needs discussion with wider audience about the needs.
+
+Implementator/developer maintain system path content.
+All chart should be added in directories (not archived)
+
+Repository role is responsible for retrieving mentioned Helm charts. It copies all the directories, archive them (`.tgz`), generates helm index file and serve in apache server.
+
+
+
+## Installing Helm charts from repository
+
+Installation of particular Helm charts is performed in separate role. Each other particular role that needs to install Helm chart has to trigger separate single helm chart installation task:
+`roles/helm/tasks/install-chart.yml`
+
+
+
+Single Helm installation task is responsible for installing already existing charts from repository.
+
+It is possible to overwrite chart values within the specification config.
+Single helm chart task expects 3 parameters to be passed:
+
+```yaml
+    disable_helm_chart:
+    helm_chart_name: 
+    helm_chart_values:
+```
+
+Example usage:
+
+```yaml
+---
+- name: Set Helm chart values from custom configuration
+  set_fact:
+    _helm_chart_values: "{{ specification.helm_chart_values }}"
+  when: specification.helm_chart_values is defined
+- name: Set Helm chart name from custom configuration
+  set_fact:
+    _helm_chart_name: "{{ specification.helm_chart_name }}"
+  when: specification.helm_chart_name is defined
+- name: Set Helm chart disable flag from custom configuration
+  set_fact:
+    _disable_helm_chart: "{{ specification.disable_helm_chart }}"
+  when: specification.disable_helm_chart is defined
+- name: Mychart
+  include_role:
+    name: helm
+    tasks_from: install-chart
+  vars:
+    disable_helm_chart: "{{ _disable_helm_chart }}"
+    helm_chart_name: "{{ _helm_chart_name }}"
+    helm_chart_values:  "{{ _helm_chart_values }}"
+```
+
+Example config:
+
+```yaml
+kind: configuration/helm-mychart
+title: "Helm mychart"
+name: default
+specification:
+  helm_chart_name: mychart
+  disable_helm_chart: false
+  helm_chart_values:
+    service:
+      port: 8080
+    nameOverride: mychart_custom_name
+```