✨(helm) add the django base Helm chart

to avoid rewriting a helm chart from scratch for all django based
applications, we need to create a generic base chart that can be used as a subchart
for django apps.

charts/base-django/.helmignore

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+# Patterns to ignore when building packages.
+# This supports shell glob matching, relative path matching, and
+# negation (prefixed with !). Only one pattern per line.
+.DS_Store
+# Common VCS dirs
+.git/
+.gitignore
+.bzr/
+.bzrignore
+.hg/
+.hgignore
+.svn/
+# Common backup files
+*.swp
+*.bak
+*.tmp
+*.orig
+*~
+# Various IDEs
+.project
+.idea/
+*.tmproj
+.vscode/

charts/base-django/Chart.yaml

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+apiVersion: v2
+name: django
+description: A Helm chart for Kubernetes
+
+# A chart can be either an 'application' or a 'library' chart.
+#
+# Application charts are a collection of templates that can be packaged into versioned archives
+# to be deployed.
+#
+# Library charts provide useful utilities or functions for the chart developer. They're included as
+# a dependency of application charts to inject those utilities and functions into the rendering
+# pipeline. Library charts do not define any templates and therefore cannot be deployed.
+type: application
+
+# This is the chart version. This version number should be incremented each time you make changes
+# to the chart and its templates, including the app version.
+# Versions are expected to follow Semantic Versioning (https://semver.org/)
+version: 0.1.0
+
+# This is the version number of the application being deployed. This version number should be
+# incremented each time you make changes to the application. Versions are not expected to
+# follow Semantic Versioning. They should reflect the version the application is using.
+# It is recommended to use it with quotes.
+appVersion: "0.1.0"
+dependencies:
+  - condition: postgresql.enabled
+    name: postgresql
+    repository: https://charts.bitnami.com/bitnami
+    version: 12.x.x

charts/base-django/README.md

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+# Django Helm Chart 
+
+This chart's aims is to deploy a django app using Helm. This chart follows the structure of the Django apps developped by 
+France Université Numérique. Is is intended to be used as a subchart for Django app Deployments. 
+
+This chart allows the user to either create a Postgresql database or connect to an external database (it depends on the variable `postgreqsl.enabled`)
+
+To deploy your own Django app, create your own Helm chart, add this one as a subchart and overwrite its parameters as needed. To do this you have to add a section in your own values file as follows:
+
+```
+django:
+  image:
+    repository: fundocker/<app_image>
+    pullPolicy: IfNotPresent
+    tag: <image_tag>
+  appDjangoSettingsModule: <settings_module>
+  appDjangoConfiguration: <app_configuration>
+
+```
+Since we have not yet created our own helm chart repository, in order to use this chart as a subchart, you need to:
+
+1) Build this helm chart dependencies: ` helm dependency build `
+
+2) Package this chart: ` helm package . ` , a .tgz file will be created.
+
+3) Copy the .tgz in `<your-chart>/charts` directory

charts/base-django/templates/_helpers.tpl

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+{{/*
+Expand the name of the chart.
+*/}}
+{{- define "django.name" -}}
+{{- default .Chart.Name .Values.nameOverride | trunc 63 | trimSuffix "-" }}
+{{- end }}
+
+{{/*
+Create a default fully qualified app name.
+We truncate at 63 chars because some Kubernetes name fields are limited to this (by the DNS naming spec).
+If release name contains chart name it will be used as a full name.
+*/}}
+{{- define "django.fullname" -}}
+{{- if .Values.fullnameOverride }}
+{{- .Values.fullnameOverride | trunc 63 | trimSuffix "-" }}
+{{- else }}
+{{- $name := default .Chart.Name .Values.nameOverride }}
+{{- if contains $name .Release.Name }}
+{{- .Release.Name | trunc 63 | trimSuffix "-" }}
+{{- else }}
+{{- printf "%s-%s" .Release.Name $name | trunc 63 | trimSuffix "-" }}
+{{- end }}
+{{- end }}
+{{- end }}
+
+{{/*
+Create chart name and version as used by the chart label.
+*/}}
+{{- define "django.chart" -}}
+{{- printf "%s-%s" .Chart.Name .Chart.Version | replace "+" "_" | trunc 63 | trimSuffix "-" }}
+{{- end }}
+
+{{/*
+Common labels
+*/}}
+{{- define "django.labels" -}}
+helm.sh/chart: {{ include "django.chart" . }}
+{{ include "django.selectorLabels" . }}
+{{- if .Chart.AppVersion }}
+app.kubernetes.io/version: {{ .Chart.AppVersion | quote }}
+{{- end }}
+app.kubernetes.io/managed-by: {{ .Release.Service }}
+{{- end }}
+
+{{/*
+Selector labels
+*/}}
+{{- define "django.selectorLabels" -}}
+app.kubernetes.io/name: {{ include "django.name" . }}
+app.kubernetes.io/instance: {{ .Release.Name }}
+{{- end }}
+
+{{/*
+Return the proper Docker Image Registry Secret Names
+*/}}
+{{- define "django.imagePullSecrets" -}}
+{{- $pullSecrets := .Values.imagePullSecrets }}
+  {{- if (not (empty $pullSecrets)) }}
+imagePullSecrets:
+    {{- range $pullSecrets }}
+  - name: {{ . }}
+    {{- end }}
+  {{- end -}}
+{{- end }}
+
+{{/*
+Return the host
+*/}}
+{{- define "django.host" -}}
+django.{{ .Release.Namespace }}.{{ .Values.domainName }}
+{{- end }}

charts/base-django/templates/app/configmap.yaml

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+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: {{ include "django.fullname" . }}-dotenv
+  namespace: {{ .Release.Namespace | quote }}
+  labels: {{- include "django.labels" . | nindent 4 }}
+    {{- if .Values.commonLabels }}
+    {{ toYaml .Values.commonLabels | nindent 4 }}
+    {{- end }}
+    app.kubernetes.io/component: django
+  {{- if .Values.commonAnnotations }}
+  annotations: {{ toYaml .Values.commonAnnotations | nindent 4 }}
+  {{- end }}
+data:
+  DJANGO_SILENCED_SYSTEM_CHECKS: "security.W008,security.W004"

charts/base-django/templates/app/deploy.yaml

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+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: {{ include "django.fullname" . }}
+  namespace: {{ .Release.Namespace | quote }}
+  labels: {{- include "django.labels" . | nindent 4 }}
+    {{- if .Values.commonLabels }}
+    {{ toYaml .Values.commonLabels | nindent 4 }}
+    {{- end }}
+    app.kubernetes.io/component: django
+  {{- if .Values.commonAnnotations }}
+  annotations: {{ toYaml .Values.commonAnnotations | nindent 4 }}
+  {{- end }}
+spec:
+  replicas: {{ .Values.replicaCount }}
+  selector:
+    matchLabels: {{- include "django.selectorLabels" . | nindent 6 }}
+      app.kubernetes.io/component: django
+  template:
+    metadata:
+      labels: {{- include "django.labels" . | nindent 8 }}
+        app.kubernetes.io/component: django
+        {{- if .Values.podLabels }}
+        {{ toYaml .Values.podLabels | nindent 8 }}
+        {{- end }}
+    annotations:
+      {{- if .Values.podAnnotations }}
+      {{- toYaml .Values.podAnnotations | nindent 8 }}
+      {{- end }}
+    spec: {{- include "django.imagePullSecrets" . | nindent 6 }}
+      {{- if .Values.affinity }}
+      affinity: {{- toYaml .Values.affinity | nindent 8 }}
+      {{- else -}}
+      affinity:
+        podAntiAffinity:
+          preferredDuringSchedulingIgnoredDuringExecution:
+            - podAffinityTerm:
+                labelSelector:
+                  matchLabels: {{- include "django.selectorLabels" . | nindent 20 }}
+                    app.kubernetes.io/component: django
+                namespaces: 
+                  - {{ .Release.Namespace | quote }}
+                topologyKey: kubernetes.io/hostname
+              weight: 100
+      {{- end }}
+      {{- if .Values.podSecurityContext }}
+      securityContext: {{ toYaml .Values.podSecurityContext | nindent 8 }}
+      {{- end }}
+      containers:
+        - name: django
+          image: "{{ .Values.image.repository }}:{{ .Values.image.tag }}"
+          imagePullPolicy: {{ .Values.image.pullPolicy }}
+          {{- if .Values.containerSecurityContext.enabled }}
+          securityContext: {{- omit .Values.containerSecurityContext "enabled" | toYaml | nindent 12 }}
+          {{- end }}
+          env:
+            - name: DB_HOST
+              value: {{ include "django.fullname" . }}-postgresql
+            - name: DB_NAME
+              value: {{ .Values.databaseName }}
+            - name: DB_PORT
+              value: {{ .Values.databasePort | quote }}
+            - name: DJANGO_ALLOWED_HOSTS
+              value: {{ include  "django.host" . }}
+            - name: DJANGO_CONFIGURATION
+              value: {{ .Values.appDjangoConfiguration }}
+            - name: DJANGO_SETTINGS_MODULE
+              value: {{ .Values.appDjangoSettingsModule }}
+          envFrom:
+            - secretRef:
+                name: {{ include "django.fullname" . }}
+            - configMapRef:
+                name: {{ include "django.fullname" . }}-dotenv
+          {{- if .Values.customLivenessProbe }}
+          livenessProbe: {{- toYaml .Values.customLivenessProbe | nindent 12 }}
+          {{ else }}
+          livenessProbe:
+            httpGet:
+              path: {{.Values.livenessProbe.path }}
+              port: {{ .Values.service.port }}
+              httpHeaders:
+                - name: Host
+                  value: "{{ include  "django.host" .   }}"
+            initialDelaySeconds: {{ .Values.livenessProbe.initialDelaySeconds }}
+            periodSeconds: {{ .Values.livenessProbe.periodeSeconds }}
+          {{- end }}
+          {{- if .Values.customReadinessProbe }}
+          readinessProbe: {{- toYaml .Values.customReadinessProbe | nindent 12 }}
+          {{ else }}
+          readinessProbe:
+            httpGet:
+              path: {{ .Values.readinessProbe.path }}
+              port: {{ .Values.service.port }}
+              httpHeaders:
+                - name: Host
+                  value: "{{ include "django.host" .   }}"
+            initialDelaySeconds: {{ .Values.readinessProbe.initialDelaySeconds }}
+            periodSeconds: {{ .Values.readinessProbe.periodeSeconds }}
+          {{- end }}
+          {{- if .Values.resources }}
+          resources: {{ toYaml .Values.resources | nindent 12 }}
+          {{- end }}

charts/base-django/templates/app/ingress.yaml

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+apiVersion: networking.k8s.io/v1
+kind: Ingress
+metadata:
+  name: {{ include "django.fullname" . }}-ingress
+  namespace: {{ .Release.Namespace | quote }}
+  labels: {{- include "django.labels" . | nindent 4 }}
+    {{- if .Values.commonLabels }}
+    {{ toYaml .Values.commonLabels | nindent 4 }}
+    {{- end }}
+    app.kubernetes.io/component: django
+  annotations:
+{{- if .Values.commonAnnotations }}
+{{- toYaml .Values.commonAnnotations | nindent 4 }}
+{{- end }}
+{{- if .Values.ingress.acmeIssuerName }}
+    cert-manager.io/issuer: {{ .Values.ingress.acmeIssuerName }}
+{{- end }}
+{{- if .Values.ingress.activateHttpBasicAuth }}
+    nginx.ingress.kubernetes.io/auth-type: basic 
+    nginx.ingress.kubernetes.io/auth-secret: {{ .Values.ingress.htpasswdSecretName }}
+    nginx.ingress.kubernetes.io/auth-realm: {{ .Values.ingress.httpBasicAuthMessage }}
+{{- end }}
+{{- if  and .Values.ingress.activateHttpBasicAuth .Values.ingress.bypassHtaccessIpWhitelist }}
+    nginx.ingress.kubernetes.io/satisfy: "any"
+    nginx.ingress.kubernetes.io/whitelist-source-range: {{ join "," .Values.ingress.bypassHtaccessIpWhitelist }}
+{{- end }}
+spec:
+  ingressClassName: nginx
+  rules:
+  - host: {{ include "django.host" . | quote }}
+    http:
+      paths:
+      - path: /
+        pathType: Prefix
+        backend:
+          service:
+            name: {{ include "django.fullname" . }}
+            port:
+              number: {{ .Values.service.port }}
+  tls:
+    - hosts:
+      - {{ include "django.host" .  }}
+      secretName: {{ .Values.ingress.tlsSecretName }}
+---
+{{ if .Values.ingress.adminIpWhitelist }}
+apiVersion: networking.k8s.io/v1
+kind: Ingress
+metadata:
+  name: {{ include "django.fullname" . }}-ingress-admin
+  namespace: {{ .Release.Namespace | quote }}
+  labels: {{- include "django.labels" . | nindent 4 }}
+    {{- if .Values.commonLabels }}
+    {{ toYaml .Values.commonLabels | nindent 4 }}
+    {{- end }}
+    app.kubernetes.io/component: django
+  annotations:
+{{- if .Values.ingress.acmeIssuerName -}}
+    cert-manager.io/issuer: {{ .Values.ingress.acmeIssuerName }}
+{{ end }}
+    nginx.ingress.kubernetes.io/whitelist-source-range: {{ join "," .Values.ingress.adminIpWhitelist }}
+spec:
+  ingressClassName: nginx
+  rules:
+  - host: {{ include "django.host" . | quote }}
+    http:
+      paths:
+      - path: /admin
+        pathType: Prefix
+        backend:
+          service:
+            name: {{ include "django.fullname" . }}
+            port:
+              number: {{ .Values.service.port }}
+  tls:
+    - hosts:
+      - {{ include "django.host" .  }}
+      secretName: {{ .Values.ingress.tlsSecretName }}
+{{ end }}