helm/docs/sql-storage.md

Store release information in an SQL database

You may be willing to store release information in an SQL database - in particular, if your releases weigh more than 1MB and therefore can't be stored in ConfigMaps or Secrets.

We recommend using PostgreSQL.

This document describes how to deploy postgres atop Kubernetes. This being said, using an out-of-cluster (managed or not) PostreSQL instance is totally possible as well.

Here's a Kubernetes manifest you can apply to get a minimal PostreSQL pod running on your Kubernetes cluster. Don't forget to change the credentials and, optionally, enable TLS in production deployments.

apiVersion: v1
kind: Service
metadata:
  name: tiller-postgres
  namespace: kube-system
spec:
  ports:
    - port: 5432
  selector:
    app: helm
    name: postgres
---
apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: tiller-postgres
  namespace: kube-system
spec:
  serviceName: tiller-postgres
  selector:
    matchLabels:
      app: helm
      name: postgres
  replicas: 1
  template:
    metadata:
      labels:
        app: helm
        name: postgres
    spec:
      containers:
        - name: postgres
          image: postgres:11-alpine
          imagePullPolicy: Always
          ports:
            - containerPort: 5432
          env:
          - name: POSTGRES_DB
            value: helm
          - name: POSTGRES_USER
            value: helm
          - name: POSTGRES_PASSWORD
            value: changemeforgodssake
          - name: PGDATA
            value: /var/lib/postgresql/data/pgdata
          resources:
            limits:
              memory: 128Mi
            requests:
              cpu: 50m
              memory: 128Mi
          volumeMounts:
            - mountPath: /var/lib/postgresql/data
              name: tiller-postgres-data
  volumeClaimTemplates:
  - metadata:
      name: tiller-postgres-data
    spec:
      accessModes: ["ReadWriteOnce"]
      storageClassName: default
      resources:
        requests:
          storage: 5Gi

Once postgres is deployed, you'll need to install Tiller using helm init, with a few custom CLI flags:

helm init \
  --override \
    'spec.template.spec.containers[0].args'='{--storage=sql,--sql-dialect=postgres,--sql-connection-string=postgresql://tiller-postgres:5432/helm?user=helm&password=changemeforgodssake&sslmode=disable}'