Dependencies & Subcharts

# Chart.yaml
apiVersion: v2
name: myapp
version: 1.0.0
dependencies:
  - name: postgresql
    version: "12.x.x"
    repository: "https://charts.bitnami.com/bitnami"
    condition: postgresql.enabled    # Toggle on/off
  - name: redis
    version: "17.x.x"
    repository: "https://charts.bitnami.com/bitnami"
    condition: redis.enabled
  - name: common
    version: "2.x.x"
    repository: "https://charts.bitnami.com/bitnami"
    tags:
      - infrastructure

# Download dependencies (creates charts/ dir with .tgz files)
helm dependency update ./myapp

# List dependencies and their status
helm dependency list ./myapp

# Rebuild from Chart.lock (reproducible builds)
helm dependency build ./myapp

# values.yaml of parent chart
# Subchart values go under a key matching the subchart name

postgresql:
  enabled: true
  auth:
    postgresPassword: "secretpass"
    database: myappdb
  primary:
    resources:
      requests:
        cpu: 250m
        memory: 256Mi

redis:
  enabled: true
  architecture: standalone
  auth:
    enabled: false

# values.yaml
global:
  imageRegistry: myregistry.azurecr.io
  storageClass: managed-premium

# In ANY template (parent or subchart):
image: {{ .Values.global.imageRegistry }}/myapp:v1
# Both parent and subcharts can access .Values.global

# Developer workflow:
# 1. Change a dependency version in Chart.yaml
vim Chart.yaml   # Update postgresql from 12.x.x to 13.x.x

# 2. Re-resolve dependencies (updates Chart.lock + downloads .tgz)
helm dependency update .

# 3. COMMIT BOTH Chart.yaml AND Chart.lock to Git
git add Chart.yaml Chart.lock
git commit -m "chore: upgrade postgresql subchart to 13.x.x"

# CI/CD workflow (reproducible):
# Use 'build' (not 'update') to install from the lockfile exactly
helm dependency build .
# ↑ This uses Chart.lock to get the EXACT same versions
# If Chart.lock is missing or out of date, 'build' fails

# Create a chart with a PostgreSQL dependency
helm create depslab
cd depslab

# Add dependency to Chart.yaml
cat >> Chart.yaml <<EOF

dependencies:
  - name: postgresql
    version: "12.12.10"
    repository: "https://charts.bitnami.com/bitnami"
    condition: postgresql.enabled
EOF

# Add subchart values to values.yaml
cat >> values.yaml <<EOF

postgresql:
  enabled: true
  auth:
    postgresPassword: "demopass"
    database: depslab_db
EOF

# Download the dependency
helm dependency update .

# Verify
ls charts/   # Should show postgresql-12.12.10.tgz
helm dependency list .

# Render to see all resources (parent + subchart)
helm template test . | grep "kind:" | sort | uniq -c

# Install with dependency
helm install depslab . -n demo --create-namespace

# Disable the dependency
helm upgrade depslab . -n demo --set postgresql.enabled=false

# Cleanup
helm uninstall depslab -n demo

# You need to add the repo first
helm repo add bitnami https://charts.bitnami.com/bitnami
helm repo update

# Then update dependencies
helm dependency update ./mychart

# Values for subcharts must be nested under the subchart name
# WRONG:
auth:
  database: mydb   # Parent chart's auth, NOT postgresql's

# RIGHT:
postgresql:
  auth:
    database: mydb  # Goes to postgresql subchart

# Verify what gets passed:
helm template test . | grep -A 10 "kind: Secret"

# "Error: chart requires postgresql >= 12.0.0, found 11.9.0"

# Check current lock:
cat Chart.lock

# Fix: Update the version range in Chart.yaml
# Then re-resolve:
helm dependency update .

# After running helm dependency update, your chart breaks
# because the subchart changed its values schema

# Step 1: Check what version changed
diff <(git show HEAD:Chart.lock) Chart.lock
# Shows: postgresql went from 12.12.10 to 13.1.0

# Step 2: Check the subchart's changelog/release notes
helm show chart bitnami/postgresql --version 13.1.0

# Step 3: Rollback — restore the old lockfile
git checkout Chart.lock
helm dependency build .   # Reinstall old versions

# Step 4: Fix forward (when ready)
# Read migration guide, update values.yaml for new schema
# Example: auth.postgresPassword → auth.password (Bitnami change)
# Test: helm template test . | grep postgres
# Then: helm dependency update . → commit both files