Instruction file imported from egovhealthcare/gcp_template (.github/instructions/helm.instructions.md). Copyright stays with the author.

Helm Chart Conventions

Chart Structure

Each chart under helm_charts/ contains:

Current charts: gateway, redis, metabase, care_be, care_fe, dcm4chee, care_metrics_exporter.

Common Helpers

All charts implement an identical set of helper templates in _helpers.tpl:

When creating a new chart, copy _helpers.tpl from an existing chart and update the template name prefix.

Deployment Patterns

• Use checksum annotations for ConfigMap/Secret-driven rolling updates:

  checksum/config: {{ include (print $.Template.BasePath "/configmap.yaml") . | sha256sum }}

• Define resource requests and limits explicitly in values.yaml.
• Define liveness and readiness probes explicitly.
• Exporter charts collected by Google Managed Service for Prometheus use monitoring.googleapis.com/v1 PodMonitoring, not Prometheus Operator ServiceMonitor.

Global Values Contract

Terraform injects a global block via common_helm_values in deploy/locals.tf:

global:
  cloudProvider: gcp
  namespace: <namespace>
  gateway:
    name: care-regional-gateway
    namespace: <namespace>
    gatewayClassName: gke-l7-regional-external-managed
  backendPolicy:
    enabled: true
    securityPolicy: <cloud-armor-policy-name>
  httpRoute:
    enabled: true

All charts should reference global.* for gateway routing and backend policy configuration.

Value Injection from Terraform

• Chart-specific values are defined as locals in deploy/helm-values.tf and passed directly to helm_release resources via yamlencode(). File-based generation under deploy/generated_values/ is currently disabled.
• Image configuration originates from var.helm_config.<chart_key> with repository and tag keys.
• Domain hostnames for HTTPRoute come from var.web_domain_name, var.api_domain_name, etc.
• Secret references use envFromSecret pointing to Kubernetes secrets created in deploy/secrets.tf.

Routing

• Gateway API resources (HTTPRoute, Gateway) are the default routing mechanism.
• Legacy GCE Ingress is optional, controlled by the enable_legacy_ingress feature flag in Terraform.
• Each chart with external access includes httproute.yaml and backend-policy.yaml templates.

Adding a New Chart

1. Create helm_charts/<name>/ with Chart.yaml, values.yaml, and templates/.
2. Copy _helpers.tpl from an existing chart and update the template name prefix.
3. Define chart-specific values as a local in deploy/helm-values.tf.
4. Add a helm_release resource in deploy/helm.tf, merging common_helm_values via yamlencode().
5. Add image configuration to the helm_config variable and environments/sample.tfvars.