Cal.diy on GKE Autopilot

Cal.diy is the MIT-licensed, self-hostable fork of Cal.com — the open-source scheduling platform used by millions worldwide to eliminate back-and-forth meeting coordination. This module deploys Cal.diy on GKE Autopilot on top of the App_GKE foundation, which provisions and manages the shared Google Cloud and Kubernetes infrastructure.

This guide focuses on the cloud services Cal.diy uses and how to explore and operate them from the Google Cloud Console and the command line. For the mechanics that are common to every GKE application — Workload Identity, ingress, autoscaling, CI/CD, Cloud Armor, IAP, Binary Authorization, VPC Service Controls, backups, and the deployment lifecycle — refer to the App_GKE foundation guide rather than repeating them here.

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1. Overview

Cal.diy runs as a Next.js (Node.js) web workload. The deployment wires together a focused set of Google Cloud services:

Capability	Google Cloud service	Notes
Compute	GKE Autopilot	Next.js pods, 2 vCPU / 2 GiB by default, horizontally autoscaled
Database	Cloud SQL for PostgreSQL 15	Required — Cal.diy uses Prisma ORM targeting PostgreSQL
Object storage	Cloud Storage	A data bucket provisioned by default
Secrets	Secret Manager	Auto-generated NEXTAUTH_SECRET and CALENDSO_ENCRYPTION_KEY
Ingress	Cloud Load Balancing	External LoadBalancer, optional custom domain + managed certificate

Sensible defaults worth knowing up front:

• PostgreSQL 15 is mandatory. The database engine is fixed; selecting MySQL or NONE breaks startup.
• Redis is disabled by default. Enable it for multi-replica deployments to share session state across pods.
• Session affinity is None by default. Cal.diy stores sessions in PostgreSQL (NextAuth.js), so sticky routing is not required — but enabling Redis is recommended for multi-replica production.
• Three initialization jobs run on first deploy: db-init (PostgreSQL setup), db-migrate (Prisma schema migrations), and seed-app-store (seeds the Cal.diy app store table). All are idempotent and run sequentially.
• NEXTAUTH_SECRET and CALENDSO_ENCRYPTION_KEY are generated automatically and stored in Secret Manager; you never set them in plain text.
• NEXT_PUBLIC_WEBAPP_URL and NEXTAUTH_URL are set to the $(GKE_SERVICE_URL) sentinel, which App_GKE resolves to the actual LoadBalancer IP or custom domain at apply time.
• calcom/cal.diy has no latest tag — always pin application_version to a versioned release (e.g., v6.2.0).

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2. Google Cloud Services & How to Explore Them

All commands assume you have run gcloud container clusters get-credentials <cluster> --region <region> --project <project> and that PROJECT, REGION, and NAMESPACE are set. The namespace and other identifiers are reported in the deployment Outputs.

A. GKE Autopilot — the Cal.diy workload

Cal.diy pods are scheduled on Autopilot, which bills for the CPU/memory the pods actually request. Horizontal Pod Autoscaling sizes the deployment between the minimum and maximum replica counts.

• Console: Kubernetes Engine → Workloads → select the Cal.diy workload to see pods, revisions, and events. Kubernetes Engine → Services & Ingress shows the external IP.
• CLI:

  kubectl get pods,svc,hpa -n "$NAMESPACE"
  kubectl logs -n "$NAMESPACE" deploy/<service-name> --tail=100
  kubectl describe hpa -n "$NAMESPACE"          # current vs target utilisation

See App_GKE for how Autopilot, scaling, and the workload type (Deployment vs StatefulSet) are managed.

B. Cloud SQL for PostgreSQL 15

Cal.diy stores all application data (bookings, users, schedules, integrations) in a managed Cloud SQL for PostgreSQL 15 instance. Pods reach it privately through the Cloud SQL Auth Proxy sidecar over a Unix socket, so no public IP is exposed. On first deploy a sequence of initialization Jobs creates the database and user, runs Prisma schema migrations, and seeds the app store.

• Console: SQL → select the instance for connections, backups, flags, and metrics.
• CLI:

  gcloud sql instances list --project "$PROJECT"
  gcloud sql instances describe <instance-name> --project "$PROJECT"
  # Open an interactive shell to inspect schema/data:
  gcloud sql connect <instance-name> --user=<db-user> --database=<db-name> --project "$PROJECT"

The instance name, database name, user, and the Secret Manager secret holding the password are all surfaced in the Outputs. For the connection model, automated backups, and password rotation, see App_GKE.

C. Cloud Storage

A default Cloud Storage bucket (suffix data) is provisioned and the workload service account is granted access automatically. Cal.diy does not require shared NFS storage by default — the database stores all booking state.

• Console: Cloud Storage → Buckets.
• CLI:

  gcloud storage buckets list --project "$PROJECT"
  gcloud storage ls gs://<data-bucket>/          # bucket name is in the Outputs

See App_GKE for CMEK and additional bucket options.

D. Secret Manager

NEXTAUTH_SECRET (NextAuth.js session signing) and CALENDSO_ENCRYPTION_KEY (Cal.diy data encryption) are generated automatically and stored as Secret Manager secrets. The database password is also managed here. Secrets are injected into pods at runtime; plaintext never appears in configuration.

• Console: Security → Secret Manager.
• CLI:

  gcloud secrets list --project "$PROJECT"
  gcloud secrets versions access latest --secret=<secret-name> --project "$PROJECT"

The database password secret name is in the Outputs. See App_GKE for the Secret Store CSI integration and rotation.

E. Networking & ingress

By default the workload is exposed through an external Cloud Load Balancing IP. A custom domain with a Google-managed certificate can be enabled, and a static IP can be reserved so the address survives redeploys.

• Console: Network services → Load balancing; VPC network → IP addresses.
• CLI:

  kubectl get ingress,svc -n "$NAMESPACE"
  gcloud compute addresses list --project "$PROJECT"

See App_GKE for custom domains, Cloud CDN, and static IP details.

F. Cloud Logging & Monitoring

Pod stdout/stderr flow to Cloud Logging; GKE and Cloud SQL metrics flow to Cloud Monitoring. Optional uptime checks and alert policies are available.

• Console: Logging → Logs Explorer; Monitoring → Dashboards / Alerting.
• CLI:

  gcloud logging read 'resource.type="k8s_container" AND resource.labels.namespace_name="'"$NAMESPACE"'"' \
    --project "$PROJECT" --limit 50

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3. Cal.diy Application Behaviour

• First-deploy initialization sequence. Three Kubernetes Jobs run before the application starts, in order:

  Job	Image	Purpose
  db-init	postgres:15-alpine	Creates the PostgreSQL database and user, grants privileges
  db-migrate	Cal.diy app image	Runs prisma migrate deploy to apply the full schema
  seed-app-store	Cal.diy app image	Seeds the App table with available integrations

  All three are idempotent and safe to re-run. Inspect their status:

  kubectl get jobs -n "$NAMESPACE" --sort-by=.metadata.creationTimestamp
  kubectl logs -n "$NAMESPACE" job/db-init
  kubectl logs -n "$NAMESPACE" job/db-migrate
  kubectl logs -n "$NAMESPACE" job/seed-app-store

• DATABASE_URL assembly. The entrypoint script assembles DATABASE_URL and DATABASE_DIRECT_URL from DB_* environment variables at container start, then launches the Next.js server. This makes database connectivity independent of which image variant (base mirror or CI/CD-built) is deployed.

• Startup probe. Health probes target /api/auth/session (HTTP 200 when NextAuth is ready). A generous startup window (initial_delay=60s, failure_threshold=12, period=10s ≈ 2 minutes) accommodates db-migrate and seed-app-store which must complete before the application serves requests.

• Public URL wiring. NEXT_PUBLIC_WEBAPP_URL and NEXTAUTH_URL are set to the $(GKE_SERVICE_URL) sentinel at deploy time. App_GKE replaces this with the actual LoadBalancer IP or custom domain. When using a custom domain, set NEXT_PUBLIC_WEBAPP_URL in environment_variables to the custom domain URL so OAuth callbacks and booking links are correct.

• Email (SMTP). Cal.diy uses SMTP for booking confirmations, cancellation notices, reminders, and password resets. Configure SMTP_HOST, SMTP_PORT, SMTP_USER, EMAIL_FROM in environment_variables and store SMTP_PASSWORD as a secret_environment_variables reference before going live.

• No scheduled tasks required. Unlike traditional queue-based apps, Cal.diy does not require separately scheduled background jobs — bookings and reminders are handled by Next.js API routes triggered by calendar webhooks and client interactions.

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4. Configuration Variables

Variables are grouped exactly as they appear on the deployment platform. Only settings specific to or notable for Cal.diy are listed; every other input is inherited from App_GKE with its standard behaviour and defaults.

Group 1 — Project & Identity

Variable	Default	Description
project_id	(required)	Target Google Cloud project.
region	us-central1	Region for the workload and regional resources.

Group 2 — Deployment Environment

Variable	Default	Description
tenant_deployment_id	demo	Short suffix that makes resource names unique per environment.
support_users	[]	Emails granted project access and monitoring alerts.
resource_labels	{}	Labels applied to all resources for cost/ownership tracking.

Group 3 — Application Identity

Variable	Default	Description
application_name	cal	Base name for resources. Do not change after first deploy.
application_display_name	Cal.com Scheduling	Friendly name shown in the Console.
application_description	(set)	Workload description annotation.
application_version	v6.2.0	Cal.diy image version tag — no latest tag exists, always pin to a versioned release.

Group 4 — Runtime & Scaling

Variable	Default	Description
deploy_application	true	Set false to provision infrastructure only.
container_image_source	prebuilt	prebuilt uses the official Cal.diy image; custom builds via Cloud Build.
container_image	""	Override container image URI. Leave empty to use default.
container_resources	{ cpu_limit="2000m", memory_limit="2Gi" }	CPU and memory limits; raise memory_limit to 4Gi for production multi-user load.
container_port	3000	Cal.diy's native Next.js port. Do not change.
container_protocol	http1	HTTP protocol version: http1 or h2c.
min_instance_count	1	Minimum replicas. GKE Autopilot has no scale-to-zero by default; keep ≥ 1.
max_instance_count	5	Maximum replicas (autoscaler ceiling).
enable_cloudsql_volume	true	Cloud SQL Auth Proxy sidecar for socket connections. Must be true when database_type != "NONE".
enable_image_mirroring	true	Mirror the Cal.diy image into Artifact Registry before deployment.
enable_vertical_pod_autoscaling	false	Let Autopilot tune resource requests automatically.
timeout_seconds	300	Maximum seconds the load balancer waits for a pod response.

Group 5 — Environment Variables & Secrets

Variable	Default	Description
environment_variables	SMTP skeleton	Plain-text settings. Set SMTP_HOST, SMTP_PORT, SMTP_USER, EMAIL_FROM here. Also set NEXT_PUBLIC_WEBAPP_URL once a custom domain is known.
secret_environment_variables	{}	Map of env var → Secret Manager secret name. Use for SMTP_PASSWORD.
secret_propagation_delay	30	Seconds to wait after secret creation before proceeding.
secret_rotation_period	2592000s	Secret Manager rotation notification period.
enable_auto_password_rotation	false	Zero-downtime DB password rotation.
rotation_propagation_delay_sec	90	Seconds to wait after rotation before restarting pods.

Group 6 — GKE Backend & Cluster

Variable	Default	Description
gke_cluster_name	""	GKE cluster name; auto-discovered if empty.
namespace_name	""	Kubernetes namespace; auto-generated if empty.
service_type	LoadBalancer	How the Service is exposed.
workload_type	null	Auto-resolves to StatefulSet when per-pod storage is enabled.
session_affinity	None	None recommended — Cal.diy sessions are stored in PostgreSQL.
network_tags	['nfsserver']	Node/pod tags for VPC firewall rules.
deployment_timeout	1800	Maximum seconds Terraform waits for rollout to complete.

Group 7 — Reliability Policies

Variable	Default	Description
enable_pod_disruption_budget	false	Protect availability during node upgrades. Enable when max_instance_count > 1.
pdb_min_available	1	Minimum pods available during disruptions.
enable_topology_spread	false	Spread pods across availability zones.
topology_spread_strict	false	Reject pods if zone spread cannot be satisfied.

Group 8 — Resource Quota

Variable	Default	Description
enable_resource_quota	false	Cap namespace CPU/memory/object counts.
quota_memory_requests / quota_memory_limits	""	Must use binary units (4Gi, 8192Mi) — bare integers are read as bytes and block scheduling.

Group 10 — Observability & Health

Variable	Default	Description
startup_probe / startup_probe_config	HTTP /api/auth/session, 60s delay, 12 × 10s failure window	Cal.diy's /api/auth/session returns 200 when NextAuth is ready.
liveness_probe / health_check_config	HTTP /api/auth/session	Liveness probe after startup.
uptime_check_config	disabled	Optional Cloud Monitoring uptime check.
alert_policies	[]	Optional metric alert policies.

Group 11 — Jobs & Scheduled Tasks

Variable	Default	Description
initialization_jobs	[]	Leave empty to use the built-in db-init, db-migrate, and seed-app-store jobs.
cron_jobs	[]	Recurring Kubernetes CronJobs. Cal.diy does not require scheduled tasks by default.
additional_services	[]	Sidecar or helper services to run alongside the main container.

Group 12 — CI/CD & GitHub Integration

Standard App_GKE Cloud Build / Cloud Deploy integration — see App_GKE. Key inputs: enable_cicd_trigger, github_repository_url, github_token, enable_cloud_deploy.

Group 13 — Filesystem (NFS)

Variable	Default	Description
enable_nfs	false	NFS is not required for Cal.diy — enable only if custom storage is needed.
nfs_mount_path	/mnt/nfs	Mount path inside the container.

Group 14 — Cloud Storage & Artifact Registry

Variable	Default	Description
create_cloud_storage	true	Provision the default data bucket.
storage_buckets	[{ name_suffix = "data" }]	Additional buckets to provision.
gcs_volumes	[]	GCS Fuse mounts.
manage_storage_kms_iam / enable_artifact_registry_cmek	false	CMEK options.

Group 15 — StatefulSet

Variable	Default	Description
stateful_pvc_enabled	false	Enable PVC templates (auto-selects StatefulSet).
stateful_pvc_size	10Gi	Storage size per PVC.
stateful_pvc_mount_path	/data	Container path where the PVC is mounted.
stateful_pvc_storage_class	""	Kubernetes StorageClass; uses cluster default if empty.
stateful_headless_service	false	Headless Service for stable DNS pod identities.
stateful_pod_management_policy	OrderedReady	OrderedReady or Parallel.
stateful_update_strategy	RollingUpdate	RollingUpdate or OnDelete.
stateful_fs_group	null	fsGroup GID for volume ownership.

Group 16 — Database Backend

Variable	Default	Description
database_type	POSTGRES_15	Fixed — do not change. Cal.diy requires PostgreSQL.
application_database_name	calcom	Database name. Immutable after first deploy.
application_database_user	calcom	Application user. Immutable after first deploy.
database_password_length	32	Generated password length (16–64).
enable_postgres_extensions	false	Install PostgreSQL extensions after provisioning.
postgres_extensions	[]	List of extensions to install (e.g., ['uuid-ossp']).

Group 17 — Backup & Maintenance

Variable	Default	Description
backup_schedule	0 2 * * *	Automated backup cron (UTC).
backup_retention_days	7	Retention; raise to 30–90 for production/compliance.
enable_backup_import / backup_source / backup_uri / backup_format	restore options	Restore from a backup on deploy.

Group 18 — Custom SQL Scripts

enable_custom_sql_scripts, custom_sql_scripts_bucket, custom_sql_scripts_path, custom_sql_scripts_use_root — run SQL from a GCS bucket after provisioning. See App_GKE.

Group 19 — Custom Domain, Static IP & Networking

Variable	Default	Description
enable_custom_domain	true	Provision Ingress for custom hostnames + managed certificate.
application_domains	[]	Hostnames to serve. When set, also update NEXT_PUBLIC_WEBAPP_URL in environment_variables.
reserve_static_ip	true	Stable external IP across redeploys.
enable_cdn	false	Enable Cloud CDN on the load balancer backend.

Group 20 — Identity-Aware Proxy (IAP)

Variable	Default	Description
enable_iap	false	Require Google sign-in in front of Cal.diy.
iap_authorized_users / iap_authorized_groups	[]	Who may access.
iap_oauth_client_id / iap_oauth_client_secret	""	Required when IAP is enabled (sensitive).
iap_support_email	""	Shown on the OAuth consent screen.

Group 21 — Redis Cache

Variable	Default	Description
enable_redis	false	Use Redis for session caching. Recommended when max_instance_count > 1.
redis_host	""	Redis endpoint. Required when enable_redis = true.
redis_port	6379	Redis port.
redis_auth	""	Optional Redis auth password (sensitive).
enable_cloud_armor	false	Attach a Cloud Armor (WAF) policy to the Ingress backend.
admin_ip_ranges	[]	CIDRs allowed privileged access.
cloud_armor_policy_name	default-waf-policy	Cloud Armor policy name.

Group 22 — VPC Service Controls & Audit Logging

Variable	Default	Description
enable_vpc_sc	false	Enforce a VPC-SC perimeter (requires organization_id).
vpc_cidr_ranges / vpc_sc_dry_run	(set)	Access level CIDRs / dry-run mode.
enable_audit_logging	false	Detailed Cloud Audit Logs.

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5. Outputs

These values are returned on a successful deployment and are the quickest way to locate and explore the running resources.

Output	Description
service_name	Kubernetes Service name.
namespace	Namespace the workload runs in.
service_cluster_ip	In-cluster ClusterIP.
stage_service_cluster_ips	Map of ClusterIPs for stage-specific services (Cloud Deploy).
service_external_ip	External LoadBalancer IP (when a static IP is reserved).
service_url	URL to reach Cal.diy.
database_instance_name	Cloud SQL instance name.
database_name	Application database name.
database_user	Application database user.
database_password_secret	Secret Manager secret holding the DB password.
database_host / database_port	DB endpoint (127.0.0.1 via Auth Proxy) / port.
storage_buckets	Created Cloud Storage buckets.
network_name / network_exists / regions	VPC network, presence, available regions.
container_image / container_registry	Deployed image and Artifact Registry repo.
monitoring_enabled / monitoring_notification_channels	Monitoring status and channels.
initialization_jobs / db_import_job	Names of the setup and (optional) import jobs.
deployment_id / tenant_id / resource_prefix	Naming identifiers.
project_id / project_number	Project identifiers.
cicd_enabled / github_repository_url / github_repository_owner / github_repository_name / cicd_configuration	CI/CD status and details.
artifact_registry_repository / cloudbuild_trigger_name / cloudbuild_trigger_id	Registry and build trigger.
kubernetes_ready	Whether the cluster/workload is ready.
vpc_sc_enabled / vpc_sc_perimeter_name / vpc_sc_dry_run_mode	VPC-SC status.
audit_logging_enabled / artifact_registry_cmek_enabled	Audit logging and CMEK status.

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6. Configuration Pitfalls & Sensible Defaults

Risk: Critical (data loss / outage / security) — High (service degraded) — Medium (cost or partial degradation) — Low (minor).

Setting	Sensible value	Risk	Consequence if wrong
database_type	POSTGRES_15	Critical	Cal.diy requires PostgreSQL with Prisma ORM; MySQL or NONE breaks schema migrations and startup.
container_port	3000	Critical	Cal.diy's Next.js server listens on 3000; any other value misdirects health checks and traffic routing.
enable_cloudsql_volume	true	Critical	Cal.diy connects to Cloud SQL via Unix socket; disabling removes the socket and all DB connections fail.
application_database_name / _user	set once	Critical	Immutable after first deploy; renaming recreates the DB/user and orphans existing data.
application_version	pinned release	Critical	calcom/cal.diy has no latest tag; an invalid version fails the image pull.
enable_backup_import	false unless restoring	Critical	Enabling without a valid backup_uri fails the import job and may overwrite live data on subsequent applies.
NEXT_PUBLIC_WEBAPP_URL	match public URL	Critical	Cal.diy embeds this in Next.js chunks; a mismatch breaks OAuth callbacks and booking links.
NEXTAUTH_URL	match public URL	Critical	NextAuth validates OAuth redirect URIs against this; a mismatch blocks all logins.
quota_memory_requests / _limits	binary units	Critical	Bare integers are bytes — blocks all pod scheduling.
container_resources.memory_limit	2Gi minimum	High	Cal.diy startup (DB migration + seed) requires ≥ 2 GiB; OOM kills before the app is ready.
startup_probe.failure_threshold	12 (10s period ≈ 2 min)	High	Reducing too aggressively kills pods before db-migrate and seed-app-store complete.
enable_redis	true for multi-replica	High	Without Redis, sessions are per-pod; users are logged out when requests land on different pods.
redis_host	required when enable_redis=true	High	Empty redis_host with Redis enabled injects a malformed URL; session operations fail at runtime.
enable_pod_disruption_budget	true when max > 1	Medium	Without PDB, cluster maintenance can evict all pods simultaneously.
pdb_min_available vs min_instance_count	leave headroom	Medium	1/1 can stall node upgrades (single pod cannot be evicted).
enable_topology_spread	enable for production	Medium	Without spread, all replicas may run in a single zone; a zone failure takes down the service.
min_instance_count	1	Medium	Cal.diy's first-boot startup is 3–5 minutes; 0 with scale-to-zero adds significant cold-start latency.
SMTP_HOST / EMAIL_FROM	real SMTP config	Medium	Without valid SMTP, booking confirmations, reminders, and password resets are never delivered.
organization_id	set explicitly for VPC-SC	Medium	VPC-SC perimeter is only activated when organization_id is set; enable_vpc_sc = true alone has no effect.

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For the foundation behaviour referenced throughout — IAM and Workload Identity, autoscaling, ingress and certificates, CI/CD, Cloud Armor, IAP, Binary Authorization, VPC-SC, backups, and image mirroring — see App_GKE. Cal.diy-specific application configuration shared with the Cloud Run variant is described in Cal_Common.