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Certification track: Associate Cloud Engineer (ACE)

Cal.diy on GKE Autopilot

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.


What Cal.diy costs on RAD, and how that compares​

Cal.diy on RAD's GKE Autopilot module costs about US$129 a month in your own Google Cloud project, with no extra licence fee — Cal.diy is open source. In a project RAD manages for you, the same deployment is metered at 101 credits a day (about 3,030 a month, about US$303 at the top-up price). Or see the Cloud Run guide for the lower-cost option. If you only need Cal.diy occasionally — studying, a demo, a short-lived project — a RAD-managed project can be deleted and restored within 30 days for a few credits, so that monthly figure becomes a few dollars instead. See Pause it for free, below.

What you pay on RAD​

Cal.diy is open source, so there is no licence fee. You pay for three things:

In a Google Cloud project you ownIn a project RAD manages for you
Module fee, once per deployment110 credits (US$11 at the top-up price)99 credits (10% lower)
Build timeA few credits per build (roughly 3–6 credits)The same
Google Cloud running costBilled by Google to your own billing account, about US$129 a month for the default configuration (table below)Metered hourly in credits; RAD publishes 101 credits a day, about 3,030 a month (about US$303 at the top-up price)
Who owns whatYou own the project and its billing; RAD deploys and updates itRAD owns the project, with guardrails, quotas and budget alerts; you get console access, and a minimum purchased balance is held in reserve

10 credits cost US$1 on a one-off top-up, and less on a monthly plan. In a project RAD manages, the database, file server and network are shared by every application in the project, so a second application does not add a second database.

Default running cost in your own project (us-central1, Google list prices):

Resource (module default)Per month
GKE Autopilot pod, 2x vCPU / 2 GiBUS$72.16
Cloud SQL for PostgreSQL, 1 vCPU / 3.75 GB, zonal, 10 GB SSDUS$51.02
Cloud NAT and networkingUS$5
Cloud Storage (add-ons, backups)US$1
GKE cluster management feeshared across every GKE app in the project; $0 if this is your only cluster, else ~73
Total (excluding the shared GKE cluster fee)about US$129

These prices are the same in africa-south1 (Johannesburg).

  • GKE Autopilot does not scale to zero. At least one pod always runs, so the cost above applies whether or not anyone is using the app; extra pods are added only under load.

How it compares, for a team self-hosting without per-seat licensing​

Cal.diy exists specifically as a self-hostable fork, so there is no official hosted Cal.diy plan to compare against (Cal.com's own hosted plans are a different codebase and licence, so they are not quoted here as a stand-in). The honest comparison is a bare server:

  • A Hetzner CPX22 or DigitalOcean droplet (2 vCPU/4 GB, about US$24/month) or a GCP e2-standard-2 (2 vCPU/8 GB, about US$49/month) would run Cal.diy and its PostgreSQL database — roughly the same class of machine this module itself uses.
  • On a bare VPS you run PostgreSQL, backups, security patches and upgrades yourself. RAD's module gives you managed Cloud SQL, Secret Manager and Cloud Monitoring for the module fee plus the Google Cloud usage above.

Pause it for free: delete a RAD-managed project, restore it when you need it​

If Cal.diy runs in a project RAD manages for you, deleting the whole project — rather than deleting just this module — unlinks its billing first, then asks Google to delete the project outright. Google keeps it, recoverable, for 30 days, and because billing is already unlinked, nothing is charged while it waits. Unlike deleting one module, this does not tear down Cloud SQL, any VM or the compute resource one by one: the whole project simply stops.

  • Restoring is a check, not a rebuild. Within 30 days, the project's owner can ask Google to undelete the project and reattach its billing account, then run Update on each deployment to confirm everything came back. Because nothing was individually destroyed, that Update finds the same resources already there, and an Update never charges the module fee again. For a typical 2–3-deployment chain this costs only a handful of credits in total (roughly 5–10 credits, under US$1).
  • What this needs. You must own the project (not one RAD only manages billing for), restore it yourself within 30 days — after that Google deletes it for good — and clear the tier's admission floor again (100 credits for the sandbox tier most study/demo use fits). Google says most services are fully working again within 36 hours of a restore.
  • One real gap: nightly backups do not survive. Backups are written to a bucket inside the project, and that bucket has Cloud Storage's soft-delete turned off, so it is very likely gone as soon as the project is deleted — even though the project itself is recoverable for 30 days. Copy a backup out (to Google Drive, or a bucket outside the project) before deleting if there is anything in it worth keeping; for a default install with nothing irreplaceable, this does not matter.

Source: Delete and restore projects.

Pay only while you use it, the other way: delete and redeploy​

In your own project, or once the 30-day restore window above has passed, the way to stop paying is to delete the deployment and deploy it again when you need it.

  • What a redeploy costs. The module fee again, plus the builds: about 114 credits (about US$11.40) at the top-up price, and roughly 15–20 minutes of build time (RAD's own platform average). Deleting saves money only once Cal.diy would otherwise sit unused for about 2 days or more — in your own project that is about US$4.31 a day, and in a RAD-managed one it is 101 credits a day.
  • Most of the running cost here is usually the database and/or the shared file/cache VM or cluster. They stop only when nothing else in the project uses them, so deleting Cal.diy while another application shares the project saves only Cal.diy's own compute part.
  • Keep data first. Nightly backups go to a bucket inside the deployment and are deleted with it, so copy the latest backup out before deleting if you want to keep it.

Lab sessions and Managed Environments​

  • Lab sessions, for training. A trainer runs a session for a class. Each participant gets the app in their own Google Cloud project for 15 minutes to 24 hours, within an allowance the trainer sets. Either the trainer funds every place, or each participant pays for their own. Everything is deleted when the session ends and unused credits go back to the trainer.
  • Managed Environments, for consultancies. A partner runs the app for a client from a ring-fenced wallet it funds, and settles with the client directly. If the wallet runs low, billing pauses and the data is kept, so nobody receives an unexpected charge. At the end the partner hands the project over and the deployments become the client's own.

Credits can be bought in more than 20 currencies, including XAF, XOF, NGN, GHS, KES and ZAR, by card, bank transfer or mobile money.

Sources (8 October 2026): Google Cloud list prices from the Cloud Billing Catalog API; RAD fees and the daily-credit estimate from radmodules.dev/pricing; Delete and restore projects for the pause/restore window and backup-bucket caveat; prices change, check each source before relying on a figure.

1. Overview​

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

CapabilityGoogle Cloud serviceNotes
ComputeGKE AutopilotNext.js pods, 2 vCPU / 2 GiB by default, horizontally autoscaled
DatabaseCloud SQL for PostgreSQL 15Required — Cal.diy uses Prisma ORM targeting PostgreSQL
Object storageCloud StorageA data bucket provisioned by default
SecretsSecret ManagerAuto-generated NEXTAUTH_SECRET and CALENDSO_ENCRYPTION_KEY
IngressCloud Load BalancingExternal 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).

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

3. Cal.diy Application Behaviour​

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

    JobImagePurpose
    db-initpostgres:15-alpineCreates the PostgreSQL database and user, grants privileges
    db-migrateCal.diy app imageRuns prisma migrate deploy to apply the full schema
    seed-app-storeCal.diy app imageSeeds 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.

  • Reminders need an external cron call. Bookings work without scheduled jobs, but cal.com sends booking and Workflow reminders only when something calls its /api/cron/* endpoints with the shared CRON_API_KEY. With no key those calls are rejected (401) and no reminder ever fires, while the app otherwise looks healthy. To enable reminders, set cron_api_key (stored in Secret Manager) and add a cron_jobs entry that calls the endpoint.


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​

VariableDefaultDescription
project_id(required)Target Google Cloud project.
regionus-central1Region for the workload and regional resources.

Group 2 — Deployment Environment​

VariableDefaultDescription
tenant_iddemoShort 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​

VariableDefaultDescription
application_namecaldiyBase name for resources. Do not change after first deploy.
application_display_nameCal.com SchedulingFriendly name shown in the Console.
application_description(set)Workload description annotation.
application_versionv6.2.0Cal.diy image version tag — no latest tag exists, always pin to a versioned release.

Group 4 — Runtime & Scaling​

VariableDefaultDescription
deploy_applicationtrueSet false to provision infrastructure only.
container_image_sourcecustomcustom builds the wrapper image via Cloud Build; prebuilt uses the official Cal.diy image. Keep it the same as the Cloud Run variant: both publish to the same image tag, so a prebuilt variant would overwrite the custom 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_port3000Cal.diy's native Next.js port. Do not change.
container_protocolhttp1HTTP protocol version: http1 or h2c.
min_instance_count1Minimum replicas. GKE Autopilot has no scale-to-zero by default; keep ≥ 1.
max_instance_count5Maximum replicas (autoscaler ceiling).
enable_cloudsql_volumetrueCloud SQL Auth Proxy sidecar for socket connections. Must be true when database_type != "NONE".
enable_image_mirroringtrueMirror the Cal.diy image into Artifact Registry before deployment.
enable_vertical_pod_autoscalingfalseLet Autopilot tune resource requests automatically.
timeout_seconds300Maximum seconds the load balancer waits for a pod response.

Group 5 — Environment Variables & Secrets​

VariableDefaultDescription
environment_variablesSMTP skeletonPlain-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_delay30Seconds to wait after secret creation before proceeding.
secret_rotation_period2592000sSecret Manager rotation notification period.
enable_auto_password_rotationfalseZero-downtime DB password rotation.
rotation_propagation_delay_sec90Seconds to wait after rotation before restarting pods.

Group 6 — GKE Backend & Cluster​

VariableDefaultDescription
gke_cluster_name""GKE cluster name; auto-discovered if empty.
namespace_name""Kubernetes namespace; auto-generated if empty.
service_typeLoadBalancerHow the Service is exposed.
workload_typenullAuto-resolves to StatefulSet when per-pod storage is enabled.
session_affinityNoneNone recommended — Cal.diy sessions are stored in PostgreSQL.
network_tags['nfsserver']Node/pod tags for VPC firewall rules.
deployment_timeout1800Maximum seconds Terraform waits for rollout to complete.

Group 7 — Reliability Policies​

VariableDefaultDescription
enable_pod_disruption_budgetfalseProtect availability during node upgrades. Enable when max_instance_count > 1.
pdb_min_available1Minimum pods available during disruptions.
enable_topology_spreadfalseSpread pods across availability zones.
topology_spread_strictfalseReject pods if zone spread cannot be satisfied.

Group 8 — Resource Quota​

VariableDefaultDescription
enable_resource_quotafalseCap 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​

VariableDefaultDescription
startup_probe / startup_probe_configHTTP /api/auth/session, 60s delay, 12 × 10s failure windowCal.diy's /api/auth/session returns 200 when NextAuth is ready.
liveness_probe / health_check_configHTTP /api/auth/sessionLiveness probe after startup.
uptime_check_configdisabledOptional Cloud Monitoring uptime check.
alert_policies[]Optional metric alert policies.

Group 11 — Jobs & Scheduled Tasks​

VariableDefaultDescription
initialization_jobs[]Leave empty to use the built-in db-init, db-migrate, and seed-app-store jobs.
cron_jobs[]Recurring Kubernetes CronJobs. Needed for reminders: add one that calls /api/cron/* with CRON_API_KEY (see cron_api_key).
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)​

VariableDefaultDescription
enable_nfsfalseNFS is not required for Cal.diy — enable only if custom storage is needed.
nfs_mount_path/mnt/nfsMount path inside the container.

Group 14 — Cloud Storage & Artifact Registry​

VariableDefaultDescription
create_cloud_storagetrueProvision 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_cmekfalseCMEK options.

Group 15 — StatefulSet​

VariableDefaultDescription
stateful_pvc_enabledfalseEnable PVC templates (auto-selects StatefulSet).
stateful_pvc_size10GiStorage size per PVC.
stateful_pvc_mount_path/dataContainer path where the PVC is mounted.
stateful_pvc_storage_class""Kubernetes StorageClass; uses cluster default if empty.
stateful_headless_servicefalseHeadless Service for stable DNS pod identities.
stateful_pod_management_policyOrderedReadyOrderedReady or Parallel.
stateful_update_strategyRollingUpdateRollingUpdate or OnDelete.
stateful_fs_groupnullfsGroup GID for volume ownership.

Group 16 — Database Backend​

VariableDefaultDescription
database_typePOSTGRES_15Fixed — do not change. Cal.diy requires PostgreSQL.
application_database_namecalcomDatabase name. Immutable after first deploy.
application_database_usercalcomApplication user. Immutable after first deploy.
database_password_length32Generated password length (16–64).
enable_postgres_extensionsfalseInstall PostgreSQL extensions after provisioning.
postgres_extensions[]List of extensions to install (e.g., ['uuid-ossp']).

Group 17 — Backup & Maintenance​

VariableDefaultDescription
backup_schedule0 2 * * *Automated backup cron (UTC).
backup_retention_days7Retention; raise to 30–90 for production/compliance.
enable_backup_import / backup_source / backup_uri / backup_formatrestore optionsRestore 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​

VariableDefaultDescription
enable_custom_domaintrueProvision Ingress for custom hostnames + managed certificate.
application_domains[]Hostnames to serve. When set, also update NEXT_PUBLIC_WEBAPP_URL in environment_variables.
reserve_static_iptrueStable external IP across redeploys.
enable_cdnfalseEnable Cloud CDN on the load balancer backend.

Group 20 — Identity-Aware Proxy (IAP)​

VariableDefaultDescription
enable_iapfalseRequire 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​

VariableDefaultDescription
enable_redisfalseUse Redis for session caching. Recommended when max_instance_count > 1.
redis_host""Redis endpoint. Required when enable_redis = true.
redis_port6379Redis port.
redis_auth""Optional Redis auth password (sensitive).
enable_cloud_armorfalseAttach a Cloud Armor (WAF) policy to the Ingress backend.
admin_ip_ranges[]CIDRs allowed privileged access.
cloud_armor_policy_namedefault-waf-policyCloud Armor policy name.

Group 22 — VPC Service Controls & Audit Logging​

VariableDefaultDescription
enable_vpc_scfalseEnforce a VPC-SC perimeter (requires organization_id).
vpc_cidr_ranges / vpc_sc_dry_run(set)Access level CIDRs / dry-run mode.
enable_audit_loggingfalseDetailed Cloud Audit Logs.

5. Outputs​

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

OutputDescription
service_nameKubernetes Service name.
namespaceNamespace the workload runs in.
service_cluster_ipIn-cluster ClusterIP.
stage_service_cluster_ipsMap of ClusterIPs for stage-specific services (Cloud Deploy).
service_external_ipExternal LoadBalancer IP (when a static IP is reserved).
service_urlURL to reach Cal.diy.
database_instance_nameCloud SQL instance name.
database_nameApplication database name.
database_userApplication database user.
database_password_secretSecret Manager secret holding the DB password.
database_host / database_portDB endpoint (127.0.0.1 via Auth Proxy) / port.
storage_bucketsCreated Cloud Storage buckets.
network_name / network_exists / regionsVPC network, presence, available regions.
container_image / container_registryDeployed image and Artifact Registry repo.
monitoring_enabled / monitoring_notification_channelsMonitoring status and channels.
initialization_jobs / db_import_jobNames of the setup and (optional) import jobs.
deployment_id / tenant_id / resource_prefixNaming identifiers.
project_id / project_numberProject identifiers.
cicd_enabled / github_repository_url / github_repository_owner / github_repository_name / cicd_configurationCI/CD status and details.
artifact_registry_repository / cloudbuild_trigger_name / cloudbuild_trigger_idRegistry and build trigger.
kubernetes_readyWhether the cluster/workload is ready.
vpc_sc_enabled / vpc_sc_perimeter_name / vpc_sc_dry_run_modeVPC-SC status.
audit_logging_enabled / artifact_registry_cmek_enabledAudit logging and CMEK status.

6. Configuration Pitfalls & Sensible Defaults​

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

SettingSensible valueRiskConsequence if wrong
database_typePOSTGRES_15CriticalCal.diy requires PostgreSQL with Prisma ORM; MySQL or NONE breaks schema migrations and startup.
container_port3000CriticalCal.diy's Next.js server listens on 3000; any other value misdirects health checks and traffic routing.
enable_cloudsql_volumetrueCriticalCal.diy connects to Cloud SQL via Unix socket; disabling removes the socket and all DB connections fail.
application_database_name / _userset onceCriticalImmutable after first deploy; renaming recreates the DB/user and orphans existing data.
application_versionpinned releaseCriticalcalcom/cal.diy has no latest tag; an invalid version fails the image pull.
enable_backup_importfalse unless restoringCriticalEnabling without a valid backup_uri fails the import job and may overwrite live data on subsequent applies.
NEXT_PUBLIC_WEBAPP_URLmatch public URLCriticalCal.diy embeds this in Next.js chunks; a mismatch breaks OAuth callbacks and booking links.
NEXTAUTH_URLmatch public URLCriticalNextAuth validates OAuth redirect URIs against this; a mismatch blocks all logins.
quota_memory_requests / _limitsbinary unitsCriticalBare integers are bytes — blocks all pod scheduling.
container_resources.memory_limit2Gi minimumHighCal.diy startup (DB migration + seed) requires ≥ 2 GiB; OOM kills before the app is ready.
startup_probe.failure_threshold12 (10s period ≈ 2 min)HighReducing too aggressively kills pods before db-migrate and seed-app-store complete.
enable_redistrue for multi-replicaHighWithout Redis, sessions are per-pod; users are logged out when requests land on different pods.
redis_hostrequired when enable_redis=trueHighEmpty redis_host with Redis enabled injects a malformed URL; session operations fail at runtime.
enable_pod_disruption_budgettrue when max > 1MediumWithout PDB, cluster maintenance can evict all pods simultaneously.
pdb_min_available vs min_instance_countleave headroomMedium1/1 can stall node upgrades (single pod cannot be evicted).
enable_topology_spreadenable for productionMediumWithout spread, all replicas may run in a single zone; a zone failure takes down the service.
min_instance_count1MediumCal.diy's first-boot startup is 3–5 minutes; 0 with scale-to-zero adds significant cold-start latency.
SMTP_HOST / EMAIL_FROMreal SMTP configMediumWithout valid SMTP, booking confirmations, reminders, and password resets are never delivered.
organization_idset explicitly for VPC-SCMediumVPC-SC perimeter is only activated when organization_id is set; enable_vpc_sc = true alone has no effect.

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 CalDiy_Common.

Need RAD to do something it does not do yet? Request it on the roadmap, or vote on what is already there.