Moodle on GKE Autopilot

Moodle is the world's most popular open-source Learning Management System (LMS), used by universities, schools, corporations, and online training providers worldwide. This module deploys Moodle 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 Moodle uses and how to explore and operate them from the Google Cloud Console and the command line. For the mechanics 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

Moodle runs as a PHP 8.3/Apache web workload backed by PostgreSQL. The deployment wires together a focused set of Google Cloud services:

Capability	Google Cloud service	Notes
Compute	GKE Autopilot	PHP 8.3/Apache pods, 2 vCPU / 4 GiB by default, horizontally autoscaled
Database	Cloud SQL for PostgreSQL 15	Required — Moodle does not support MySQL in this deployment
Shared files	Filestore (NFS)	Moodle moodledata directory shared across all replicas; mandatory
Object storage	Cloud Storage	A data bucket and any additional user-defined buckets
Cache & sessions	Redis	Enabled by default; falls back to the NFS host IP when no Redis host is given
Secrets	Secret Manager	Auto-generated cron password, SMTP password, and database password
Scheduler	Cloud Scheduler	Auto-provisioned cron job (every minute) against /admin/cron.php
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 and MOODLE_DB_TYPE = "pgsql" is hardcoded; selecting MySQL or NONE breaks startup.
• NFS is mandatory. The Moodle moodledata directory must be a shared writable filesystem accessible across all replicas. enable_nfs defaults to true.
• Redis is enabled by default. With more than one replica, a shared cache is required to keep PHP session and Moodle application state consistent across pods.
• Session affinity is ClientIP. Moodle relies on PHP sessions, so requests from a browser are pinned to one pod.
• Custom domain is enabled by default (enable_custom_domain = true) so Moodle's wwwroot resolves to a stable address rather than a transient pod IP.
• A Cloud Scheduler job is auto-provisioned. It fires every minute to /admin/cron.php using a secure, auto-generated cron password stored in Secret Manager.
• The cron password and SMTP password are generated automatically and stored in Secret Manager; you never set them in plain text.

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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 Moodle workload

Moodle 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 Moodle 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

Moodle stores all application data (courses, users, grades, activity logs) 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 an initialization job creates the application database and user and enables the pg_trgm extension for Moodle's full-text search.

• 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. Filestore (NFS) and Cloud Storage

Moodle's moodledata directory is written to a Filestore (NFS) share mounted into every pod so all replicas see the same uploaded files, course materials, and user submissions. A dedicated Cloud Storage data bucket is also provisioned; the workload service account is granted access automatically.

• Console: Filestore → Instances for the NFS share; Cloud Storage → Buckets for the data bucket.
• CLI:

  gcloud filestore instances list --project "$PROJECT"
  gcloud storage buckets list --project "$PROJECT"
  gcloud storage ls gs://<data-bucket>/          # bucket name is in the Outputs
  # Confirm the NFS share is mounted inside a pod:
  kubectl exec -n "$NAMESPACE" deploy/<service-name> -- df -h | grep nfs

See App_GKE for NFS provisioning, GCS Fuse, and CMEK options.

D. Redis cache

Redis backs Moodle's PHP session handling and application cache. When no external Redis host is configured and NFS is enabled, the NFS host IP is used as the Redis endpoint — suitable for development. For production with multiple replicas, set redis_host to a Cloud Memorystore instance IP.

• Console: Memorystore → Redis (if using a managed instance).
• CLI:

  redis-cli -h <redis-host> ping           # from a host with network access
  redis-cli -h <redis-host> info keyspace

E. Secret Manager

The Moodle cron password and SMTP password are generated automatically by Moodle_Common and stored as Secret Manager secrets. The database password is generated and managed by the foundation. All three are injected into pods at runtime; plaintext never appears in configuration files.

• 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. After deployment, update the SMTP password secret with your real SMTP credential:

echo -n "your-smtp-password" | \
  gcloud secrets versions add <smtp-password-secret> --data-file=- --project "$PROJECT"

See App_GKE for the Secret Store CSI integration and rotation.

F. Cloud Scheduler

A Cloud Scheduler job is auto-provisioned on every deployment to drive Moodle's internal task queue. It fires every minute and authenticates using the auto-generated MOODLE_CRON_PASSWORD.

• Console: Cloud Scheduler → Jobs.
• CLI:

  gcloud scheduler jobs list --project "$PROJECT"
  gcloud scheduler jobs describe <job-name> --location "$REGION" --project "$PROJECT"
  # Manually trigger a cron run:
  gcloud scheduler jobs run <job-name> --location "$REGION" --project "$PROJECT"

G. 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. enable_custom_domain defaults to true so Moodle's wwwroot is always resolvable to a stable address.

• 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.

H. 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. Moodle Application Behaviour

• First-deploy database setup. Two initialization jobs run before the application starts. The db-init job creates the Moodle database and user, enables the pg_trgm extension, and grants privileges (idempotent, safe to re-run). The nfs-init job creates the required Moodle subdirectories (filedir, temp, cache, localcache) on the NFS share and sets www-data ownership.
• Automatic cron scheduling. A Cloud Scheduler job fires every minute targeting /admin/cron.php?password=<MOODLE_CRON_PASSWORD>. This drives all Moodle scheduled tasks: course backups, email notifications, badge processing, and activity completions. The job is always created and cannot be disabled.
• Health path. Readiness/liveness use /health.php, which returns HTTP 200 when PHP is operational. The startup probe allows up to 10 minutes for first-boot schema creation and plugin registration.
• SMTP outbound email. SMTP settings are injected as environment variables. Override the defaults using environment_variables (see Group 5). The SMTP password is auto-generated and stored in Secret Manager; update the secret with your real credential after deployment.
• wwwroot resolution. Moodle's config.php resolves wwwroot from the APP_URL environment variable, falling back to GKE_SERVICE_URL. Custom domains require enable_custom_domain = true (the default) to produce a stable URL.
• Admin login. The initial admin username and email are configurable via environment_variables. The admin password is set during Moodle's first install via admin/cli/install_database.php.

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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 Moodle 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	moodle	Base name for resources. Do not change after first deploy.
application_display_name	Moodle LMS	Friendly name shown in the Console.
application_description	Moodle Learning Management System on GKE Autopilot	Workload description annotation.
application_version	4.5.1	Container image version tag; increment to roll out a new version.

Group 4 — Runtime & Scaling

Variable	Default	Description
deploy_application	true	Set false to provision infrastructure only.
cpu_limit	2000m	CPU per pod; 2 vCPU recommended for Moodle.
memory_limit	4Gi	Memory per pod; 4 GiB recommended (avoids PHP OOM on imports).
min_instance_count	0	Minimum replicas. Set to 1 for production to keep scheduled tasks running.
max_instance_count	5	Maximum replicas (autoscaler ceiling).
container_port	8080	Moodle/Apache listens on port 8080.
enable_cloudsql_volume	true	Cloud SQL Auth Proxy sidecar for Unix socket connections.

Group 5 — Environment Variables & Secrets

Variable	Default	Description
environment_variables	{}	Extra non-secret settings. Override auto-injected SMTP defaults here (e.g., MOODLE_SMTP_HOST, MOODLE_ADMIN_EMAIL).
secret_environment_variables	{}	Map of env var → Secret Manager secret name.

Group 6 — GKE Backend & Cluster

Variable	Default	Description
service_type	LoadBalancer	How the Service is exposed.
session_affinity	ClientIP	Sticky routing required for Moodle PHP sessions.
workload_type	null	Auto-resolves to StatefulSet when per-pod storage is enabled.
network_tags	['nfsserver']	Node/pod tags; nfsserver is required for NFS connectivity.

Group 7 — StatefulSet

Variable	Default	Description
stateful_pvc_enabled	null	Enable PVC templates for per-pod persistent storage.
stateful_pvc_size	10Gi	Storage size per PVC.
stateful_pvc_mount_path	/data	Container path where the PVC is mounted.

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 all scheduling.

Group 9 — Reliability Policies

Variable	Default	Description
enable_pod_disruption_budget	true	Protect availability during node upgrades.
pdb_min_available	1	Raise min_instance_count above 1 if you need eviction headroom.
enable_topology_spread	false	Spread pods across zones.

Group 10 — Observability & Health

Variable	Default	Description
startup_probe	HTTP /health.php, 20 failures × 30 s	Up to 10 minutes for Moodle to complete first-boot setup.
liveness_probe	HTTP /health.php, 120 s initial delay	Periodic health check after startup.
uptime_check_config	disabled, path /	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 and nfs-init jobs.
cron_jobs	[]	Supplemental Kubernetes CronJobs (the Cloud Scheduler Moodle cron is always created separately).

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	true	Shared Filestore volume for Moodle moodledata (keep enabled — required for all deployments).
nfs_mount_path	/mnt/nfs	Mount path inside the container; injected as MOODLE_DATA_DIR.
nfs_volume_name	nfs-data-volume	Kubernetes volume name for the NFS mount.

Group 14 — Cloud Storage & Artifact Registry

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

Group 15 — Redis Cache

Variable	Default	Description
enable_redis	true	Use Redis for PHP sessions and Moodle application cache.
redis_host	""	Leave empty to use the NFS host IP (development only); set to a Cloud Memorystore IP for production.
redis_port	6379	Redis port (string type).
redis_auth	""	Optional Redis auth password (sensitive).

Group 16 — Database Backend

Variable	Default	Description
database_type	POSTGRES	Fixed at PostgreSQL — do not change.
application_database_name	gkeapp	Database name. Immutable after first deploy.
application_database_user	gkeapp	Application user. Immutable after first deploy.
db_name	moodle	Moodle-specific database name alias; keep consistent with application_database_name.
db_user	moodle	Moodle-specific user alias; keep consistent with application_database_user.
database_password_length	32	Generated password length.
enable_auto_password_rotation	false	Zero-downtime DB password rotation.

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	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. Use this to run additional PostgreSQL extensions or seed data. See App_GKE.

Group 19 — Custom Domain, Static IP & Networking

Variable	Default	Description
enable_custom_domain	true	Provision Ingress for custom hostnames + managed certificate (required for correct Moodle wwwroot).
application_domains	[]	Hostnames to serve.
reserve_static_ip	true	Stable external IP across redeploys.

Group 20 — Identity-Aware Proxy (IAP)

Variable	Default	Description
enable_iap	false	Require Google sign-in in front of Moodle.
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 — Cloud Armor

Variable	Default	Description
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	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.
service_external_ip	External LoadBalancer IP (when a static IP is reserved).
service_url	URL to reach Moodle.
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 (via the Auth Proxy) / port.
storage_buckets	Created Cloud Storage buckets.
network_name / network_exists / regions	VPC network, presence, available regions.
nfs_server_ip	Private IP of the Filestore NFS server (sensitive).
nfs_mount_path	Container path where the NFS share is mounted.
nfs_share_path	Export path on the NFS server.
container_image / container_registry	Deployed image and Artifact Registry repo.
monitoring_enabled / monitoring_notification_channels	Monitoring status and channels.
initialization_jobs / db_import_job / nfs_setup_job	Names of the setup and (optional) import/NFS jobs.
deployment_id / tenant_id / resource_prefix	Naming identifiers.
project_id / project_number	Project identifiers.
cicd_enabled / cicd_configuration	CI/CD status and details (repo, trigger, registry).
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	Critical	Moodle requires PostgreSQL; MOODLE_DB_TYPE = "pgsql" is hardcoded — any other engine breaks startup.
enable_nfs	true	Critical	Without shared NFS storage, moodledata is not shared across replicas and uploads are lost on pod restart.
application_database_name / db_name	set once, keep consistent	Critical	Immutable after first deploy; renaming recreates the DB and destroys data.
enable_backup_import	false unless restoring	Critical	Enabling without a valid backup_uri fails the import job.
quota_memory_requests / _limits	binary units	Critical	Bare integers are bytes and block all pod scheduling.
enable_redis	true	High	With >1 replica, isolated per-pod caches cause PHP session inconsistency.
redis_host	"" (NFS) or explicit	High	No valid endpoint if Redis is on but NFS is off and no host is set.
memory_limit	4Gi	High	Too little memory causes PHP OOM during course imports or large file uploads.
session_affinity	ClientIP	High	Without stickiness, multi-replica Moodle logins lose session state.
min_instance_count	1 for production	High	0 can leave the Cloud Scheduler cron job with no pod to deliver to during scale-to-zero periods.
enable_custom_domain	true (default)	High	Without a stable URL, Moodle's wwwroot resolves to a transient pod IP, breaking absolute links and file paths.
nfs_mount_path	/mnt/nfs	High	Must match MOODLE_DATA_DIR; changing after first deploy moves the data root and breaks the installation.
enable_iap / enable_cloud_armor	enable for admin-facing	Medium	The admin UI is otherwise publicly reachable.
backup_retention_days	7 (raise for prod)	Medium	Too short for compliance retention.
pdb_min_available vs min_instance_count	leave headroom	Medium	1/1 can stall node upgrades (single pod cannot be evicted).

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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. Moodle-specific shared configuration is described in Moodle_Common.