Ghost on GKE Autopilot

Ghost is a modern open-source publishing platform powering 2M+ publications with built-in membership, subscriptions, and newsletters. This module deploys Ghost 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 Ghost 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

Ghost runs as a Node.js web workload. The deployment wires together a focused set of Google Cloud services:

Capability	Google Cloud service	Notes
Compute	GKE Autopilot	Node.js pods, 2 vCPU / 4 GiB by default, horizontally autoscaled
Database	Cloud SQL for MySQL 8.0	Required — Ghost 6.x does not support PostgreSQL
Shared files	Filestore (NFS)	Uploaded content and themes shared across all replicas
Object storage	Cloud Storage	A dedicated content bucket (ghost-content) provisioned automatically
Cache	Redis	Enabled by default; falls back to the NFS host IP when no Redis host is given
Secrets	Secret Manager	Database password managed automatically
Ingress	Cloud Load Balancing	External LoadBalancer, optional custom domain + managed certificate

Sensible defaults worth knowing up front:

• MySQL 8.0 is mandatory. Ghost 6.x requires MySQL; PostgreSQL is not supported and will not start.
• database__client = "mysql" is injected automatically. Without this Ghost silently falls back to SQLite — the module handles it so you never need to set it manually.
• Redis is enabled by default. Ghost uses Redis for page caching to reduce database load and improve response times.
• Session affinity is ClientIP. Ghost's admin panel and membership portal use server-side sessions; requests from a browser are pinned to one pod.
• A ghost-content GCS bucket is provisioned automatically by Ghost_Common and does not need to be added to storage_buckets.
• A db-init job runs on every apply to idempotently create the Ghost MySQL database and user.
• Health probes target / with a 90-second initial delay to allow Ghost to run database migrations and compile themes on first boot.
• The database password is generated automatically and stored in Secret Manager.

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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 Ghost workload

Ghost 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 Ghost 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 MySQL 8.0

Ghost stores all application data (posts, members, settings) in a managed Cloud SQL for MySQL 8.0 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 db-init Job creates the application database and user.

• 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> --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

Uploaded content (images, themes, files) is written to a Filestore (NFS) share mounted into every pod so all replicas see the same files. A dedicated Cloud Storage bucket (ghost-content) is also provisioned automatically for content; the workload service account is granted access automatically.

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

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

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

D. Redis cache

Redis backs Ghost's page caching. When no external Redis host is configured and NFS is enabled, the NFS host IP is used as the Redis endpoint.

• 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
  # Confirm Redis env vars are set in the Ghost pod:
  kubectl exec -n "$NAMESPACE" deploy/<service-name> -- env | grep -i redis

E. Secret Manager

The database password is stored as a Secret Manager secret and 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.

F. Networking & ingress

The workload is exposed through an external Cloud Load Balancing IP. enable_custom_domain defaults to true, provisioning a Kubernetes Ingress with a Google-managed certificate for the hostnames in application_domains; a static IP is reserved by default (reserve_static_ip = true) 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.

G. 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. Ghost Application Behaviour

• First-deploy database setup. A db-init Job connects to Cloud SQL via the Auth Proxy and idempotently creates the Ghost database (with utf8mb4 charset and utf8mb4_0900_ai_ci collation), creates the application user, and grants full privileges. The job runs on every apply and is safe to re-run.
• Slow first boot. Ghost runs database migrations and compiles themes on first start. The startup probe allows 90 seconds of initial delay (initial_delay_seconds = 90, failure_threshold = 10) — do not reduce this below 60 seconds or Ghost will be killed before it finishes initialising.
• Dynamic URL detection. The custom entrypoint script queries the Cloud Run/GKE metadata server at startup to discover the service URL and export it as url and admin__url for Ghost. An explicit url environment variable always takes precedence.
• Database connection. The entrypoint maps the foundation's DB_HOST, DB_USER, DB_NAME, DB_PASSWORD, and DB_PORT variables to Ghost's database__connection__* settings automatically. When DB_HOST starts with / it is treated as a Unix socket path.
• SMTP for email. Ghost requires SMTP for member sign-ups, password resets, and newsletter delivery. Pre-populated environment_variables (SMTP_HOST, SMTP_PORT, SMTP_USER, SMTP_PASSWORD, SMTP_SSL, EMAIL_FROM) — configure them before inviting members.
• Admin login. Ghost's admin panel is at <url>/ghost. On first boot Ghost creates an admin user interactively.
• Health path. Readiness/liveness probes target /, which returns HTTP 200 when Ghost is fully initialised.

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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 Ghost 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	ghost	Base name for resources. Do not change after first deploy.
application_display_name	Ghost Blog	Friendly name shown in the Console.
application_description	Ghost Publishing Platform on GKE Autopilot	Workload description annotation.
application_version	6.14.0	Ghost 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 minimum for Ghost 6.x.
memory_limit	4Gi	Memory per pod; 4 GiB recommended (Ghost OOMs below 1 GiB).
min_instance_count	1	Minimum replicas. Keep ≥ 1 to avoid cold starts and migration delays.
max_instance_count	5	Maximum replicas (autoscaler ceiling).
container_port	2368	Ghost's native HTTP port. Do not change unless your Dockerfile binds to a different port.
container_image_source	custom	custom builds via Cloud Build (default); prebuilt deploys an existing image.
enable_cloudsql_volume	true	Cloud SQL Auth Proxy sidecar for socket connections. Required for Ghost.
enable_vertical_pod_autoscaling	false	Let Autopilot tune resource requests automatically.

Group 5 — Environment Variables & Secrets

Variable	Default	Description
environment_variables	{SMTP_HOST="", SMTP_PORT="587", SMTP_USER="", SMTP_PASSWORD="", SMTP_SSL="false", EMAIL_FROM="ghost@example.com"}	SMTP settings pre-populated for Ghost email delivery. database__client=mysql is injected automatically — do not set it here.
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 Ghost admin and membership 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 per-pod PVCs for StatefulSet deployments.
stateful_pvc_size	10Gi	Storage per pod. Provision more for active media-heavy publications.
stateful_pvc_mount_path	/data	Container path for the per-pod PVC.
stateful_pvc_storage_class	standard-rwo	Kubernetes StorageClass for PVCs.

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 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 / 90s initial delay, 10 failures	HTTP probe against Ghost's root path (200 when ready). Generous delay for first-boot migrations.
liveness_probe	HTTP / 60s initial delay	Liveness probe targeting Ghost's root path.
uptime_check_config	disabled	Optional Cloud Monitoring uptime check.
alert_policies	[]	Optional metric alert policies.

Group 11 — Workload Automation

Variable	Default	Description
initialization_jobs	[]	Leave empty to use the built-in db-init job (mysql:8.0-debian).
cron_jobs	[]	Scheduled Kubernetes CronJobs for Ghost maintenance tasks.

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 Ghost content (keep enabled for multi-replica).
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 additional bucket from storage_buckets. The ghost-content bucket is always provisioned automatically.
storage_buckets	[{name_suffix="data"}]	Additional buckets beyond the auto-provisioned content bucket.
gcs_volumes	[]	GCS Fuse mounts.
manage_storage_kms_iam / enable_artifact_registry_cmek	false	CMEK options.

Group 15 — Redis Cache

Variable	Default	Description
enable_redis	true	Use Redis for Ghost page caching.
redis_host	""	Leave empty to use the NFS host IP; set explicitly when NFS is disabled.
redis_port	6379	Redis port.
redis_auth	""	Optional Redis auth password (sensitive).

Group 16 — Database Backend

Variable	Default	Description
database_type	MYSQL_8_0	Ghost requires MySQL 8.0 — do not change.
db_name	ghost	MySQL database name. Immutable after first deploy.
db_user	ghost	Application user. Immutable after first deploy.
application_database_name	gkeappdb	Cloud SQL database name (App_GKE variable). Override to ghost for consistency.
application_database_user	gkeappuser	Cloud SQL user (App_GKE variable). Override to ghost for consistency.
database_password_length	32	Generated password length (16–64).
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 / 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. Ghost must know its public URL at startup — ensure the domain matches.
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 Ghost.
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.
service_external_ip	External LoadBalancer IP (when a static IP is reserved).
service_url	URL to reach Ghost.
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 the Auth Proxy) / port.
storage_buckets	Created Cloud Storage buckets (includes the ghost-content bucket).
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 / 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	MYSQL_8_0	Critical	Ghost requires MySQL 8.0; any other engine breaks startup.
db_name / db_user	set once	Critical	Immutable after first deploy; renaming recreates the DB/user and destroys all data.
enable_nfs	true	Critical	Without shared storage, uploaded content is lost on pod restart and not shared across replicas.
container_port	2368	Critical	Ghost's native port; mismatching it causes all health probes to fail.
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 scheduling.
startup_probe initial_delay_seconds	90	High	Reducing below 60 causes Kubernetes to kill Ghost before it finishes running migrations.
enable_redis	true	High	Without Redis, Ghost serves all pages without a cache, increasing database load.
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 Node.js OOM during newsletter sends or theme compilation.
session_affinity	ClientIP	High	Without stickiness, multi-replica Ghost admin sessions fail intermittently.
environment_variables SMTP settings	real SMTP server	High	No email delivery means no member sign-ups, no password resets, no newsletters.
container_image_source	custom	High	The upstream Ghost image lacks the custom entrypoint that maps DB credentials and detects the service URL.
min_instance_count	1	Medium	0 causes cold starts during which Ghost runs migrations, making first requests time out.
enable_iap / enable_cloud_armor	enable for admin-facing	Medium	The Ghost admin panel (/ghost) 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. Ghost-specific application configuration shared with the Cloud Run variant is described in Ghost_Common.