Zammad on GKE Autopilot

Zammad is an open-source helpdesk and customer support platform — a GDPR-compliant alternative to Zendesk and Freshdesk. This module deploys Zammad 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 Zammad 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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What Zammad costs on RAD, and how that compares

Running Zammad on GKE Autopilot pods in your own Google Cloud project costs about $149.81/month in Google Cloud charges, on top of a one-off 300-credit RAD module fee charged once at deploy time. Zammad needs a PostgreSQL database and a shared NFS/cache file server for attachments, which together with the pod itself make up the $149.81 above. In a RAD-managed project the module fee drops to 270 credits (10% lower) and the running cost is metered hourly in credits instead of billed directly by Google — see Pause it for free below for the one RAD-managed advantage a self-hosted VPS cannot match — or see the Cloud Run guide for the lower-cost option.

What you pay on RAD

	Own project	RAD-managed project
Module fee (one-off)	300 credits	270 credits (10% lower)
Build time	~3-6 credits per build, either way	~3-6 credits per build, either way
Google Cloud running cost	$149.81/month, billed by Google at list price	~111 credits/day, metered at list price plus RAD's margin

Default running cost in your own project

Resource	US$/month (Google list price, us-central1)
GKE Autopilot pod, 2x vCPU / 4 GiB	$79.35
Cloud SQL for PostgreSQL, 1 vCPU / 3.75 GB, zonal, 10 GB SSD	$51.02
NFS/cache file server (small VM)	$13.43
Cloud NAT and networking	$5.00
Cloud Storage (add-ons, backups)	$1.00
GKE cluster management fee	shared across every GKE app in the project; $0 if this is your only cluster, else ~73
Total	$149.81

The GKE cluster management fee is excluded from the total above because it is shared across every GKE app in the project — $0 if this is the only one, otherwise roughly $73/month split across however many you run.

How it compares

• Zammad, the vendor behind this open-source project, also sells a hosted cloud version: its pricing page (checked 8 October 2026) lists Starter v2 at €7-9/agent/month (up to 5 agents), Professional v2 at €16-18/agent/month (up to 35 agents) and Plus v2 at €25-27/agent/month (unlimited agents), excluding VAT.
• That per-agent pricing means Zammad's own cloud gets more expensive the more support staff you add — a 10-agent Professional team would run roughly €160-180/month (about $170-195) — while RAD's flat $149.81/month running cost plus the one-off module fee doesn't change with headcount, which favours RAD once a support team grows past a handful of agents.
• A bare-VPS alternative also works: a GCP Compute Engine e2-standard-2 (2 vCPU/8GB) at about $49/mo, or a similarly sized Hetzner/DigitalOcean box at about $24/mo, can self-host Zammad and Postgres together — cheaper than either RAD or Zammad's own cloud in cash terms, with none of the managed backups, patching or monitoring either provides.

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

This is the headline advantage of a RAD-managed project, and it costs nothing while paused. Deleting a RAD-managed project unlinks its billing first, then asks Google to delete the project outright — Google's own 30-day recoverable soft delete. 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, and nothing is charged while it waits, because billing is already unlinked.

Restoring, within 30 days and only by the project's owner, asks Google to undelete the project and reattaches its billing account, then asks you to run Update on each deployment to confirm everything came back. Because nothing was individually destroyed, that Update finds the same resources already there — it is a check, not a rebuild, and an Update never charges the module fee again. This costs only a handful of credits (under US$1) in total for a typical 2-3-deployment chain.

What this needs: you must own the project (not one RAD only manages billing for), you must restore it yourself within 30 days — after that Google deletes it for good — and restoring is admitted like creating a new project, so your purchased credit balance must still clear the tier's floor (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 are written to a bucket inside the project, and that bucket has Cloud Storage's soft-delete explicitly turned off, so it is very likely gone as soon as you delete the project — even though the project itself is recoverable for 30 days. If you've customised Zammad and want to keep that work, copy a backup out (to Google Drive, or a bucket outside the project) before deleting. For a default install with nothing irreplaceable in it, this does not matter.

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

In your own project, or once 30 days have passed on a RAD-managed one, there is no free pause — deleting removes the resources for good, and bringing Zammad back means redeploying from scratch. That costs about 303-306 credits (the 300-credit module fee plus a build).

Deleting only saves money once Zammad would otherwise sit unused long enough to clear that redeploy cost against its own running cost — for Zammad, that's about 7 days or more. Most of this running cost is usually the database and any shared file/cache VM — those stop only once nothing else in the project uses them, so deleting this app while something else shares the project saves only its own compute share.

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 Billing Catalog API list prices; radmodules.dev/pricing for RAD's own fees and daily-credit estimates; Google's project delete/restore documentation for the pause/restore claims. Zammad hosted-cloud prices from zammad.com/en/pricing, checked 8 October 2026.

1. Overview

Zammad runs as a Ruby on Rails (railsserver) workload. The deployment wires together a focused set of Google Cloud services:

Capability	Google Cloud service	Notes
Compute	GKE Autopilot	Rails pods, 2 vCPU / 4 GiB by default, horizontally autoscaled
Database	Cloud SQL for PostgreSQL 15	Required — Zammad does not support MySQL
Attachment storage	Filestore (NFS)	Ticket attachments at /opt/zammad/storage, shared across all replicas
Object storage	Cloud Storage	A dedicated zammad-attachments bucket, always provisioned
Cache & job queue	Redis	Enabled by default; required for ActionCable WebSocket pub/sub and Sidekiq
Secrets	Secret Manager	Database password managed automatically
Ingress	Cloud Load Balancing	External LoadBalancer, optional custom domain + managed certificate

Sensible defaults worth knowing up front:

• PostgreSQL 15 is required. The database engine is fixed; MySQL is not supported and is rejected at plan time.
• Redis is required. Zammad uses Redis for real-time ticket updates (ActionCable) and background job processing (Sidekiq). Without it, Zammad fails to start.
• A custom image is built via Cloud Build. container_image_source = "custom" is the default — Cloud Build wraps the official zammad/zammad Docker Hub image with a GCP-specific entrypoint.sh that maps Foundation DB_* variables to Zammad's POSTGRESQL_* convention.
• Database migrations run on every pod start (idempotent via zammad-init). The startup probe allows ample time for first-boot migration.
• Session affinity is ClientIP, but ActionCable WebSocket real-time push does not actually work. additional_services is empty by default for this module, so the zammad-websocket process (port 6042) is never exposed via a Kubernetes Service — the browser's WebSocket handshake cannot reach it, the same gap documented for Cloud Run in Zammad_Common/scripts/entrypoint.sh. Session affinity only pins ordinary HTTP requests to one pod; the UI falls back to polling for live ticket updates.
• PodDisruptionBudget is enabled by default. At least one Zammad pod stays up during node maintenance.

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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 Zammad workload

Zammad 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 Zammad workload to see pods, events, and resource usage. 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

Zammad stores all helpdesk data (tickets, users, channels, SLA records) in a managed Cloud SQL for PostgreSQL 15 instance. Pods reach it privately through the Cloud SQL Auth Proxy sidecar over a Unix socket — no public IP is exposed. On the first deploy, an initialization Job creates the application database and user. On every subsequent pod start, zammad-init applies any pending schema migrations.

• 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

Ticket attachments and uploaded files are written to a Filestore (NFS) share mounted at /opt/zammad/storage inside every pod so all replicas see the same files. A dedicated Cloud Storage (zammad-attachments) bucket is also provisioned automatically; the workload service account is granted access.

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

  gcloud filestore instances list --project "$PROJECT"
  gcloud storage buckets list --project "$PROJECT"
  gcloud storage ls gs://<attachments-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 and job queue

Redis is mandatory for Zammad and serves two critical roles:

1. ActionCable pub/sub — delivers real-time ticket updates to agents across multiple pods.
2. Sidekiq — processes background jobs (email dispatch, SLA notifications, LDAP sync, scheduler tasks).

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
  redis-cli -h <redis-host> info keyspace
  redis-cli -h <redis-host> client list    # active Sidekiq/ActionCable connections

E. Secret Manager

The database password is stored as a Secret Manager secret and injected into pods at runtime; plaintext never appears in configuration. Zammad manages its own internal signing keys at startup — no application-level secret is auto-generated.

• 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

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.

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. Zammad Application Behaviour

• First-deploy database setup. An initialization Job (db-init) runs before the application starts. It connects to Cloud SQL via the Auth Proxy and idempotently creates the Zammad database, user, and grants privileges. It is safe to re-run.
• Migrations on every start. The custom entrypoint.sh calls zammad-init (Rails DB migration + seed) before starting the railsserver on every pod start. Pending migrations are applied; already-run ones are skipped.
• Variable bridging. The Foundation module injects database credentials as DB_HOST, DB_USER, DB_PASSWORD, etc. The custom entrypoint.sh maps these to Zammad's POSTGRESQL_* convention at runtime.
• WebSocket connectivity — real-time push does not actually work on GKE either. The zammad-websocket (ActionCable) process starts on port 6042 alongside the railsserver, but main.tf forwards additional_services = var.additional_services (empty by default, never populated with a 6042 entry for this module), so no Kubernetes Service exposes that port — the browser's WebSocket handshake cannot reach it. The UI falls back to polling gracefully, the same limitation documented for Cloud Run in Zammad_Common/scripts/entrypoint.sh. enable_redis = true is still mandatory for production because Sidekiq (background jobs) depends on it regardless of ActionCable's reachability.
• Health path. Both startup and liveness probes target / by default, which returns HTTP 200 only when Zammad is fully initialised (path can be overridden, e.g. to /api/v1/ping). The startup probe allows a generous tolerance (60-second initial delay, up to 30 retries) to accommodate first-boot schema migration.
• Email integration. Zammad sends email notifications for ticket events and password resets. Configure SMTP after first login at Admin → Channels → Email. SMTP credentials can be injected as secret environment variables.
• Inspect running jobs:

  kubectl get jobs -n "$NAMESPACE" --sort-by=.metadata.creationTimestamp
  kubectl get cronjobs -n "$NAMESPACE"

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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 Zammad 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.
elasticsearch_url	""	Elasticsearch HTTP endpoint for full-text search. Leave empty to disable.
elasticsearch_username	""	Elasticsearch username. Leave empty when security is disabled.

Group 2 — Deployment Environment

Variable	Default	Description
tenant_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	zammad	Base name for resources. Do not change after first deploy.
application_display_name	Zammad Helpdesk	Friendly name shown in the Console.
application_description	Zammad Open-source Helpdesk on GKE Autopilot	Workload description annotation.
application_version	6.4.1	Zammad image version tag; increment to roll out a new build.

Group 4 — Runtime & Scaling

Variable	Default	Description
deploy_application	true	Set false to provision infrastructure only.
container_image_source	custom	custom builds via Cloud Build (required for the GCP entrypoint); prebuilt skips the build.
container_image	""	Override container image URI. Leave empty for Cloud Build to manage.
container_resources	{ cpu_limit: "2000m", memory_limit: "4Gi" }	CPU/memory limits and optional requests. Validated at plan time.
container_port	3000	Zammad railsserver port. Must match ZAMMAD_RAILSSERVER_PORT.
min_instance_count	1	Minimum replicas. Keep ≥ 1 so agents avoid long cold starts.
max_instance_count	5	Maximum replicas (autoscaler ceiling).
enable_cloudsql_volume	true	Cloud SQL Auth Proxy sidecar. Do not disable.
enable_vertical_pod_autoscaling	false	Let Autopilot tune resource requests automatically.
enable_image_mirroring	true	Mirrors the Zammad Docker Hub image into Artifact Registry before deploy.

Group 5 — Environment Variables & Secrets

Variable	Default	Description
environment_variables	{}	Extra non-secret settings. Core POSTGRESQL_* and RAILS_* values are set automatically.
secret_environment_variables	{}	Map of env var → Secret Manager secret name (e.g. for SMTP passwords).
secret_propagation_delay	30	Seconds to wait after secret creation before proceeding.
secret_rotation_period	2592000s	Secret Manager rotation notification frequency.

Group 6 — GKE Backend & Cluster

Variable	Default	Description
service_type	LoadBalancer	How the Service is exposed.
session_affinity	ClientIP	Sticky routing required for WebSocket session continuity.
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.
termination_grace_period_seconds	60	Kubernetes waits this long after SIGTERM before forcibly stopping the container.

Group 7 — StatefulSet

Variable	Default	Description
stateful_pvc_enabled	null	Enables PVC templates; automatically selects StatefulSet workload type.
stateful_pvc_size	10Gi	Storage size for each StatefulSet PVC.
stateful_pvc_mount_path	/data	Container path where the per-pod PVC is mounted.
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 for zone-failure resilience.

Group 10 — Observability & Health

Variable	Default	Description
startup_probe / startup_probe_config	/, 120s delay, 15 retries (override path for /api/v1/ping)	Generous tolerance for schema migration on first boot.
liveness_probe / health_check_config	/, 60s delay (override path for /api/v1/ping)	Restarts the container after 3 consecutive failures.
uptime_check_config	disabled, path = "/"	Optional Cloud Monitoring uptime check; override path if enabling with /api/v1/ping.
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 job. Non-empty list replaces it entirely.
cron_jobs	[]	Scheduled CronJobs — Zammad handles its own internal scheduling; add custom maintenance jobs here.
additional_services	[]	Sidecar or helper GKE services deployed alongside Zammad.

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, enable_binary_authorization.

Group 13 — Filesystem (NFS)

Variable	Default	Description
enable_nfs	true	Shared Filestore volume for Zammad attachment storage (keep enabled).
nfs_mount_path	/opt/zammad/storage	Mount path inside the container. Must match Zammad's storage configuration.
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 additional GCS buckets. The zammad-attachments bucket is always created.
storage_buckets / gcs_volumes	(set)	Additional buckets / GCS Fuse mounts.
manage_storage_kms_iam / enable_artifact_registry_cmek	false	CMEK options.

Group 15 — Redis Cache & Job Queue

Variable	Default	Description
enable_redis	true	Required. Use Redis for ActionCable and Sidekiq.
redis_host	""	Leave empty to use the NFS host IP; set explicitly for Memorystore or a dedicated Redis server.
redis_port	6379	Redis port.
redis_auth	""	Optional Redis auth password (sensitive).

Group 16 — Database Backend

Variable	Default	Description
database_type	POSTGRES_15	Fixed — do not change. Zammad requires PostgreSQL.
application_database_name	zammad	Database name. Immutable after first deploy.
application_database_user	zammad	Application user. Immutable after first deploy.
database_password_length	32	Generated password length (16–64).
enable_postgres_extensions / postgres_extensions	off / []	Install additional PostgreSQL extensions after provisioning.
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. See App_GKE.

Group 19 — Custom Domain, Static IP & Networking

Variable	Default	Description
enable_custom_domain	true	Provision Kubernetes Ingress for custom hostnames + managed certificate.
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 Zammad.
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.
enable_cdn	false	Enable Cloud CDN on the GKE Ingress backend.

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 Zammad.
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 (including zammad-attachments).
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	Zammad requires PostgreSQL; MySQL is rejected at plan time.
container_image_source	custom (default)	Critical	Using prebuilt without the custom entrypoint means DB_* → POSTGRESQL_* mapping does not happen and all database connections fail on startup.
enable_cloudsql_volume	true	Critical	Disabling removes the Auth Proxy socket; all database connections fail.
application_database_name / _user	set once	Critical	Immutable after first deploy; renaming recreates the DB/user and destroys all helpdesk data.
enable_backup_import	false unless restoring	Critical	Enabling without a valid backup_uri fails the import job; enabling on every apply overwrites live data.
quota_memory_requests / _limits	binary units	Critical	Bare integers are bytes and block all scheduling.
enable_redis	true	Critical	Without Redis, ActionCable and Sidekiq fail to initialise; Zammad will not start.
redis_host	explicit or NFS IP	Critical	Empty with NFS disabled means no valid Redis endpoint — Zammad fails to start.
container_resources.memory_limit	4Gi	High	Zammad OOMs during schema migration or under load below 2 GiB.
nfs_mount_path	/opt/zammad/storage	High	Changing this causes attachments to be written to ephemeral pod storage; existing NFS attachments become inaccessible.
enable_nfs	true	High	Without NFS, all uploaded attachments are lost on pod restart or rolling update.
min_instance_count	1	High	0 causes 60–90-second cold starts for the first agent to open a ticket.
session_affinity	ClientIP	Medium	Affects only ordinary HTTP request routing across replicas; it does NOT enable ActionCable — additional_services is empty by default so port 6042 is never exposed via a Kubernetes Service, and real-time WebSocket push does not work regardless of this setting. Do not rely on it for live ticket updates.
stateful_pvc_enabled = true with workload_type = "Deployment"	avoid	High	This combination fails at plan time.
startup_probe.initial_delay_seconds	60 (or higher)	High	Too short causes restart loops on first boot while schema migration is running.
max_instance_count > 1 without Redis	configure Redis first	Medium	Multiple pods without Redis cause race conditions on ticket assignment and real-time state divergence.
enable_topology_spread	enable for multi-replica	Medium	Without spread, all pods may land in one zone; a zone failure takes down the helpdesk.
enable_iap / enable_cloud_armor	enable for admin-facing	Medium	The Zammad 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. Zammad-specific application configuration shared with the Cloud Run variant is described in Zammad_Common.

Related guides

• Hands-on lab: Zammad on GKE Autopilot — deploy it step by step, with the console screens and commands at each stage.
• Zammad on Google Cloud Run — the same application on Cloud Run, for when you need the other deployment target.
• Zammad Common — Shared Application Configuration — the configuration shared by both deployment targets.