TechnitiumDNS on GKE Autopilot

⚠️ Scoping disclosure: this module deploys Technitium's web admin console + REST API only (port 5380/HTTP). Technitium's core DNS resolver function (port 53/udp+tcp) cannot be exposed through this module's standard HTTP(S) Gateway pattern — no raw L4 UDP/TCP port-53 LoadBalancer is provisioned. No client anywhere can query this deployment as a DNS resolver. See §1 and §7 below for the full explanation.

Technitium DNS Server is a self-hosted, open-source, cross-platform authoritative and recursive DNS server (.NET) with a full-featured web admin console and REST API for managing zones, records, DNS-based ad/tracker blocking, conditional forwarding, and DNS-over-HTTPS/TLS. This module deploys the official technitium/dns-server image on GKE Autopilot, unmodified, 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 TechnitiumDNS 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

TechnitiumDNS runs as a single prebuilt web workload. The deployment wires together a deliberately small set of Google Cloud services — TechnitiumDNS has no database or cache dependency of its own:

Capability	Google Cloud service	Notes
Compute	GKE Autopilot	Single Deployment, 500m vCPU / 512 MiB by default
Database	None	database_type = "NONE"; zones/settings/logs are local flat files, no Cloud SQL provisioned
Persistence	Cloud Storage (GCS FUSE, default) or block PVC (StatefulSet)	Config bucket mounted at /etc/dns; switch to a StatefulSet block PVC for a real block device
Object storage	Cloud Storage	One auto-created "config" bucket (also the persistence layer above)
Cache / queue	None	No Redis; TechnitiumDNS needs no external cache
Secrets	Secret Manager	One auto-generated secret: DNS_SERVER_ADMIN_PASSWORD
Ingress	Cloud Load Balancing	External LoadBalancer Service (web console only); optional custom domain + managed certificate

Sensible defaults worth knowing up front:

• No database is provisioned. database_type = "NONE" — TechnitiumDNS keeps zones, settings, and logs as local flat files under /etc/dns. The database-related variables exist for completeness but are inert.
• Persistent by default via GCS FUSE. workload_type = "Deployment" with a GCS-mounted volume at /etc/dns — config survives pod restarts. Switch to a StatefulSet block PVC (stateful_pvc_enabled = true with stateful_pvc_mount_path = "/etc/dns") for a real block device with stronger write-locking guarantees; the module automatically disables the GCS volume in that case.
• Single replica by default (min_instance_count = 1, max_instance_count = 1) — a low-traffic admin console needs no horizontal scale.
• Exposed via a LoadBalancer Service (service_type = "LoadBalancer") with an ephemeral IP (reserve_static_ip = false) by default, conserving the project's often-scarce static-IP quota — the console does not bake a self-referencing URL into its boot-time config.
• The health endpoint is /, the console's unauthenticated root page, which returns HTTP 200 with the full console HTML as soon as the server binds its port.
• The GKE variant runs on its own tenant namespace. Give TechnitiumDNS_GKE a distinct tenant_deployment_id (e.g. "gke") if deployed alongside TechnitiumDNS_CloudRun on the same tenant, to avoid a naming collision.
• One auto-generated secret. DNS_SERVER_ADMIN_PASSWORD bootstraps the initial admin account on the very first boot only; later restarts ignore it.
• No DNS resolver. See §7 below — this is the single most important thing to understand before deploying this module.

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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 TechnitiumDNS workload

TechnitiumDNS pods are scheduled on Autopilot, which bills for the CPU/memory the pods actually request. By default the workload is a stateless Deployment with a single replica; switching to a StatefulSet provisions a per-pod block PVC for a real block device at /etc/dns.

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

  kubectl get pods,svc -n "$NAMESPACE"
  kubectl logs -n "$NAMESPACE" deploy/<service-name> --tail=100
  kubectl get statefulset -n "$NAMESPACE"          # when stateful_pvc_enabled = true

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

B. Persistence — the config Cloud Storage bucket (or block PVC)

TechnitiumDNS has no Cloud SQL instance. All zones, settings, the auth database, and logs live under /etc/dns. By default this is backed by a GCS FUSE-mounted Cloud Storage bucket; switch to a StatefulSet block PVC for a real block device:

• Console: Cloud Storage → Buckets (GCS volume); Kubernetes Engine → Storage → PersistentVolumeClaims (block PVC).
• CLI:

  gcloud storage buckets list --project "$PROJECT" --filter="name~-config"
  kubectl get pvc -n "$NAMESPACE"                                # StatefulSet PVCs
  kubectl exec -n "$NAMESPACE" <pod> -- ls -l /etc/dns           # config/zone location

See App_GKE for the GCS FUSE CSI driver and StatefulSet PVC models.

C. Secret Manager

TechnitiumDNS generates exactly one secret at deploy time: the initial admin password.

• Console: Security → Secret Manager.
• CLI:

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

See App_GKE for the Secret Store CSI integration and rotation.

D. Networking & ingress

By default the workload is exposed through an external Cloud Load Balancing IP via a LoadBalancer Service — this is the web console, not a DNS endpoint. A custom domain with a Google-managed certificate can be enabled for the console; a static IP is NOT reserved by default (set reserve_static_ip = true for a stable address across 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.

E. Cloud Logging & Monitoring

Pod stdout/stderr flow to Cloud Logging; GKE 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. TechnitiumDNS Application Behaviour

• No first-deploy database setup. TechnitiumDNS has no external database and no migration step. It reads/writes local flat files under /etc/dns from the moment it boots.
• First-boot admin bootstrap. DNS_SERVER_ADMIN_PASSWORD is applied only when /etc/dns/auth.config does not yet exist. On every later restart or redeploy, the persisted auth.config wins.
• imagePullPolicy = Always is NOT forced for this module — the image is pulled fresh (prebuilt, digest-resolved) rather than a custom-built/mirrored tag, so App_GKE's stale-cache concern for rebuilt images does not apply here in the same way; a version bump still requires a new application_version.
• Health path. Startup and liveness probes target /, which returns HTTP 200 with the full console HTML as soon as the server binds port 5380. Verify from inside the cluster:

  kubectl run curl --rm -it --image=curlimages/curl -n "$NAMESPACE" -- \
    curl -s -o /dev/null -w '%{http_code} %{size_download}\n' \
    http://<service-name>.$NAMESPACE.svc.cluster.local/

• Log in. Reach the external IP/hostname in a browser, sign in as admin with the Secret-Manager password, and change it from the console's own user-management page immediately (Technitium does not re-read DNS_SERVER_ADMIN_PASSWORD after first boot).
• REST API. All console actions are also available over the REST API using a session token obtained via /api/user/login. See Technitium's API docs.
• No DNS resolution from this deployment. See §7 below.

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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 TechnitiumDNS 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 / 3 — Deployment Environment & Application Identity

Variable	Default	Description
tenant_deployment_id	demo	Short suffix; use a distinct value (e.g. "gke") alongside the CloudRun variant on the same tenant.
application_name	technitiumdns	Base name for resources. Do not change after first deploy.
application_version	latest	TechnitiumDNS image version tag (e.g. latest, 13.5.1).

Group 4 — Runtime & Scaling

Variable	Default	Description
deploy_application	true	Set false to provision infrastructure only.
container_image_source	prebuilt	Deploys the official image as-is; custom accepted for forward-compatibility.
min_instance_count	1	Minimum replicas (GKE has no scale-to-zero for Deployments).
max_instance_count	1	Maximum replicas.
container_resources	{ cpu_limit="500m", memory_limit="512Mi" }	Per-pod CPU/memory.
container_port	5380	The web console's default port.
workload_type	Deployment	Stateless default; StatefulSet for a durable per-pod block PVC.
enable_cloudsql_volume	false	Off — TechnitiumDNS has no database.
enable_image_mirroring	true	Mirror the TechnitiumDNS image into Artifact Registry.

Group 5 — Identity-Aware Proxy (IAP)

Variable	Default	Description
enable_iap	false	Require Google sign-in. Strongly recommended — needs iap_oauth_client_id / _secret.

Group 6 — Environment Variables & Secrets

Variable	Default	Description
environment_variables	{}	Extra DNS_SERVER_* settings (e.g. DNS_SERVER_FORWARDERS, DNS_SERVER_DOMAIN).
secret_environment_variables	{}	Map of env var → Secret Manager secret name (additional secrets; DNS_SERVER_ADMIN_PASSWORD is already wired).

Group 6 — GKE Cluster

Variable	Default	Description
gke_cluster_name	""	Leave empty to auto-discover the Services_GCP cluster.
service_type	LoadBalancer	How the Service is exposed.
session_affinity	None	Single replica by default; no stickiness needed.

Group 7 — StatefulSet (durable config storage)

Variable	Default	Description
stateful_pvc_enabled	null	Set true for a per-pod block PVC at /etc/dns instead of the GCS FUSE volume.
stateful_pvc_size	10Gi	Per-pod PVC storage size.
stateful_pvc_mount_path	/etc/dns	Mount path for the block PVC.
stateful_pvc_storage_class	standard-rwo	StorageClass for the PVC.

Group 9 — Reliability Policies

Variable	Default	Description
enable_pod_disruption_budget	true	Protect availability during node upgrades.
pdb_min_available	1	Minimum pods available during voluntary disruptions.

Group 10 — Observability & Health

Variable	Default	Description
startup_probe_config	HTTP /	Startup probe targeting the console's public root page.
health_check_config	HTTP /	Liveness probe.
uptime_check_config	disabled	Optional Cloud Monitoring uptime check.

Group 13 / 14 — Filesystem & Cloud Storage

Variable	Default	Description
enable_nfs	false	Not needed by default — the GCS volume at /etc/dns already persists state.
gcs_volumes	[]	Additional GCS buckets; the config bucket at /etc/dns is auto-added.
storage_buckets	[]	Additional buckets beyond the auto-created config bucket.

Group 16 — Database Backend

Variable	Default	Description
database_type	NONE	TechnitiumDNS has no external database; leave NONE.
application_database_name / application_database_user	technitiumdns	Inert — no database is provisioned.

Group 15 — Redis Cache

Variable	Default	Description
enable_redis	false	Not required — TechnitiumDNS has no Redis dependency.

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.
reserve_static_ip	false	Ephemeral IP by default to conserve static-IP quota; set true for a stable production address.

All other inputs follow standard App_GKE behaviour.

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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.
service_url	URL to reach the web console (not a DNS endpoint).
database_instance_name / database_name / database_user	Database identifiers — empty for the default NONE engine.
database_password_secret / database_host / database_port	Database endpoint fields — unused for NONE.
storage_buckets	Created Cloud Storage buckets (the config 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 any setup and import jobs (none by default).
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).
github_repository_url / github_repository_owner / github_repository_name	CI/CD GitHub 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).

Inherited plan-time validation. This module passes its configuration through the App_GKE foundation engine, which validates values and combinations at plan time — IAP with no OAuth credentials, enable_cloudsql_volume = true with database_type = "NONE", min_instance_count > max_instance_count, quota_memory_* without binary units. The GKE variant's own validation.tf enforces these guards. Invalid configuration fails the plan with a clear, named error before any resource is created.

Setting	Sensible value	Risk	Consequence if wrong
Expecting this to be a DNS resolver	Do not point client DNS settings at this deployment	Critical	Port 53/udp+tcp is never exposed by this module's HTTP(S) Gateway pattern — DNS queries against this deployment simply fail; only the web console/API is reachable.
enable_iap	true for anything beyond a quick test	Critical	Without IAP, the console is protected only by its own admin password over the public internet.
DNS_SERVER_ADMIN_PASSWORD rotation	Change the password from the console after first login	High	Technitium never re-reads the env var after first boot — rotating the Secret Manager value alone does NOT change the effective console password.
stateful_pvc_mount_path	/etc/dns	High	Mounting the PVC anywhere other than /etc/dns leaves the actual config path unpersisted.
enable_cloudsql_volume	false	High	Setting true with database_type = "NONE" starts an Auth Proxy sidecar with no instance to reach — rejected by the plan-time guard.
enable_iap credentials	Set both iap_oauth_client_id and _secret together	High	Enabling IAP without both values is rejected at plan time by the validation guard.
quota_memory_requests / _limits	binary units (4Gi, 8192Mi)	Critical	Bare integers are bytes and block all pod scheduling in the namespace.
enable_pod_disruption_budget	true	Medium	Disabling allows GKE to evict all pods simultaneously during maintenance.
reserve_static_ip	true for production	Medium	An ephemeral IP can change on Service recreation, breaking any bookmarked/hardcoded console URL.
application_version	Pin an explicit version in production	Low	latest tracks upstream releases; pin explicitly to control upgrade timing.

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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. TechnitiumDNS-specific application configuration shared with the Cloud Run variant is described in TechnitiumDNS_Common.