Element on GKE Autopilot

Element is the leading open-source (AGPLv3) Matrix web client — a self-hosted, end-to-end-encrypted messaging and collaboration app. This module deploys Element on GKE Autopilot on top of the App_GKE foundation, which provisions and manages the shared Google Cloud and Kubernetes infrastructure.

Element is a static nginx single-page application (SPA): the browser talks directly to a Matrix homeserver (such as Synapse or Dendrite) over HTTPS, so the pod itself holds no server-side state — no database, no Redis, no persistent volume, and no secrets.

This guide focuses on the cloud services Element 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, and the deployment lifecycle — refer to the App_GKE foundation guide rather than repeating them here.

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1. Overview

Element runs as a stateless nginx web workload. The deployment wires together a deliberately small set of Google Cloud services:

Capability	Google Cloud service	Notes
Compute	GKE Autopilot	nginx static SPA pods, 500m vCPU / 512 MiB by default, horizontally autoscaled
Container build	Cloud Build + Artifact Registry	Thin custom image FROM vectorim/element-web with a runtime config.json entrypoint
Ingress	Cloud Load Balancing	External LoadBalancer Service, optional custom domain + managed certificate
Secrets	—	None. Element requires no secrets
Database	—	None. The Matrix homeserver holds all state, not Element
Object storage	—	None. Element is stateless (no PVC, no bucket, no NFS)

Sensible defaults worth knowing up front:

• Element is stateless. All chat state, encryption keys, and media live on the Matrix homeserver and in the user's browser. Element itself stores nothing server-side, so the workload is a plain Deployment with no database, Redis, PVC, GCS bucket, or Secret Manager secret.
• The homeserver is runtime configuration. homeserver_url / homeserver_name are written into /app/config.json by the container entrypoint on every start, so one image can point at any homeserver without a rebuild. Leaving them blank defaults to the public matrix.org.
• Custom build with a pinned version. container_image_source = "custom" builds a thin image over vectorim/element-web. application_version = "latest" resolves to the pinned known-good tag v1.11.86 via an app-specific ELEMENT_VERSION build ARG. App_GKE sets imagePullPolicy=Always for the reused custom tag so rebuilds are actually pulled.
• Minimum 1 replica is maintained (GKE does not scale to zero) so the client UI is always reachable. No session affinity is needed because Element is stateless.
• Port 80. nginx serves the SPA on port 80; probes target /.

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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 Element workload

Element 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 Element workload to see pods 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. Container image — Cloud Build & Artifact Registry

The Element image is built by Cloud Build from a thin Dockerfile that layers a config.json-generating entrypoint on top of vectorim/element-web, then pushed to Artifact Registry. application_version = "latest" builds the pinned v1.11.86.

• Console: Cloud Build → History; Artifact Registry → Repositories.
• CLI:

  gcloud builds list --project "$PROJECT" --limit 5
  gcloud artifacts docker images list <region>-docker.pkg.dev/<project>/<repo> --project "$PROJECT"

See App_GKE for the build pipeline, image mirroring, and the imagePullPolicy=Always behaviour for reused custom tags.

C. Networking & ingress

By default the workload is exposed through an external Cloud Load Balancing IP (service_type = LoadBalancer). A custom domain with a Google-managed certificate can be enabled, and a static IP is reserved by default 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.

D. Identity-Aware Proxy (optional)

Element ships open by default so users can log in against the homeserver. To restrict who can even load the client UI to your Google identities, enable IAP (enable_iap = true) with an OAuth client.

• Console: Security → Identity-Aware Proxy.
• CLI:

  gcloud iap web get-iam-policy --resource-type=backend-services --project "$PROJECT"

See App_GKE for the IAP + BackendConfig wiring.

E. Cloud Logging & Monitoring

Pod stdout/stderr (nginx access/error logs) 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. Element Application Behaviour

• Runtime config generation. The container entrypoint writes /app/config.json on every start from HOMESERVER_URL / HOMESERVER_NAME, then hands off to nginx. Changing the homeserver is a redeploy with new env values — no image rebuild.
• No database, no migrations, no init job. Element serves static assets; the pod is Ready as soon as nginx binds port 80.
• Login is a browser-to-homeserver flow. Element authenticates the user directly against the configured Matrix homeserver; there is no server-side session in the pod and nothing to seed in Secret Manager.
• Verify the injected homeserver. Confirm the running pod's env matches your intended homeserver, and that the LoadBalancer answers:

  kubectl exec -n "$NAMESPACE" deploy/<service-name> -- env | grep HOMESERVER
  kubectl get svc -n "$NAMESPACE" <service-name> -o jsonpath='{.status.loadBalancer.ingress[0].ip}'

  Then curl -s http://<external-ip>/config.json should return the JSON with your base_url.
• Health path. Startup and liveness probes target /, which nginx answers immediately and unauthenticated.
• Upgrading Element. Bump application_version (or pin a newer element-web tag) and redeploy; a new image builds and, because imagePullPolicy=Always is set for the reused custom tag, the rollout pulls the fresh layers.

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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 Element 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.

Group 3 — Application Identity

Variable	Default	Description
application_name	element	Base name for resources. Do not change after first deploy.
application_version	latest	Element image tag; latest builds the pinned v1.11.86. Pin a specific element-web tag in production.
homeserver_url	""	Matrix homeserver base URL written into config.json. Blank → matrix.org.
homeserver_name	""	Matrix server name (delegation identity) advertised by Element. Blank → matrix.org.

Group 4 — Runtime & Scaling

Variable	Default	Description
deploy_application	true	Set false to provision infrastructure only.
container_image_source	custom	Builds the thin Element image via Cloud Build.
container_image	""	Override with a prebuilt/mirrored image URI.
enable_image_mirroring	true	Mirror the image into Artifact Registry before deployment.
min_instance_count	1	Minimum replicas; GKE does not scale to zero.
max_instance_count	3	Maximum replicas.
container_port	80	nginx listens on port 80.
container_resources	{ cpu_limit = "500m", memory_limit = "512Mi" }	CPU/memory limits — Element is lightweight.
enable_cloudsql_volume	false	No database — Auth Proxy sidecar not deployed.

Group 5 — Environment Variables & Secrets

Variable	Default	Description
environment_variables	{}	Extra settings merged with the injected HOMESERVER_URL / HOMESERVER_NAME.
secret_environment_variables	{}	Secret Manager references. Element needs none.
secret_rotation_period / secret_propagation_delay	(set)	Rotation notification / propagation wait.

Group 6 — GKE Backend & Cluster

Variable	Default	Description
service_type	LoadBalancer	How the Kubernetes Service is exposed.
workload_type	null	Element is stateless; the foundation auto-resolves this to a Deployment.
session_affinity	None	No sticky routing needed — Element holds no server-side session.
namespace_name	""	Namespace for the workload; empty means auto-derived from the service name.
enable_network_segmentation	false	Create Kubernetes NetworkPolicy resources.
termination_grace_period_seconds	30	Seconds to wait after SIGTERM before SIGKILL.

Group 7 — StatefulSet

Inherited and not used by Element (stateless Deployment). stateful_pvc_enabled (default null), stateful_pvc_size, stateful_pvc_mount_path, stateful_pvc_storage_class, stateful_headless_service, stateful_pod_management_policy, stateful_update_strategy, stateful_fs_group.

Group 8 — Resource Quota

Variable	Default	Description
enable_resource_quota	false	Enforce a namespace ResourceQuota.
quota_cpu_requests / quota_cpu_limits	(set)	Namespace CPU quota.
quota_memory_requests / quota_memory_limits	(set)	Namespace memory quota. Must use binary units (4Gi, 8192Mi).
quota_max_pods / quota_max_services / quota_max_pvcs	(set)	Namespace object caps.

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.
enable_topology_spread / topology_spread_strict	(set)	Spread pods across zones/nodes.

Group 10 — Observability & Health

Variable	Default	Description
startup_probe	HTTP / 10 s delay, 6 failures	Startup probe.
liveness_probe	HTTP / 15 s delay	Liveness probe.
startup_probe_config / health_check_config	(set)	App_GKE-level infrastructure probes.
uptime_check_config	disabled — /	Optional Cloud Monitoring uptime check; disabled by default.
alert_policies	[]	Optional metric alert policies.

Group 11 — Jobs & Scheduled Tasks

Variable	Default	Description
initialization_jobs	[]	Element declares no init jobs.
cron_jobs	[]	Scheduled Kubernetes CronJobs.
additional_services	[]	Sidecar or helper services.

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)

Inherited and off by default — Element is stateless. enable_nfs (false), nfs_mount_path, nfs_volume_name, nfs_instance_name, nfs_instance_base_name.

Group 14 — Cloud Storage & Artifact Registry

Variable	Default	Description
create_cloud_storage	false	Create GCS buckets defined in storage_buckets. Off — Element is stateless and declares none.
storage_buckets	[]	Additional buckets. Element declares none.
gcs_volumes	[]	GCS Fuse volume mounts.
manage_storage_kms_iam / enable_artifact_registry_cmek	false	CMEK options.
max_images_to_retain / delete_untagged_images / image_retention_days	(set)	Artifact Registry cleanup policy.

Group 15 — Redis Cache & Queue

Inherited from App_GKE and inert — a static SPA has no server-side cache or queue. enable_redis, redis_host, redis_port, redis_auth.

Group 16 — Database Backend

Inherited from App_GKE and inert — Element_Common sets database_type = "NONE". No Cloud SQL instance, user, or password is created.

Group 17 — Backup & Maintenance

Inherited and no-ops for Element (nothing to back up). backup_schedule, backup_retention_days, enable_backup_import, backup_source, backup_uri, backup_format.

Group 18 — Custom SQL Scripts

Inherited; not used by Element. enable_custom_sql_scripts, custom_sql_scripts_bucket, custom_sql_scripts_path, custom_sql_scripts_use_root.

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	true	Stable external IP across redeploys.
static_ip_name / network_tags / network_name	(set)	IP name, node tags, VPC network.

Group 20 — Identity-Aware Proxy (IAP)

Note: Enabling IAP requires Google identity authentication before the client UI even loads. Users still authenticate to the homeserver afterwards; IAP is an outer access gate, not a replacement for Matrix login.

Variable	Default	Description
enable_iap	false	Require Google sign-in in front of Element.
iap_authorized_users / iap_authorized_groups	[]	Who may access.
iap_oauth_client_id / iap_oauth_client_secret	""	Required when IAP is enabled (sensitive).

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 — worthwhile for static assets.

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 Element.
storage_buckets	Created Cloud Storage buckets (empty for Element).
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	Names of setup jobs (none for Element).
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 authorized identities, a Deployment workload with stateful_pvc_enabled = true, bare-integer quota_memory_* values. Invalid configuration fails the plan with a clear, named error before any resource is created.

Setting	Sensible value	Risk	Consequence if wrong
homeserver_url / homeserver_name	Your real homeserver, or blank for matrix.org	High	A wrong or unreachable homeserver leaves users unable to log in — the UI loads but authentication fails.
application_version	Pin a real element-web tag	High	latest is not a valid element-web tag; the module pins v1.11.86, but a hand-set raw latest build ARG would fail with MANIFEST_UNKNOWN.
container_image_source	custom	High	prebuilt with an image lacking the config.json entrypoint ships Element pointed at the wrong homeserver.
min_instance_count	1	High	GKE requires min ≥ 1; the validation guard rejects invalid values. Keeping 1 ensures the UI is always reachable.
quota_memory_requests / _limits	binary units (4Gi, 8192Mi)	Critical	Bare integers are bytes and block all pod scheduling in the namespace.
enable_iap	Enable to gate the UI	Medium	Without IAP anyone with the URL can load the client (they still need homeserver credentials to log in).
enable_pod_disruption_budget	true	Medium	Disabling allows GKE to evict all pods simultaneously during maintenance.
Database / Redis / Backup / NFS inputs	Leave default	Low	Inert for Element; setting them has no effect.

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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, and image mirroring — see App_GKE. Element-specific application configuration shared with the Cloud Run variant is described in Element_Common.