Langfuse on GKE Autopilot

Langfuse is an open-source, MIT-licensed LLM engineering and observability platform — tracing, prompt management, evaluations, and metrics for applications built on large language models. This module deploys Langfuse 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 Langfuse 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

Langfuse runs as a Next.js web workload. This module deploys the v2 line (Postgres-only); Langfuse v3 additionally requires ClickHouse, Redis, and S3 and is out of scope. The deployment wires together a focused set of Google Cloud services:

Capability	Google Cloud service	Notes
Compute	GKE Autopilot	Next.js pods, 2 vCPU / 4 GiB by default, horizontally autoscaled
Database	Cloud SQL for PostgreSQL 15	Required — Langfuse v2 does not support MySQL or other engines
Object storage	Cloud Storage	A dedicated bucket provisioned automatically; optional NFS share for exports
Secrets	Secret Manager	Auto-generated NEXTAUTH_SECRET and SALT; database password
Ingress	Cloud Load Balancing	External LoadBalancer, optional custom domain + managed certificate

Sensible defaults worth knowing up front:

• Langfuse v2 (Postgres-only) is pinned. The image is built FROM langfuse/langfuse:2 via the LANGFUSE_VERSION build ARG; application_version = "latest" resolves to 2.
• PostgreSQL 15 is mandatory. The database engine is fixed by the shared application layer; selecting any other engine breaks startup.
• NEXTAUTH_SECRET and SALT are generated automatically and stored in Secret Manager, materialised into the namespace, and injected as env vars. Langfuse's zod env validation refuses to boot without both — NEXTAUTH_SECRET signs session JWTs, SALT hashes API keys.
• Prisma migrations run on every start. The cloud entrypoint composes DATABASE_URL from the injected DB_* vars, then hands off to Langfuse's own startup, which runs prisma migrate deploy. The db-init job only creates the role and database.
• The first user to sign up becomes the owner. AUTH_DISABLE_SIGNUP = "false" is injected; there is no pre-seeded admin credential.
• Session affinity is ClientIP by default so a client's requests reach the same pod.
• Minimum 1 replica is maintained (GKE has no scale-to-zero); a PodDisruptionBudget keeps the service available through node upgrades.
• No Redis. Langfuse v2 uses a PostgreSQL-backed queue and cache; enable_redis stays false.

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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 Langfuse workload

Langfuse 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 Langfuse 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

Langfuse stores all application data (traces, observations, scores, prompts, users, projects, API keys) in a managed Cloud SQL for PostgreSQL 15 instance. Pods reach it privately through the Cloud SQL Auth Proxy sidecar over a loopback listener; no public IP is exposed. On first deploy an initialization Job creates the application role and database; Langfuse then applies its schema via prisma migrate deploy on start.

• 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"
  gcloud sql connect <instance-name> --user=langfuse --database=langfuse --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. Cloud Storage

A dedicated Cloud Storage bucket is provisioned automatically; the workload service account is granted access. Langfuse v2 keeps all trace and observability data in PostgreSQL; the bucket (and the optionally-mounted NFS share) are available for exports and media.

• Console: Cloud Storage → Buckets.
• CLI:

  gcloud storage buckets list --project "$PROJECT"
  gcloud storage ls gs://<bucket>/          # bucket name is in the Outputs

See App_GKE for CMEK options and GCS Fuse mounts.

D. Secret Manager

Two cryptographic secrets are generated automatically and stored in Secret Manager: NEXTAUTH_SECRET (signs session JWTs) and SALT (hashes API keys). Both are materialised into the namespace via the Secret Store CSI driver and injected as env vars, and both are required at boot. The database password is managed separately by the foundation.

• 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.

E. 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 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.

F. 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. Langfuse Application Behaviour

• First-deploy database setup. An initialization Job runs db-init.sh using postgres:15-alpine. It connects through the Cloud SQL Auth Proxy and idempotently creates the application role and database and grants privileges. It does not create tables — the job is safe to re-run.
• Prisma migrations on start. The cloud entrypoint composes DATABASE_URL and delegates to Langfuse's own startup, which runs prisma migrate deploy before launching the server. Upgrading the application version applies schema changes without a separate migration step.
• NEXTAUTH_SECRET and SALT are immutable after first boot. They are generated once and written to Secret Manager. Changing NEXTAUTH_SECRET invalidates all active sessions; changing SALT permanently invalidates all existing API keys (SDK clients then get 401). Only rotate during a planned maintenance window.
• First user is the owner. On first visit, the Langfuse sign-up page creates the initial account, which becomes the instance owner. After onboarding, set AUTH_DISABLE_SIGNUP = "true" in environment_variables to prevent further self-service registration.
• External IP for ingestion. The default service_type = LoadBalancer exposes an external IP so your LLM app's SDK clients can POST traces. Set NEXTAUTH_URL to the external URL after the LoadBalancer IP or custom domain is assigned:

  kubectl patch deploy <service-name> -n "$NAMESPACE" \
    -p '{"spec":{"template":{"spec":{"containers":[{"name":"langfuse","env":[
      {"name":"NEXTAUTH_URL","value":"https://langfuse.example.com"}
    ]}]}}}}'

  Or set environment_variables in the module configuration before deploying.
• Health path. Startup and liveness probes target / by default. The startup probe's wide failure threshold (30 × 15s) accommodates first-boot Prisma migrations.
• NFS rollouts use Recreate. When NFS is enabled and a shared server is discovered, App_GKE sets the Recreate update strategy so two pods never contend on the shared volume during an update.

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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 Langfuse 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	langfuse	Base name for resources. Do not change after first deploy.
application_display_name	Langfuse Helpdesk	Human-readable name shown in the Console. Known clone-rot in source (copied from a helpdesk app template) — override with "Langfuse" for a real deployment.
application_description	Langfuse Open-source Helpdesk on GKE Autopilot	Brief description. Same clone-rot as application_display_name — override for a real deployment.
application_version	2	Langfuse image tag. Pinned to the v2 (Postgres-only) line.

Group 4 — Runtime & Scaling

Variable	Default	Description
deploy_application	true	Set false to provision infrastructure only.
container_image_source	custom	Langfuse builds a thin wrapper image from langfuse/langfuse:2.
container_resources	{ cpu_limit = "2000m", memory_limit = "4Gi" }	CPU/memory limits and requests; minimum 2 GiB memory.
min_instance_count	1	Minimum replicas; GKE has no scale-to-zero.
max_instance_count	5	Maximum replicas (HPA upper bound).
container_port	3000	Langfuse (Next.js) listens on port 3000.
timeout_seconds	300	Maximum backend pod response duration (0–3600 seconds).
enable_cloudsql_volume	true	Cloud SQL Auth Proxy sidecar for connections.
enable_image_mirroring	true	Mirror the Langfuse image into Artifact Registry before deployment.

Group 5 — Environment Variables & Secrets

Variable	Default	Description
environment_variables	{}	Extra non-secret settings. Do not set NEXTAUTH_SECRET, SALT, or DATABASE_URL here. Set AUTH_DISABLE_SIGNUP = "true" here after onboarding.
secret_environment_variables	{}	Map of env var → Secret Manager secret name.
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 Kubernetes Service is exposed.
workload_type	Deployment (auto)	Deployment (default stateless) or StatefulSet.
session_affinity	ClientIP	Sticky routing so a client's requests reach the same pod.
network_tags	["nfsserver"]	Node/pod network tags; nfsserver is required when enable_nfs = true.
termination_grace_period_seconds	60	Seconds to wait after SIGTERM before SIGKILL.
enable_network_segmentation	false	Create Kubernetes NetworkPolicy resources.

Group 7 — StatefulSet

Variable	Default	Description
stateful_pvc_enabled	null (auto)	Enable PVC templates. Not recommended — Langfuse stores all state in PostgreSQL.
stateful_pvc_size	10Gi	Per-pod PVC storage size.
stateful_pvc_mount_path	/data	Container mount path for the PVC.
stateful_pvc_storage_class	standard-rwo	Kubernetes StorageClass for PVCs.
stateful_headless_service	null (auto)	Create a headless Service for stable pod DNS names.
stateful_pod_management_policy	null (OrderedReady)	Pod creation order.
stateful_update_strategy	null (RollingUpdate)	Update strategy.

Group 8 — Resource Quota

Variable	Default	Description
enable_resource_quota	false	Create a Kubernetes ResourceQuota in the namespace.
quota_cpu_requests / quota_cpu_limits	""	Total CPU requests/limits across all pods.
quota_memory_requests / quota_memory_limits	""	Total memory requests/limits (binary suffix e.g. 4Gi).

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	false	Distribute pods evenly across zones.

Group 10 — Observability & Health

Variable	Default	Description
startup_probe	HTTP /, 60s delay, 30 × 15s failure window	Startup probe. Covers first-boot Prisma migrations.
liveness_probe	HTTP /, 60s delay	Liveness probe.
startup_probe_config / health_check_config	HTTP /, App_GKE-level infrastructure probes	Structured probes.
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 job.
cron_jobs	[]	Scheduled Kubernetes CronJobs.
additional_services	[]	Sidecar or helper services deployed alongside Langfuse.

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	Mount an NFS share at /opt/langfuse/storage for optional exports/media.
nfs_mount_path	/opt/langfuse/storage	Mount path inside the container.
nfs_volume_name	nfs-data-volume	Volume name for the NFS mount.

Group 14 — Cloud Storage & Artifact Registry

Variable	Default	Description
create_cloud_storage	true	Create GCS buckets defined in storage_buckets.
storage_buckets	[{ name_suffix = "data" }]	Buckets to provision.
gcs_volumes	[]	GCS Fuse volume mounts via the CSI driver.
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

Variable	Default	Description
enable_redis	false	Langfuse v2 uses a PostgreSQL-backed queue and cache — leave false.
redis_host / redis_port / redis_auth	"" / 6379 / ""	Only used if externalizing to Redis.

Group 16 — Database Backend

Variable	Default	Description
database_type	POSTGRES_15	Fixed — Langfuse requires PostgreSQL 15+.
application_database_name	langfuse	PostgreSQL database name. Immutable after first deploy.
application_database_user	langfuse	Application database user. Immutable after first deploy.
database_password_length	32	Generated password length (16–64).
enable_auto_password_rotation	false	Zero-downtime DB password rotation.
rotation_propagation_delay_sec	90	Seconds to wait after rotation before rolling-restarting pods.

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.
reserve_static_ip	true	Stable external IP across redeploys.

Group 20 — Identity-Aware Proxy (IAP)

Warning: Enabling IAP requires Google identity authentication for all inbound requests, including SDK trace ingestion. Only enable IAP when public ingestion is not needed.

Variable	Default	Description
enable_iap	false	Require Google sign-in in front of Langfuse.
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.

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 Langfuse.
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.
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).
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 — a read replica without its primary, IAP with no authorized identities, a gen1 runtime with NFS/GCS mounts, a database_type that does not match an enabled extension, an out-of-range redis_port/backup_retention_days. Invalid configuration fails the plan with a clear, named error before any resource is created, so most mistakes below are caught up front rather than at apply or runtime.

Setting	Sensible value	Risk	Consequence if wrong
NEXTAUTH_SECRET (auto-generated)	Never rotate after first boot	Critical	Rotating it invalidates all active sessions, forcing immediate re-login for everyone.
SALT (auto-generated)	Never rotate after first boot	Critical	Rotating it permanently invalidates all existing API keys — every SDK client using them gets 401 until re-keyed.
application_database_name / application_database_user	Set once	Critical	Immutable after first deploy; renaming recreates the DB/user and destroys all trace data.
application_version	2 (v2 line)	Critical	A v3 tag points the build at an image needing ClickHouse + Redis + S3 this module does not provision — the pod fails to start.
enable_backup_import	false unless restoring	Critical	Enabling without a valid backup fails the import job.
container_resources.memory_limit	4Gi (≥ 2Gi)	High	Below 2 GiB, Langfuse OOM-kills during first-boot migrations or under ingestion load.
session_affinity	ClientIP	High	Without stickiness, UI sessions can bounce between pods.
min_instance_count	1	High	GKE requires min ≥ 1; the validation guard rejects invalid values. Keeping 1 ensures ingestion is always available.
enable_cloudsql_volume	true	High	The Auth Proxy sidecar is required for PostgreSQL connectivity; disabling it is blocked by a plan-time validation guard.
AUTH_DISABLE_SIGNUP (auto-injected "false")	Disable after first owner	High	Leaving sign-up open lets anyone with the URL create an account.
enable_iap	only when SDK ingestion not needed	High	IAP blocks all unauthenticated requests, including SDK trace ingestion.
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.
backup_retention_days	7 (raise for prod)	Medium	Too short for compliance retention.

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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. Langfuse-specific application configuration shared with the Cloud Run variant is described in Langfuse_Common.