PostHog on GKE Autopilot

PostHog is an open-source product-analytics platform — event analytics, session replay, feature flags, A/B testing, and funnels — released under a hybrid MIT/PostHog-commercial license. It runs as a Python/Django web application with a co-located Celery worker+beat scheduler, and its event pipeline is built around two additional stateful services: Kafka as the ingestion backbone and ClickHouse as the actual analytics event store. This module deploys PostHog 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 PostHog 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.

No Cloud Run variant, by design. PostHog's event pipeline mandates Kafka and ClickHouse — both stateful, long-lived services incompatible with Cloud Run's serverless, scale-to-zero model. Only PostHog_GKE and PostHog_Common exist.

Deployment prerequisite (recommended, not enforced): Deploying ClickHouse_GKE first and pointing clickhouse_host at it is the recommended production path — matching this catalogue's RAGFlow_GKE → Elasticsearch_GKE cross-module-dependency precedent. Unlike RAGFlow's mandatory elasticsearch_hosts, PostHog also offers an in-module single-node ClickHouse fallback (enable_inline_clickhouse = true) for dev/test use, so the plan is not rejected outright without an external instance — but the plan-time validation guard does still require ONE of the two paths to resolve.

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1. Overview

PostHog runs as a single containerised Python/Django workload with a co-located Celery worker+beat scheduler (matching the upstream image's own default all-in-one entrypoint — the same shape as this catalogue's Saleor/Woodpecker co-located-worker pattern). The deployment wires together four independent data stores, each with a distinct job, and none of them optional:

Capability	Google Cloud service	Notes
Compute	GKE Autopilot	Custom-built PostHog pod, 4 vCPU / 8 GiB by default
App metadata	Cloud SQL for PostgreSQL 15	Django's own app tables only — users, teams, feature flags, dashboards. No analytics data.
Analytics event store	ClickHouse	Mandatory. External ClickHouse_GKE recommended (production); in-module single-node fallback for dev/test
Ingestion backbone	Kafka	Mandatory. Bundled single-node Redpanda broker by default (no standalone Kafka module in this catalogue yet)
Cache / broker	Redis	Mandatory. Celery broker, plugin-server pub/sub, Django cache — the platform injects the NFS-server co-hosted Redis IP by default
Object storage	Cloud Storage (S3-interop)	Session-replay recordings and data exports, via PostHog's native S3-compatible client — not a GCS FUSE mount
Secrets	Secret Manager	Django SECRET_KEY, S3-interop HMAC key pair, DB password, optional external CLICKHOUSE_PASSWORD
Ingress	Cloud Load Balancing	External LoadBalancer service; optional custom domain + managed certificate

Sensible defaults worth knowing up front:

• PostgreSQL 15 is fixed, and it is NOT where your analytics data lives. Postgres holds only Django's application metadata. Every event, person, session recording index, and insight query runs against ClickHouse instead — a structurally different shape from most database-backed apps in this catalogue.
• Redis is mandatory, and cannot be disabled. A plan-time validation guard rejects enable_redis = false outright. With no redis_host, the platform injects the NFS-server co-hosted Redis IP — which is why enable_nfs defaults to true even though PostHog itself has no filesystem media dependency.
• ClickHouse is mandatory, external by default. clickhouse_host is empty and enable_inline_clickhouse = false out of the box — set clickhouse_host to a separately deployed ClickHouse_GKE instance for production, or flip enable_inline_clickhouse = true for a single-node, no-persistence dev/test fallback.
• Kafka is mandatory, bundled by default. enable_inline_kafka = true deploys a single-node Redpanda broker (Kafka-API-compatible, Zookeeper-free) as an additional_services entry — no persistent volume, acceptable for an ingestion pipeline since events are re-sent/re-captured on loss.
• Scale-out is disabled. max_instance_count is hard-capped at 1 — validated at plan time. The main container co-locates the Celery worker with its beat scheduler (--with-scheduler); N replicas would run N duplicate beat schedulers, firing every periodic task N times.
• A custom image is always built. Cloud Build extends posthog/posthog with a cloud entrypoint and a docker-boot.sh override (see §3) — unlike most latest-tag apps in this catalogue, posthog/posthog publishes a genuinely fresh latest tag tracking master, so no rolling-tag substitution is needed, only the standard build-ARG naming workaround.
• Object storage is S3-interop, not GCS FUSE. Session-replay/export storage goes through PostHog's native S3-compatible client against GCS's S3-interop API via a dedicated service account + HMAC key pair.
• enable_custom_domain defaults to true. Combined with the default reserve_static_ip = true, this provisions a managed certificate and HTTPS out of the box via a <ip>.nip.io hostname even when application_domains is left empty.
• CPU/memory are pre-sized above generic defaults. cpu_limit = "4000m" / memory_limit = "8Gi" — both bumped after live verification of PostHog's genuinely heavy first boot (Django registers ~80 products sub-apps, plus the co-located Celery worker+beat).

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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 PostHog workload

The PostHog pod runs the Django/gunicorn web server and the co-located Celery worker+beat scheduler in one container, matching PostHog's own default bin/docker boot sequence.

• Console: Kubernetes Engine → Workloads → select the PostHog workload to see pods, revisions, and events.
• CLI:

  kubectl get pods,svc -n "$NAMESPACE"
  kubectl logs -n "$NAMESPACE" deploy/<service-name> --tail=100
  # First lines of a healthy boot show the resolved config the cloud entrypoint composed:
  kubectl logs -n "$NAMESPACE" deploy/<service-name> | grep -A6 'cloud-entrypoint'

See App_GKE for how Autopilot, scaling, and the workload type (Deployment vs StatefulSet) are managed. Note that max_instance_count is hard-capped at 1 for this module — see §4.

B. Cloud SQL for PostgreSQL 15 — Django app metadata only

PostHog stores its own Django application metadata (user accounts, teams/projects, feature-flag definitions, dashboards) in a managed Cloud SQL for PostgreSQL 15 instance, reached privately via the Cloud SQL Auth Proxy sidecar over 127.0.0.1. This is NOT where analytics data lives — see §C. On first deploy an initialization Job (db-init) creates the application database and user; PostHog's own Django migrations run automatically on every container 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=<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. ClickHouse — the actual analytics event store

Every event, person record, session-replay index, and insight/funnel query runs against ClickHouse, not Postgres — this is PostHog's foundational design, not an implementation detail. This module does not manage a durable ClickHouse instance directly:

• Recommended (production): deploy ClickHouse_GKE separately and set clickhouse_host to its internal Service DNS/IP. clickhouse_password_secret accepts a Secret Manager secret ID (e.g. the output of that deployment) and is injected as CLICKHOUSE_PASSWORD.
• Dev/test fallback: enable_inline_clickhouse = true deploys a single-node ClickHouse instance as a GKE additional_service alongside PostHog — no persistent volume; data is lost on every pod restart.

# Confirm PostHog can reach ClickHouse (native protocol, port 9000):
kubectl exec -n "$NAMESPACE" deploy/<service-name> -- \
  sh -c 'echo "SELECT 1" | curl -s "http://$CLICKHOUSE_HOST:8123/" --data-binary @-'

# If using the in-module fallback, inspect it directly:
kubectl get pods -n "$NAMESPACE" -l app=<service-name>-clickhouse
kubectl logs -n "$NAMESPACE" deploy/<service-name>-clickhouse

The in-module fallback required a genuinely extensive bootstrap to make PostHog's schema migrations succeed against a single node — an embedded ClickHouse Keeper (PostHog's migration tracking tables use ReplicatedMergeTree, which needs a ZooKeeper-compatible coordinator even for one node), cluster/shard/replica macros, ten named clusters (all pointed at the same node), named collections for Kafka Engine tables, and a fixed shared password (a blank password disables network access for the default user entirely — it does not mean "open, unauthenticated," confirmed against the official clickhouse/clickhouse-server entrypoint). PostHog's own ClickHouse migration also needs the HTTP interface (port 8123) in addition to the native protocol (port 9000) — this module's use of a second port on one additional_services entry is what motivated a new extra_ports field added to App_GKE itself (see §3).

D. Kafka — the ingestion backbone

Kafka sits between event capture and ClickHouse. Without it, PostHog's ingestion pipeline (confirmed against the current docker-compose.hobby.yml: web/worker/plugin-server all depend on it) has nowhere to queue incoming events.

• Default: enable_inline_kafka = true deploys a single-node Redpanda broker (Kafka-API-compatible, Zookeeper-free — officially supports a single-process "dev-container" mode) as a GKE additional_service. No persistent volume — a pod reschedule loses unconsumed events, acceptable for an ingestion pipeline where events are re-sent/re-captured.
• Production alternative: set kafka_hosts to point at an externally operated broker.

kubectl get pods -n "$NAMESPACE" -l app=<service-name>-kafka
kubectl logs -n "$NAMESPACE" deploy/<service-name>-kafka --tail=50

E. Redis — Celery broker, plugin-server pub/sub, Django cache

Redis is mandatory and cannot be disabled — enable_redis = false is rejected at plan time. With no redis_host set, the platform injects the NFS-server co-hosted Redis IP (which is why enable_nfs defaults to true, even though PostHog has no filesystem media dependency of its own).

• CLI:

  redis-cli -h <redis-host> ping
  redis-cli -h <redis-host> info clients

F. Cloud Storage — S3-interop object storage

PostHog has no filesystem media library. Session-replay recordings and data exports go through PostHog's native S3-compatible client, pointed at GCS's S3-interop XML API via a dedicated service account and HMAC key pair — not a GCS FUSE mount.

• Console: Cloud Storage → Buckets.
• CLI:

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

G. Secret Manager

Django's SECRET_KEY (session signing — generated once, never regenerated on redeploy; rotating it invalidates every active session), the S3-interop HMAC access/secret key pair, and the database password are all stored as Secret Manager secrets and injected into pods at runtime.

• Console: Security → Secret Manager.
• CLI:

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

H. Networking & ingress

enable_custom_domain defaults to true, which routes the workload through the Gateway API load balancer with a Google-managed certificate — automatically serving HTTPS on a <ip>.nip.io hostname when application_domains is empty. site_url (injected as SITE_URL, used by PostHog to build absolute links — dashboards, shared insights, webhook payloads) should be set once a real hostname or static IP is configured; it defaults to the predicted in-cluster URL otherwise.

kubectl get ingress,svc -n "$NAMESPACE"
gcloud compute addresses list --project "$PROJECT"

See App_GKE for custom domains, Cloud CDN, and static IP details.

I. 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.

gcloud logging read 'resource.type="k8s_container" AND resource.labels.namespace_name="'"$NAMESPACE"'"' \
  --project "$PROJECT" --limit 50

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3. PostHog Application Behaviour

• First-deploy database setup. An initialization Job (db-init, postgres:15-alpine) creates the PostgreSQL database and user before the application starts. No extensions are installed — unlike many apps in this catalogue, PostHog needs none; all analytics-specific storage is in ClickHouse.
• A second, dedicated clickhouse-migrate init job runs to completion before the app boots. PostHog's own bin/migrate (run on every container start) launches ClickHouse schema migration in a backgrounded subshell that runs concurrently with the foreground Postgres migration — and reaches its async-migration check (run_async_migrations, which queries ClickHouse for tables the backgrounded job may still be creating) before ever waiting on that background job. On a fresh database this crashes with IndexError: list index out of range on every single boot, forever — restarting does not let ClickHouse "catch up" because bin/migrate always re-races the same way from a cold start. This module's clickhouse-migrate job pre-runs bin/migrate --scope=clickhouse to completion with nothing else competing for the same timing budget, sidestepping the race entirely.
• Django migrations run automatically on every container start, via ./bin/migrate (part of the default boot sequence baked into the custom image).
• The Node.js plugin-server component is missing from the current upstream image. Live-verified: /code/nodejs is absent from posthog/posthog (both :latest and a 6-day-old build), but the upstream boot script still retries connecting to it every 2 seconds forever, pinning CPU at 100% and starving the process that must answer the startup probe. This module's docker-boot.sh skips that component — core event ingestion and analytics work fine; plugin-dependent features may not until upstream restores it. See PostHog_Common for the full diagnosis.
• Immutable secrets generated on first boot. SECRET_KEY and the S3-interop HMAC key pair are generated once and never regenerated on redeploy — rotating SECRET_KEY after first boot invalidates every active session.
• Health endpoints. GET /_readyz (startup) performs deep dependency checks (Postgres migration status, ClickHouse, Kafka, Celery broker, cache — source-verified against posthog/health.py) with a deliberately large failure_threshold = 145 (~25 minutes) to accommodate first-boot Django migrations. GET /_livez (liveness) is the lightweight check that does not verify downstream dependencies.
• First run is interactive. Visit the web UI after deploy and create the administrator account on the sign-up screen — no pre-seeded admin credential exists in Secret Manager.
• Single-replica by design. max_instance_count is capped at 1 — the main container co-locates the Celery worker with its beat scheduler; running N replicas would fire every periodic task N times.

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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 PostHog 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.
clickhouse_host	""	ClickHouse endpoint (bare hostname/IP, no scheme). Recommended: the internal Service DNS/IP of a separately deployed ClickHouse_GKE.
clickhouse_port	9000	ClickHouse native-protocol TCP port (used only when clickhouse_host is set).
kafka_hosts	""	Kafka broker address(es), host:port. Leave empty for the bundled Redpanda broker.

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	posthog	Base name for resources. Do not change after first deploy.
display_name	PostHog Product Analytics	Friendly name shown in the Console.
application_version	latest	posthog/posthog image tag. PostHog publishes a genuinely fresh latest tag tracking master — used as-is, no rolling-tag substitution.

Group 4 — Runtime & Scaling

Variable	Default	Description
deploy_application	true	Set false to provision infrastructure only.
cpu_limit	4000m	Bumped from a generic 2000m default after live-verified startup-probe timeouts (~95% CPU saturation during first boot).
memory_limit	8Gi	Bumped after live-verified OOM kills at both 4Gi and 6Gi during first boot.
container_port	8000	The Django/gunicorn server's native port.
min_instance_count	1	Minimum replicas.
max_instance_count	1	Hard-capped at 1, validated at plan time — co-located Celery beat scheduler.
enable_cloudsql_volume	true	Cloud SQL Auth Proxy sidecar for socket connections.

Group 5 — Environment Variables & Secrets

Variable	Default	Description
environment_variables	{}	Extra non-secret settings. Do not override CLICKHOUSE_*, KAFKA_HOSTS, OBJECT_STORAGE_* — these are injected automatically.
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.
network_tags	["nfsserver"]	Node/pod tags; nfsserver is required for NFS connectivity (see the enable_nfs note in Group 13).

Group 7 — StatefulSet Configuration

Applies only when workload_type = "StatefulSet" or stateful_pvc_enabled = true; PostHog itself has no per-pod persistent storage requirement (analytics data is ClickHouse-resident, not local).

Group 10 — Observability & Health

Variable	Default	Description
startup_probe_config / startup_probe	HTTP /_readyz, deep dependency checks	failure_threshold deliberately large (~25 min) to cover first-boot Django migrations.
health_check_config / liveness_probe	HTTP /_livez	Lightweight liveness check — does not verify downstream dependencies.
uptime_check_config	{ enabled=false, path="/_livez" }	Optional Cloud Monitoring uptime check; disabled by default.

Group 11 — Jobs & Scheduled Tasks

Variable	Default	Description
initialization_jobs	[]	Leave empty to use the built-in db-init + clickhouse-migrate jobs.
additional_services	[]	Operator-supplied extra services only — the bundled Redpanda broker and optional in-module ClickHouse fallback are injected automatically and are NOT part of this list.

Group 13 — Filesystem (NFS)

Variable	Default	Description
enable_nfs	true	Kept true solely because it is the mechanism that makes the co-hosted Redis IP available — PostHog has no filesystem media dependency of its own.
nfs_mount_path	/usr/src/app/upload	Inert for PostHog.

Group 14 — Cloud Storage

Variable	Default	Description
create_cloud_storage	true	Provision the GCS bucket used by PostHog's native S3-compatible client (session replay, exports).
storage_buckets	[{ name_suffix="storage" }]	The single bucket PostHog's S3-interop client writes to.
gcs_volumes	[]	Not used — PostHog has no filesystem media library.

Group 15 — ClickHouse & Kafka

Variable	Default	Description
clickhouse_database	posthog	ClickHouse database name events are read/written to.
clickhouse_user	default	ClickHouse username.
clickhouse_password_secret	""	Secret Manager secret ID holding the ClickHouse password (e.g. from a separately deployed ClickHouse_GKE). Leave empty for the in-module fallback's default user.
enable_inline_clickhouse	false	Single-node ClickHouse as a GKE additional_service. Dev/test only — no persistent volume.
clickhouse_image_tag	26.6.1.1193	Pinned to the exact version PostHog's own docker-compose.base.yml uses — a generic recent tag (e.g. 24.12-alpine) fails a TTL-expression check in one of PostHog's own migrations.
enable_inline_kafka	true	Single-node Redpanda broker as a GKE additional_service — the default.
kafka_image_tag	v25.1.9	Redpanda image tag.

Group 16 — Database Backend

Variable	Default	Description
database_type	POSTGRES (fixed to POSTGRES_15 by PostHog_Common)	App metadata only — analytics data lives in ClickHouse.
db_name	posthog	Database name. Immutable after first deploy.
db_user	posthog	Application user. Immutable after first deploy.
database_password_length	32	Generated password length (16–64).

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.
site_url	""	Injected as SITE_URL — used to build absolute links (dashboards, shared insights, webhook payloads). Defaults to the predicted in-cluster URL; set once a custom domain or static IP is configured.

Group 21 — Redis

Variable	Default	Description
enable_redis	true	Mandatory, validated — cannot be disabled. Celery broker, plugin-server pub/sub, Django cache.
redis_host	""	Redis host. When empty and NFS is enabled, the NFS server IP is used.
redis_port	6379	Redis port.

For every other group (CI/CD, Backup & Maintenance, Custom SQL, IAP, Cloud Armor, VPC Service Controls) PostHog inherits the standard App_GKE behaviour with no application-specific overrides.

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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).
web_url	URL for the PostHog web UI — served by the primary service itself (the co-located Django/gunicorn container), not a separate frontend.
database_instance_name	Cloud SQL instance name.
database_name	Application database name (app metadata only).
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 (S3-interop object storage).
container_image / container_registry	Deployed image and Artifact Registry repo.
initialization_jobs	Names of the db-init and clickhouse-migrate jobs.
deployment_id / tenant_id / resource_prefix	Naming identifiers.
project_id / project_number	Project identifiers.
kubernetes_ready	Whether the cluster/workload is ready. false on first apply of a new inline cluster — re-run apply to complete deployment.

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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
enable_redis	true (cannot be disabled)	Critical	PostHog's Celery broker, plugin-server pub/sub, and Django cache all require Redis; the server refuses to start without it.
clickhouse_host / enable_inline_clickhouse	one must resolve	Critical	Without a reachable ClickHouse endpoint, PostHog's entire analytics event pipeline cannot function — no events, no insights, no session replay.
kafka_hosts / enable_inline_kafka	one must resolve (default: inline)	Critical	Without Kafka, ingested events have nowhere to queue — the pipeline stalls.
max_instance_count	1 (validated, cannot exceed)	Critical	The co-located Celery beat scheduler fires every periodic task once per replica; N replicas means N-fold duplicate execution of scheduled jobs.
enable_inline_clickhouse	false for production	Critical	The in-module fallback has no persistent volume — every pod restart loses all analytics data (events, session replays, insights).
enable_inline_kafka	true acceptable for most, false + external broker for durable queueing	High	The bundled Redpanda has no persistent volume — a pod reschedule loses unconsumed events (acceptable for re-sent ingestion, not for a durable queue).
redis_host	explicit host, or leave "" with enable_nfs=true	Critical	With neither set, REDIS_HOST is empty and PostHog fails fast at boot with a clear error.
db_name / db_user	set once	Critical	Immutable after first deploy; renaming recreates the database/user. Note this only affects app metadata, not analytics data (ClickHouse-resident).
cpu_limit / memory_limit	4000m / 8Gi minimum	High	Below these, PostHog's genuinely heavy first boot (Django registering ~80 sub-apps, plus the co-located Celery worker+beat) live-verified to trigger startup-probe timeouts (CPU) or OOM kills (memory, confirmed at both 4Gi and 6Gi).
clickhouse_image_tag (inline fallback)	26.6.1.1193 — do not use a generic recent tag	High	A generic recent version (e.g. 24.12-alpine) fails a TTL-expression validation check used by one of PostHog's own ClickHouse migrations, with no config workaround.
SECRET_KEY rotation	never rotate after first boot	Critical	Rotating Django's signing key invalidates every active session.
enable_iap / enable_cloud_armor	enable for production	Medium	PostHog's web UI (and the initial admin sign-up screen) is otherwise publicly reachable.
site_url	set once a custom domain/static IP exists	Medium	Left at the predicted in-cluster default, dashboard links / shared insights / webhook payloads point at an unreachable internal URL once external access is configured.
application_version	latest (genuinely fresh, unlike several apps in this catalogue)	Medium	Incrementing triggers an image rebuild and rolling restart; verify Postgres + ClickHouse schema compatibility for major version jumps.

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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. PostHog-specific application configuration is described in PostHog_Common.