Mixpost on GKE Autopilot

Mixpost is an open-source, self-hosted social media scheduling and management platform — a Buffer/Hootsuite alternative for composing, scheduling, publishing, and analysing posts across multiple social accounts from one dashboard. It ships as a Laravel application (nginx + PHP-FPM + supervisord running the queue worker and scheduler inside one container). This module deploys Mixpost 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 Mixpost 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

Mixpost runs as a single, self-contained web workload (the official inovector/mixpost image). The deployment wires together a focused set of Google Cloud services:

Capability	Google Cloud service	Notes
Compute	GKE Autopilot	nginx + PHP-FPM + supervisord pod on port 80, 2 vCPU / 2 GiB by default
Database	Cloud SQL for MySQL 8.0	Required — the engine is fixed at MYSQL_8_0
Queue, cache & sessions	Redis	Enabled by default; drives QUEUE_CONNECTION/CACHE_DRIVER/SESSION_DRIVER; defaults to the co-located NFS server IP when no external host is given
File persistence	Cloud Filestore (NFS)	Media/uploads persist under /mnt/nfs, shared across pods; also the default Redis host source
Object storage	Cloud Storage	A storage bucket provisioned automatically by Mixpost_Common
Secrets	Secret Manager	Auto-generated Laravel APP_KEY; database password
Ingress	Cloud Load Balancing	External LoadBalancer with a reserved static IP; optional custom domain + managed certificate

Sensible defaults worth knowing up front:

• MySQL 8.0 is mandatory. The database engine is fixed by the shared application layer (Mixpost_Common sets database_type = "MYSQL_8_0" and DB_CONNECTION = "mysql"); other engines are not supported.
• Cloud SQL is reached via the Auth Proxy sidecar over plain TCP loopback, not a socket. The variant sets DB_HOST = 127.0.0.1; on GKE the Cloud SQL Auth Proxy (enable_cloudsql_volume = true) is a plain TCP listener on 127.0.0.1:3306 (unlike Cloud Run's Unix socket). Keep this true — disabling it makes the db-init job connect over the private IP and finish before the proxy starts, so its quitquitquit shutdown signal misses and the proxy sidecar runs forever, hanging the job.
• Redis is on by default and effectively required. enable_redis = true wires QUEUE_CONNECTION, CACHE_DRIVER, and SESSION_DRIVER to redis (falling back to sync/file only when disabled). When redis_host is empty, the module defaults to the NFS server IP — a plan-time validation guard enforces that either redis_host is set or enable_nfs is true.
• min_instance_count = 1, max_instance_count = 5. Unlike the Cloud Run variant's cold-start default, GKE keeps at least one pod running continuously, so the supervisord-managed Laravel scheduler and queue worker operate without any external cron — the CLAUDE.md convention of externalising scheduled work via Cloud Scheduler (used for the Cloud Run variant's schedule:run) does not apply here.
• NFS is enabled by default (enable_nfs = true, mounted at /mnt/nfs) for shared media/file storage, and doubles as the default Redis host.
• Session affinity is ClientIP so a client's requests reach the same pod.
• No separate migration job. The prebuilt inovector/mixpost image runs php artisan migrate --force and seeds the admin account itself on every boot via its built-in supervisord entrypoint; the only init job is the idempotent db-init database/user creation.
• Laravel DB env mapping. main.tf hardcodes db_user_env_var_name = "DB_USERNAME" and db_name_env_var_name = "DB_DATABASE" so the tenant-scoped DB_USER/DB_NAME the Foundation creates are exposed under the names Laravel's env() actually reads — this is not operator-configurable.
• APP_KEY is generated automatically and stored in Secret Manager; the GKE variant suffixes its resource prefix with -gke so the secret does not collide with a same-tenant Cloud Run deployment.

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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 Mixpost workload

Mixpost pods are scheduled on Autopilot, which bills for the CPU/memory the pods actually request. Because the workload is NFS-backed by default, the Deployment uses the Recreate strategy (a rolling update would run two pods against the same NFS volume and shared DB and deadlock).

• Console: Kubernetes Engine → Workloads → select the Mixpost workload for pods, revisions, 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 describe pod -n "$NAMESPACE" -l app=<service-name>

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

B. Cloud SQL for MySQL 8.0

Mixpost stores all application data (accounts, posts, media metadata, users) in a managed Cloud SQL for MySQL 8.0 instance. Pods reach it through the Cloud SQL Auth Proxy sidecar listening on 127.0.0.1:3306 (plain TCP loopback — not a Unix socket on GKE). On first deploy the db-init job creates the application database (utf8mb4/utf8mb4_0900_ai_ci), user, and grants, then signals the proxy sidecar to shut down.

• Console: SQL → select the instance for connections, backups, flags, metrics.
• CLI:

  gcloud sql instances list --project "$PROJECT"
  gcloud sql instances describe <instance-name> --project "$PROJECT"
  gcloud sql connect <instance-name> --user=<db-user> --database=<db-name> --project "$PROJECT"

The instance name, database, user, and the Secret Manager secret holding the password are all in the Outputs. See App_GKE for the connection model, automated backups, and password rotation.

C. Redis — queue, cache & sessions

Mixpost's background publishing pipeline, response cache, and sessions all run through Redis when enable_redis = true (the default). No dedicated Memorystore instance is provisioned by this module — unless redis_host is overridden to an external instance, Redis is expected to be reachable at the NFS server IP (the same Compute Engine VM that serves NFS also runs Redis in this repository's shared-infrastructure convention).

• Console: Memorystore → Redis instances (only if you point redis_host at a managed instance); otherwise Compute Engine → VM instances for the NFS/Redis host.
• CLI:

  kubectl exec -n "$NAMESPACE" deploy/<service-name> -- env | grep -E 'QUEUE_CONNECTION|CACHE_DRIVER|SESSION_DRIVER|REDIS'
  gcloud compute instances list --project "$PROJECT" --filter="name~nfs"

D. Cloud Storage & file persistence (NFS)

A dedicated Cloud Storage bucket (suffix storage) is provisioned automatically and the workload service account is granted access. Separately, Mixpost's media/upload tree lives on NFS (Cloud Filestore) at /mnt/nfs, shared across pods.

• Console: Cloud Storage → Buckets; Filestore → Instances.
• CLI:

  gcloud storage buckets list --project "$PROJECT" --filter="name~storage"
  gcloud filestore instances list --project "$PROJECT"
  kubectl get pvc -n "$NAMESPACE"

See App_GKE for CMEK options and GCS Fuse mounts.

E. Secret Manager

One Mixpost-specific secret is generated automatically: the Laravel APP_KEY (secret-<resource_prefix>-gke-mixpost-app-key), a random 32-character value base64-encoded in Laravel's native base64:<value> format. The database password is managed separately by the foundation. On GKE, secrets are projected into pods via the Secret Store CSI driver.

• Console: Security → Secret Manager.
• CLI:

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

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 (service_type = LoadBalancer, reserve_static_ip = true so the address survives redeploys). A custom domain with a Google-managed certificate can be enabled.

• Console: Network services → Load balancing; VPC network → IP addresses.
• CLI:

  kubectl get svc,ingress -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. Mixpost Application Behaviour

• First-deploy database setup. The db-init job runs scripts/db-init.sh using mysql:8.0-debian. It connects through the Cloud SQL Auth Proxy sidecar over TCP (--get-server-public-key, needed because caching_sha2_password refuses to send a password over an unencrypted-looking loopback connection), idempotently creates the application database with utf8mb4/ utf8mb4_0900_ai_ci, drops and recreates the application user, grants privileges, verifies the app user can connect, then POSTs quitquitquit to the proxy sidecar on port 9091 to shut it down. The job is safe to re-run (execute_on_apply = true, max_retries = 1).
• No separate migration job. The prebuilt inovector/mixpost image's built-in supervisord entrypoint runs php artisan migrate --force and seeds the admin account on every boot; there is no distinct migrate init job.
• Admin account defaults are baked into the image, not configurable via this module. Initial login defaults to admin@example.com / changeme regardless of mixpost_admin_email — that variable is declared for variant forwarding but is not currently injected into the running config (the image seeds the admin account itself). Change the admin password immediately after first login.
• DB env-var mapping. The Foundation injects DB_HOST (127.0.0.1, the proxy sidecar), DB_PORT, and DB_PASSWORD; main.tf hardcodes db_user_env_var_name = "DB_USERNAME" and db_name_env_var_name = "DB_DATABASE" so the tenant-scoped database user/name land on the Laravel-native variable names.
• Redis wiring. QUEUE_CONNECTION, CACHE_DRIVER, and SESSION_DRIVER are set to redis when enable_redis = true (the default), falling back to sync/file otherwise. Mixpost_Common does not set these itself — the GKE variant's own main.tf locals merge sets them based on enable_redis.
• NFS-backed rollouts use Recreate. Updates terminate the old pod before starting the new one, avoiding two pods deadlocking on the shared NFS volume and DB locks.
• Health probes are TCP, not HTTP, at the pod level. Mixpost answers / with a 302 redirect to https://<app_url>/; the GKE kubelet HTTP probe follows redirects, landing on https://<pod-ip>:443 where nothing listens — connection refused, probe failure, restart loop (0/1 pods) even though the app serves fine on :80. startup_probe_config and health_check_config (the variables the Foundation actually uses for the Deployment's startupProbe/livenessProbe) therefore default to type = "TCP" on port 80. (Cloud Run's probe does not follow redirects, which is why the same HTTP probe works unmodified on that variant.) The separate startup_probe/liveness_probe variables forwarded into the application config default to HTTP and are cosmetic at the config-object level — the real pod probes come from startup_probe_config/health_check_config.
• Scheduler runs continuously in-pod. With min_instance_count = 1, one pod is always running, so the supervisord-managed Laravel scheduler and queue worker publish scheduled posts without any external Cloud Scheduler wiring (a contrast with the Cloud Run variant's cold-start default, which needs an externalised schedule:run cron hit).
• Inspect the init job and running config:

  kubectl get jobs -n "$NAMESPACE"
  kubectl logs -n "$NAMESPACE" job/<db-init-job-name>
  kubectl exec -n "$NAMESPACE" deploy/<service-name> -- env | grep -E 'DB_|APP_KEY|QUEUE_CONNECTION'

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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 Mixpost are listed; every other input is inherited from App_GKE with its standard behaviour and defaults.

Group 3 — Application Identity

Variable	Default	Description
application_name	mixpost	Base name for resources. Do not change after first deploy.
application_version	latest	inovector/mixpost image tag deployed directly (prebuilt, no custom build).

Group 4 — Runtime & Scaling

Variable	Default	Description
container_image_source	prebuilt	Deploys inovector/mixpost directly; forwarded explicitly so the Foundation does not treat this as a custom build with no Dockerfile.
cpu_limit	2000m	2 vCPU default.
memory_limit	2Gi	2 GiB default.
min_instance_count	1	Keeps the in-pod Laravel scheduler/queue worker running continuously.
max_instance_count	5	HPA maxReplicas ceiling.
container_port	80	nginx + PHP-FPM serve plain HTTP.
enable_cloudsql_volume	true	Auth Proxy sidecar (TCP loopback) — required on GKE; disabling it hangs the db-init job.

Group 6 — GKE Backend & Cluster

Variable	Default	Description
service_type	LoadBalancer	External IP for the Mixpost UI.
workload_type	null → Deployment	Deployment (NFS-backed, Recreate strategy).
session_affinity	ClientIP	Sticky routing so a client reaches the same pod.

Group 10 — Observability & Health

Variable	Default	Description
startup_probe_config	TCP /, 90s delay, period 15s, failure_threshold 20	The actual pod-level startup probe. TCP avoids the 302-redirect trap.
health_check_config	TCP /, 120s delay, period 30s, failure_threshold 3	The actual pod-level liveness probe. TCP for the same reason.
startup_probe / liveness_probe	HTTP / (90s / 120s)	Forwarded into the application config object; cosmetic — superseded by the TCP probes above for the real Deployment spec.

Group 13 — Filesystem (NFS)

Variable	Default	Description
enable_nfs	true	NFS is on by default for shared media/uploads, and doubles as the default Redis host source.
nfs_mount_path	/mnt/nfs	Where Mixpost stores media/uploads.

Group 15 — Redis

Variable	Default	Description
enable_redis	true	Wires QUEUE_CONNECTION/CACHE_DRIVER/SESSION_DRIVER to redis. Plan-time guard requires redis_host set or enable_nfs = true.
redis_host	"" → NFS server IP	Override to point at an external Redis/Memorystore instance.
redis_port	6379	Redis port.
redis_auth	""	Redis AUTH password, if the target instance requires one.

Group 16 — Database Backend

Variable	Default	Description
database_type	MYSQL_8_0	Fixed by Mixpost_Common; not overridable to another engine.
application_database_name	mixpost	Database name. Immutable after first deploy.
application_database_user	mixpost	Application database user; password auto-generated in Secret Manager.

Group 19 — Custom Domain, Static IP & Networking

Variable	Default	Description
reserve_static_ip	true	Stable external IP across redeploys.
application_domains	[]	Custom hostnames + managed certificate.

Group 23 — Mixpost Application Settings

Variable	Default	Description
mixpost_admin_email	admin@example.com	Declared for variant forwarding; not currently injected into the running config — the image seeds admin@example.com / changeme itself regardless.
mail_from_name	Mixpost	Sender display name on outgoing emails.
mail_from_address	mixpost@example.com	Sender address on outgoing emails.

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 (when a static IP is reserved).
service_url	URL to reach Mixpost.
database_instance_name	Cloud SQL instance name.
database_name / database_user	Application database name / 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 (db-init) 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 StatefulSet forced alongside a stateless setting, IAP with no authorized identities, quota_memory_* given as bare integers, an out-of-range container_port/backup_retention_days. Mixpost_GKE's own validation.tf adds four more guards (min/max instance ordering, Redis host source, IAP OAuth credentials, Cloud SQL volume vs database_type = "NONE"). 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
database_type	MYSQL_8_0 (fixed)	Critical	Not overridable to another engine; Mixpost_Common hardcodes MySQL regardless of this variable's face value.
application_database_name / application_database_user	Set once	Critical	Immutable after first deploy; renaming recreates the DB/user and orphans all data.
APP_KEY (auto-generated)	Never change	Critical	Rotating the Laravel key after first boot invalidates encrypted session/cookie data and any encrypted DB fields.
enable_cloudsql_volume	true	Critical	Disabling it makes the db-init job's quitquitquit shutdown signal miss the not-yet-started proxy, hanging the job indefinitely on GKE.
enable_redis + redis_host / enable_nfs	true + NFS on, or an explicit redis_host	High	Enabling Redis with no host source (no redis_host, no NFS) leaves REDIS_HOST empty — blocked at plan time by validation.tf, but overriding both to off/empty breaks queueing, caching, and sessions.
startup_probe_config / health_check_config	type = "TCP"	High	Switching these to HTTP reintroduces the 302-redirect-to-:443 failure — the Deployment restart-loops at 0/1 even though the app is healthy.
enable_nfs	true	High	Disabling it removes both shared media persistence and (unless redis_host is set) the default Redis host, degrading publishing reliability.
min_instance_count	1	High	Scaling to 0 stops the in-pod Laravel scheduler and queue worker — scheduled social posts silently stop publishing.
mixpost_admin_email	Retrieve real credentials post-deploy	Medium	The variable is not injected into the running config; the first login is always admin@example.com / changeme regardless — change it immediately after first login.
memory_limit	2Gi	High	Below the working set for PHP-FPM + supervisord-managed workers, pods OOM under load.
quota_memory_requests / _limits	binary units (4Gi, 8192Mi)	Critical	Bare integers are treated as bytes and block all pod scheduling in the namespace.
reserve_static_ip	true	Medium	Without it, the external IP can change across redeploys, breaking DNS and any registered social-platform OAuth redirect URIs.
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. Mixpost-specific application configuration (the APP_KEY secret, the db-init script, and the environment variables merged into the container) is shared with the Cloud Run variant via the internal Mixpost_Common module, which is not deployed directly and does not yet have its own configuration guide.