Firefly III on GKE Autopilot

Firefly III is a free, open-source, AGPL-licensed self-hosted personal-finance manager. It tracks accounts, transactions, budgets, bills, categories, and recurring transactions, and exposes a full REST API. This module deploys Firefly III 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 Firefly III 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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What Firefly III costs on RAD, and how that compares

In a Google Cloud project you own, Firefly III on RAD's GKE Autopilot module costs about US$110 a month, plus US$11 once per deployment and no per-user licence. For the lowest cost, the Cloud Run module runs the same Firefly III for about US$84 a month. Firefly III is a free, open-source personal finance manager with double-entry bookkeeping, budgets and rule-based transaction classification. Figures are as at 8 October 2026; sources are listed at the end of this section.

If this runs in a project RAD manages for you, it can be deleted and restored within 30 days for a few credits instead of sitting there running — so an occasional-use deployment costs a few dollars a month, not US$110. See Pause it for free, below.

What you pay on RAD

	In a Google Cloud project you own	In a project RAD manages for you
Module fee, once per deployment	110 credits (US$11 at the top-up price)	99 credits (10% lower)
Build time	A few credits per build	The same
Google Cloud running cost	Billed by Google to your own billing account, about US$110 a month for the default configuration (table below)	Metered hourly in credits; RAD publishes 99 credits a day, about 2,970 a month (about US$297 at the top-up price)
Who owns what	You own the project and its billing; RAD deploys and updates it	RAD owns the project, with guardrails, quotas and budget alerts; you get console access, and a minimum purchased balance is held in reserve

10 credits cost US$1 on a one-off top-up, and less on a monthly plan. In a project RAD manages, the database, file server and network are shared by every application in the project, so a second application does not add a second database.

Default running cost in your own project (us-central1, Google list prices):

Resource (module default)	Per month
GKE Autopilot pod, 1 vCPU / 2 GiB, running all the time	US$40
Cloud SQL for PostgreSQL, 1 vCPU / 3.75 GB, zonal, 10 GB SSD	US$51
NFS/cache file server: a small VM	US$13
Cloud NAT gateway and IP address	US$5
Cloud Storage for backups	US$1
Total	about US$110

GKE's free tier covers the management fee of one Autopilot or zonal cluster per billing account, so the total above assumes this is that cluster; otherwise add about US$73 a month.

How it compares

We could not find a commercial managed/SaaS plan specifically for Firefly III itself as at 8 October 2026, so the honest comparison is against running it yourself:

Option	Per month	Who runs it
Hetzner CPX22 (2 vCPU/4GB)	~US$24	You: OS, updates, backups, security patches
DigitalOcean 2 vCPU/4GB Droplet	US$24	You: OS, updates, backups, security patches
GCP Compute Engine e2-standard-2 (2 vCPU/8GB)	~US$49	You: OS, updates, backups, security patches
RAD, GKE Autopilot, your own project	US$110, plus US$11 once	RAD's automation, in your project
RAD, Cloud Run	about US$84; see the Cloud Run guide	RAD

Firefly III's own footprint here (1 vCPU / 2 GiB) is lighter than that reference box, so a smaller, cheaper tier from the same providers would comfortably run it too.

• RAD is usually not cheaper in cash than a bare VPS — the difference is what is managed for you. A VPS price does not include the admin's own time for backups, security patches and OS upgrades; RAD's managed Cloud SQL (where this app uses a database), Secret Manager and monitoring cover that instead.
• Firefly III is a free, open-source personal finance manager with double-entry bookkeeping, budgets and rule-based transaction classification. That shapes which column matters: predictable, hands-off operation is worth more to most teams running this kind of tool than shaving a few dollars off the monthly bill.

Pause it for free: delete a RAD-managed project, restore it when you need it

If Firefly III runs in a project RAD manages for you, you have an option beyond scaling down: delete the whole project, and restore it within 30 days for close to nothing. This suits a deployment you only need occasionally — studying for a certification, a demo, a seasonal need — far better than running it continuously.

• How it works. Deleting a RAD-managed project unlinks its billing first, then asks Google to delete the project. Google does not remove it immediately: it keeps it, recoverable, for 30 days, and because billing is already unlinked, nothing is charged while it waits. Unlike deleting one module, this does not tear down Cloud SQL, the VM or GKE Autopilot one by one — the whole project, and everything in it, simply stops.
• Restoring costs a handful of credits, not a rebuild. Within 30 days, the project's owner can restore it. RAD asks Google to undelete the project and reattaches its billing account, then asks you to run Update on each deployment to confirm everything came back. Because nothing was individually destroyed, that Update finds the same resources already there — it is a check, not a rebuild, and an Update never charges the module fee again. That costs a handful of build-time credits in total (under US$1) for a typical 2–3-deployment chain.
• So a month of occasional use can cost a few dollars, not US$110. Deploy Firefly III, use it for a session, delete the project. Restore it next time you want it, confirm with Update, and delete it again when you're done. You pay only for the module fee once, the builds, and whatever hours it was actually live.
• What this needs. You must own the project (not a bring-your-own one RAD only manages billing for), and you restore it yourself within the 30 days — after that, Google deletes it for good. Restoring is admitted like creating a new project: your purchased credit balance must still clear the tier's floor (100 credits for the sandbox tier most study/demo use fits). Google says most services are fully working again within 36 hours of a restore.
• One real gap: nightly backups do not survive. Backups are written to a bucket inside the project, and that bucket has Cloud Storage's soft-delete explicitly turned off, so it is very likely gone as soon as you delete the project — even though the project itself is recoverable for 30 days. If you've customised this deployment and want to keep that work, copy a backup out (to Google Drive, or a bucket outside the project) before deleting. For a default install with nothing irreplaceable in it, this does not matter.

Pay only while you use it, the other way: delete and redeploy

GKE keeps at least one pod running, so Firefly III never scales to zero on its own. The option above only applies to a RAD-managed project; in your own project, or once the 30-day window has passed, the way to stop paying is to delete the deployment and deploy it again when you need it.

• What a redeploy costs. The module fee again plus the builds: about 115 credits (US$11.50). Deleting saves money if Firefly III would otherwise sit unused for about 4 days or more in your own project (about US$3.67 a day), or about 2 days or more in a RAD-managed one (99 credits a day).
• Delete everything Firefly III uses. Most of the running cost is usually the database and any shared file/cache VM. They stop only when nothing else in the project uses them, so deleting this app while something else shares the project saves only this app's own compute part.
• Keep data first. Nightly backups go to a bucket inside the deployment and are deleted with it, so copy the latest backup out before deleting if you want to keep it.
• Note your settings. RAD does not recreate a deleted deployment for you; you enter the settings again when you deploy.

Lab sessions and Managed Environments

• Lab sessions, for training. A trainer runs a session for a class. Each participant gets Firefly III in their own Google Cloud project for 15 minutes to 24 hours, within an allowance the trainer sets. Either the trainer funds every place, or each participant pays for their own. Everything is deleted when the session ends and unused credits go back to the trainer.
• Managed Environments, for consultancies. A partner runs the app for a client from a ring-fenced wallet it funds, and settles with the client directly. If the wallet runs low, billing pauses and the data is kept, so nobody receives an unexpected charge. At the end the partner hands the project over and the deployments become the client's own.

Credits can be bought in more than 20 currencies, including XAF, XOF, NGN, GHS, KES and ZAR, by card, bank transfer or mobile money.

Sources (8 October 2026): Google Cloud list prices from the Cloud Billing Catalog API; RAD's own fees and daily-credit estimate from radmodules.dev/pricing; Delete and restore projects for the pause/restore mechanism. Prices change; check each source before relying on a figure.

1. Overview

Firefly III runs as a Laravel/PHP (Apache) web workload. The deployment wires together a focused set of Google Cloud services:

Capability	Google Cloud service	Notes
Compute	GKE Autopilot	PHP/Apache pods, 1 vCPU / 2 GiB by default
Database	Cloud SQL for PostgreSQL 15	Fixed engine — DB_CONNECTION = pgsql; MySQL is not used
Object storage	Cloud Storage	A dedicated fireflyiii-uploads bucket provisioned automatically
Persistent files	Filestore (NFS, optional)	Attachments and runtime data mounted at /var/lib/fireflyiii
Secrets	Secret Manager	Auto-generated Laravel APP_KEY and STATIC_CRON_TOKEN; database password
Ingress	Cloud Load Balancing	External LoadBalancer, optional custom domain + managed certificate

Sensible defaults worth knowing up front:

• PostgreSQL 15 is mandatory. The engine is fixed by the shared application layer. On GKE the pod reaches Cloud SQL through the Cloud SQL Auth Proxy sidecar on 127.0.0.1:5432 (DB_HOST = 127.0.0.1), which terminates TLS to Cloud SQL — so the loopback hop is plaintext and PGSQL_SSL_MODE = prefer (do not force require).
• APP_KEY is generated automatically and stored in Secret Manager, materialised into the namespace via the Secret Store CSI driver. This Laravel key encrypts sensitive fields and must never be rotated after first boot.
• STATIC_CRON_TOKEN is generated automatically. Firefly does no background scheduling on its own; something must hit GET /api/v1/cron/<STATIC_CRON_TOKEN> to run recurring transactions, bills, and auto-budgets. The module ships a built-in firefly-cron Kubernetes CronJob that does this daily at 03:00 UTC.
• Exposed via an external LoadBalancer with session_affinity = ClientIP so a user's session stays on one pod.
• Set APP_URL to the external host. The URL is not known at plan time; set application_domains (or APP_URL via environment_variables) once the LoadBalancer IP is assigned so Firefly builds correct absolute links.
• First run is /register. No admin is pre-seeded — the first account created becomes the owner/administrator. Disable open registration afterward.
• NFS is enabled by default to persist attachments and runtime data at /var/lib/fireflyiii.
• Minimum 1 replica is maintained (GKE does not support scale-to-zero).

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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 Firefly III workload

Firefly III pods are scheduled on Autopilot, which bills for the CPU/memory the pods actually request.

• Console: Kubernetes Engine → Workloads → select the Firefly III 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

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

B. Cloud SQL for PostgreSQL 15

Firefly III stores all application data in a managed Cloud SQL for PostgreSQL 15 instance. Pods reach it privately through the Cloud SQL Auth Proxy sidecar over 127.0.0.1:5432; no public IP is exposed. On first deploy an initialization Job creates the application role and database and grants privileges.

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

  gcloud sql instances list --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 surfaced in the Outputs. For the connection model, backups, and password rotation, see App_GKE.

C. Cloud Storage & NFS

A dedicated Cloud Storage uploads bucket is provisioned automatically. When NFS is enabled (the default), Firefly III's attachments and runtime directory is mounted from a Filestore/NFS volume at /var/lib/fireflyiii.

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

  gcloud storage buckets list --project "$PROJECT"
  kubectl get pvc -n "$NAMESPACE"

See App_GKE for CMEK options and GCS Fuse mounts.

D. Secret Manager

Two cryptographic secrets are generated automatically: the Laravel APP_KEY and the STATIC_CRON_TOKEN. They are materialised into the namespace via the Secret Store CSI driver. The database password is managed separately by the foundation.

• Console: Security → Secret Manager.
• CLI:

  gcloud secrets list --project "$PROJECT" --filter="name~app-key OR name~cron-token"
  POD=$(kubectl get pods -n "$NAMESPACE" -o jsonpath='{.items[0].metadata.name}')
  kubectl exec -n "$NAMESPACE" "$POD" -- env | grep -E 'APP_KEY|STATIC_CRON_TOKEN'

See App_GKE for the Secret Store CSI integration and rotation.

E. Cron (recurring transactions)

Firefly III runs recurring transactions, bill reminders, and auto-budgets only when a caller hits its cron endpoint. There is no in-process scheduler.

• A built-in firefly-cron Kubernetes CronJob (curlimages/curl, 0 3 * * *) calls the cron endpoint daily. Any cron_jobs entries you define are appended to it rather than replacing it.

F. 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 can be reserved 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.

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. Firefly III Application Behaviour

• First-deploy database setup. An initialization Job runs db-init.sh using postgres:15-alpine. It idempotently creates the application role and database and grants privileges on the database and public schema. The job is safe to re-run.
• Schema created on container start. There is no separate migrate job. The fireflyiii/core image runs php artisan migrate --force and firefly-iii:upgrade-database on every boot, so upgrading application_version applies schema changes automatically once db-init has provisioned the database.
• APP_KEY is immutable after first boot. Rotating it makes all previously encrypted fields unreadable.
• Set APP_URL to the external host after the LoadBalancer IP is assigned:

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

  Or set application_domains / environment_variables before deploying.
• First run is /register. Create the owner account, then disable further registration in Administration → Settings.
• Cron endpoint drives recurring items. The built-in firefly-cron CronJob calls GET <host>/api/v1/cron/<STATIC_CRON_TOKEN> daily; check it with kubectl get cronjobs -n "$NAMESPACE".
• Health path. The startup probe is TCP on port 8080. The liveness probe is HTTP on Firefly III's unauthenticated /status JSON endpoint (HTTP 200, no login).

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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 Firefly III 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_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	fireflyiii	Base name for resources. Do not change after first deploy.
application_version	latest	fireflyiii/core image tag; pin to a release (e.g. version-6.1.21) in production.

Group 4 — Runtime & Scaling

Variable	Default	Description
deploy_application	true	Set false to provision infrastructure only.
container_image_source	prebuilt	Deploys the official fireflyiii/core image directly.
min_instance_count	1	Minimum replicas (GKE requires ≥ 1).
max_instance_count	1	Maximum replicas.
container_port	8080	Firefly III (Apache) listens on port 8080.
enable_cloudsql_volume	true	Auth Proxy sidecar; required for loopback connectivity to Cloud SQL.
enable_image_mirroring	true	Mirror the image into Artifact Registry before deployment.
timeout_seconds	300	Max request duration.

Group 5 — Environment Variables & Secrets

Variable	Default	Description
environment_variables	{}	Extra non-secret settings. Core values (DB_CONNECTION, PGSQL_SSL_MODE, TRUSTED_PROXIES, APP_ENV, DB_HOST=127.0.0.1) are set automatically; add APP_URL.
secret_environment_variables	{}	Map of env var → Secret Manager secret name. APP_KEY and STATIC_CRON_TOKEN are injected automatically.
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	null	Resolves to Deployment when unset; set StatefulSet explicitly if needed.
session_affinity	ClientIP	Sticky routing keeps a user's session on one pod.
network_tags	["nfsserver"]	nfsserver is required when enable_nfs = true.
termination_grace_period_seconds	30	Seconds to wait after SIGTERM before SIGKILL.

Group 7 — StatefulSet

Variable	Default	Description
stateful_pvc_enabled	null	Not required — Firefly III stores all state in PostgreSQL.
stateful_pvc_size / stateful_pvc_mount_path / stateful_pvc_storage_class	10Gi / /data / standard-rwo	Per-pod PVC settings.

Group 9 — Reliability Policies

Variable	Default	Description
enable_pod_disruption_budget	false	Off by default because max_instance_count = 1 (a PDB equal to the replica count blocks node drains).
pdb_min_available	1	Minimum pods available during voluntary disruptions.

Group 10 — Observability & Health

Variable	Default	Description
startup_probe	TCP port 8080	Startup probe.
liveness_probe	HTTP /status, 300 s delay	Firefly III's unauthenticated JSON health endpoint.
health_check_config / startup_probe_config	App_GKE-level probes	Infrastructure probes.
uptime_check_config	disabled	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	[]	Extra CronJobs. The daily firefly-cron call to /api/v1/cron/<STATIC_CRON_TOKEN> is built in and always added alongside these.
additional_services	[]	Sidecar or helper services deployed alongside Firefly III.

Group 13 — Filesystem (NFS)

Variable	Default	Description
enable_nfs	true	Persist attachments and runtime data at /var/lib/fireflyiii.
nfs_mount_path	/var/www/html/storage/upload	Mount path inside the container.

Group 14 — Cloud Storage & Artifact Registry

Variable	Default	Description
create_cloud_storage	true	Create additional GCS buckets beyond the uploads bucket.
storage_buckets	[{ name_suffix = "data" }]	Additional 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	7 / true / 30	Artifact Registry cleanup policy.

Group 15 — Redis Cache

Variable	Default	Description
enable_redis	false	Optional cache/session backend; Firefly III uses the database by default.
redis_host / redis_port / redis_auth	"" / 6379 / ""	Redis endpoint and auth.

Group 16 — Database Backend

Variable	Default	Description
database_type	"POSTGRES_15"	Set explicitly, matching the engine FireflyIII_Common fixes for this app.
application_database_name	fireflyiii	Database name, injected as DB_DATABASE. Immutable after first deploy.
application_database_user	fireflyiii	Application user, injected as DB_USERNAME. Immutable after first deploy.
database_password_length	32	Generated password length (16–64).
enable_auto_password_rotation / rotation_propagation_delay_sec	off	DB password rotation.

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_file / backup_format	restore options	Restore from a backup on deploy.

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; also sets APP_URL.
reserve_static_ip	true	Stable external IP across redeploys.

Group 20 — Identity-Aware Proxy (IAP)

Recommended for personal-finance data. Firefly III holds sensitive financial data — putting IAP in front restricts access to authenticated, authorized Google identities.

Variable	Default	Description
enable_iap	false	Require Google sign-in in front of Firefly III.
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.
enable_cdn	false	Enable Cloud CDN on the GKE Ingress backend.

Group 8 / 22 — Resource Quota, VPC-SC & Audit Logging

Variable	Default	Description
enable_resource_quota	false	Namespace ResourceQuota. Memory values need binary suffixes (4Gi).
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.
service_external_ip	External LoadBalancer IP (when a static IP is reserved).
service_url	URL to reach Firefly III.
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 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.
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, 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
APP_KEY (auto-generated)	Never rotate after first boot	Critical	Rotating it makes all previously encrypted fields unreadable — data is effectively lost.
application_database_name / application_database_user	Set once	Critical	Immutable after first deploy; renaming recreates the DB/user and destroys all data.
enable_backup_import	false unless restoring	Critical	Enabling without a valid backup_file fails the import job.
PGSQL_SSL_MODE (auto prefer)	Leave as set	High	Forcing require against the plaintext Auth Proxy loopback fails ("SSL is not enabled on the server").
enable_cloudsql_volume	true	High	The Auth Proxy sidecar is required for loopback connectivity to Cloud SQL.
APP_URL	External LoadBalancer / domain URL	High	An unset or wrong URL breaks absolute links, redirects, and OAuth callbacks.
STATIC_CRON_TOKEN / cron job	Leave the built-in firefly-cron job in place	High	Without a scheduled cron call, recurring transactions, bills, and auto-budgets never fire.
enable_nfs	true	High	Disabling it puts attachments on ephemeral pod storage — files vanish on pod restart.
session_affinity	ClientIP	High	Without stickiness, session state can route to different pods and disrupt the UI.
enable_iap	enable for private data	High	Firefly III holds financial data; leaving it publicly reachable exposes it.
First-run registration	Disable after first admin	High	Leaving registration open lets anyone with the URL create an account.
quota_memory_requests / _limits	binary units (4Gi, 8192Mi)	Critical	Bare integers are bytes and block all pod scheduling in the namespace.
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. Firefly III-specific application configuration shared with the Cloud Run variant is described in FireflyIII_Common.

Related guides

• Hands-on lab: Firefly III on GKE Autopilot — deploy it step by step, with the console screens and commands at each stage.
• Firefly III on Google Cloud Run — the same application on Cloud Run, for when you need the other deployment target.
• Firefly III Common — Shared Application Configuration — the configuration shared by both deployment targets.