Shlink on GKE Autopilot — Lab Guide

Overview

Estimated time: 45–90 minutes

Shlink is a self-hosted, open-source URL shortener with a REST API, QR code generation, and detailed visit-tracking analytics. This lab takes you through the full operational lifecycle of the Shlink on GKE Autopilot module on Google Cloud: deploy it, access and verify it, run it day-to-day, observe it, diagnose common problems, and tear it down.

The lab focuses on operating the GKE module and the Google Cloud platform, not on Shlink product features. For the complete list of provisioned services and every configuration input (organised by group), see the Configuration Guide — this lab deliberately does not duplicate that detail so it stays accurate over time.

Objectives

By the end of this lab you will be able to:

Deploy the module from the RAD platform and locate the resources it provisions.
Connect to the GKE cluster and access the running workload.
Retrieve the auto-generated API key and create your first short URL.
Perform day-2 operations — inspect, scale, update, and manage secrets and the database.
Observe the workload with Cloud Logging and Cloud Monitoring.
Diagnose and resolve the most common deployment and runtime issues.
Tear the deployment down cleanly.

Prerequisites

Services_GCP deployed in the target project (provides the VPC, GKE Autopilot cluster, Cloud SQL, Artifact Registry, and shared service accounts this module depends on).
A Google Cloud project with billing enabled.
gcloud CLI and kubectl installed; gcloud auth login and gcloud auth application-default login completed.
Project Owner (or equivalent) IAM on the project.
RAD platform access with permission to deploy modules into the project.

Set these shell variables once; every task below reuses them:

export PROJECT="<your-gcp-project-id>"
export REGION="us-central1"           # the region you deploy into

Task 1 — Deploy the module [Automated]

Click Deploy in the RAD platform top navigation, open Shlink (GKE) from the Platform Modules list to start configuration, set project_id, and review the inputs. Configure only what you need — the Configuration Guide documents every input by group, with defaults. Review the estimated cost (if credits are enabled) and click Deploy, which opens the deployment status page with real-time logs.
The platform deploys the workload into the GKE Autopilot cluster, provisions a Cloud SQL (PostgreSQL 15) database with its Secret Manager secrets (the database password and the auto-generated INITIAL_API_KEY), builds the thin wrapper container image (FROM shlinkio/shlink:stable), and runs a one-shot db-init job that creates the application role and database. Shlink needs no GCS bucket or NFS share — all state lives in PostgreSQL. First deploys take roughly 20–35 minutes (Cloud SQL creation dominates).

Connect to the cluster and discover the namespace with name-agnostic filters:

CLUSTER=$(gcloud container clusters list --project="$PROJECT" --format="value(name)" --limit=1)
gcloud container clusters get-credentials "$CLUSTER" --region="$REGION" --project="$PROJECT"

NS=$(kubectl get ns -o name | grep shlink | head -1 | cut -d/ -f2)
echo "Cluster: $CLUSTER   Namespace: $NS"
kubectl get all -n "$NS"

Task 2 — Access & verify [Manual]

Confirm the workload is running and find its external address. Shlink is exposed through a LoadBalancer Service with a reserved static IP by default:

kubectl get pods,svc -n "$NS"
EXTERNAL_IP=$(kubectl get svc -n "$NS" \
  -o jsonpath='{.items[?(@.spec.type=="LoadBalancer")].status.loadBalancer.ingress[0].ip}')
echo "External IP: $EXTERNAL_IP"

Confirm the service is healthy. Shlink's health path is /rest/health — an unauthenticated, public endpoint returning HTTP 200 with {"status":"pass",...}. Do not test / — Shlink is API-first and has no web homepage, so the root path 404s by design:
```
curl -s "http://${EXTERNAL_IP}/rest/health"
# {"status":"pass","version":"...","links":{...}}
```

Retrieve the auto-generated API key from Secret Manager and create your first short URL through the REST API. Shlink has no admin username/password login — all access is API-key based:

API_SECRET=$(gcloud secrets list --project="$PROJECT" \
  --filter="name~shlink AND name~initial-api-key" --format="value(name)" --limit=1)
API_KEY=$(gcloud secrets versions access latest --secret="$API_SECRET" --project="$PROJECT")

curl -s -X POST "http://${EXTERNAL_IP}/rest/v3/short-urls" \
  -H "X-Api-Key: $API_KEY" -H "Content-Type: application/json" \
  -d '{"longUrl": "https://cloud.google.com/kubernetes-engine"}'

Follow the returned shortUrl in a browser (or curl -I) and confirm the redirect; then list recorded visits:

curl -s "http://${EXTERNAL_IP}/rest/v3/short-urls" -H "X-Api-Key: $API_KEY"

Post-deploy hardening/setup: set DEFAULT_DOMAIN to the external IP or custom domain so generated short URLs carry the right host — it is not preset by the module:
```
SERVICE=$(kubectl get deploy -n "$NS" -o jsonpath='{.items[0].metadata.name}')
kubectl set env deploy/"$SERVICE" -n "$NS" DEFAULT_DOMAIN="${EXTERNAL_IP}"
```
Optionally add a GEOLITE_LICENSE_KEY via environment_variables and Update to enable visit geolocation. For a browser UI, point the hosted shlink-web-client at http://${EXTERNAL_IP} with your API key.

Task 3 — Operate & keep it running (Day-2) [Manual]

Inspect the workload — deployment and pods (Shlink deploys as a stateless Deployment with the default RollingUpdate strategy; there is no PVC or StatefulSet to check):
```
kubectl get deploy,pods,hpa -n "$NS"
kubectl describe deploy -n "$NS"
```
Scale by changing the min/max instance inputs and clicking Update on the deployment details page — the module owns the workload spec, so scaling is a configuration change, not a manual kubectl scale (a manual edit would be reverted on the next apply). Shlink is stateless per-request against PostgreSQL (default min_instance_count = 1, max_instance_count = 3), so raising the ceiling is safe without further tuning. session_affinity = ClientIP is set by default for sticky routing.
Update the application version by changing the version input in the RAD platform and applying it via Update. Note that application_version is not wired into the image build for Shlink — the Dockerfile always builds FROM shlinkio/shlink:stable, so this triggers a rebuild/redeploy of the same upstream tag rather than pinning a specific release. Shlink runs its own schema migrations automatically on the new pods' first start.

Manage secrets and jobs:

kubectl get secrets -n "$NS"
gcloud secrets list --project="$PROJECT" --filter="name~shlink"
kubectl get jobs -n "$NS"          # db-init job

Open a database session for inspection or maintenance:

INSTANCE=$(gcloud sql instances list --project="$PROJECT" --format="value(name)" --limit=1)
gcloud sql connect "$INSTANCE" --user=postgres --project="$PROJECT"

Task 4 — Observe: Logging & Monitoring [Manual]

Logs — from kubectl or the Logs Explorer:
```
kubectl logs -n "$NS" deploy/"$(kubectl get deploy -n "$NS" -o jsonpath='{.items[0].metadata.name}')" --tail=50
```
Logs Explorer filter: resource.type="k8s_container" AND resource.labels.namespace_name="<namespace>".
Monitoring — open the GKE / Kubernetes dashboards and review pod CPU and memory utilisation, restart counts, and request metrics. The module can provision an uptime check against /rest/health (disabled by default — uptime_check_config.enabled = false); when enabled, review Monitoring → Uptime checks and Alerting → Policies.

Task 5 — Troubleshoot & debug [Manual]

Durable techniques for the failure modes you are most likely to hit. These are platform-level diagnostics and do not change with Shlink releases.

/ returns 404: not a failure — Shlink has no web homepage. Verify health at /rest/health and interact via /rest/v3/... with the X-Api-Key header.
Pod not Ready / CrashLoopBackOff: inspect events and logs. Both the startup and liveness probes target /rest/health; the startup probe allows failure_threshold=30 at period_seconds=10 (~300s) for first-boot migrations, so don't conclude failure too early:
```
kubectl describe pod -n "$NS" <pod>          # Events section shows scheduling/probe/mount errors
kubectl logs -n "$NS" <pod> --previous       # logs from the crashed container
```
Database connection errors: confirm the Cloud SQL instance is RUNNABLE, the DB password secret materialised into the namespace, and the db-init job completed. Never set DB_USER/DB_NAME manually in environment_variables — the foundation injects tenant-scoped values, and overriding them to the short shlink/shlink names causes password authentication failed against a role that was never created.

db-init job failed: inspect the job and its pod logs:

kubectl get jobs -n "$NS"
kubectl logs -n "$NS" job/<db-init-job-name>

Pending pod / no external IP: check kubectl describe pod events for resource or quota issues, and confirm the LoadBalancer Service has an assigned IP:
```
kubectl get svc -n "$NS" -o wide
```
401 on API calls: the X-Api-Key header must carry the value of the INITIAL_API_KEY secret (or a key you created with it). Re-fetch it from Secret Manager as in Task 2 — Shlink has no admin login to fall back on.
Wrong host in generated short URLs: set DEFAULT_DOMAIN to the external IP or custom domain (see Task 2 step 4) — until then Shlink may build short URLs against the wrong host.
Image pull errors: confirm the image exists in Artifact Registry and the node service account can pull it.

See the Configuration Guide's Configuration Pitfalls section for setting-specific gotchas (including the immutability of application_database_name/application_database_user after first deploy, and why DB_NAME/DB_USER must never be set manually).

Task 6 — Tear down [Automated]

On the Deployments page, open the deployment and click the Trash icon (Delete). Delete runs terraform destroy and is irreversible (the deployment record is retained for history). If a deployment is stuck and the RAD platform can no longer manage it (for example after manual changes that conflict with the Terraform state), use Purge instead — it removes the deployment from RAD's records without destroying the cloud resources (it makes RAD forget the project). This removes everything the module created — the Kubernetes workload and namespace, Cloud SQL database, and Secret Manager secrets (including the initial API key). Resources owned by Services_GCP (the VPC, GKE cluster, shared Cloud SQL, registry) are managed separately and are not removed here.

Summary

Task	Type	Outcome
1 — Deploy	Automated	Module deploys the GKE workload, Cloud SQL (PostgreSQL 15), secrets, and runs `db-init`
2 — Access & verify	Manual	Connect to the cluster; `/rest/health` passes; first short URL created via the REST API with the bootstrap key
3 — Operate	Manual	Inspect workload, scale, update version, manage secrets, DB access
4 — Observe	Manual	Query Cloud Logging; review Cloud Monitoring metrics and uptime check
5 — Troubleshoot	Manual	Diagnose pod, database, init-job, API-key, scheduling, and image-pull issues
6 — Tear down	Automated	Delete (Trash) removes all module resources

By Dr Shiyghan Emmanuel Navti · Google Cloud certified: ACE · PCA · PCD · PDE · PSE · CDL

Overview​

Objectives​

Prerequisites​

Task 1 — Deploy the module [Automated]​

Task 2 — Access & verify [Manual]​

Task 3 — Operate & keep it running (Day-2) [Manual]​

Task 4 — Observe: Logging & Monitoring [Manual]​

Task 5 — Troubleshoot & debug [Manual]​

Task 6 — Tear down [Automated]​

Summary​