From 820fcca9acc10845506f777e8df70391c602dd09 Mon Sep 17 00:00:00 2001
From: Markus Opolka <markus@martialblog.de>
Date: Thu, 21 Jul 2022 15:05:24 +0200
Subject: [PATCH] Add simple Kubernetes example

---
 examples/README.md                         |  1 +
 examples/kubernetes-simple/README.md       | 51 +++++++++++++
 examples/kubernetes-simple/deployment.yaml | 84 ++++++++++++++++++++++
 3 files changed, 136 insertions(+)
 create mode 100644 examples/kubernetes-simple/README.md
 create mode 100644 examples/kubernetes-simple/deployment.yaml

diff --git a/examples/README.md b/examples/README.md
index d75ad03..a2484f3 100644
--- a/examples/README.md
+++ b/examples/README.md
@@ -2,3 +2,4 @@
 
 - [Nginx simple reverse proxy example](./nginx-simple)
 - [Nginx reverse proxy example with defined location directive (different context path)](./nginx-contextpath)
+- [Kubernetes simple deployment](./kubernetes-simple)
diff --git a/examples/kubernetes-simple/README.md b/examples/kubernetes-simple/README.md
new file mode 100644
index 0000000..aed252a
--- /dev/null
+++ b/examples/kubernetes-simple/README.md
@@ -0,0 +1,51 @@
+# PlantUML Kubernetes Deployment
+
+In this example, PlantUML is deployed on an Kubernetes cluster using a `Deployment`, a `Service` and an `Ingress`.
+
+## Quick start
+
+Install:
+
+```bash
+# Hint: Adjust the Ingress host to your URL
+
+kubectl create ns plantuml
+kubectl -n plantuml apply -f deployment.yaml
+```
+
+Uninstall:
+
+```bash
+kubectl -n plantuml delete -f deployment.yaml
+kubectl delete ns plantuml
+```
+
+## TLS configuration
+
+Create a TLS `Secret` and extend the `Ingress` spec with a TLS configuration:
+
+```bash
+[...]
+  tls:
+  - hosts:
+    - plantuml-example.localhost
+    secretName: plantuml-tls
+```
+
+Since the `Ingress Controller` terminates the TLS and routes `http` to the application, we might need to tell the application explicitly that it got a forwarded request.
+
+This configuration changes depending on the `Ingress Controller`. Here an nginx example:
+
+```
+annotations:
+  kubernetes.io/ingress.class: nginx
+  nginx.ingress.kubernetes.io/configuration-snippet: |
+    more_set_headers "X-Forwarded-Proto: https";
+```
+
+## Useful commands
+
+```bash
+# see whats going on inside your Deployment
+kubectl -n plantuml logs -l "app.kubernetes.io/name=plantuml"
+```
diff --git a/examples/kubernetes-simple/deployment.yaml b/examples/kubernetes-simple/deployment.yaml
new file mode 100644
index 0000000..f0c2d04
--- /dev/null
+++ b/examples/kubernetes-simple/deployment.yaml
@@ -0,0 +1,84 @@
+---
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: plantuml
+  labels:
+    app.kubernetes.io/name: plantuml
+    app.kubernetes.io/instance: plantuml
+spec:
+  replicas: 3  # Can be adjusted
+  selector:
+    matchLabels:
+      app.kubernetes.io/name: plantuml
+      app.kubernetes.io/instance: plantuml
+  template:
+    metadata:
+      labels:
+        app.kubernetes.io/name: plantuml
+        app.kubernetes.io/instance: plantuml
+    spec:
+      containers:
+        - name: plantuml
+          securityContext:
+            allowPrivilegeEscalation: false
+          image: plantuml/plantuml-server:jetty-v1.2022.6
+          imagePullPolicy: Always
+          # env:  # In case of different base URL
+          #   - name: BASE_URL
+          #     value: plantuml
+          ports:
+            - name: http
+              containerPort: 8080
+              protocol: TCP
+          livenessProbe:
+            tcpSocket:
+              port: http
+          readinessProbe:
+            tcpSocket:
+              port: http
+          resources:
+            limits:
+              cpu: 500m
+              memory: 2048Mi
+            requests:
+              cpu: 250m
+              memory: 1024Mi
+---
+apiVersion: v1
+kind: Service
+metadata:
+  name: plantuml
+  labels:
+    app.kubernetes.io/name: plantuml
+    app.kubernetes.io/instance: plantuml
+spec:
+  type: ClusterIP
+  ports:
+    - port: 80
+      targetPort: http
+      protocol: TCP
+      name: http
+  selector:
+    app.kubernetes.io/name: plantuml
+    app.kubernetes.io/instance: plantuml
+---
+apiVersion: networking.k8s.io/v1
+kind: Ingress
+metadata:
+  name: plantuml
+  labels:
+    app.kubernetes.io/name: plantuml
+    app.kubernetes.io/instance: plantuml
+spec:
+  rules:
+  - host: plantuml-example.localhost
+    http:
+      paths:
+      - backend:
+          service:
+            name: plantuml
+            port:
+              number: 80
+        path: /
+        pathType: Prefix