feat(minecraft-router) add automatic mc service discovery to minecraft-router (#38128)

Add auto discovery with annotations for minecraft-router to find all
minecraft-java instances.

⚒️ Fixes  # <!--(issue)-->

**⚙️ Type of change**

- [X] ⚙️ Feature/App addition
- [ ] 🪛 Bugfix
- [ ] ⚠️ Breaking change (fix or feature that would cause existing
functionality to not work as expected)
- [ ] 🔃 Refactor of current code
- [X] 📜 Documentation Changes

**🧪 How Has This Been Tested?**
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**📃 Notes:**
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**✔️ Checklist:**

- [X] ⚖️ My code follows the style guidelines of this project
- [X] 👀 I have performed a self-review of my own code
- [ ] #️⃣ I have commented my code, particularly in hard-to-understand
areas
- [X] 📄 I have made changes to the documentation
- [ ] 🧪 I have added tests to this description that prove my fix is
effective or that my feature works
- [X] ⬆️ I increased versions for any altered app according to semantic
versioning
- [X] I made sure the title starts with `feat(chart-name):`,
`fix(chart-name):`, `chore(chart-name):`, `docs(chart-name):` or
`fix(docs):`

**➕ App addition**

If this PR is an app addition please make sure you have done the
following.

- [ ] 🖼️ I have added an icon in the Chart's root directory called
`icon.png`

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charts/stable/minecraft-router/Chart.yaml

@@ -37,5 +37,4 @@ sources:
   - https://github.com/truecharts/charts/tree/master/charts/stable/minecraft-router
   - https://hub.docker.com/r/itzg/mc-router
 type: application
-version: 2.4.1
-
+version: 2.5.0

charts/stable/minecraft-router/docs/how-to.md

@@ -10,6 +10,8 @@ Default server can be given in the case an unknown URL is detected.
 More information about linking charts and Cluster Internal Domain can be found in the common documentation.
 Example deployment, used with Cluster Internal Domain names:
 
+## Manual Discovery
+
 ```yaml
 mcrouter:
    default: minecraft-java.minecraft-java.svc.cluster.local:25565
@@ -18,3 +20,18 @@ mcrouter:
       - ${SERVER2_URL}=truecharts-mcserver-minecraft-java.truecharts-mcserver.svc.cluster.local:25565
       - ${SERVER3_URL}=kidsplayground-server-minecraft-java.kidsplayground-server.svc.cluster.local:25565
 ````
+
+## Automatic Discovery
+
+You can add the following annotations to your minecraft-java instances like so for the main service to be auto discovered by minecraft-router.
+
+```yaml
+service:
+  main:
+    enabled: true
+    annotations: 
+      # only 1 service should have this enabled
+      mc-router.itzg.me/defaultServer: "true"
+      # the domain that users will connect to!
+      mc-router.itzg.me/externalServerName: "external.host.domain"
+```

charts/stable/minecraft-router/values.yaml

@@ -14,11 +14,13 @@ service:
         enabled: true
         port: 25564
 
+# manual option
 mcrouter:
-  default: vanilla:25565
-  mappings:
-    - vanilla:25565
-    - forge:25565
+  # vanilla:25565
+  default: ""
+  mappings: []
+    # - vanilla:25565
+    # - forge:25565
 
 workload:
   main:
@@ -44,5 +46,30 @@ workload:
           env:
             API_BINDING: ":{{ .Values.service.api.ports.api.port }}"
             PORT: "{{ .Values.service.main.ports.main.port }}"
+            # enabled for auto discovery to work
+            IN_KUBE_CLUSTER: true
+            # leave blank for all namespaces
+            # KUBE_NAMESPACE: ""
             DEFAULT: "{{ .Values.mcrouter.default }}"
             MAPPING: '{{ join "," .Values.mcrouter.mappings }}'
+
+rbac:
+  main:
+    enabled: true
+    primary: true
+    clusterWide: true
+    rules:
+      - apiGroups: [""]
+        resources:
+          - "services"
+        verbs:
+          - "list"
+          - "watch"
+
+serviceAccount:
+  main:
+    enabled: true
+    primary: true
+
+podOptions:
+  automountServiceAccountToken: true