Add initial Kubernetes config files

This includes all the resources currently running on https://gitea.kosmos.org

It sets up a persistent data volume for the MySQL database, one for the
Gitea data, that Gitea calls the custom folder (config, attachment,
avatars, logs, etc). We mount that persistent data volume as
/data/gitea. It also creates a Let's Encrypt certificate for
gitea.kosmos.org, also saved to the custom folder.

This also includes two scripts:

* `./script/get_secrets` downloads the secrets to the local filesystem so
they can be edited
* `./script/replace_secrets` deletes the remote secrets and creates them
again from the local ones in kubernetes/config/*

Closes #6

kubernetes/gitea-db.yaml

@@ -0,0 +1,69 @@
+apiVersion: extensions/v1beta1
+kind: Deployment
+metadata:
+  name: gitea-db
+spec:
+  replicas: 1
+  strategy:
+    type: Recreate
+  template:
+    metadata:
+      labels:
+        name: gitea-db
+    spec:
+      containers:
+      - env:
+        - name: MYSQL_DATABASE
+          value: gitea
+        - name: MYSQL_ROOT_PASSWORD
+          valueFrom:
+            secretKeyRef:
+              name: mysql-pass
+              key: password
+        - name: MYSQL_PASSWORD
+          valueFrom:
+            secretKeyRef:
+              name: gitea-mysql-pass
+              key: password
+        - name: MYSQL_USER
+          value: gitea
+        image: mariadb:10.3.10
+        name: gitea-db
+        resources: {}
+        ports:
+          - containerPort: 3306
+            name: mysql
+        volumeMounts:
+        - mountPath: /var/lib/mysql
+          name: gitea-db-data
+      restartPolicy: Always
+      volumes:
+      - name: gitea-db-data
+        persistentVolumeClaim:
+          claimName: gitea-db-data
+---
+apiVersion: v1
+kind: PersistentVolumeClaim
+metadata:
+  name: gitea-db-data
+  labels:
+    name: gitea-db-data
+spec:
+  accessModes:
+  - ReadWriteOnce
+  resources:
+    requests:
+      storage: 1Gi
+---
+apiVersion: v1
+kind: Service
+metadata:
+  name: gitea-db
+  labels:
+    service: gitea-db
+spec:
+  selector:
+    name: gitea-db
+  type: ClusterIP
+  ports:
+  - port: 3306