communication: fix MAS container entrypoint

services/communication/mas-deployment.yaml

@@ -28,33 +28,41 @@ spec:
                   - key: hardware
                     operator: In
                     values: ["rpi5","rpi4"]
-      containers:
-        - name: mas
-          image: ghcr.io/element-hq/matrix-authentication-service:0.20.0
+      initContainers:
+        - name: render-config
+          image: alpine:3.20
           command: ["/bin/sh","-c"]
           args:
             - |
               set -euo pipefail
               umask 077
-
               DB_PASS_ESCAPED="$(printf '%s' "${MAS_DB_PASSWORD}" | sed 's/[\\/&]/\\&/g')"
-              sed "s/@@MAS_DB_PASSWORD@@/${DB_PASS_ESCAPED}/g" /etc/mas/config.yaml > /var/run/mas-config.yaml
-
-              exec mas-cli server --config /var/run/mas-config.yaml
+              sed "s/@@MAS_DB_PASSWORD@@/${DB_PASS_ESCAPED}/g" /etc/mas/config.yaml > /rendered/config.yaml
           env:
             - name: MAS_DB_PASSWORD
               valueFrom:
                 secretKeyRef:
                   name: mas-db
                   key: password
+          volumeMounts:
+            - name: config
+              mountPath: /etc/mas/config.yaml
+              subPath: config.yaml
+              readOnly: true
+            - name: rendered
+              mountPath: /rendered
+              readOnly: false
+      containers:
+        - name: mas
+          image: ghcr.io/element-hq/matrix-authentication-service:0.20.0
+          args: ["server","--config","/rendered/config.yaml"]
           ports:
             - name: http
               containerPort: 8080
               protocol: TCP
           volumeMounts:
-            - name: config
-              mountPath: /etc/mas/config.yaml
-              subPath: config.yaml
+            - name: rendered
+              mountPath: /rendered
               readOnly: true
             - name: secrets
               mountPath: /etc/mas/secrets
@@ -76,6 +84,8 @@ spec:
             items:
               - key: config.yaml
                 path: config.yaml
+        - name: rendered
+          emptyDir: {}
         - name: secrets
           secret:
             secretName: mas-secrets-runtime