require bind mounts from mergerfs for nfs root before nfs service starts

ansible/inventory/hosts.yaml

@@ -41,6 +41,8 @@ linux:
       cockpit: true
       snapraid: true
       proxmox__acpi_lax: true
+      nfs__required_services:
+        - srv-nfs-media.mount
       nfs__exports:
         - /srv/nfs  *(rw,fsid=0,no_subtree_check,all_squash)
         - /srv/nfs/media  *(rw,fsid=10,no_subtree_check,all_squash,anonuid=1000,anongid=1000)

ansible/roles/nfs/defaults/main.yaml

@@ -5,3 +5,4 @@ nfs__supported_distributions:
 
 nfs__root_dir: /srv/nfs
 nfs__exports: []
+nfs__required_services: []

ansible/roles/nfs/handlers/main.yaml

@@ -1,3 +1,7 @@
 ---
-- name: reload nfs
-  ansible.builtin.command: 'exportfs -ra'
+- name: Reload nfs
+  ansible.builtin.command: "exportfs -ra"
+
+- name: Reload systemd
+  ansible.builtin.systemd:
+    daemon_reload: true

ansible/roles/nfs/tasks/main.yaml

@@ -33,10 +33,31 @@
         owner: root
         group: root
         mode: "0644"
-      notify: reload nfs
+      notify: Reload nfs
 
     - name: Enable and start NFS server
       ansible.builtin.service:
         name: "{{ nfs__server_daemon }}"
         state: started
         enabled: true
+
+- name: Make services required for NFS
+  when: nfs__required_services | length
+  block:
+    - name: Create NFS systemd override directory
+      ansible.builtin.file:
+        path: /etc/systemd/system/nfs-server.service.d
+        state: directory
+        owner: root
+        group: root
+        mode: "0755"
+
+    - name: Create NFS systemd override
+      ansible.builtin.copy:
+        # /srv/nfs/media would become `srv-nfs-media.mount`
+        content: "Requires=network.target proc-fs-nfsd.mount {{ nfs__required_services.strip().join(' ') }}"
+        dest: /etc/systemd/system/nfs-server.service.d/override.conf
+        owner: root
+        group: root
+        mode: "0644"
+      notify: Reload systemd