F #91: Improve ds "generic" and "simple" modes (#92)

- Assume true if "managed" attribute is undefined.
- Assert that all symlink targets must exist.
- Provide rationale for manual "generic" ds id management.

roles/datastore/frontend/README.md

@@ -33,7 +33,7 @@ Example Playbook
         # Configure OpenNebula to use "ssh" datastores.
         # Create symlinks accordingly.
         # NOTE: In case of HA OpenNebula, image and file datastores
-        # should be shared among all Frontends.
+        #       should be shared among all Frontends.
         ds:
           mode: ssh
           config:
@@ -68,6 +68,11 @@ Example Playbook
       vars:
         # Configure OpenNebula to use "shared" image and system datastores.
         # Create new datastores and symlinks accordingly.
+        # NOTE: 1. In OpenNebula all user-created datastores start from ID=100.
+        #       2. If the 'id' attribute refers to an existing datastore, then one-deploy tries to update it.
+        #       3. If 2. is false, then a new datastore is created using the next available ID.
+        #       4. Users *MUST* provide the 'id' attribute for each new entry in the 'ds.config' dict
+        #          (starting from 100, then incrementing by 1 further down the line).
         ds:
           mode: generic
           config:

roles/datastore/generic/defaults/main.yml

@@ -11,7 +11,7 @@ ds_defaults:
       enabled: true
       symlink:
         groups: [node]
-        src: /var/lib/one/datastores/
+        src: /var/lib/one/datastores/ # this skips symlinking
       template:
         TYPE: SYSTEM_DS
         TM_MAD: ssh
@@ -21,7 +21,7 @@ ds_defaults:
       managed: true
       symlink:
         groups: [frontend, node]
-        src: /var/lib/one/datastores/
+        src: /var/lib/one/datastores/ # this skips symlinking
       template:
         TYPE: IMAGE_DS
         DS_MAD: fs
@@ -32,7 +32,7 @@ ds_defaults:
       managed: true
       symlink:
         groups: [frontend]
-        src: /var/lib/one/datastores/
+        src: /var/lib/one/datastores/ # this skips symlinking
       template:
         TYPE: FILE_DS
         DS_MAD: fs

roles/datastore/generic/tasks/common.yml

@@ -7,14 +7,13 @@
       {{ _items | items2dict }}
   vars:
     _ds: >-
-      {{ ds_defaults | combine(ds.config | default({}), recursive=true) }}
+      {{ ds_defaults | combine(ds.config | d({}), recursive=true) }}
     _items: >-
       {{ _ds | dict2items
              | map(attribute='value')
              | map('dict2items')
              | flatten
-             | selectattr('value.managed', 'true')
-             | list }}
+             | rejectattr('value.managed', 'false') }}
 
 - name: Ensure /var/lib/one/datastores/ exists
   ansible.builtin.file:
@@ -31,26 +30,43 @@
 
       if [[ -L '{{ _base_path }}' ]]; then exit 0; fi
 
-      if [[ -d '{{ _base_path }}/' ]] && ! rmdir '{{ _base_path }}/'; then exit 1; fi
+      if ! [[ -d '{{ _mount_path }}' ]]; then
+        echo "Symlink target does not exist or is not a directory." >&2
+        exit 1
+      fi
 
-      if ! ln -s '{{ _mount_path }}/' '{{ _base_path }}'; then exit 1; fi
+      if [[ -d '{{ _base_path }}' ]] && ! rmdir '{{ _base_path }}'; then exit 1; fi
+
+      if ! ln -s '{{ _mount_path }}' '{{ _base_path }}'; then exit 1; fi
 
       exit 78
     executable: /bin/bash
-  when: inventory_hostname in _hosts and _mount_path != '/var/lib/one/datastores'
+  when:
+    - inventory_hostname in _hosts
+    # NOTE: It doesn't really make sense to symlink /var/lib/one/datastores/,
+    #       so we use that as a skip condition.
+    - _mount_path != '/var/lib/one/datastores'
   vars:
+    # This isn't strictly a "mountpoint" (that's completely irrelevant).
     _mount_path: >-
-      {{ ds_dict[item].symlink.src | normpath }}
+      {{ ds_dict[item].symlink.src | d('/var/lib/one/datastores/') | normpath }}
+    # NOTE: 1. In OpenNebula all user-created datastores start from ID=100.
+    #       2. If the ds_dict[item].id refers to an existing datastore, then one-deploy tries to update it (later).
+    #       3. If 2. is false, then a new datastore is created using the next available ID (later).
+    #       4. If 3. is true, then at this exact point in time one-deploy does *NOT* know the ID.
+    #       5. The 'generic' mode has been specifically designed in such a way that reduces code complexity.
+    #          Users *MUST* provide the 'id' attribute for each new entry in the 'ds.config' dict
+    #          (starting from 100, then incrementing by 1 further down the line).
     _base_path: >-
       /var/lib/one/datastores/{{ ds_dict[item].id }}
     _hosts: >-
-      {{ ds_dict[item].symlink.groups | map('extract', groups)
+      {{ ds_dict[item].symlink.groups | d([])
+                                      | map('extract', groups)
                                       | flatten
-                                      | unique
-                                      | list }}
-  loop: "{{ ds_names }}"
+                                      | unique }}
   register: shell
   changed_when:
     - shell.rc == 78 # EREMCHG "Remote address changed" 8^)
   failed_when:
     - shell.rc != 0 and shell.rc != 78
+  loop: "{{ ds_names }}"

roles/datastore/generic/tasks/frontend.yml

@@ -25,9 +25,9 @@
     _document: >-
       {{ shell.stdout | from_json }}
     _datastores: >-
-      {{ [_document.DATASTORE_POOL.DATASTORE | default([])] | flatten | list }}
+      {{ [_document.DATASTORE_POOL.DATASTORE | d([])] | flatten }}
     _names: >-
-      {{ _datastores | map(attribute='NAME') | default([]) | list }}
+      {{ _datastores | map(attribute='NAME') | d([]) | list }}
 
 - when: inventory_hostname == leader
   block:

roles/datastore/simple/tasks/frontend.yml

@@ -9,9 +9,14 @@
 
       if [[ -L '{{ _base_path }}' ]]; then exit 0; fi
 
-      if [[ -d '{{ _base_path }}/' ]] && ! rmdir '{{ _base_path }}/'; then exit 1; fi
+      if ! [[ -d '{{ _mount_path }}' ]]; then
+        echo "Symlink target does not exist or is not a directory." >&2
+        exit 1
+      fi
 
-      if ! ln -s '{{ _mount_path }}/' '{{ _base_path }}'; then exit 1; fi
+      if [[ -d '{{ _base_path }}' ]] && ! rmdir '{{ _base_path }}'; then exit 1; fi
+
+      if ! ln -s '{{ _mount_path }}' '{{ _base_path }}'; then exit 1; fi
 
       exit 78
     executable: /bin/bash

roles/datastore/simple/tasks/node.yml

@@ -11,9 +11,14 @@
 
           if [[ -L '{{ _base_path }}' ]]; then exit 0; fi
 
-          if [[ -d '{{ _base_path }}/' ]] && ! rmdir '{{ _base_path }}/'; then exit 1; fi
+          if ! [[ -d '{{ _mount_path }}' ]]; then
+            echo "Symlink target does not exist or is not a directory." >&2
+            exit 1
+          fi
 
-          if ! ln -s '{{ _mount_path }}/' '{{ _base_path }}'; then exit 1; fi
+          if [[ -d '{{ _base_path }}' ]] && ! rmdir '{{ _base_path }}'; then exit 1; fi
+
+          if ! ln -s '{{ _mount_path }}' '{{ _base_path }}'; then exit 1; fi
 
           exit 78
         executable: /bin/bash