fix: do not use become for changing hostdir ownership, and expose sub…

…uid/subgid info

When creating host directories, do not use `become`, because if
it needs to change ownership, that must be done by `root`, not
as the rootless podman user.

In order to test this, I have changed the role to export the subuid and subgid
information for the rootless users as two dictionaries:
`podman_subuid_info` and `podman_subgid_info`.  See `README.md` for
usage.

NOTE that depending on the namespace used by your containers, you might not
be able to use the subuid and subgid information, which comes from `getsubids`
if available, or directly from the files `/etc/subuid` and `/etc/subgid` on
the host.

QE: The test tests_basic.yml has been extended for this.

Signed-off-by: Rich Megginson <[email protected]>

README.md

@@ -418,6 +418,34 @@ PodmanArgs=--secret=my-app-pwd,type=env,target=MYAPP_PASSWORD
 {% endif %}
 ```
 
+### podman_subuid_info, podman_subgid_info
+
+The role needs to ensure any users and groups are present in the subuid and
+subgid information.  Once it extracts this data, it will be available in
+`podman_subuid_info` and `podman_subgid_info`. These are dicts.  The key is the
+user or group name, and the value is a `dict` with two fields:
+
+* `start` - the start of the id range for that user or group, as an `int`
+* `range` - the id range for that user or group, as an `int`
+
+```yaml
+podman_host_directories:
+  "/var/lib/db":
+    mode: "0777"
+    owner: "{{ 1001 + podman_subuid_info['dbuser']['start'] - 1 }}"
+    group: "{{ 1001 + podman_subgid_info['dbgroup']['start'] - 1 }}"
+```
+
+Where `1001` is the uid for user `dbuser`, and `1001` is the gid for group
+`dbgroup`.
+
+**NOTE**: depending on the namespace used by your containers, you might not be
+able to use the subuid and subgid information, which comes from `getsubids` if
+available, or directly from the files `/etc/subuid` and `/etc/subgid` on the
+host.  See
+[podman user namespace modes](https://www.redhat.com/sysadmin/rootless-podman-user-namespace-modes)
+for more information.
+
 ## Example Playbooks
 
 Create rootless container with volume mount:

tasks/create_update_kube_spec.yml

@@ -32,8 +32,6 @@
     __defaults: "{{ {'path': item} | combine(__podman_hostdirs_defaults) |
       combine(__owner_group) }}"
   loop: "{{ __podman_volumes }}"
-  become: "{{ __podman_rootless | ternary(true, omit) }}"
-  become_user: "{{ __podman_rootless | ternary(__podman_user, omit) }}"
   when:
     - podman_create_host_directories | bool
     - __podman_volumes | d([]) | length > 0

tasks/create_update_quadlet_spec.yml

@@ -16,8 +16,6 @@
     __defaults: "{{ {'path': item} | combine(__podman_hostdirs_defaults) |
       combine(__owner_group) }}"
   loop: "{{ __podman_volumes }}"
-  become: "{{ __podman_rootless | ternary(true, omit) }}"
-  become_user: "{{ __podman_rootless | ternary(__podman_user, omit) }}"
   when:
     - podman_create_host_directories | bool
     - __podman_volumes | d([]) | length > 0

tasks/handle_user_group.yml

@@ -52,43 +52,75 @@
     - name: Check user with getsubids
       command: getsubids {{ __podman_user | quote }}
       changed_when: false
+      register: __podman_register_subuids
 
     - name: Check group with getsubids
       command: getsubids -g {{ __podman_group_name | quote }}
       changed_when: false
+      register: __podman_register_subgids
+
+    - name: Set user subuid and subgid info
+      set_fact:
+        podman_subuid_info: "{{ podman_subuid_info | d({}) |
+          combine({__podman_user:
+            {'start': __subuid_data[2] | int, 'range': __subuid_data[3] | int}})
+          if __subuid_data | length > 0 else podman_subuid_info | d({}) }}"
+        podman_subgid_info: "{{ podman_subgid_info | d({}) |
+          combine({__podman_group_name:
+            {'start': __subgid_data[2] | int, 'range': __subgid_data[3] | int}})
+          if __subgid_data | length > 0 else podman_subgid_info | d({}) }}"
+      vars:
+        __subuid_data: "{{ __podman_register_subuids.stdout.split() | list }}"
+        __subgid_data: "{{ __podman_register_subgids.stdout.split() | list }}"
 
 - name: Check subuid, subgid files if no getsubids
   when:
     - not __podman_stat_getsubids.stat.exists
     - __podman_user not in ["root", "0"]
     - __podman_group not in ["root", "0"]
   block:
-    - name: Check if user is in subuid file
-      find:
-        path: /etc
-        pattern: subuid
-        use_regex: true
-        contains: "^{{ __podman_user }}:.*$"
-      register: __podman_uid_line_found
+    - name: Get subuid file
+      slurp:
+        path: /etc/subuid
+      register: __podman_register_subuids
+
+    - name: Get subgid file
+      slurp:
+        path: /etc/subgid
+      register: __podman_register_subgids
+
+    - name: Set user subuid and subgid info
+      set_fact:
+        podman_subuid_info: "{{ podman_subuid_info | d({}) |
+          combine({__podman_user:
+            {'start': __subuid_data[1] | int, 'range': __subuid_data[2] | int}})
+          if __subuid_data else podman_subuid_info | d({}) }}"
+        podman_subgid_info: "{{ podman_subgid_info | d({}) |
+          combine({__podman_group_name:
+            {'start': __subgid_data[1] | int, 'range': __subgid_data[2] | int}})
+          if __subgid_data else podman_subgid_info | d({}) }}"
+      vars:
+        __subuid_match_line: "{{
+          (__podman_register_subuids.content | b64decode).split('\n') | list |
+          select('match', '^' ~ __podman_user ~ ':') | list }}"
+        __subuid_data: "{{ __subuid_match_line[0].split(':') | list
+          if __subuid_match_line else null }}"
+        __subgid_match_line: "{{
+          (__podman_register_subgids.content | b64decode).split('\n') | list |
+          select('match', '^' ~ __podman_group_name ~ ':') | list }}"
+        __subgid_data: "{{ __subgid_match_line[0].split(':') | list
+          if __subgid_match_line else null }}"
 
     - name: Fail if user not in subuid file
       fail:
         msg: >
           The given podman user [{{ __podman_user }}] is not in the
           /etc/subuid file - cannot continue
-      when: not __podman_uid_line_found.matched
-
-    - name: Check if group is in subgid file
-      find:
-        path: /etc
-        pattern: subgid
-        use_regex: true
-        contains: "^{{ __podman_group_name }}:.*$"
-      register: __podman_gid_line_found
+      when: not __podman_user in podman_subuid_info
 
     - name: Fail if group not in subgid file
       fail:
         msg: >
           The given podman group [{{ __podman_group_name }}] is not in the
           /etc/subgid file - cannot continue
-      when: not __podman_gid_line_found.matched
+      when: not __podman_group_name in podman_subuid_info

tests/tests_basic.yml

@@ -8,6 +8,8 @@
     podman_host_directories:
       "/tmp/httpd1-create":
         mode: "0777"
+        owner: "{{ 1001 + podman_subuid_info['user1']['start'] - 1 }}"
+        group: "{{ 1001 + podman_subgid_info['user1']['start'] - 1 }}"
     podman_run_as_user: root
     test_names_users:
       - [httpd1, user1, 1001]