output slurm config as facts

Author: sjpb

README.md

@@ -136,6 +136,14 @@ You will need to configure these variables if you have set `openhpc_enable.datab
 
 `openhpc_slurmdbd_mysql_username`: Username for authenticating with the database, defaults to `slurm`.
 
+## Facts
+
+This role creates local facts from the live Slurm configuration, which can be
+accessed (with facts gathering enabled) using `ansible_local.slurm`. As per the
+`scontrol show config` man page, uppercase keys are derived parameters and keys
+in mixed case are from from config files. Note the facts are only refreshed
+when this role is run.
+
 ## Example Inventory
 
 And an Ansible inventory as this:

filter_plugins/slurm_conf.py

@@ -91,11 +91,43 @@ def dict2parameters(d):
     parts = ['%s=%s' % (k, v) for k, v in d.items()]
     return ' '.join(parts)
 
+def config2dict(lines):
+    """ Convert a sequence of output lines from `scontrol show config` to a dict.
+        
+        As per man page uppercase keys are derived parameters, mixed case are from
+        from config files.
+
+        The following case-insensitive conversions of values are carried out:
+        - '(null)' and 'n/a' are converted to None.
+        - yes and no are converted to True and False respectively
+        
+        Except for these, values are always strings.
+    """
+    cfg = {}
+    for line in lines:
+        if '=' not in line: # ditch blank/info lines
+            continue
+        else:
+            k, v = (x.strip() for x in line.split('='))
+            small_v = v.lower()
+            if small_v == '(null)':
+                v = None
+            elif small_v == 'n/a':
+                v = None
+            elif small_v == 'no':
+                v = False
+            elif small_v == 'yes':
+                v = True
+            cfg[k] = v
+    return cfg
+
+
 class FilterModule(object):
 
     def filters(self):
         return {
             'hostlist_expression': hostlist_expression,
             'error': error,
             'dict2parameters': dict2parameters,
+            'config2dict': config2dict,
         }

tasks/facts.yml

@@ -0,0 +1,27 @@
+- name: Capture configuration from scontrol
+  # this includes any dynamically-generated config, not just what is set in
+  # slurm.conf
+  ansible.builtin.command: scontrol show config
+  register: _scontrol_config
+
+- name: Create facts directory
+  ansible.builtin.file:
+    path: /etc/ansible/facts.d/
+    state: directory
+    owner: root
+    group: root
+    mode: ugo=rwX
+
+- name: Template slurm configuration facts
+  copy:
+    dest: /etc/ansible/facts.d/slurm.fact
+    content: "{{ _scontrol_config.stdout_lines | config2dict | to_nice_json }}"
+    owner: slurm
+    group: slurm
+    mode: ug=rw,o=r # any user can run scontrol show config anyway
+  register: _template_facts
+
+- name: Reload facts if necessary
+  ansible.builtin.setup:
+    filter: ansible_local
+  when: _template_facts.changed

tasks/runtime.yml

@@ -216,3 +216,5 @@
     enabled: "{{ openhpc_slurm_service_enabled | bool }}"
     state: "{{ 'started' if openhpc_slurm_service_started | bool else 'stopped' }}"
   when: openhpc_enable.batch | default(false) | bool
+
+- import_tasks: facts.yml