Add run_once option for handlers

This adds the run_once option for the two handler types (shell and
command). The variables `prometheus_target_handler_command_run_once`
and `prometheus_target_handler_shell_run_once` are introduced to
control this behavior.

For this change a switch from the Ansible Handlers to regular tasks was
necessary to  enforce run_once behavior with delegated hosts. If you
don't rely on handler specific features such as deferring, nothing
changes when using the role.

Signed-off-by: Colin Wilk <colin.wilk@tum.de>

3 files changed, 46 insertions, 3 deletions

diff --git a/tasks/handlers.yml b/tasks/handlers.yml
new file mode 100644
index 0000000..b1d9b59
--- /dev/null
+++ b/tasks/handlers.yml
@@ -0,0 +1,34 @@
+---
+- name: Run command hook # noqa inline-env-var
+  ansible.builtin.command:
+    argv: '{{ prometheus_target_handler_command.argv | default(omit) }}'
+    chdir: '{{ prometheus_target_handler_command.chdir | default(omit) }}'
+    cmd: '{{ prometheus_target_handler_command.cmd | default(omit) }}'
+    creates: '{{ prometheus_target_handler_command.creates | default(omit) }}'
+    free_form: '{{ prometheus_target_handler_command.free_form | default(omit) }}'
+    removes: '{{ prometheus_target_handler_command.removes | default(omit) }}'
+    stdin: '{{ prometheus_target_handler_command.stdin | default(omit) }}'
+    stdin_add_newline: '{{ prometheus_target_handler_command.stdin_add_newline | default(omit) }}'
+  become: '{{ prometheus_target_handler_command_become }}'
+  become_method: '{{ prometheus_target_handler_command_become_method | default(omit) }}'
+  become_user: '{{ prometheus_target_handler_command_become_user | default(omit) }}'
+  delegate_to: '{{ prometheus_target_host }}'
+  run_once: '{{ prometheus_target_handler_command_run_once }}'
+  when: prometheus_target_handler_command_enabled
+
+- name: Run shell hook
+  ansible.builtin.shell:
+    chdir: '{{ prometheus_target_handler_shell.chdir | default(omit) }}'
+    cmd: '{{ prometheus_target_handler_shell.cmd | default(omit) }}'
+    creates: '{{ prometheus_target_handler_shell.creates | default(omit) }}'
+    executable: '{{ prometheus_target_handler_shell.executable | default(omit) }}'
+    free_form: '{{ prometheus_target_handler_shell.free_form | default(omit) }}'
+    removes: '{{ prometheus_target_handler_shell.removes | default(omit) }}'
+    stdin: '{{ prometheus_target_handler_shell.stdin | default(omit) }}'
+    stdin_add_newline: '{{ prometheus_target_handler_shell.stdin_add_newline | default(omit) }}'
+  become: '{{ prometheus_target_handler_shell_become }}'
+  become_method: '{{ prometheus_target_handler_shell_become_method | default(omit) }}'
+  become_user: '{{ prometheus_target_handler_shell_become_user | default(omit) }}'
+  delegate_to: '{{ prometheus_target_host }}'
+  run_once: '{{ prometheus_target_handler_shell_run_once }}'
+  when: prometheus_target_handler_shell_enabled
diff --git a/tasks/lineinfile.yml b/tasks/lineinfile.yml
index 0367be9..8c60ba0 100644
--- a/tasks/lineinfile.yml
+++ b/tasks/lineinfile.yml
@@ -17,6 +17,8 @@
   delegate_to: '{{ prometheus_target_host }}'
   loop: '{{ prometheus_target_exporter +
          ([] if prometheus_target_skip_default_exporters else prometheus_target_default_exporters) }}'
-  notify:
-    - Run command hook
-    - Run shell hook
+  register: lineinfile
+
+- name: Export fact
+  ansible.builtin.set_fact:
+    changed: '{{ changed or lineinfile.changed }}'
diff --git a/tasks/main.yml b/tasks/main.yml
index 158191d..f8d6caa 100644
--- a/tasks/main.yml
+++ b/tasks/main.yml
@@ -2,3 +2,10 @@
 - name: Select strategy
   ansible.builtin.include_tasks:
     file: '{{ prometheus_target_strategy }}.yml'
+  vars:
+    changed: false
+
+- name: Run handlers
+  ansible.builtin.include_tasks:
+    file: handlers.yml
+  when: changed