From 302a3e76ca1d4d303fd6938cfb26505e4ce3e73d Mon Sep 17 00:00:00 2001
From: Benjamin Brahmer <info@b-brahmer.de>
Date: Tue, 26 Mar 2024 13:19:51 +0100
Subject: [PATCH] check installed node_exporter version instead of always
 downloading

---
 roles/batman/tasks/main.yml                   |  1 +
 .../files/get_node_exporter_version.py        | 20 ++++++
 roles/prometheus/tasks/download.yml           | 64 +++++++++++++++++
 roles/prometheus/tasks/main.yml               | 72 +++----------------
 4 files changed, 96 insertions(+), 61 deletions(-)
 create mode 100644 roles/prometheus/files/get_node_exporter_version.py
 create mode 100644 roles/prometheus/tasks/download.yml

diff --git a/roles/batman/tasks/main.yml b/roles/batman/tasks/main.yml
index 6311aed..db1a7de 100644
--- a/roles/batman/tasks/main.yml
+++ b/roles/batman/tasks/main.yml
@@ -1,6 +1,7 @@
 - name: Install basic packages
   ansible.builtin.apt:
     name: dkms
+
 - name: Check for currently installed batman-adv
   ansible.builtin.script: files/get_batman_version.py
   args:
diff --git a/roles/prometheus/files/get_node_exporter_version.py b/roles/prometheus/files/get_node_exporter_version.py
new file mode 100644
index 0000000..ab8d036
--- /dev/null
+++ b/roles/prometheus/files/get_node_exporter_version.py
@@ -0,0 +1,20 @@
+#! python3
+
+import subprocess
+import sys
+import re
+
+# compile regex for installed node_exporter version
+pattern = re.compile(r"node_exporter, version (\d\.\d\.\d)")
+
+# check current node_exporter
+node_exporter = subprocess.check_output(["/opt/node_exporter/node_exporter", "--version"]).decode("utf-8")
+
+# use regex to find installed version
+result = pattern.match(node_exporter)
+
+if result:
+    # print only the version, without newline otherwise ansible will store the newline
+    print(result[1], end="")
+else:
+    print("not_installed", end="")
\ No newline at end of file
diff --git a/roles/prometheus/tasks/download.yml b/roles/prometheus/tasks/download.yml
new file mode 100644
index 0000000..8b707f9
--- /dev/null
+++ b/roles/prometheus/tasks/download.yml
@@ -0,0 +1,64 @@
+- name: Detected Architecture
+  ansible.builtin.debug:
+    var: go_arch
+
+- name: Download node_exporter
+  ansible.builtin.get_url:
+    url: >
+      https://github.com/prometheus/node_exporter/releases/download/v{{ node_exporter_version }}/node_exporter-{{ node_exporter_version }}.linux-{{ go_arch }}.tar.gz
+    dest: /opt/node_exporter-{{ node_exporter_version }}.linux-{{ go_arch }}.tar.gz
+    mode: '0644'
+    owner: root
+    group: root
+
+- name: Unpack node_exporter
+  ansible.builtin.unarchive:
+    src: /opt/node_exporter-{{ node_exporter_version }}.linux-{{ go_arch }}.tar.gz
+    dest: /opt
+    remote_src: true
+    mode: '0644'
+    owner: root
+    group: root
+  when: not ansible_check_mode
+
+- name: Delete node_exporter archive
+  ansible.builtin.file:
+    path: /opt/node_exporter-{{ node_exporter_version }}.linux-{{ go_arch }}.tar.gz
+    state: absent
+
+- name: Stop node_exporter service
+  ansible.builtin.systemd:
+    daemon-reload: true
+    enabled: true
+    name: node_exporter
+    state: stopped
+
+- name: Move node exporter to target directory
+  ansible.builtin.copy:
+    remote_src: true
+    src: /opt/node_exporter-{{ node_exporter_version }}.linux-{{ go_arch }}/
+    dest: /opt/node_exporter/
+    force: true
+    mode: '0744'
+    owner: prometheus
+    group: prometheus
+
+- name: Delete node_exporter directory
+  ansible.builtin.file:
+    path: /opt/node_exporter-{{ node_exporter_version }}.linux-{{ go_arch }}/
+    state: absent
+
+- name: Adjust node_exporter permissions
+  ansible.builtin.file:
+    path: /opt/node_exporter/node_exporter
+    owner: prometheus
+    group: prometheus
+    mode: '0744'
+    state: file
+
+- name: Start node_exporter service
+  ansible.builtin.systemd:
+    daemon-reload: true
+    enabled: true
+    name: node_exporter
+    state: restarted
diff --git a/roles/prometheus/tasks/main.yml b/roles/prometheus/tasks/main.yml
index f0308e9..654ddd4 100644
--- a/roles/prometheus/tasks/main.yml
+++ b/roles/prometheus/tasks/main.yml
@@ -12,67 +12,17 @@
     system: true
     create_home: false
 
-- name: Detected Architecture
-  ansible.builtin.debug:
-    var: go_arch
-
-- name: Download node_exporter
-  ansible.builtin.get_url:
-    url: >
-      https://github.com/prometheus/node_exporter/releases/download/v{{ node_exporter_version }}/node_exporter-{{ node_exporter_version }}.linux-{{ go_arch }}.tar.gz
-    dest: /opt/node_exporter-{{ node_exporter_version }}.linux-{{ go_arch }}.tar.gz
-    mode: '0644'
-    owner: root
-    group: root
-
-- name: Unpack node_exporter
-  ansible.builtin.unarchive:
-    src: /opt/node_exporter-{{ node_exporter_version }}.linux-{{ go_arch }}.tar.gz
-    dest: /opt
-    remote_src: true
-    mode: '0644'
-    owner: root
-    group: root
-  when: not ansible_check_mode
-
-- name: Delete node_exporter archive
-  ansible.builtin.file:
-    path: /opt/node_exporter-{{ node_exporter_version }}.linux-{{ go_arch }}.tar.gz
-    state: absent
-
-- name: Stop node_exporter service
-  ansible.builtin.systemd:
-    daemon-reload: true
-    enabled: true
-    name: node_exporter
-    state: stopped
+- name: Check for currently installed node_exporter
+  ansible.builtin.script: files/get_node_exporter_version.py
+  args:
+    executable: python3
+  register: installed_node_exporter_version
 
-- name: Move node exporter to target directory
-  ansible.builtin.copy:
-    remote_src: true
-    src: /opt/node_exporter-{{ node_exporter_version }}.linux-{{ go_arch }}/
-    dest: /opt/node_exporter/
-    force: true
-    mode: '0744'
-    owner: prometheus
-    group: prometheus
-
-- name: Delete node_exporter directory
-  ansible.builtin.file:
-    path: /opt/node_exporter-{{ node_exporter_version }}.linux-{{ go_arch }}/
-    state: absent
+- name: Print node_exporter version and target
+  ansible.builtin.debug:
+    msg: "Currently installed node_exporter: {{ installed_node_exporter_version.stdout }} ,target is: {{ node_exporter_version }}"
 
-- name: Adjust node_exporter permissions
-  ansible.builtin.file:
-    path: /opt/node_exporter/node_exporter
-    owner: prometheus
-    group: prometheus
-    mode: '0744'
-    state: file
+- name: Check if node_exporter-adv needs to be installed or upgraded
+  ansible.builtin.include_tasks: download.yml
+  when: installed_node_exporter_version.stdout != node_exporter_version
 
-- name: Start node_exporter service
-  ansible.builtin.systemd:
-    daemon-reload: true
-    enabled: true
-    name: node_exporter
-    state: restarted