From 09eba9de8049c766f6fb2891f50b3b9f2b720853 Mon Sep 17 00:00:00 2001
From: "Joshua M. Boniface" <joshua@boniface.me>
Date: Sun, 10 Dec 2023 12:39:35 -0500
Subject: [PATCH] Add Prometheus Zookeeper exporter

---
 roles/pvc/handlers/main.yml                 |  5 +++++
 roles/pvc/tasks/zookeeper/main.yml          | 20 ++++++++++++++++++++
 roles/pvc/templates/zookeeper/prometheus.j2 |  5 +++++
 roles/pvc/templates/zookeeper/zoo.cfg.j2    |  5 ++++-
 4 files changed, 34 insertions(+), 1 deletion(-)
 create mode 100644 roles/pvc/templates/zookeeper/prometheus.j2

diff --git a/roles/pvc/handlers/main.yml b/roles/pvc/handlers/main.yml
index 34cb628..5b2e485 100644
--- a/roles/pvc/handlers/main.yml
+++ b/roles/pvc/handlers/main.yml
@@ -4,6 +4,11 @@
     name: zookeeper
     state: restarted
 
+- name: restart prometheus-zookeeper
+  service:
+    name: prometheus-zookeeper-exporter
+    state: restarted
+
 - name: restart libvirtd
   service:
     name: libvirtd
diff --git a/roles/pvc/tasks/zookeeper/main.yml b/roles/pvc/tasks/zookeeper/main.yml
index 07f94b3..d7d22ec 100644
--- a/roles/pvc/tasks/zookeeper/main.yml
+++ b/roles/pvc/tasks/zookeeper/main.yml
@@ -21,6 +21,26 @@
     - zoo.cfg
   notify: restart zookeeper
 
+- name: install Prometheus zookeeper exporter if enabled
+  apt:
+    name:
+      - prometheus-zookeeper-exporter
+  register: apt_res
+  retries: 5
+  until: apt_res is success
+  when: enable_prometheus_exporters is defined and enable_prometheus_exporters
+
+- name: install Prometheus zookeeper exporter config if enabled
+  template:
+    src: patroni/prometheus.env.j2
+    dest: /etc/default/prometheus-zookeeper-exporter
+    owner: prometheus
+    group: prometheus
+    mode: 0640
+  notify:
+    - restart prometheus-zookeeper
+  when: enable_prometheus_exporters is defined and enable_prometheus_exporters
+
 - name: install daily vacuum script
   template:
     src: zookeeper/zookeeper-vacuum.j2
diff --git a/roles/pvc/templates/zookeeper/prometheus.j2 b/roles/pvc/templates/zookeeper/prometheus.j2
new file mode 100644
index 0000000..a3ebe22
--- /dev/null
+++ b/roles/pvc/templates/zookeeper/prometheus.j2
@@ -0,0 +1,5 @@
+# Zookeeper Prometheus exporter arguments
+# {{ ansible_managed }}
+
+# Set the zk-hosts to our cluster local IP address as this is where Zookeeper listens
+ARGS="-zk-hosts='{% for node in pvc_nodes if node.hostname == this_node %}{{ node.cluster_ip }}{% endfor %}:2181'"
diff --git a/roles/pvc/templates/zookeeper/zoo.cfg.j2 b/roles/pvc/templates/zookeeper/zoo.cfg.j2
index e0da718..530ec28 100644
--- a/roles/pvc/templates/zookeeper/zoo.cfg.j2
+++ b/roles/pvc/templates/zookeeper/zoo.cfg.j2
@@ -19,11 +19,14 @@ maxClientCnxns=200
 autopurge.snapRetainCount=3
 autopurge.purgeInterval=1
 
-# Enable Prometheus metrics (someday, but not today under Debian 12 or less)
+# Enable internal Prometheus metrics (someday, but not today under Debian 12 or less)
 #metricsProvider.className=org.apache.zookeeper.metrics.prometheus.PrometheusMetricsProvider
 #metricsProvider.httpPort=9181
 #metricsProvider.exportJvmInfo=true
 
+# Enable all 4LW commands; need MNTR for external Prometheus metrics
+4lw.commands.whitelist=*
+
 # Listen on port 2181 on the cluster IP
 clientPort=2181
 clientPortAddress={% for node in pvc_nodes if node.hostname == this_node %}{{ node.cluster_ip }}{% endfor %}