#+title: Prometheus
#+setupfile: ../org-templates/page.org

** Download and install
Go to [[https://prometheus.io/download/]] and download the latest version.
#+BEGIN_SRC shell
export PROM_VER="2.54.0"
wget "https://github.com/prometheus/prometheus/releases/download/v${PROM_VER}/prometheus-${PROM_VER}.linux-amd64.tar.gz"
#+END_SRC

Verify the checksum is correct.

Unpack the tarball:
#+BEGIN_SRC shell
tar xvfz prometheus-*.tar.gz
rm prometheus-*.tar.gz
#+END_SRC

Create two directories for Prometheus to use. ~/etc/prometheus~ for configuration files and ~/var/lib/prometheus~ for application data.
#+BEGIN_SRC shell
sudo mkdir /etc/prometheus /var/lib/prometheus
#+END_SRC

Move the ~prometheus~ and ~promtool~ binaries to ~/usr/local/bin~:
#+BEGIN_SRC shell
cd prometheus-*
sudo mv prometheus promtool /usr/local/bin
#+END_SRC

Move the configuration file to the configuration directory:
#+BEGIN_SRC shell
sudo mv prometheus.yml /etc/prometheus/prometheus.yml
#+END_SRC

Move the remaining files to their appropriate directories:
#+BEGIN_SRC shell
sudo mv consoles/ console_libraries/ /etc/prometheus/
#+END_SRC

Verify that Prometheus is installed:
#+BEGIN_SRC shell
prometheus --version
#+END_SRC

** Configure prometheus.service
Create a prometheus user and assign ownership to directories:
#+BEGIN_SRC shell
sudo useradd -rs /bin/false prometheus
sudo chown -R prometheus: /etc/prometheus /var/lib/prometheus
#+END_SRC

Save the following contents to a file at ~/etc/systemd/system/prometheus.service~:
#+BEGIN_SRC systemd
[Unit]
Description=Prometheus
Wants=network-online.target
After=network-online.target

[Service]
User=prometheus
Group=prometheus
Type=simple
Restart=on-failure
RestartSec=5s
ExecStart=/usr/local/bin/prometheus \
    --config.file /etc/prometheus/prometheus.yml \
    --storage.tsdb.path /var/lib/prometheus/ \
    --web.console.templates=/etc/prometheus/consoles \
    --web.console.libraries=/etc/prometheus/console_libraries \
    --web.listen-address=0.0.0.0:9090 \
    --web.enable-lifecycle \
    --log.level=info

[Install]
WantedBy=multi-user.target
#+END_SRC

Reload the system daemons:
#+BEGIN_SRC shell
sudo systemctl daemon-reload
#+END_SRC

Start and enable ~prometheus.service~:
#+BEGIN_SRC shell
sudo systemctl enable --now prometheus.service
#+END_SRC

#+BEGIN_QUOTE
For systems running SELinux, the following policy settings must be applied.
#+END_QUOTE

#+BEGIN_SRC selinux
module prometheus 1.0;

require {
        type init_t;
        type websm_port_t;
        type user_home_t;
        type unreserved_port_t;
        type hplip_port_t;
        class file { execute execute_no_trans map open read };
        class tcp_socket name_connect;
}

#============= init_t ==============
allow init_t hplip_port_t:tcp_socket name_connect;
allow init_t unreserved_port_t:tcp_socket name_connect;
allow init_t user_home_t:file { execute execute_no_trans map open read };
allow init_t websm_port_t:tcp_socket name_connect;
#+END_SRC

Now compile and import the module:
#+BEGIN_SRC shell
sudo checkmodule -M -m -o prometheus.mod prometheus.te
sudo semodule_package -o prometheus.pp -m prometheus.mod
sudo semodule -i prometheus.pp
#+END_SRC

Restart ~prometheus.service~. If it does not start, ensure all SELinux policies have been applied.
#+BEGIN_SRC shell
sudo grep "prometheus" /var/log/audit/audit.log | sudo audit2allow -M prometheus
sudo semodule -i prometheus.pp
#+END_SRC

Restart ~prometheus.service~ again.

The Prometheus web interface and dashboard should now be browsable at [[http://localhost:9090]]

** Install and configure Node Exporter on each client using Ansible

Install the prometheus.prometheus role from Ansible Galaxy.

#+BEGIN_SRC shell
ansible-galaxy collection install prometheus.prometheus
#+END_SRC

Ensure you have an inventory file with clients to setup Prometheus on.

#+BEGIN_SRC yaml
---
prometheus-clients:
  hosts:
    host0:
      ansible_user: user0
      ansible_host: host0 ip address or hostname
      ansible_python_interpreter: /usr/bin/python3
    host1:
      ...
    host2:
      ...
#+END_SRC

Create ~prometheus-setup.yml~.

#+BEGIN_SRC yaml
---
- hosts: prometheus-clients
  tasks:
    - name: Import the node_exporter role
      import_role:
        name: prometheus.prometheus.node_exporter
#+END_SRC

The default values for the node_exporter role variables should be fine.

Run ansible-playbook.

#+BEGIN_SRC shell
ansible-playbook -i inventory.yml node_exporter-setup.yml
#+END_SRC

Node Exporter should now be installed, started, and enabled on each host with the homelab label in the inventory.

To confirm that statistics are being collected on each host, navigate to ~http://host_url:9100~. A page entitled Node Exporter should be displayed containing a link for Metrics. Click the link and confirm that statistics are being collected.

Note that each node_exporter host must be accessible through the firewall on port 9100. Firewalld can be configured for the ~internal~ zone on each host.
#+BEGIN_SRC shell
sudo firewall-cmd --zone=internal --permanent --add-source=<my_ip_addr>
sudo firewall-cmd --zone=internal --permanent --add-port=9100/tcp
#+END_SRC

#+BEGIN_QUOTE
Note: I have to configure the ~internal~ zone on Firewalld to allow traffic from my IP address on ports HTTP, HTTPS, SSH, and 1965 in order to access, for example, my web services on the node_exporter host.
#+END_QUOTE

** Install Node Exporter on FreeBSD

As of FreeBSD 14.1-RELEASE, the version of Node Exporter available, v1.6.1, is outdated. To install the latest version, ensure the ports tree is checked out before running the commands below.

#+BEGIN_SRC shell
sudo cp -v /usr/ports/sysutils/node_exporter/files/node_exporter.in /usr/local/etc/rc.d/node_exporter
sudo chmod +x /usr/local/etc/rc.d/node_exporter
sudo chown root:wheel /usr/local/etc/rc.d/node_exporter
sudo pkg install gmake go
#+END_SRC

Download the latest release's source code from https://github.com/prometheus/node_exporter. Unpack the tarball.

#+BEGIN_SRC shell
tar xvf v1.8.2.tar.gz
cd node_exporter-1.8.2
gmake build
sudo mv node_exporter /usr/local/bin/
sudo chown root:wheel /usr/local/bin/node_exporter
sudo sysrc node_exporter_enable="YES"
sudo service node_exporter start
#+END_SRC

** Configure Prometheus to monitor the client nodes
Edit ~/etc/prometheus/prometheus.yml~. My Prometheus configuration looks like this:
#+BEGIN_SRC yaml
# my global config
global:
  scrape_interval: 15s # Set the scrape interval to every 15 seconds. Default is every 1 minute.
  evaluation_interval: 15s # Evaluate rules every 15 seconds. The default is every 1 minute.
  # scrape_timeout is set to the global default (10s).

# Alertmanager configuration
alerting:
  alertmanagers:
    - static_configs:
        - targets:
          # - alertmanager:9093

# Load rules once and periodically evaluate them according to the global 'evaluation_interval'.
rule_files:
  # - "first_rules.yml"
  # - "second_rules.yml"

# A scrape configuration containing exactly one endpoint to scrape:
# Here it's Prometheus itself.
scrape_configs:
  # The job name is added as a label `job=<job_name>` to any timeseries scraped from this config.
  - job_name: "prometheus"

    # metrics_path defaults to '/metrics'
    # scheme defaults to 'http'.

    static_configs:
      - targets: ["localhost:9090"]

  - job_name: "remote_collector"
    scrape_interval: 10s
    static_configs:
      - targets: ["hyperreal.coffee:9100", "box.moonshadow.dev:9100", "10.0.0.26:9100", "bttracker.nirn.quest:9100"]
#+END_SRC

The job ~remote_collector~ scrapes metrics from each of the hosts running the node_exporter. Ensure that port ~9100~ is open in the firewall, and if it is a public-facing node, ensure that port ~9100~ can only be accessed from my IP address.

** Configure Prometheus to monitor qBittorrent client nodes
For each qBittorrent instance you want to monitor, setup a Docker or Podman container with [[https://github.com/caseyscarborough/qbittorrent-exporter]]. The containers will run on the machine running Prometheus so they are accessible at localhost. Let's say I have three qBittorrent instances I want to monitor.
#+BEGIN_SRC shell
podman run \
        --name=qbittorrent-exporter-0 \
        -e QBITTORRENT_USERNAME=username0 \
        -e QBITTORRENT_PASSWORD=password0 \
        -e QBITTORRENT_BASE_URL=http://localhost:8080 \
        -p 17871:17871 \
        --restart=always \
        caseyscarborough/qbittorrent-exporter:latest

podman run \
        --name=qbittorrent-exporter-1 \
        -e QBITTORRENT_USERNAME=username1 \
        -e QBITTORRENT_PASSWORD=password1 \
        -e QBITTORRENT_BASE_URL=https://qbittorrent1.tld \
        -p 17872:17871 \
        --restart=always \
        caseyscarborough/qbittorrent-exporter:latest

podman run \
        --name=qbittorrent-exporter-2 \
        -e QBITTORRENT_USERNAME=username2 \
        -e QBITTORRENT_PASSWORD=password2 \
        -e QBITTORRENT_BASE_URL=https://qbittorrent2.tld \
        -p 17873:17871 \
        --restart=always \
        caseyscarborough/qbittorrent-exporter:latest
#+END_SRC

*** Using systemd quadlets
#+BEGIN_SRC systemd
[Unit]
Description=qbittorrent-exporter
After=network-online.target

[Container]
Image=docker.io/caseyscarborough/qbittorrent-exporter:latest
ContainerName=qbittorrent-exporter
Environment=QBITTORRENT_USERNAME=username
Environment=QBITTORRENT_PASSWORD=password
Environment=QBITTORRENT_BASE_URL=http://localhost:8080
PublishPort=17871:17871

[Install]
WantedBy=multi-user.target default.target
#+END_SRC

Now add this to the ~scrape_configs~ section of ~/etc/prometheus/prometheus.yml~ to configure Prometheus to scrape these metrics.
#+BEGIN_SRC yaml
  - job_name: "qbittorrent"
    static_configs:
      - targets: ["localhost:17871", "localhost:17872", "localhost:17873"]
#+END_SRC

** Monitor Caddy with Prometheus and Loki
*** Caddy: metrics activation
Add the ~metrics~ global option and ensure the admin endpoint is enabled.
#+BEGIN_SRC caddyfile
{
        admin 0.0.0.0:2019
        servers {
                metrics
        }
}
#+END_SRC

Restart Caddy:
#+BEGIN_SRC shell
sudo systemctl restart caddy
sudo systemctl status caddy
#+END_SRC

*** Caddy: logs activation
I have my Caddy configuration modularized with ~/etc/caddy/Caddyfile~ being the central file. It looks something like this:
#+BEGIN_SRC caddyfile
{
        admin 0.0.0.0:2019
        servers {
                metrics
        }
}

## hyperreal.coffee
import /etc/caddy/anonoverflow.caddy
import /etc/caddy/breezewiki.caddy
import /etc/caddy/cdn.caddy
...
#+END_SRC

Each file that is imported is a virtual host that has its own separate configuration and corresponds to a subdomain of hyperreal.coffee. I have logging disabled on most of them except the ones for which troubleshooting with logs would be convenient, such as the one for my Mastodon instance. For ~/etc/caddy/fedi.caddy~, I've added these lines to enable logging:
#+BEGIN_SRC caddyfile
fedi.hyperreal.coffee {
        log {
                output file /var/log/caddy/fedi.log {
                        roll_size 100MiB
                        roll_keep 5
                        roll_keep_for 100d
                }
                format json
                level INFO
        }
}
#+END_SRC

Restart caddy.
#+BEGIN_SRC shell
sudo systemctl restart caddy
sudo systemctl status caddy
#+END_SRC

Ensure port ~2019~ can only be accessed by my IP address, using Firewalld's internal zone:
#+BEGIN_SRC shell
sudo firewall-cmd --zone=internal --permanent --add-port=2019/tcp
sudo firewall-cmd --reload
sudo firewall-cmd --info-zone=internal
#+END_SRC

Add the Caddy configuration to the ~scrape_configs~ section of ~/etc/prometheus/prometheus.yml~:
#+BEGIN_SRC yaml
- job_name: "caddy"
  static_configs:
    - targets: ["hyperreal.coffee:2019"]
#+END_SRC

Restart Prometheus on the monitor host:
#+BEGIN_SRC shell
sudo systemctl restart prometheus.service
#+END_SRC

*** Loki and Promtail setup
On the node running Caddy, install the loki and promtail packages:
#+BEGIN_SRC shell
sudo apt install -y loki promtail
#+END_SRC

Edit the Promtail configuration file at ~/etc/promtail/config.yml~:
#+BEGIN_SRC yaml
- job_name: caddy
  static_configs:
  - targets:
    - localhost
    labels:
      job: caddy
      __path__: /var/log/caddy/*.log
      agent: caddy-promtail
  pipeline_stages:
  - json:
      expressions:
        duration: duration
        status: status
  - labels:
      duration:
      status:
#+END_SRC

The entire Promtail configuration should look like this:
#+BEGIN_SRC yaml
# This minimal config scrape only single log file.
# Primarily used in rpm/deb packaging where promtail service can be started during system init process.
# And too much scraping during init process can overload the complete system.
# https://github.com/grafana/loki/issues/11398

server:
  http_listen_port: 9080
  grpc_listen_port: 0

positions:
  filename: /tmp/positions.yaml

clients:
- url: http://localhost:3100/loki/api/v1/push

scrape_configs:
- job_name: system
  static_configs:
  - targets:
      - localhost
    labels:
      job: varlogs
      #NOTE: Need to be modified to scrape any additional logs of the system.
      __path__: /var/log/messages

- job_name: caddy
  static_configs:
  - targets:
      - localhost
    labels:
      job: caddy
      __path__: /var/log/caddy/*log
      agent: caddy-promtail
  pipeline_stages:
  - json:
      expressions:
        duration: duration
        status: status
  - labels:
     duration:
     status:
#+END_SRC

Restart Promtail and Loki services:
#+BEGIN_SRC shell
sudo systemctl restart promtail
sudo systemctl restart loki
#+END_SRC

To ensure that the promtail user has permissions to read caddy logs:
#+BEGIN_SRC shell
sudo usermod -aG caddy promtail
sudo chmod g+r /var/log/caddy/*.log
#+END_SRC

The [[http://localhost:9090/targets][Prometheus dashboard]] should now show the Caddy target with a state of "UP".

** Monitor TOR node
Edit ~/etc/tor/torrc~ to add Metrics info. ~x.x.x.x~ is the IP address where Prometheus is running.
#+BEGIN_SRC shell
## Prometheus exporter
MetricsPort 0.0.0.0:9035 prometheus
MetricsPortPolicy accept x.x.x.x
#+END_SRC

Configure FirewallD to allow inbound traffic to port ~9035~ on the internal zone. Ensure the internal zone's source is the IP address of the server where Prometheus is running. Ensure port ~443~ is accessible from the Internet on FirewallD's public zone.
#+BEGIN_SRC shell
sudo firewall-cmd --zone=internal --permanent --add-source=x.x.x.x
sudo firewall-cmd --zone=internal --permanent --add-port=9035/tcp
sudo firewall-cmd --zone=public --permanent --add-service=https
sudo firewall-cmd --reload
#+END_SRC

Edit ~/etc/prometheus/prometheus.yml~ to add the TOR config. ~y.y.y.y~ is the IP address where TOR is running.
#+BEGIN_SRC yaml
scrape_configs:
  - job_name: "tor-relay"
    static_configs:
      - targets: ["y.y.y.y:9035"]
#+END_SRC

Restart Prometheus.
#+BEGIN_SRC shell
sudo systemctl restart prometheus.service
#+END_SRC

Go to Grafana and import [[https://files.hyperreal.coffee/grafana/tor_stats.json][tor_stats.json]] as a new dashboard, using the Prometheus datasource.

** Monitor Synapse homeserver
On the server running Synapase, edit ~/etc/matrix-synapse/homeserver.yaml~ to enable metrics.
#+BEGIN_SRC yaml
enable_metrics: true
#+END_SRC

Add a new listener to ~/etc/matrix-synapse/homeserver.yaml~ for Prometheus metrics.
#+BEGIN_SRC yaml
listeners:
  - port: 9400
    type: metrics
    bind_addresses: ['0.0.0.0']
#+END_SRC

On the server running Prometheus, add a target for Synapse.
#+BEGIN_SRC yaml
- job_name: "synapse"
  scrape_interval: 1m
  metrics_path: "/_synapse/metrics"
  static_configs:
    - targets: ["hyperreal:9400"]
#+END_SRC

Also add the Synapse recording rules.
#+BEGIN_SRC yaml
rule_files:
  - /etc/prometheus/synapse-v2.rules
#+END_SRC

On the server running Prometheus, download the Synapse recording rules.
#+BEGIN_SRC shell
sudo wget https://files.hyperreal.coffee/prometheus/synapse-v2.rules -O /etc/prometheus/synapse-v2.rules
#+END_SRC

Restart Prometheus.

Use [[https://files.hyperreal.coffee/grafana/synapse.json][synapse.json]] for Grafana dashboard.