J’ai pu voir que cela ne se lançait pas dans /usr/local/var/log/prometheus.err.log, sans arrêt j’ai l’erreur :

component=activeQueryTracker msg="Failed to create directory for logging active queries"

J’ai donc modifié le fichier /usr/local/Cellar/prometheus/2.13.1/homebrew.mxcl.prometheus.plist et pas le fichier  /Users/XXXXXX/Library/LaunchAgents/homebrew.mxcl.prometheus.plist (inutile)

<?xml version="1.0" encoding="UTF-8"?>
  <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
  <plist version="1.0">
  <dict>
    <key>Label</key>
    <string>homebrew.mxcl.prometheus</string>
    <key>ProgramArguments</key>
    <array>
      <string>sh</string>
      <string>-c</string>
      <string>/usr/local/opt/prometheus/bin/prometheus $(&lt; /usr/local/etc/prometheus.args)</string>
    </array>
    <key>RunAtLoad</key>
    <true/>
    <key>KeepAlive</key>
    <false/>
    <key>WorkingDirectory</key>
    <string>/usr/local/opt/prometheus</string>
    <key>StandardErrorPath</key>
    <string>/usr/local/var/log/prometheus.err.log</string>
    <key>StandardOutPath</key>
    <string>/usr/local/var/log/prometheus.log</string>
  </dict>
</plist>

Je relance :

$ brew services restart prometheus
Stopping `prometheus`... (might take a while)
==> Successfully stopped `prometheus` (label: homebrew.mxcl.prometheus)
==> Successfully started `prometheus` (label: homebrew.mxcl.prometheus)

Attention pour l’écoute c’est 0.0.0.0 et pas 127.0.0.1 : http://0.0.0.0:9090 .