mongod.conf

# /opt/local/etc/mongod.conf

# Store data someplace appropriate for a port-installed service, instead of the default: /data/db/
dbpath = /opt/local/var/db/mongodb

# Only accept local connections
bind_ip = 127.0.0.1

org.mongodb.mongod.plist

<?xml version="1.0" encoding="UTF-8"?>
<!-- /Library/LaunchDaemons/org.mongodb.mongod.plist --!>
<!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>org.mongodb.mongod</string>
  <key>ProgramArguments</key>
  <array>
    <string>/opt/local/bin/mongod</string>
    <string>run</string>
    <string>--config</string>
    <string>/opt/local/etc/mongod.conf</string>
  </array>
  <key>RunAtLoad</key>
  <true/>
  <key>KeepAlive</key>
  <true/>
  <key>WorkingDirectory</key>
  <string>/opt/local</string>
  <key>StandardErrorPath</key>
  <string>/opt/local/var/log/mongodb.log</string>
  <key>StandardOutPath</key>
  <string>/opt/local/var/log/mongodb.log</string>
</dict>
</plist>