For more details, please see the blog post: https://www.srijn.net/2021/03/advanced-postgresql-monitoring-using-telegraf/

Since this is a custom plugin for Telegraf, so telegraf is required.

Python packages required:

• psycopg2
• pytz
• dateutil
• pytoml

line_protocol.py is taken from the influxdb python sdk so that installing the whole sdk is not required.

1. Copy the repo files to some location in the target system

2. Install dependencies (mentioned above)

3. Setup telegraf to run this plugin using execd.

   Sample config snippet (assuming that the script is kept in /etc/telegraf/scripts/pg_custom/):

   [[inputs.execd]]
     interval = "300s"
     data_format = "influx"
     command = ["/usr/bin/python", "/etc/telegraf/scripts/pg_custom/postgresql_query.py", "/etc/telegraf/scripts/pg_custom/postgresql_custom_data.conf"]
     restart_delay = "60s"
     signal = "STDIN"
   
   [[outputs.influxdb]]
     urls = ["http://127.0.0.1:8086"]
     database = "telegraf"

4. Setup PostgreSQL credentials so that this plugin can run queries. There are two common ways to do that:

   a. Create telegraf user with superuser access, but don't create a password

   CREATE USER telegraf SUPERUSER CONNECTION LIMIT 3;

   Since telegraf plugins run with the telegraf user, this should be sufficient.

   b. If PostgreSQL is not running on the same host that telegraf is running on, the above method will not work. In that case, create a new user with superuser access, and give it a password. Use the same command as above, but add a password.

   Then, the postgresql_custom_data.conf file can to edited to have the address parameter like:

   address="host=127.0.0.1 user=telegraf password=secret"

5. Add your queries in the postgresql_custom_data.conf. Some sample queries are included.

6. Start telegraf, and check logs. If everything is working correctly, you should see something like this:

   I! [inputs.execd] Starting process: /usr/bin/python [/etc/telegraf/scripts/pg_custom/postgresql_query.py /etc/telegraf/scripts/pg_custom/postgresql_custom_data.conf]
   

   If not, there should be enough in the logs to debug further.

7. A sample grafana dashboard is also availabled as an exported json in this repo.