I have a question here. When I execute postgres_exporter on the monitoring node, an error is reported.
The following is the error log:
[root@ocbc postgres_exporter]# ./postgres_exporter
ts=2022-09-05T10:07:13.883Z caller=main.go:124 level=error msg=“Failed to create PostgresCollector” err=“malformed dsn ""”
Here someone tell me why,please! 
The DSN refers to your database connection parameters, username, password, IP, that kind of things, something related with DSN is wrong.
Try this:
sudo -u postgres DATA_SOURCE_NAME=“postgresql://postgres_exporter:POSTGRE_REP_PASS@localhost/postgres?sslmode=disable” /usr/bin/prometheus-postgres-exporter
I just created an account to say thank you. fixed my issue 