django.db.utils.OperationalError: FATAL: no pg_hba.conf entry for host "172.21.0.3 code example

Example: django.db.utils.operationalerror: fatal: no pg_hba.conf entry for host

You obviously do not have connection profile for user "user1" against 
database "ttio" on the machine. The only remote access that your 
pg_hba.conf currently specifies is for any user to the database with 
the same name as the user from address 127.0.0.200.

You need an entry like:

host ttio user1 <ip_address> <netmask>


The <ip_address> <netmask> combination is specific to your network 
configuration and refers to the IP address of the client.