Check your pg_hba.conf in $PGDATA allows connections from node.js.
By default the pg_hba.conf is like so:
# TYPE DATABASE USER ADDRESS METHOD
# "local" is for Unix domain socket connections only
local all all trust
# IPv4 local connections:
host all all 127.0.0.1/32 trust
# IPv6 local connections:
host all all ::1/128 trust
This is fine for your standard psql connectivity via the OS owner as it allows local connections trusted for localhost IP address 127.0.0.1. However if you have an IP address set on the server, which I'm guessing you do then you need to allow an entry for that because in your node.js configuration you're referring to a host of "DB". So ping "DB" and add that IP address:
# TYPE DATABASE USER ADDRESS METHOD
# "local" is for Unix domain socket connections only
local all all trust
# IPv4 local connections:
host all all 127.0.0.1/32 trust
# IPv6 local connections:
host all all ::1/128 trust
host db myuser <ip-for-db-host> md5
Once you've changed that file you will need to perform a pg_ctl reload.
