python 在连接到 PostgreSQL 时不能使用 .pgpass

Question

I can not use .pgpass file while connecting to postgresql db using python script((( My python script to connect is without password:

conn = psycopg2.connect("dbname='postgres' user='postgres' host='192.168.136.129'");

My .pgpass:

*:*:*:postgres:password

is located in /var/lib/postgresql - home directory for postgres user. However when I connect to db locally:

psql -U postgres

no password is asked. But for python error is raised:

root@debian:/python_codes/Junior/Level1/DB1/Generator_py# python connect_db.py 
Unable to connect to db...
Traceback (most recent call last):
  File "connect_db.py", line 34, in connectdb
    conn = psycopg2.connect("dbname='postgres' user='postgres' host='192.168.136.129'");
  File "/usr/lib/python2.7/dist-packages/psycopg2/__init__.py", line 179, in connect
    connection_factory=connection_factory, async=async)
OperationalError: fe_sendauth: no password supplied

Answer 1

Based on the prompt from this output:

root@debian:/python_codes/Junior/Level1/DB1/Generator_py# python connect_db.py

you're running the commmand as Unix user root , so the corresponding .pgpass file must be located in root's HOME directory, which means not /var/lib/postgresql but probably /root or /

Also its permissions must be restricted to readable by the owner, that is, chmod 600 $HOME/.pgpass

Answer 2

To prevent user from launching pg_dump with a permanent .pgpass or use PGPASSWORD in command, one could create .pgpass just before pg_dump starts and delete it off 3 seconds later (inside a compiled program).

echo 'hostname:port:database:username:password' > /home/user/.pgpass

echo 'sleep 3; rm /home/user/.pgpass; rm /home/user/remove-pgpass.sh' > /home/user/remove-pgpass.sh

chmod 600 /home/user/.pgpass

chmod +x /home/user/remove-pgpass.sh

/home/user/remove-pgpass.sh

pg_dump -h localhost -d user-db -U db-admin > mydbdump.sql