postgresql doesn't start

hi there,

I've a big problem with my postgresql installation
I've postgresql 9.3 installed on docker; I start it via supervisord
I've never had issues with postgresql and I don't touched nothing (no
update, no changes)

this is my configuration
there's a file called postgresql.conf in /etc/supervisor/conf.d/
cat command:

[program:postgres]
command=/opt/postgresql.sh
autostart=true
autorestart=true
stopsignal=QUIT

lookt at /opt/postgresql.sh

#!/bin/sh

# This script is run by Supervisor to start PostgreSQL 9.3 in foreground
mode

if [ -d /var/run/postgresql ]; then
chmod 2775 /var/run/postgresql
else
install -d -m 2775 -o postgres -g postgres /var/run/postgresql
fi

exec su postgres -c "/usr/lib/postgresql/9.3/bin/postgres -D
/var/lib/postgresql/9.3/main -c
config_file=/etc/postgresql/9.3/main/postgresql.conf"

until yesterday there were no problem
right now I see this in the /var/log/supervisor's directory:

2015-10-01 21:40:18 UTC HINT: The file seems accidentally left over, but
it could not be removed. Please remove the file by hand and try again.
2015-10-01 21:40:20 UTC FATAL: could not remove old lock file
"postmaster.pid": Permission denied

if I remove this file with sudo permissions when I re-run the process I've
the same error and I don't understand why. I tried the same configuration
(postgresql installation and configuration) in another new docker
installation and works fine.

what's the problem?
someone help me?
I've very important databases and I dont' know how to recover it

please let me know, thanks in advance