mosquitto auth plugin database issue - postgresql

Question

I am using mosquitto auth plugin here is my mosquitto.config file
listener 1883
#listener 9001 127.0.0.1
#protocol websockets
auth_opt_backends postgres
auth_plugin /etc/mosquitto/auth-plug.so
auth_opt_dbname mqtt
auth_opt_host localhost
auth_opt_port 5432
auth_opt_user postgres
auth_opt_pass postgres
auth_opt_userquery SELECT password FROM account WHERE username = $1 limit 1
auth_opt_superquery SELECT COALESCE(COUNT(*),0) FROM account WHERE username = $1 AND super = 1
auth_opt_aclquery SELECT topic FROM acls WHERE (username = $1) AND (rw >= $2)
all postgres setting are default postgres settings.
when I run
sudo /usr/local/sbin/mosquitto -c /etc/mosquitto/mosquitto.conf
command. I am getting this error:
1456228482: mosquitto version 1.4.8 (build date 2016-02-22 18:23:09+0530) starting
1456228482: Config loaded from /etc/mosquitto/mosquitto.conf.
1456228482: |-- *** auth-plug: startup
1456228482: |-- ** Configured order: postgres
1456228482: |-- }}}} POSTGRES
1456228482: |-- HERE: SELECT COALESCE(COUNT(*),0) FROM account WHERE username = $1 AND super = 1
1456228482: |-- HERE: SELECT topic FROM acls WHERE (username = $1) AND (rw >= $2)
|-- We were unable to connect to the database
|-- *** ABORT.
If I uncomment these two line
#listener 9001 127.0.0.1
#protocol websockets
i get this error:
Error: Websockets support not available.
Error found at /etc/mosquitto/mosquitto.conf:4.
Error: Unable to open configuration file.
I was following these tutorial
Tutorial1
Tutorial2
after changing password of postgres and chaging the default port 1883
1456232627: mosquitto version 1.4.8 (build date 2016-02-22 18:23:09+0530) starting
1456232627: Config loaded from /etc/mosquitto/mosquitto.conf.
1456232627: |-- *** auth-plug: startup
1456232627: |-- ** Configured order: postgres
1456232627: |-- }}}} POSTGRES
1456232627: |-- HERE: SELECT COALESCE(COUNT(*),0) FROM account WHERE username = $1 AND super = 1
1456232627: |-- HERE: SELECT topic FROM acls WHERE (username = $1) AND (rw >= $2)
1456232627: Opening ipv4 listen socket on port 1884.
1456232627: Opening ipv6 listen socket on port 1884.
1456232627: Error: Invalid user 'mosquitto'.
from where "mosquitto" user is comming ?

Answer 1

Taking the what has been given in the comment to form an actual answer:
The websockets problem is down to not building with Websockets enabled in config.mk by modifying the following line:
WITH_WEBSOCKETS:=no
And then rebuilding. You will need to ensure you have the libwebsocket development files installed.
The We were unable to connect to the database error was a database configuration issue
Error: Invalid user 'mosquitto'. is because you are trying to run mosquitto as root and mosquitto is trying to drop the root privileges in order to safely run at a lower level. By default mosquitto will try to run as a user called mosquitto, in this case there is no mosquitto user defined on the system hence the error. You can change the user that it will try and become by adding a the following to the mosquitto.conf
user foo
This would cause mosquitto to run as user foo. You really should not leave mosquitto running as root.