Getting error: Peer authentication failed for user "postgres", when trying to get pgsql working with rails

Question

I'm getting the error:

FATAL: Peer authentication failed for user "postgres"

when I try to make postgres work with Rails.

Here's my pg_hba.conf, my database.yml, and a dump of the full trace.

I changed authentication to md5 in pg_hba and tried different things, but none seem to work.

I also tried creating a new user and database as per Rails 3.2, FATAL: Peer authentication failed for user (PG::Error)

But they don't show up on pgadmin or even when I run sudo -u postgres psql -l.

Any idea where I'm going wrong?

Answer 1

The problem is still your pg_hba.conf file (/etc/postgresql/9.1/main/pg_hba.conf*).

This line:

local   all             postgres                                peer

Should be:

local   all             postgres                                md5

* If you can't find this file, running locate pg_hba.conf should show you where the file is.

After altering this file, don't forget to restart your PostgreSQL server. If you're on Linux, that would be sudo service postgresql restart.

These are brief descriptions of both options according to the official PostgreSQL docs on authentication methods.

Peer authentication

The peer authentication method works by obtaining the client's operating system user name from the kernel and using it as the allowed database user name (with optional user name mapping). This method is only supported on local connections.

Password authentication

The password-based authentication methods are md5 and password. These methods operate similarly except for the way that the password is sent across the connection, namely MD5-hashed and clear-text respectively.

If you are at all concerned about password "sniffing" attacks then md5 is preferred. Plain password should always be avoided if possible. However, md5 cannot be used with the db_user_namespace feature. If the connection is protected by SSL encryption then password can be used safely (though SSL certificate authentication might be a better choice if one is depending on using SSL).

Sample location for pg_hba.conf:
/etc/postgresql/9.1/main/pg_hba.conf