PostgreSQL: FATAL - Peer authentication failed for user (PG::ConnectionBad)

Question

I am working with PostgreSQL and I have a user with password matching the one specified in database.yml

postgres=# select * from pg_user
;
  usename   | usesysid | usecreatedb | usesuper | usecatupd | userepl |  passwd  | valuntil | useconfig 
------------+----------+-------------+----------+-----------+---------+----------+----------+-----------
 goodsounds |    16386 | t           | t        | t         | t       | ******** |          | 
 postgres   |       10 | t           | t        | t         | t       | ******** |          | 
(2 rows)

But when I try creating a database by running the command

rails db:create

I get the error

FATAL: Peer authentication failed for user "goodsounds"

Here is my pg_hba.conf:

# Database administrative login by Unix domain socket
local   all             postgres                                peer

# TYPE  DATABASE        USER            ADDRESS                 METHOD

# "local" is for Unix domain socket connections only
local   all             all                                     peer
# IPv4 local connections:
host    all             all             127.0.0.1/32            trust
# IPv6 local connections:
host    all             all             ::1/128                 trust
# Allow replication connections from localhost, by a user with the
# replication privilege.
#local   replication     postgres                                peer
#host    replication     postgres        127.0.0.1/32            trust
#host    replication     postgres        ::1/128                 trust

Previously "trust" above was md5 but I changed to see if that would help.

Here is my database.yml:

# PostgreSQL. Versions 8.2 and up are supported.
#
# Install the pg driver:
#   gem install pg
# On Mac OS X with macports:
#   gem install pg -- --with-pg-config=/opt/local/lib/postgresql84/bin/pg_config
# On Windows:
#   gem install pg
#       Choose the win32 build.
#       Install PostgreSQL and put its /bin directory on your path.
#
# Configure Using Gemfile
# gem 'pg'
#
development:
  adapter: postgresql
  encoding: unicode
  database: goodsounds_development
  pool: 5
  username: goodsounds
  password: test

  # Connect on a TCP socket. Omitted by default since the client uses a
  # domain socket that doesn't need configuration. Windows does not have
  # domain sockets, so uncomment these lines.
  host: localhost
  port: 5432

  # Schema search path. The server defaults to $user,public
  #schema_search_path: myapp,sharedapp,public

  # Minimum log levels, in increasing order:
  #   debug5, debug4, debug3, debug2, debug1,
  #   log, notice, warning, error, fatal, and panic
  # The server defaults to notice.
  #min_messages: warning

# Warning: The database defined as "test" will be erased and
# re-generated from your development database when you run "rake".
# Do not set this db to the same as development or production.
test:
  adapter: postgresql
  encoding: unicode
  database: goodsounds_test
  pool: 5
  username: goodsounds
  password: test

production:
  adapter: postgresql
  encoding: unicode
  database: goodsounds_production
  pool: 5
  username: goodsounds
  password: test

Impassive

Answer 1

"Peer authentication" means that it's using a unix socket and expecting the connecting unix user to have the same unix username as the postgresql username.

Since your local unix username is funkdified and you're trying to connect as user goodsounds over a unix domain socket (local) connection where your pg_hba.conf specifies peer authentication, Pg correctly rejects your connection attempt.

This is the default behaviour for many installs when using unix sockets.

You can:

• Connect via TCP/IP by specifying a hostname in your database connection settings;
• edit pg_hba.conf to use md5 password authentication instead of peer authentication for unix sockets (local connection type) so Pg accepts password authentication; or
• Connect with a PostgreSQL username the same as your unix username and create the user in PostgreSQL if it doesn't exist yet.

See the docs for pg_hba.conf and the rest of the client authentication chapter of the documentation.

Note that changes to pg_hba.conf do not take effect immediately, you must restart or at least reload PostgreSQL to get it to reread pg_hba.conf.

---

Oh, also, if you have multiple PostgreSQL versions installed you might have a libpq from one version and a server from another. In this case make sure the location for the unix socket that libpq connects to by default is the same as the server's unix_socket_directories or override it with (e.g.) host=/tmp in your connection string.

Tabaret

Does 'specifying a hostname in your database connection settings' mean 'add host: localhost to database.yml'? Because that didn't work for me. – Colemancolemanite

@MaarrenSep yep. If it "doesn't work" for you, post a new question with details (versions, pg_hba.conf and database.yml contents, exact error messages, etc). Link back to this one for content and add a comment with a link to your new question here. – Tabaret

It solved my problem when I put "host：'localhost'" to my connection setting. Thank you! – Rafaelle

sudo -u postgres psql dbname would be a way for the peer method where postgres is the relevant user. – Guelph

The third point is so easily overlooked but so important. Solved my problem once I created a Postgres username that matched my Linux user name and then set it in my rails application. I did not have to add an entry for username or password then. – Pellmell

inserting "host:localhost" solved my problem. Thanks. – Alla

Answer 2

I was facing same problem on Ubuntu machine so I removed this error by following some steps. Switch to postgres user

$ sudo su - postgres

it will ask for password and by default password is postgres

After switch the user to postgres, open psql console

$ psql

so check the version of postgres if multiple versions are available

psql=# select VERSION();

PostgreSQL 9.1.13 on x86_64-unk....         # so version is 9.1

Now Open postgres user

vim /etc/postgresql/9.1/main/pg_hba.conf

9.1 is version return form upper command

and replace

local   all             postgres                                peer

to

local   all             postgres                                md5

Restart the service

sudo service postgresql restart

I write steps on my blog also

http://tarungarg402.blogspot.in/2014/10/set-up-postgresql-on-ubuntu.html

Trousseau

The question has nothing to do with psql, so specifying psql command-line options isn't a useful answer to the question. This is asking why rake db:create isn't working with a seemingly reasonably-configured Rails application. – Aec

Answer 3

If "peer authentication" does not work, try md5 authenticaion.

To specify host try something like this:

 psql -d <dbname> -U <username> -h <hostname>

or this:

 psql -d <dbname> -U <username> -h <hostname> -W

Tardif

The question has nothing to do with psql, so specifying psql command-line options isn't a useful answer to the question. This is asking why rake db:create isn't working with a seemingly reasonably-configured Rails application. – Aec

Answer 4

edit /etc/postgresql/9.3/main/pg_hba.conf

# "local" is for Unix domain socket connections only
    local   all             all                                     peer

change to below line and it works for me

# "local" is for Unix domain socket connections only
local   all             all                                     md5

Sparker

Answer 5

Here's how I solved it;

Run the command below to confirm your PostgreSQL version.

psql --version

Navigate to the PostgreSQL configuration directory on your server, which is in /etc/postgresql/10/main. Take note that 10 is the version of my PostgreSQL installation on my server. Your version might be 9.5, 11 or 12 or any other version.

cd ~
cd /etc/postgresql/10/main

Once you navigate into the /etc/postgresql/10/main directory, open the file pg_hba.conf using the command below. This file controls: which hosts are allowed to connect, how clients are authenticated, which PostgreSQL user names they can use, which databases they can access:

sudo nano pg_hba.conf

Replace the following line below:

# Database administrative login by Unix domain socket
local       all       postgres       peer

with the line below:

# Database administrative login by Unix domain socket
local       all       postgres       md5

Also, replace the following line below:

# "local" is for Unix domain socket connections only
local       all       all            peer

with the line below:

# "local" is for Unix domain socket connections only
local       all       all            md5

Additionally, we may want to allow inbound connections to the PostgreSQL database in production (to allow host connections from all databases, all users, all addresses using the md5 method).

To achieve this, add the line below at the end of the file, and then save the file:

# remote connections
host      all      all      all      md5

Still within the /etc/postgresql/10/main directory, open and edit the file postgresql.conf using the command below:

sudo nano postgresql.conf

Replace the line # listen_address='127.0.0.1' or the line listen_address='127.0.0.1' or the line # listen_address='localhost' or the line listen_address='localhost' with the line below, in order to allow PostgreSQL database to listen to connections from all addresses:

listen_addresses = '*'

Save the file, and navigate to the root directory of your server:

cd ~

Restart or reload the PostgreSQL server using the command below:

sudo systemctl restart postgresql       # To restart
sudo systemctl reload postgresql        # To reload

Opine