Rails: FATAL - Peer authentication failed for user (PG::Error)

This is the most foolproof way to get your rails app working with postgres in the development environment in Ubuntu 13.10.

1) Create rails app with postgres YAML and 'pg' gem in the Gemfile:

$ rails new my_application -d postgresql 

2) Give it some CRUD functionality. If you're just seeing if postgres works, create a scaffold:

$ rails g scaffold cats name:string age:integer colour:string 

3) As of rails 4.0.1 the -d postgresql option generates a YAML that doesn't include a host parameter. I found I needed this. Edit the development section and create the following parameters:

encoding: UTF-8 host: localhost database: my_application_development username: thisismynewusername password: thisismynewpassword 

Note the database parameter is for a database that doesn't exit yet, and the username and password are credentials for a role that doesn't exist either. We'll create those later on!

This is how config/database.yml should look (no shame in copypasting :D ):

development: adapter: postgresql pool: 5 # these are our new parameters encoding: UTF-8 database: my_application_development host: localhost username: thisismynewusername password: thisismynewpassword test: # this won't work adapter: postgresql encoding: unicode database: my_application_test pool: 5 username: my_application password: production: # this won't work adapter: postgresql encoding: unicode database: my_application_production pool: 5 username: my_application password: 

4) Start the postgres shell with this command:

$ psql 

4a) You may get this error if your current user (as in your computer user) doesn't have a corresponding administration postgres role.

psql: FATAL: role "your_username" does not exist 

Now I've only installed postgres once, so I may be wrong here, but I think postgres automatically creates an administration role with the same credentials as the user you installed postgres as.

4b) So this means you need to change to the user that installed postgres to use the psql command and start the shell:

$ sudo su postgres 

And then run

$ psql 

5) You'll know you're in the postgres shell because your terminal will look like this:

$ psql psql (9.1.10) Type "help" for help. postgres=# 

6) Using the postgresql syntax, let's create the user we specified in config/database.yml's development section:

postgres=# CREATE ROLE thisismynewusername WITH LOGIN PASSWORD 'thisismynewpassword'; 

Now, there's some subtleties here so let's go over them.

• The role's username, thisismynewusername, does not have quotes of any kind around it
• Specify the keyword LOGIN after the WITH. If you don't, the role will still be created, but it won't be able to log in to the database!
• The role's password, thisismynewpassword, needs to be in single quotes. Not double quotes.
• Add a semi colon on the end ;)

You should see this in your terminal:

postgres=# CREATE ROLE postgres=# 

That means, "ROLE CREATED", but postgres' alerts seem to adopt the same imperative conventions of git hub.

7) Now, still in the postgres shell, we need to create the database with the name we set in the YAML. Make the user we created in step 6 its owner:

postgres=# CREATE DATABASE my_application_development OWNER thisismynewusername; 

You'll know if you were successful because you'll get the output:

CREATE DATABASE 

8) Quit the postgres shell:

\q 

9) Now the moment of truth:

$ RAILS_ENV=development rake db:migrate 

If you get this:

== CreateCats: migrating ================================================= -- create_table(:cats) -> 0.0028s == CreateCats: migrated (0.0028s) ======================================== 

Congratulations, postgres is working perfectly with your app.

9a) On my local machine, I kept getting a permission error. I can't remember it exactly, but it was an error along the lines of

Can't access the files. Change permissions to 666. 

Though I'd advise thinking very carefully about recursively setting write privaledges on a production machine, locally, I gave my whole app read write privileges like this:

9b) Climb up one directory level:

$ cd .. 

9c) Set the permissions of the my_application directory and all its contents to 666:

$ chmod -R 0666 my_application 

9d) And run the migration again:

$ RAILS_ENV=development rake db:migrate == CreateCats: migrating ================================================= -- create_table(:cats) -> 0.0028s == CreateCats: migrated (0.0028s) ======================================== 

Some tips and tricks if you muck up

Try these before restarting all of these steps:

The mynewusername user doesn't have privileges to CRUD to the my_app_development database? Drop the database and create it again with mynewusername as the owner:

1) Start the postgres shell:

$ psql 

2) Drop the my_app_development database. Be careful! Drop means utterly delete!

postgres=# DROP DATABASE my_app_development; 

3) Recreate another my_app_development and make mynewusername the owner:

postgres=# CREATE DATABASE my_application_development OWNER mynewusername; 

4) Quit the shell:

postgres=# \q 

The mynewusername user can't log into the database? Think you wrote the wrong password in the YAML and can't quite remember the password you entered using the postgres shell? Simply alter the role with the YAML password:

1) Open up your YAML, and copy the password to your clipboard:

 development: adapter: postgresql pool: 5 # these are our new parameters encoding: UTF-8 database: my_application_development host: localhost username: thisismynewusername password: musthavebeenverydrunkwheniwrotethis 

2) Start the postgres shell:

$ psql 

3) Update mynewusername's password. Paste in the password, and remember to put single quotes around it:

postgres=# ALTER ROLE mynewusername PASSWORD `musthavebeenverydrunkwheniwrotethis`; 

4) Quit the shell:

postgres=# \q 

Trying to connect to localhost via a database viewer such as Dbeaver, and don't know what your postgres user's password is? Change it like this:

1) Run passwd as a superuser:

$ sudo passwd postgres 

2) Enter your accounts password for sudo (nothing to do with postgres):

[sudo] password for starkers: myaccountpassword 

3) Create the postgres account's new passwod:

Enter new UNIX password: databasesarefun Retype new UNIX password: databasesarefun passwd: password updated successfully 

Getting this error message?:

Run `$ bin/rake db:create db:migrate` to create your database $ rake db:create db:migrate PG::InsufficientPrivilege: ERROR: permission denied to create database 

4) You need to give your user the ability to create databases. From the psql shell:

ALTER ROLE thisismynewusername WITH CREATEDB 

For permanent solution:

The problem is with your pg_hba. This line:

local all postgres peer 

Should be

local all postgres md5 

Then restart your postgresql server after changing this file.

If you're on Linux, command would be

sudo service postgresql restart 

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

Adding host: localhost was the magic for me

development: adapter: postgresql database: database_name_here host: localhost username: user_name_here 

You can go to your /var/lib/pgsql/data/pg_hba.conf file and add trust in place of Ident It worked for me.

local all all trust host all 127.0.0.1/32 trust 

For further details refer to this issue Ident authentication failed for user

I also faced this same issue while working in my development environment, the problem was that I left host: localhost commented out in the config/database.yml file.

So my application could not connect to the PostgreSQL database, simply uncommenting it solved the issue.

development: <<: *default database: database_name username: database_username password: database_password host: localhost 

That's all.

I hope this helps

If you get that error message (Peer authentication failed for user (PG::Error)) when running unit tests, make sure the test database exists.

In my case i was missing host: localhost in:

development: host: localhost