The psql: FATAL: Ident authentication failed for user 'username' error typically indicates that the PostgreSQL server is configured to use the ident authentication method, but it was unable to verify the identity of the user username. This can be caused by a number of factors, including incorrect username or password, incorrect configuration of the pg_hba.conf file, or lack of an ident entry in the pg_ident.conf file.
To resolve this error, you can try the following solutions:
Make sure that you are using the correct username and password when connecting to the PostgreSQL server.
Check the pg_hba.conf file to make sure that it is configured correctly. The pg_hba.conf file controls how the PostgreSQL server authenticates incoming connections, and it should contain an entry for the ident authentication method. Make sure that the entry is correct and that it allows connections from the host that you are connecting from.
Check the pg_ident.conf file to make sure that it contains an entry for the ident authentication method. The pg_ident.conf file maps system user names to PostgreSQL user names, and it should contain an entry for the ident authentication method. Make sure that the entry is correct and that it maps the system user name to the correct PostgreSQL user name.
If the above steps don't resolve the issue, you can try disabling the ident authentication method by commenting out the ident entry in the pg_hba.conf file and restarting the PostgreSQL server. This will allow you to connect using a different authentication method, such as md5 or peer.
It's important to note that the specific steps to resolve the psql: FATAL: Ident authentication failed for user 'username' error may vary depending on your system and the version of PostgreSQL that you are using. Consult the PostgreSQL documentation and online resources for more information on how to troubleshoot and resolve authentication issues in PostgreSQL.