Problem with Postgresql db:migrate when deploy

```
deploy:migrating
01 /usr/local/rvm/bin/rvm default do bundle exec rake db:migrate
01 rake aborted!
01 PG::ConnectionBad: FATAL: password authentication failed for user "customuser"
...
Tasks: TOP => db:migrate
```

1) I can normally login to psql under customuser
2) command on server` RAILS_ENV=production rake db:migrate` is workling
3) database.yml :
```
production:
<<: *default
database: app_production
host: localhost
username: customuser
password: mypassword
```
4) /etc/postgresql/10/main/pg_hba.conf :
```
# "local" is for Unix domain socket connections only
local all all md5
```
also tried `peer`

Start by comparing the deploy:migrating command with the successful RAILS_ENV=production rake db:migrate invocation. Review database.yml and /etc/postgresql/10/main/pg_hba.conf alongside the deployment configuration; done would require isolating why deployment authentication differs and documenting a confirmed fix.

Written by the indexing model from the issue text.