Connection to Postgres doesn't use DB_HOST env. variable

When I try to enable mod-marccat in Okapi for tenant I have an error with Postgres address name resolution:

org.postgresql.util.PSQLException: Connection to localhost:5432 refused. Check that the hostname and port are correct and that the postmaster is accepting TCP/IP connections.

Expected behavior: use Postgress address from 'DB_HOST' env. variable.
Env. variable in container is presents:

bash-5.0$ echo $DB_HOST
pg-folio

Environment: 'Scratch' based on Kubernetes engine.