This Adminer plugin keeps you logged in for up to 30 days by extending the login session lifetime.

compose.yaml

services:
  db:
    image: postgres:18
    container_name: ${COMPOSE_PROJECT_NAME}_postgres
    restart: always
    environment:
      POSTGRES_USER: user
      POSTGRES_PASSWORD: password
      POSTGRES_DB: db
    # ports:
    #   - 5432:5432
    volumes:
      - postgres-data:/var/lib/postgresql

  adminer:
    image: adminer:5
    container_name: ${COMPOSE_PROJECT_NAME}_adminer
    restart: always
    # ports:
    #   - 8080:8080
    # environment:
    #   ADMINER_DESIGN: custom
    volumes:
    #   - ./adminer.css:/var/www/html/designs/custom/adminer.css:ro
      - ./permanent-login.php:/var/www/html/plugins-enabled/permanent-login.php:ro
    depends_on:
      - db

volumes:
  postgres-data:

permanent-login.php

<?php
class AdminerPermanentLogin {
    function permanentLogin($create = false) {
        return 'your-very-strong-unique-secret-key-here';
    }
}

return new AdminerPermanentLogin();

Replace your-very-strong-unique-secret-key-here with your own unique secret key. You can generate one using the command:

openssl rand -hex 32