MariaDB Connection Refused

Summary

• The application and Adminer could not connect to MariaDB because the database service was down and the system tables were missing or corrupted.
• The MariaDB system tables were re-initialized, the service was started, credentials were configured, and connectivity was verified. The issue is resolved.

Symptoms

• “Connection refused” reported by Adminer and the application.
• systemctl status mariadb indicated the service failed to start due to missing system tables:
  • “Table ‘mysql.plugin’ does not exist.”
  • “Table ‘mysql.servers’ does not exist.”
  • “Table ‘mysql.db’ does not exist.”

Root Cause

• The MariaDB data directory (/var/lib/mysql) did not contain initialized system tables (the mysql.* schema was incomplete). Without these, the server cannot start and therefore refuses TCP connections on 127.0.0.1:3306.

Diagnostics Performed

• Service status
  • sudo systemctl status mariadb.
• Failure confirmation
  • Verified errors indicating missing system tables.
• Port availability
  • After re-initialization, confirmed the listener on 127.0.0.1:3306 via sudo ss -ltnp | grep 3306.
• Client connectivity validation
  • Executed mysql -h 127.0.0.1 -P 3306 -u root -proot -e "SELECT 1;".

Remediation Steps

1. Stopped MariaDB and inspected the data directory

   • sudo systemctl stop mariadb
   • sudo ls -la /var/lib/mysql
   • Ensured ownership:
     • sudo chown -R mysql:mysql /var/lib/mysql

2. Initialized MariaDB system tables (creates mysql.*)

   • sudo mariadb-install-db --user=mysql --basedir=/usr --datadir=/var/lib/mysql

3. Started the service and verified it is listening

   • sudo systemctl start mariadb
   • sudo systemctl status mariadb
   • sudo ss -ltnp | grep 3306 → listening on 127.0.0.1:3306

4. Configured credentials and created the application database

   • Entered the shell:
     • sudo mysql
   • In MariaDB prompt:
     • ALTER USER 'root'@'localhost' IDENTIFIED BY 'root';
     • CREATE USER IF NOT EXISTS 'root'@'127.0.0.1' IDENTIFIED BY 'root';
     • FLUSH PRIVILEGES;
     • CREATE DATABASE IF NOT EXISTS muhasebe_api CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;

5. Verified connectivity as used by the application

   • mysql -h 127.0.0.1 -P 3306 -u root -proot -e "SELECT 1;"

Rationale

• mariadb-install-db populated the missing system tables (mysql.*), allowing MariaDB to boot correctly.
• Starting the service made it listen on 127.0.0.1:3306, so TCP connections stopped being refused.
• Setting the root password for both localhost (socket) and 127.0.0.1 (TCP) made authentication consistent with your .env.
• Creating the muhasebe_api database ensured Adminer and the app had a valid target schema.

Adminer Configuration (Non‑Docker)

• System: MySQL
• Server: 127.0.0.1
• Username: root
• Password: root
• Database: muhasebe_api

Laravel .env (reference)

DB_CONNECTION=mysql
DB_HOST=127.0.0.1
DB_PORT=3306
DB_DATABASE=muhasebe_api
DB_USERNAME=root
DB_PASSWORD=root

Recommended Hardening (Optional)

• Create a dedicated app user instead of using root over TCP:
  • In MariaDB:
    • CREATE USER IF NOT EXISTS 'muhasebe_user'@'127.0.0.1' IDENTIFIED BY 'strong_password';
    • GRANT ALL PRIVILEGES ON muhasebe_api.* TO 'muhasebe_user'@'127.0.0.1';
    • FLUSH PRIVILEGES;
  • Update .env and Adminer to use this user.

Prevention Checklist

• Service health: sudo systemctl is-active mariadb should be “active”.
• Port listening: sudo ss -ltnp | grep 3306 should show 127.0.0.1:3306.
• Backups: Regularly back up /var/lib/mysql or individual databases (mysqldump).
• Avoid accidental deletion: Do not delete mysql system schema contents in /var/lib/mysql.
• Preferred auth: For TCP clients (Adminer/app), use users defined with '127.0.0.1' host and a password.