⚡ TIL: PostgreSQL Docker Volume Password Issue

💡 The Lesson

Docker volumes persist data between container restarts. When PostgreSQL initializes for the first time, it creates the database with the initial password and stores it in the mounted volume. Subsequent restarts use the existing data from the volume, ignoring new environment variables.

🔧 Quick Fix

Nuclear option (starts fresh):

# Stop containers and remove volumes
docker-compose down -v

# Start fresh with new password
docker-compose up

Surgical option (keep data):

# Connect to running PostgreSQL container
docker exec -it your_postgres_container psql -U postgres

# Change password from inside PostgreSQL
ALTER USER postgres PASSWORD 'new_password';

🎯 Key Takeaway

Environment variables only affect the initial setup, not subsequent runs with existing data.

Never forget: Docker volumes are persistent storage, not configuration!