Fix Docker “port is already allocated” on Mac

The examples use 5432 (Postgres); swap in your port: 3306 for MySQL, 6379 for Redis, 3000 or 8080 for an app.

docker ps --filter publish=5432

CONTAINER ID   IMAGE         …   PORTS                    NAMES
3f9c1a2b7d4e   postgres:16   …   0.0.0.0:5432->5432/tcp   shop-db-1

Usually it’s the same service from another project’s Compose file, or from an older checkout. Stop just that container, or the whole project it belongs to:

docker stop shop-db-1

# or the whole Compose project, from anywhere:
docker compose ls
docker compose -p shop down

docker compose down stops and removes the containers but keeps named volumes, so the database’s data survives. Add -v only if you want the data gone.

lsof -nP -iTCP:5432 -sTCP:LISTEN

COMMAND  PID USER   FD   TYPE  DEVICE SIZE/OFF NODE NAME
postgres 611 you    7u  IPv6  0x4e19…      0t0  TCP [::1]:5432 (LISTEN)
postgres 611 you    8u  IPv4  0x9b02…      0t0  TCP 127.0.0.1:5432 (LISTEN)

The classic case is a database installed with Homebrew that starts at login. Killing it isn’t enough, because launchd starts it again. Stop it through Homebrew, which also keeps it from starting at the next login:

brew services list
brew services stop postgresql@16

Postgres.app, DBngin and Laravel Herd run databases too; quit them from their own menu. A dev server on the port is a plain leftover: see How to kill the process on a port. On 5000 or 7000, it’s AirPlay Receiver.

If you want both running, say Homebrew Postgres for one project and a container for another, change only the host side, the number before the colon:

docker run -p 5433:5432 postgres:16

# compose.yaml
services:
  db:
    image: postgres:16
    ports:
      - "${DB_PORT:-5432}:5432"

Then DB_PORT=5433 docker compose up, and connect to localhost:5433 from your Mac. Other containers in the same Compose project still reach it as db:5432.

• A restart policy. Containers started with restart: always or unless-stopped come back whenever Docker starts. Check with docker inspect -f '{{.HostConfig.RestartPolicy.Name}}' shop-db-1 and turn it off with docker update --restart=no shop-db-1.
• A Homebrew service. brew services stop unregisters it; kill doesn’t. See Homebrew services.
• Nothing holds it, but Docker still says allocated. Docker Desktop occasionally keeps a port after a container crashed. docker ps -a shows nothing using it; quit and reopen Docker Desktop (or OrbStack) to release it.

Portlivo lists Docker and OrbStack containers by name next to your dev servers and Homebrew services, with the host port each one publishes. Stopping a container runs docker stop and stopping a service runs brew services stop, so neither comes straight back.