How to run multiple postgres docker instances on local machine

When working on multiple projects, I run separate postgres instance for each of them.

Since these are docker instances, this is not a problem as long as they are not running at the same time

If I’m actively working working on multiple projects parallelly, then there are two problems :

1. Resources : My laptop becomes slow. There is no solution for this ¹
2. Assuming you have LOTs of memory, second problem still remains. Both instances try to bind to local port 5432 the default port. Which does not work. So you need to bind other postgres instances to different local ports like 5433, 5434 and so on. This is controlled via -p in the docker command.

The format is :

-p <host_port>:<container_port> (Easier to remember that way)

So you’ll have docker commands like -p 5433:5432 and -p 5434:5432 etc.

and local ports 5432, 5433 and 5434 will all be listening on different postgres servers.

Off course, if you do not have local psql and instead use docker exec (like I do) you have no problem.

On the other hand, if you use local psql you’ll need to specify p 5433 and -p 5434 to connect different postgres instances. (Probably along with -h 127.0.0,1)