(On a Mac, Boot2Docker, docker v 1.1.1)
Having trouble where Docker will not release the ports that it uses when assigning host ports. For instance, I start 3 containers with the same image. My docker ps returns the following:
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
9875e2d28c3b 49ffc1050348 /sbin/my_init 19 hours ago Up 1 seconds 0.0.0.0:49169->22/tcp, 0.0.0.0:49170->3306/tcp boring_goldstine
f0a40c3bb4a1 49ffc1050348 /sbin/my_init 19 hours ago Up 6 seconds 0.0.0.0:49167->22/tcp, 0.0.0.0:49168->3306/tcp sleepy_wright
0fb913db3528 49ffc1050348 /sbin/my_init 19 hours ago Up About a minute 0.0.0.0:49165->22/tcp, 0.0.0.0:49166->3306/tcp agitated_jones
Scrolling over to ports you'll see that 49170 is the last allocated port.
If I stop and rm those containers and run another, Docker used to use the lowest available port. However now the number just keeps increasing:
docker run -P -d 49ffc1050348
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
82fdf0e54846 49ffc1050348 /sbin/my_init 19 hours ago Up 3 seconds 0.0.0.0:49171->22/tcp, 0.0.0.0:49172->3306/tcp high_euclid
How do I get it to reuse the old ports?
The portmapper logic changed in version 1.1.0. The logic is now written to increase until 65535, until it resets to BeginPortRange which is 49153.
You can use docker run -p <host port>:<container port> to map a host port to a container port.