In  continuation of my previous blog on “8. DevOps:How to control and operate docker containers”, in this blog I would like to show some lab practice on “docker Containers housekeeping”.

From the previous lab sessions, we have seen many containers when we used ps -a option.

We have used two containers most of the times.

Others are not required. This time we will see how to remove a container physically.

Let us consider the below containers to remove using rm command:

32bc16b508d4        ubuntu 
a744246ffb8e        hello-world
1dd55efde43f        hello-world

$sudo docker rm 1dd55efde43f 
$sudo docker rm a744246ffb8e 
$sudo docker rm 32bc16b508d4 
================ You can see the above three containers are removed =========>
vskumar@ubuntu:~$ sudo docker rm 1dd55efde43f 
1dd55efde43f
vskumar@ubuntu:~$ sudo docker rm a744246ffb8e 
a744246ffb8e
vskumar@ubuntu:~$ sudo docker rm 32bc16b508d4 
32bc16b508d4
vskumar@ubuntu:~$ sudo docker ps -a |more
CONTAINER ID        IMAGE               COMMAND                 CREATED         
    STATUS                         PORTS               NAMES
f123dbd09116        ubuntu:16.04        "/bin/bash"             18 minutes ago  
    Exited (0) 18 minutes ago                          elastic_nightingale
3cfdea29ce6e        ubuntu              "bash"                  27 minutes ago  
    Exited (0) 26 minutes ago                          gallant_nobel
155f4b0764b1        ubuntu:16.04        "/bin/bash"             About an hour ag
o   Exited (0) 12 minutes ago                          zen_volhard
11e293722c64        ubuntu:16.04        "/bin/bash"             About an hour ag
o   Exited (0) About an hour ago                       dreamy_bassi
d10ad2bd62f7        ubuntu:16.04        "/bin/bash"             About an hour ag
o   Exited (0) About an hour ago                       cranky_dijkstra
cb1ff260d48e        ubuntu              "ls /usr/src"           11 hours ago    
    Exited (0) 11 hours ago                            wonderful_hawking
b20691fd8fb5        ubuntu              "ls /usr"               11 hours ago    
    Exited (0) 11 hours ago                            friendly_mirzakhani
431ba4c53028        ubuntu              "ls"                    11 hours ago    
    Exited (0) 28 minutes ago                          affectionate_nobel
2c31684bb1f4        ubuntu              "ls -la"                11 hours ago    
    Exited (0) 11 hours ago                            zealous_meitner
fe2e3b449daf        ubuntu              "ls -la /home/."        11 hours ago    
    Exited (0) 11 hours ago                            dreamy_shirley
c44bdd05b94d        ubuntu              "ls -la home."          11 hours ago    
    Exited (2) 11 hours ago                            elastic_pasteur
8b8afa82859a        ubuntu              "ls -la"                11 hours ago    
    Exited (0) 11 hours ago                            festive_panini
2811eb37af61        ubuntu              "ls -la 604831dbce2a"   11 hours ago    
    Exited (2) 11 hours ago                            jolly_swartz
604831dbce2a        ubuntu:16.04        "/bin/bash"             11 hours ago    
    Exited (0) 11 hours ago                            vibrant_ride
718636415a7f        ubuntu:16.04        "/bin/bash"             12 hours ago    
    Exited (0) 12 hours ago                            reverent_noyce
53a7751d4673        ubuntu:16.04        "/bin/bash"             13 hours ago    
    Exited (0) 13 hours ago                            musing_chandrasekhar
1ba71598b7b8        hello-world         "/hello"                16 hours ago    
    Exited (0) 16 hours ago                            musing_kare
vskumar@ubuntu:~$  
==============>
Now let us consider some more examples  as below:
3cfdea29ce6e        ubuntu 
cb1ff260d48e        ubuntu 
b20691fd8fb5        ubuntu 
431ba4c53028        ubuntu 
c31684bb1f4        ubuntu 
2c31684bb1f4        ubuntu 
fe2e3b449daf        ubuntu
c44bdd05b94d        ubuntu 
2811eb37af61        ubuntu
Now, let us use the below rm commands:
$sudo docker rm 3cfdea29ce6e
$sudo docker rm cb1ff260d48e
$sudo docker rm b20691fd8fb5 
$sudo docker rm 431ba4c53028 
$sudo docker rm 2c31684bb1f4
$sudo docker rm fe2e3b449daf 
$sudo docker rm c44bdd05b94d
$sudo docker rm 2811eb37af61
=================>
See the below output also:
 ================== Container removal ==========>
vskumar@ubuntu:~$ clear

vskumar@ubuntu:~$ sudo docker rm 3cfdea29ce6e
3cfdea29ce6e
vskumar@ubuntu:~$ sudo docker rm cb1ff260d48e
cb1ff260d48e
vskumar@ubuntu:~$ sudo docker rm b20691fd8fb5
b20691fd8fb5
vskumar@ubuntu:~$ sudo docker rm 431ba4c53028
431ba4c53028
vskumar@ubuntu:~$ sudo docker rm 2c31684bb1f4
2c31684bb1f4
vskumar@ubuntu:~$ sudo docker rm fe2e3b449daf
fe2e3b449daf
vskumar@ubuntu:~$ sudo docker rm fc44bdd05b94d
Error: No such container: fc44bdd05b94d
vskumar@ubuntu:~$ sudo docker rm c44bdd05b94d
c44bdd05b94d
vskumar@ubuntu:~$ sudo docker rm 2811eb37af61
2811eb37af61
vskumar@ubuntu:~$ 
==========================>
Now we can see the list of available containers:
============= List of latest containers ==============>
vskumar@ubuntu:~$ sudo docker ps -a |more
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS                         PORTS               NAMES
f123dbd09116        ubuntu:16.04        "/bin/bash"         28 minutes ago      Exited (0) 28 minutes ago                          elastic_nigh
tingale
155f4b0764b1        ubuntu:16.04        "/bin/bash"         About an hour ago   Exited (0) 22 minutes ago                          zen_volhard
11e293722c64        ubuntu:16.04        "/bin/bash"         About an hour ago   Exited (0) About an hour ago                       dreamy_bassi
d10ad2bd62f7        ubuntu:16.04        "/bin/bash"         2 hours ago         Exited (0) About an hour ago                       cranky_dijks
tra
8b8afa82859a        ubuntu              "ls -la"            11 hours ago        Exited (0) 11 hours ago                            festive_pani
ni
604831dbce2a        ubuntu:16.04        "/bin/bash"         12 hours ago        Exited (0) 11 hours ago                            vibrant_ride
718636415a7f        ubuntu:16.04        "/bin/bash"         12 hours ago        Exited (0) 12 hours ago                            reverent_noy
ce
53a7751d4673        ubuntu:16.04        "/bin/bash"         13 hours ago        Exited (0) 13 hours ago                            musing_chand
rasekhar
1ba71598b7b8        hello-world         "/hello"            16 hours ago        Exited (0) 16 hours ago                            musing_kare
vskumar@ubuntu:~$ 
===========================>
Now, I wan to keep very few containers only and remove the below containers:

604831dbce2a        ubuntu:16.04
718636415a7f        ubuntu:16.04 
53a7751d4673        ubuntu:16.04
8b8afa82859a        ubuntu 
I want to use the below  commands to remove  the above containers:
$sudo docker rm 604831dbce2a
$sudo docker rm 718636415a7f
$sudo docker rm 53a7751d4673
$sudo docker rm 8b8afa82859a

========================= We can see the latest/limited containers =======>
vskumar@ubuntu:~$ sudo docker rm 604831dbce2a
604831dbce2a
vskumar@ubuntu:~$ sudo docker rm 718636415a7f
718636415a7f
vskumar@ubuntu:~$ sudo docker rm 53a7751d4673
53a7751d4673
vskumar@ubuntu:~$ sudo docker rm 8b8afa82859a
8b8afa82859a
vskumar@ubuntu:~$ sudo docker ps -a
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS                         PORTS               NAMES
f123dbd09116        ubuntu:16.04        "/bin/bash"         36 minutes ago      Exited (0) 36 minutes ago                          elastic_nightingale
155f4b0764b1        ubuntu:16.04        "/bin/bash"         About an hour ago   Exited (0) 30 minutes ago                          zen_volhard
11e293722c64        ubuntu:16.04        "/bin/bash"         About an hour ago   Exited (0) About an hour ago                       dreamy_bassi
d10ad2bd62f7        ubuntu:16.04        "/bin/bash"         2 hours ago         Exited (0) About an hour ago                       cranky_dijkstra
1ba71598b7b8        hello-world         "/hello"            16 hours ago        Exited (0) 16 hours ago                            musing_kare
vskumar@ubuntu:~$ sudo docker ps 
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES
vskumar@ubuntu:~$ 
================================>
We can also see the current container ids as below:
========== Listing containers ids ===============>
vskumar@ubuntu:~$ sudo docker ps -aq
f123dbd09116
155f4b0764b1
11e293722c64
d10ad2bd62f7
1ba71598b7b8
vskumar@ubuntu:~$ 
===============================>
To remove the inactive containers there is a prune command. Let us try with it.
Before doing it I want to make a container active and try this prune command on it:
================= I have made one container Active ======>
vskumar@ubuntu:~$ sudo docker ps -a
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS                         PORTS               NAMES
f123dbd09116        ubuntu:16.04        "/bin/bash"         About an hour ago   Exited (0) About an hour ago                       elastic_nightingale
155f4b0764b1        ubuntu:16.04        "/bin/bash"         2 hours ago         Exited (0) 40 minutes ago                          zen_volhard
11e293722c64        ubuntu:16.04        "/bin/bash"         2 hours ago         Exited (0) 2 hours ago                             dreamy_bassi
d10ad2bd62f7        ubuntu:16.04        "/bin/bash"         2 hours ago         Exited (0) 2 hours ago                             cranky_dijkstra
1ba71598b7b8        hello-world         "/hello"            17 hours ago        Exited (0) 17 hours ago                            musing_kare
vskumar@ubuntu:~$ sudo docker start 155f4b0764b1
155f4b0764b1
vskumar@ubuntu:~$ sudo docker ps 
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES
155f4b0764b1        ubuntu:16.04        "/bin/bash"         2 hours ago         Up 6 seconds                            zen_volhard
vskumar@ubuntu:~$ 
========================>
To use prune , below format should be used:
$ sudo docker container prune
=========== The usage of prune command =======>
vskumar@ubuntu:~$ 
vskumar@ubuntu:~$ sudo docker container prune
WARNING! This will remove all stopped containers.
Are you sure you want to continue? [y/N] y
Deleted Containers:
f123dbd09116561a042e12060f449daa9a36d9a59034b1dd1b96846e66ead14d
11e293722c646a0def7a8a1f2cdf85a47654eb62ef7701bd2d7221c7e69a943f
d10ad2bd62f7a8de379272f21dfccec89c0e5829b3a58ce01927530b6b44ea01
1ba71598b7b8d97fcbd3a589a6665238690be99936b6782647b5040eeb82aafa
Total reclaimed space: 844B
vskumar@ubuntu:~$ 
========== You can see the removed container ids =============>
You can see the existing  containers:
====== Available containers after Housekeeping is done =========>
vskumar@ubuntu:~$ 
vskumar@ubuntu:~$ sudo docker ps
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES
155f4b0764b1        ubuntu:16.04        "/bin/bash"         2 hours ago         Up 6 minutes                            zen_volhard
vskumar@ubuntu:~$ sudo docker ps -a
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES
155f4b0764b1        ubuntu:16.04        "/bin/bash"         2 hours ago         Up 6 minutes                            zen_volhard
vskumar@ubuntu:~$ sudo docker ps -aq
155f4b0764b1
vskumar@ubuntu:~$
===================>
In this exercise we have seen the housekeeping of containers well.
Please note if you have deleted all the containers by mistake, you need to install the containers again. 
Follow the containers creation exercise.

I would like to break this session at this point. In the next blog I would like to present the lab practice on:

 “How to Build images from Docker containers?“