Docker: Committing Image, Linking Containers, Creating Volume, Backup and Deleting a container

Committing the image with some message, as we do in git.

-bash-4.2$ sudo docker commit -m "Added httpd on CentOS" -a "Shantanu" f3bc073ecc85 shaan2212/centos:versionnew

sha256:adbc83d26a394399663e4730e0a9c98f7906a12ab2bcab703d926abb6e82edd6

-bash-4.2$ sudo docker images

REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE

shaan2212/centos    versionnew          adbc83d26a39        15 seconds ago      269MB

ubuntu              latest              775349758637        4 weeks ago         64.2MB

centos              latest              0f3e07c0138f        8 weeks ago         220MB

hello-world         latest              fce289e99eb9        11 months ago       1.84kB

training/webapp     latest              6fae60ef3446        4 years ago         349MB

-bash-4.2$

Pushing the new image named as "centos:versionnew" to dockerhub

-bash-4.2$ sudo docker push shaan2212/centos:versionnew

The push refers to repository [docker.io/shaan2212/centos]

8c4f4ced0acf: Pushed

9e607bb861a7: Mounted from library/centos

versionnew: digest: sha256:c51555b889b09b3dc5b3f3ddf0a70a3ee676ffd92a3350939bd7f44d6119703b size: 741

-bash-4.2$

https://hub.docker.com/repository/docker/shaan2212/centos   === We can find it here now

Remove a docker image from the local system.

-bash-4.2$ sudo docker rmi shaan2212/centos:versionnew

Untagged: shaan2212/centos:versionnew

Untagged: shaan2212/centos@sha256:c51555b889b09b3dc5b3f3ddf0a70a3ee676ffd92a3350939bd7f44d6119703b

Deleted: sha256:adbc83d26a394399663e4730e0a9c98f7906a12ab2bcab703d926abb6e82edd6

Deleted: sha256:c6320d74c682c7ae027d1b8a10db9723640d5a83e0162a42341e5ac31b33060e

-bash-4.2$

-bash-4.2$ sudo docker images

REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE

ubuntu              latest              775349758637        4 weeks ago         64.2MB

centos              latest              0f3e07c0138f        8 weeks ago         220MB

hello-world         latest              fce289e99eb9        11 months ago       1.84kB

training/webapp     latest              6fae60ef3446        4 years ago         349MB

-bash-4.2$

Linking Containers using --link command:

Links allow containers to discover each other and securely transfer information about one container to another container. When you set up a link, you create a conduit between a source container and a recipient container. The recipient can then access select data about the source.

Running a container on postgres image with name "dblink"

-bash-4.2$ sudo docker run -d --name dblink training/postgres

Unable to find image 'training/postgres:latest' locally

latest: Pulling from training/postgres

Image docker.io/training/postgres:latest uses outdated schema1 manifest format. Please upgrade to a schema2 image for better future compatibility. More information at https://docs.docker.com/registry/spec/deprecated-schema-v1/

a3ed95caeb02: Pull complete

6e71c809542e: Pull complete

2978d9af87ba: Pull complete

e1bca35b062f: Pull complete

500b6decf741: Pull complete

74b14ef2151f: Pull complete

7afd5ed3826e: Pull complete

3c69bb244f5e: Pull complete

d86f9ec5aedf: Pull complete

010fabf20157: Pull complete

Digest: sha256:a945dc6dcfbc8d009c3d972931608344b76c2870ce796da00a827bd50791907e

Status: Downloaded newer image for training/postgres:latest

cd1e31374441740e45500f0dfc1c89c6c05da692f3f6506ec7eb9216997d0170

-bash-4.2$ sudo docker ps

CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS               NAMES

cd1e31374441        training/postgres   "su postgres -c '/us…"   26 seconds ago      Up 24 seconds       5432/tcp            dblink

-bash-4.2$ sudo docker logs dblink

2019-11-29 06:06:45 UTC LOG:  database system was interrupted; last known up at 2014-06-02 23:51:25 UTC

2019-11-29 06:06:45 UTC LOG:  database system was not properly shut down; automatic recovery in progress

2019-11-29 06:06:45 UTC LOG:  redo starts at 0/1782F38

2019-11-29 06:06:45 UTC LOG:  record with zero length at 0/17835C8

2019-11-29 06:06:45 UTC LOG:  redo done at 0/1783598

2019-11-29 06:06:45 UTC LOG:  last completed transaction was at log time 2014-06-02 23:51:25.978993+00

2019-11-29 06:06:45 UTC LOG:  database system is ready to accept connections

2019-11-29 06:06:45 UTC LOG:  autovacuum launcher started

Started another container with name "web" and linked it with the previous container by using --link dblink:dblinknew (--link <name or id>:alias)

-bash-4.2$ sudo docker run -d -P --name web --link dblink:dblinknew training/webapp python app.py

eb3041503270bce10dcb8a9da2fbcecfbd87d302a5f2bb6004b6db313d8f93bb

-bash-4.2$ sudo docker ps

CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS                     NAMES

eb3041503270        training/webapp     "python app.py"          9 seconds ago       Up 7 seconds        0.0.0.0:32768->5000/tcp   web

cd1e31374441        training/postgres   "su postgres -c '/us…"   5 minutes ago       Up 5 minutes        5432/tcp                  dblink

-bash-4.2$ curl http://0.0.0.0:32768

Hello world!-bash-4.2$

Link can be checked by inspecting the web container:

-bash-4.2$ sudo docker inspect web | grep -i link

            "Links": [

                "/dblink:/web/dblinknew"

            "LinkLocalIPv6Address": "",

            "LinkLocalIPv6PrefixLen": 0,

                    "Links": null,

-bash-4.2$

Docker creates several environment variables when you link containers. Docker automatically creates environment variables in the target container based on the --link parameters. It also exposes all environment variables originating from Docker from the source container. These include variables from:

the ENV commands in the source container’s Dockerfile

the -e, --env, and --env-file options on the docker run command when the source container is started

--rm can be used when we want to exit/terminate the container after fulfilling the requirement.

--rm : Remove container after run. Ignored in detached mode.

-bash-4.2$ sudo docker run --rm --name web3 --link dblink:dblinknew training/webapp env

PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin

HOSTNAME=d40aac4fbaad

DBLINKNEW_PORT=tcp://172.17.0.2:5432

DBLINKNEW_PORT_5432_TCP=tcp://172.17.0.2:5432

DBLINKNEW_PORT_5432_TCP_ADDR=172.17.0.2

DBLINKNEW_PORT_5432_TCP_PORT=5432

DBLINKNEW_PORT_5432_TCP_PROTO=tcp

DBLINKNEW_NAME=/web3/dblinknew

DBLINKNEW_ENV_PG_VERSION=9.3

HOME=/root

-bash-4.2$ sudo docker ps

CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS                     NAMES

eb3041503270        training/webapp     "python app.py"          7 minutes ago       Up 7 minutes        0.0.0.0:32768->5000/tcp   web

cd1e31374441        training/postgres   "su postgres -c '/us…"   12 minutes ago      Up 12 minutes       5432/tcp                  dblink

-bash-4.2$

In addition to the environment variables, Docker adds a host entry for the source container to the /etc/hosts file. Here’s an entry for the web container. You can see two relevant host entries. The first is an entry for the dblink ontainer that uses the Container ID as a host name. The second entry uses the link alias to reference the IP address of the new container.

-bash-4.2$ sudo docker run -ti --rm --link dblink:web training/webapp /bin/bash

root@32c9ca99e004:/opt/webapp# cat /etc/hosts

127.0.0.1       localhost

::1     localhost ip6-localhost ip6-loopback

fe00::0 ip6-localnet

ff00::0 ip6-mcastprefix

ff02::1 ip6-allnodes

ff02::2 ip6-allrouters

172.17.0.2      web cd1e31374441 dblink

172.17.0.4      32c9ca99e004

root@32c9ca99e004:/opt/webapp#

-bash-4.2$ sudo docker stop dblink

dblink

-bash-4.2$ sudo docker stop web

web

-bash-4.2$ sudo docker ps

CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES

-bash-4.2$ sudo docker images

REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE

ubuntu              latest              775349758637        4 weeks ago         64.2MB

centos              latest              0f3e07c0138f        8 weeks ago         220MB

hello-world         latest              fce289e99eb9        11 months ago       1.84kB

training/webapp     latest              6fae60ef3446        4 years ago         349MB

training/postgres   latest              6fa973bb3c26        5 years ago         365MB

-bash-4.2$

Creating Volume:

Volumes are the preferred mechanism for persisting data generated by and used by Docker containers. While bind mounts are dependent on the directory structure of the host machine, volumes are completely managed by Docker. Volumes have several advantages over bind mounts:

Volumes are easier to back up or migrate than bind mounts.

You can manage volumes using Docker CLI commands or the Docker API.

Volumes work on both Linux and Windows containers.

Volumes can be more safely shared among multiple containers.

Volume drivers let you store volumes on remote hosts or cloud providers, to encrypt the contents of volumes, or to add other functionality.

New volumes can have their content pre-populated by a container.

In addition, volumes are often a better choice than persisting data in a container’s writable layer, because a volume does not increase the size of the containers using it, and the volume’s contents exist outside the lifecycle of a given container.

-h : It is used to update the container hostname.

-v : It is used to specify the volume on the container.

The idea is to mount a volume in a container and write some data into it. Later on, we can share the same volume to another container and we must find out the data written to the 1st container inside the volume.

-bash-4.2$ sudo docker run -it --name container-data -h CONTAINER -v /data debian /bin/bash

Unable to find image 'debian:latest' locally

latest: Pulling from library/debian

16ea0e8c8879: Pull complete

Digest: sha256:79f0b1682af1a6a29ff63182c8103027f4de98b22d8fb50040e9c4bb13e3de78

Status: Downloaded newer image for debian:latest

root@CONTAINER:/# ls

bin  boot  data  dev  etc  home  lib  lib64  media  mnt  opt  proc  root  run  sbin  srv  sys  tmp  usr  var

root@CONTAINER:/# df -Ph

Filesystem               Size  Used Avail Use% Mounted on

overlay                   17G  2.9G   15G  17% /

tmpfs                     64M     0   64M   0% /dev

tmpfs                    487M     0  487M   0% /sys/fs/cgroup

shm                       64M     0   64M   0% /dev/shm

/dev/mapper/centos-root   17G  2.9G   15G  17% /data

tmpfs                    487M     0  487M   0% /proc/asound

tmpfs                    487M     0  487M   0% /proc/acpi

tmpfs                    487M     0  487M   0% /proc/scsi

tmpfs                    487M     0  487M   0% /sys/firmware

root@CONTAINER:/#

root@CONTAINER:/#

root@CONTAINER:/# cd /data

root@CONTAINER:/data# pwd

/data

root@CONTAINER:/data#

root@CONTAINER:/data#

root@CONTAINER:/data# ls -l

total 0

root@CONTAINER:/data#

root@CONTAINER:/data# echo "hello" > myfile

root@CONTAINER:/data#

root@CONTAINER:/data#

root@CONTAINER:/data# ll

bash: ll: command not found

root@CONTAINER:/data#

root@CONTAINER:/data# ls -l

total 4

-rw-r--r--. 1 root root 6 Nov 30 05:28 myfile

root@CONTAINER:/data#

root@CONTAINER:/data#

root@CONTAINER:/data# exit

exit

-bash-4.2$

-bash-4.2$ sudo docker images

REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE

debian              latest              67e34c1c9477        7 days ago          114MB

ubuntu              latest              775349758637        4 weeks ago         64.2MB

centos              latest              0f3e07c0138f        8 weeks ago         220MB

hello-world         latest              fce289e99eb9        11 months ago       1.84kB

training/webapp     latest              6fae60ef3446        4 years ago         349MB

training/postgres   latest              6fa973bb3c26        5 years ago         365MB

-bash-4.2$ sudo docker ps

CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES

-bash-4.2$

-bash-4.2$ sudo docker inspect container-data | grep -i volume

            "VolumeDriver": "",

            "VolumesFrom": null,

                "Type": "volume",

                "Source": "/var/lib/docker/volumes/54eb0fd9a42db9f4d24f3edcbb6c9f3fcbc6d74029a12b5f5575f8d7998b6445/_data",

            "Volumes": {

-bash-4.2$

On base OS, we can find the container volume on the below path.

[root@manager ~]# ls -ld /var/lib/docker/volumes/54eb0fd9a42db9f4d24f3edcbb6c9f3fcbc6d74029a12b5f5575f8d7998b6445/_data

drwxr-xr-x. 2 root root 20 Nov 30 00:28 /var/lib/docker/volumes/54eb0fd9a42db9f4d24f3edcbb6c9f3fcbc6d74029a12b5f5575f8d7998b6445/_data

[root@manager ~]#

Sharing Volumes between containers:

-bash-4.2$ sudo docker run -it --name second-container-data -h NEWCONTAINER --volumes-from container-data centos /bin/bash

[sudo] password for dockmgr:

[root@NEWCONTAINER /]# df -Ph

Filesystem               Size  Used Avail Use% Mounted on

overlay                   17G  2.9G   15G  17% /

tmpfs                     64M     0   64M   0% /dev

tmpfs                    487M     0  487M   0% /sys/fs/cgroup

shm                       64M     0   64M   0% /dev/shm

/dev/mapper/centos-root   17G  2.9G   15G  17% /data

tmpfs                    487M     0  487M   0% /proc/asound

tmpfs                    487M     0  487M   0% /proc/acpi

tmpfs                    487M     0  487M   0% /proc/scsi

tmpfs                    487M     0  487M   0% /sys/firmware

[root@NEWCONTAINER /]#

[root@NEWCONTAINER /]# cd /data

[root@NEWCONTAINER data]# ls -l

total 4

-rw-r--r--. 1 root root 6 Nov 30 05:28 myfile

[root@NEWCONTAINER data]# cat myfile

hello

[root@NEWCONTAINER data]#

Backup of a volume /data created earlier:

-bash-4.2$ sudo docker run --volumes-from container-data -v $(pwd):/backup centos tar cvf /backup/data.tar /data

[sudo] password for dockmgr:

tar: Removing leading `/' from member names

/data/

/data/myfile

-bash-4.2$ pwd

/home/dockmgr

-bash-4.2$ ls -la

total 12

drwxr-xr-x. 2 root root    22 Nov 30 01:31 .

drwxr-xr-x. 3 root root    21 Nov 28 00:55 ..

-rw-r--r--. 1 root root 10240 Nov 30 01:31 data.tar

-bash-4.2$ tar -tvf data.tar

drwxr-xr-x root/root         0 2019-11-30 00:28 data/

-rw-r--r-- root/root         6 2019-11-30 00:28 data/myfile

-bash-4.2$ sudo tar -xvf data.tar

data/

data/myfile

-bash-4.2$ ls -l

total 12

drwxr-xr-x. 2 root root    20 Nov 30 00:28 data

-rw-r--r--. 1 root root 10240 Nov 30 01:31 data.tar

-bash-4.2$ cd data

-bash-4.2$ ll

total 4

-rw-r--r--. 1 root root 6 Nov 30 00:28 myfile

-bash-4.2$ cat myfile

hello

-bash-4.2$

Pull an image, run it , rename it to usergiven name and attach a shell then create a directory inside it. Exit.. Then start the container and again attach the shell. you will notice the same container ID is available and you can see the directory created in the earlier step. But it will be not available if you create another container from the same image.

-bash-4.2$ docker pull fedora:latest

latest: Pulling from library/fedora

d318c91bf2a8: Pull complete

Digest: sha256:d4f7df6b691d61af6cee7328f82f1d8afdef63bc38f58516858ae3045083924a

Status: Downloaded newer image for fedora:latest

docker.io/library/fedora:latest

-bash-4.2$ sudo docker images

REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE

debian              latest              67e34c1c9477        7 days ago          114MB

ubuntu              latest              775349758637        4 weeks ago         64.2MB

fedora              latest              f0858ad3febd        4 weeks ago         194MB

centos              latest              0f3e07c0138f        8 weeks ago         220MB

hello-world         latest              fce289e99eb9        11 months ago       1.84kB

training/webapp     latest              6fae60ef3446        4 years ago         349MB

training/postgres   latest              6fa973bb3c26        5 years ago         365MB

-bash-4.2$ sudo docker run -it fedora

[root@2d16ab33f29e /]# ls -l

total 0

lrwxrwxrwx.   1 root root   7 Jul 25 00:35 bin -> usr/bin

dr-xr-xr-x.   2 root root   6 Jul 25 00:35 boot

drwxr-xr-x.   5 root root 360 Nov 30 06:54 dev

drwxr-xr-x.   1 root root  66 Nov 30 06:54 etc

drwxr-xr-x.   2 root root   6 Jul 25 00:35 home

lrwxrwxrwx.   1 root root   7 Jul 25 00:35 lib -> usr/lib

lrwxrwxrwx.   1 root root   9 Jul 25 00:35 lib64 -> usr/lib64

drwx------.   2 root root   6 Oct 28 05:47 lost+found

drwxr-xr-x.   2 root root   6 Jul 25 00:35 media

drwxr-xr-x.   2 root root   6 Jul 25 00:35 mnt

drwxr-xr-x.   2 root root   6 Jul 25 00:35 opt

dr-xr-xr-x. 122 root root   0 Nov 30 06:54 proc

dr-xr-x---.   2 root root 196 Oct 28 05:48 root

drwxr-xr-x.  13 root root 186 Oct 28 05:48 run

lrwxrwxrwx.   1 root root   8 Jul 25 00:35 sbin -> usr/sbin

drwxr-xr-x.   2 root root   6 Jul 25 00:35 srv

dr-xr-xr-x.  13 root root   0 Nov 30 04:56 sys

drwxrwxrwt.   2 root root  32 Oct 28 05:48 tmp

drwxr-xr-x.  12 root root 144 Oct 28 05:47 usr

drwxr-xr-x.  18 root root 235 Oct 28 05:47 var

[root@2d16ab33f29e /]# exit

exit

-bash-4.2$ sudo docker ps

CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES

-bash-4.2$ sudo docker ps -a

CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS                         PORTS               NAMES

2d16ab33f29e        fedora              "/bin/bash"              19 seconds ago      Exited (0) 7 seconds ago                           elated_noether

-bash-4.2$ sudo docker rename elated_noether shan_container_fedora

-bash-4.2$

-bash-4.2$ sudo docker start shan_container_fedora

shan_container_fedora

-bash-4.2$ sudo docker ps

CONTAINER ID        IMAGE               COMMAND             CREATED              STATUS              PORTS               NAMES

2d16ab33f29e        fedora              "/bin/bash"         About a minute ago   Up 9 seconds                            shan_container_fedora

-bash-4.2$ sudo docker attach shan_container_fedora

[root@2d16ab33f29e /]# mkdir testdir

[root@2d16ab33f29e /]# ls -l

total 0

lrwxrwxrwx.   1 root root   7 Jul 25 00:35 bin -> usr/bin

dr-xr-xr-x.   2 root root   6 Jul 25 00:35 boot

drwxr-xr-x.   5 root root 360 Nov 30 06:56 dev

drwxr-xr-x.   1 root root  66 Nov 30 06:54 etc

drwxr-xr-x.   2 root root   6 Jul 25 00:35 home

lrwxrwxrwx.   1 root root   7 Jul 25 00:35 lib -> usr/lib

lrwxrwxrwx.   1 root root   9 Jul 25 00:35 lib64 -> usr/lib64

drwx------.   2 root root   6 Oct 28 05:47 lost+found

drwxr-xr-x.   2 root root   6 Jul 25 00:35 media

drwxr-xr-x.   2 root root   6 Jul 25 00:35 mnt

drwxr-xr-x.   2 root root   6 Jul 25 00:35 opt

dr-xr-xr-x. 123 root root   0 Nov 30 06:56 proc

dr-xr-x---.   1 root root  27 Nov 30 06:54 root

drwxr-xr-x.  13 root root 186 Oct 28 05:48 run

lrwxrwxrwx.   1 root root   8 Jul 25 00:35 sbin -> usr/sbin

drwxr-xr-x.   2 root root   6 Jul 25 00:35 srv

dr-xr-xr-x.  13 root root   0 Nov 30 04:56 sys

drwxr-xr-x.   2 root root   6 Nov 30 06:56 testdir

drwxrwxrwt.   2 root root  32 Oct 28 05:48 tmp

drwxr-xr-x.  12 root root 144 Oct 28 05:47 usr

drwxr-xr-x.  18 root root 235 Oct 28 05:47 var

[root@2d16ab33f29e /]# exit

exit

-bash-4.2$ sudo docker start shan_container_fedora

shan_container_fedora

-bash-4.2$ sudo docker attach shan_container_fedora

[root@2d16ab33f29e /]# ls -l

total 0

lrwxrwxrwx.   1 root root   7 Jul 25 00:35 bin -> usr/bin

dr-xr-xr-x.   2 root root   6 Jul 25 00:35 boot

drwxr-xr-x.   5 root root 360 Nov 30 06:57 dev

drwxr-xr-x.   1 root root  66 Nov 30 06:54 etc

drwxr-xr-x.   2 root root   6 Jul 25 00:35 home

lrwxrwxrwx.   1 root root   7 Jul 25 00:35 lib -> usr/lib

lrwxrwxrwx.   1 root root   9 Jul 25 00:35 lib64 -> usr/lib64

drwx------.   2 root root   6 Oct 28 05:47 lost+found

drwxr-xr-x.   2 root root   6 Jul 25 00:35 media

drwxr-xr-x.   2 root root   6 Jul 25 00:35 mnt

drwxr-xr-x.   2 root root   6 Jul 25 00:35 opt

dr-xr-xr-x. 123 root root   0 Nov 30 06:57 proc

dr-xr-x---.   1 root root  27 Nov 30 06:54 root

drwxr-xr-x.  13 root root 186 Oct 28 05:48 run

lrwxrwxrwx.   1 root root   8 Jul 25 00:35 sbin -> usr/sbin

drwxr-xr-x.   2 root root   6 Jul 25 00:35 srv

dr-xr-xr-x.  13 root root   0 Nov 30 04:56 sys

drwxr-xr-x.   2 root root   6 Nov 30 06:56 testdir

drwxrwxrwt.   2 root root  32 Oct 28 05:48 tmp

drwxr-xr-x.  12 root root 144 Oct 28 05:47 usr

drwxr-xr-x.  18 root root 235 Oct 28 05:47 var

[root@2d16ab33f29e /]# exit

exit

-bash-4.2$ sudo docker run -it fedora

[root@b2ce8dd88a27 /]# ls -l

total 0

lrwxrwxrwx.   1 root root   7 Jul 25 00:35 bin -> usr/bin

dr-xr-xr-x.   2 root root   6 Jul 25 00:35 boot

drwxr-xr-x.   5 root root 360 Nov 30 06:57 dev

drwxr-xr-x.   1 root root  66 Nov 30 06:57 etc

drwxr-xr-x.   2 root root   6 Jul 25 00:35 home

lrwxrwxrwx.   1 root root   7 Jul 25 00:35 lib -> usr/lib

lrwxrwxrwx.   1 root root   9 Jul 25 00:35 lib64 -> usr/lib64

drwx------.   2 root root   6 Oct 28 05:47 lost+found

drwxr-xr-x.   2 root root   6 Jul 25 00:35 media

drwxr-xr-x.   2 root root   6 Jul 25 00:35 mnt

drwxr-xr-x.   2 root root   6 Jul 25 00:35 opt

dr-xr-xr-x. 123 root root   0 Nov 30 06:57 proc

dr-xr-x---.   2 root root 196 Oct 28 05:48 root

drwxr-xr-x.  13 root root 186 Oct 28 05:48 run

lrwxrwxrwx.   1 root root   8 Jul 25 00:35 sbin -> usr/sbin

drwxr-xr-x.   2 root root   6 Jul 25 00:35 srv

dr-xr-xr-x.  13 root root   0 Nov 30 04:56 sys

drwxrwxrwt.   2 root root  32 Oct 28 05:48 tmp

drwxr-xr-x.  12 root root 144 Oct 28 05:47 usr

drwxr-xr-x.  18 root root 235 Oct 28 05:47 var

[root@b2ce8dd88a27 /]# exit

exit

-bash-4.2$ sudo docker ps

CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES

-bash-4.2$ sudo docker ps -a

CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS                      PORTS               NAMES

b2ce8dd88a27        fedora              "/bin/bash"              31 seconds ago      Exited (0) 23 seconds ago                       hopeful_kepler

2d16ab33f29e        fedora              "/bin/bash"              3 minutes ago       Exited (0) 55 seconds ago                       shan_container_fedora

Deleting a container:

-bash-4.2$ sudo docker rm shan_container_fedora

[sudo] password for dockmgr:

shan_container_fedora

-bash-4.2$ sudo docker ps -a | grep -i fedora

b2ce8dd88a27        fedora              "/bin/bash"              8 minutes ago       Exited (0) 8 minutes ago                        hopeful_kepler

-bash-4.2$