Docker - working steps | Part-1 Docker Setup & Basics

Note: I created amzone machine image in AWS to test all these commands.

-- Install Docker

# mkdir docker_class
# cd docker_class/
# yum install docker -y

-- check docker version

[root@ip-172-31-38-12 docker_class]# docker --version
Docker version 20.10.17, build 100c701

-- start docker service

[root@ip-172-31-38-12 docker_class]# service docker start
Redirecting to /bin/systemctl start docker.service

-- check docker status

# service docker status
# service docker status| grep active
Redirecting to /bin/systemctl status docker.service
   Active: active (running) since Thu 2023-02-23 14:45:32 UTC; 4min 4s ago

-- enable docker service to start auotmatically when rebooted by os level

[root@ip-172-31-38-12 docker_class]# chkconfig docker on
Note: Forwarding request to 'systemctl enable docker.service'.
Created symlink from /etc/systemd/system/multi-user.target.wants/docker.service to /usr/lib/systemd/system/docker.service.
-- Docker information
[root@ip-172-31-38-12 docker_class]# docker info
Client:
 Context:    default
 Debug Mode: false
Server:
 Containers: 0
  Running: 0
  Paused: 0
  Stopped: 0
 Images: 0
 Server Version: 20.10.17
 Storage Driver: overlay2
  Backing Filesystem: xfs
  Supports d_type: true
  Native Overlay Diff: true
  userxattr: false
 Logging Driver: json-file
 Cgroup Driver: cgroupfs
 Cgroup Version: 1
 Plugins:
  Volume: local
  Network: bridge host ipvlan macvlan null overlay
  Log: awslogs fluentd gcplogs gelf journald json-file local logentries splunk syslog
 Swarm: inactive
 Runtimes: io.containerd.runc.v2 io.containerd.runtime.v1.linux runc
 Default Runtime: runc
 Init Binary: docker-init
 containerd version: 9cd3357b7fd7218e4aec3eae239db1f68a5a6ec6
 runc version: 5fd4c4d144137e991c4acebb2146ab1483a97925
 init version: de40ad0
 Security Options:
  seccomp
   Profile: default
 Kernel Version: 5.10.165-143.735.amzn2.x86_64
 Operating System: Amazon Linux 2
 OSType: linux
 Architecture: x86_64
 CPUs: 1
 Total Memory: 964.8MiB
 Name: ip-172-31-38-12.ap-southeast-1.compute.internal
 ID: GGL3:DVIA:JY5H:DZ7G:EF4W:3ATA:NJDP:5R3Y:4QD6:TYVH:VGYX:3CHB
 Docker Root Dir: /var/lib/docker
 Debug Mode: false
 Registry: https://index.docker.io/v1/
 Labels:
 Experimental: false
 Insecure Registries:
  127.0.0.0/8
 Live Restore Enabled: false
[root@ip-172-31-38-12 docker_class]#

Note:
All docker related file will be stored in below location as per above command.
Docker Root Dir: /var/lib/docker
[root@ip-172-31-38-12 docker_class]# ls /var/lib/docker
buildkit  containers  image  network  overlay2  plugins  runtimes  swarm  tmp  trust  volumes


Docker Basic commands

-- Lunch a container with download

docker run -i -t --name <container-name> <image-name> /bin/bash
[root@ip-172-31-38-12 docker_class]# docker run -i -t --name container1 ubuntu /bin/bash

-i - interactive
-t - terminal
can be used as:

docker run -it --name container1 ubuntu /bin/bash

Note: This command ll go to docker hub(hub.docker.com) and it ll download ubuntu image first and then it lunch container

e.g.,
docker run -it --name container1 ubuntu /bin/bash
[root@ip-172-31-38-12 docker_class]# docker run -it --name container1 ubuntu /bin/bash
Unable to find image 'ubuntu:latest' locally
latest: Pulling from library/ubuntu
677076032cca: Pull complete
Digest: sha256:9a0bdde4188b896a372804be2384015e90e3f84906b750c1a53539b585fbbe7f
Status: Downloaded newer image for ubuntu:latest
root@2d00a04c0b77:/#
Note: container created and we are in the container by default.


-- Verify the Operating system

root@2d00a04c0b77:/# cat /etc/os*
PRETTY_NAME="Ubuntu 22.04.1 LTS"
NAME="Ubuntu"
VERSION_ID="22.04"
VERSION="22.04.1 LTS (Jammy Jellyfish)"
VERSION_CODENAME=jammy
ID=ubuntu
ID_LIKE=debian
HOME_URL="https://www.ubuntu.com/"
SUPPORT_URL="https://help.ubuntu.com/"
BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/"
PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy"
UBUNTU_CODENAME=jammy
root@2d00a04c0b77:/#

Note: VERSION="22.04.1 LTS (Jammy Jellyfish)"  as per above output and it is the stable version.

-- To comeout from container
way-2:
exit -- stop and come out
Ctrl + pq  -- come out from container without stopping container

-- Now check running containers

docker ps -a
[root@ip-172-31-38-12 docker_class]# docker ps -a
CONTAINER ID   IMAGE     COMMAND       CREATED          STATUS          PORTS     NAMES
2d00a04c0b77   ubuntu    "/bin/bash"   24 minutes ago   Up 24 minutes             container1

Assignment-1
Create a container without passing any name and use 'exit' command to comeout from container. The list out all containers
[root@ip-172-31-38-12 docker_class]# docker run -it ubuntu /bin/bash
root@6d5b321d998e:/# exit
exit
[root@ip-172-31-38-12 docker_class]# docker ps -a
CONTAINER ID   IMAGE     COMMAND       CREATED          STATUS                     PORTS     NAMES
6d5b321d998e   ubuntu    "/bin/bash"   15 seconds ago   Exited (0) 4 seconds ago             determined_einstein
2d00a04c0b77   ubuntu    "/bin/bash"   27 minutes ago   Up 27 minutes                        container1
[root@ip-172-31-38-12 docker_class]#

Note: Here docker given a random name to newly created container

-- search images available using docker console command

docker search <image-name>

 [root@ip-172-31-38-12 docker_class]# docker search tomcat
NAME                                  DESCRIPTION                                     STARS     OFFICIAL   AUTOMATED
tomcat                                Apache Tomcat is an open source implementati…   3491      [OK]
tomee                                 Apache TomEE is an all-Apache Java EE certif…   102       [OK]
bitnami/tomcat                        Bitnami Tomcat Docker Image                     48                   [OK]
arm32v7/tomcat                        Apache Tomcat is an open source implementati…   12
arm64v8/tomcat                        Apache Tomcat is an open source implementati…   8
rightctrl/tomcat                      CentOS , Oracle Java, tomcat application ssl…   7                    [OK]
...

Here you may have long list for 'tomcat' images. But it is advised to use OFFICIAL[OK] images.

-- Download the image only

docker pull <image-name>
[root@ip-172-31-38-12 docker_class]# docker pull tomcat
Using default tag: latest
latest: Pulling from library/tomcat
10ac4908093d: Pull complete
6df15e605e38: Pull complete
2db012dd504c: Pull complete
8fa912900627: Pull complete
f8fe20946c04: Pull complete
8093daf900d2: Pull complete
49c22a329043: Pull complete
Digest: sha256:9e2525bd79c5386c9bd9ba56fe450263d7af605e41db9fead44e1969379b588a
Status: Downloaded newer image for tomcat:latest
docker.io/library/tomcat:latest
[root@ip-172-31-38-12 docker_class]#

-- List all images

docker images
[root@ip-172-31-38-12 docker_class]# docker images
REPOSITORY   TAG       IMAGE ID       CREATED       SIZE
tomcat       latest    2362f0cdbf14   3 weeks ago   474MB
ubuntu       latest    58db3edaf2be   4 weeks ago   77.8MB
Note: We can manage our images either with ID or image name.
-- start container 
docker start <container-id | container-name>
[root@ip-172-31-38-12 docker_class]# docker ps -a
CONTAINER ID   IMAGE     COMMAND       CREATED          STATUS                      PORTS     NAMES
6d5b321d998e   ubuntu    "/bin/bash"   17 minutes ago   Exited (0) 17 minutes ago             determined_einstein
2d00a04c0b77   ubuntu    "/bin/bash"   44 minutes ago   Up 44 minutes                         container1
[root@ip-172-31-38-12 docker_class]#
[root@ip-172-31-38-12 docker_class]# docker start 6d5b321d998e
6d5b321d998e
[root@ip-172-31-38-12 docker_class]# docker ps -a
CONTAINER ID   IMAGE     COMMAND       CREATED          STATUS          PORTS     NAMES
6d5b321d998e   ubuntu    "/bin/bash"   17 minutes ago   Up 5 seconds              determined_einstein
2d00a04c0b77   ubuntu    "/bin/bash"   45 minutes ago   Up 45 minutes             container1
[root@ip-172-31-38-12 docker_class]#

-- Go to container/ attach container

docker attach <container-id | container-name>
[root@ip-172-31-38-12 docker_class]# docker attach 6d5b321d998e
root@6d5b321d998e:/#

-- stop a container

docker stop <container-1 [,container-2, ... >

[root@ip-172-31-38-12 docker_class]# docker ps -a
CONTAINER ID   IMAGE     COMMAND       CREATED          STATUS          PORTS     NAMES
6d5b321d998e   ubuntu    "/bin/bash"   27 minutes ago   Up 9 minutes              determined_einstein
2d00a04c0b77   ubuntu    "/bin/bash"   54 minutes ago   Up 54 minutes             container1
[root@ip-172-31-38-12 docker_class]#
[root@ip-172-31-38-12 docker_class]# docker stop determined_einstein
determined_einstein
[root@ip-172-31-38-12 docker_class]# docker ps -a
CONTAINER ID   IMAGE     COMMAND       CREATED          STATUS                       PORTS     NAMES
6d5b321d998e   ubuntu    "/bin/bash"   27 minutes ago   Exited (137) 3 seconds ago             determined_einstein
2d00a04c0b77   ubuntu    "/bin/bash"   55 minutes ago   Up 55 minutes                          container1
[root@ip-172-31-38-12 docker_class]#


-- delete a container 

docker rm <container-name>
delete a container force fully ( delete even if running)
docker rm -f <container-name>
[root@ip-172-31-38-12 docker_class]# docker rm determined_einstein
determined_einstein
[root@ip-172-31-38-12 docker_class]# docker ps -a
CONTAINER ID   IMAGE     COMMAND       CREATED             STATUS                       PORTS     NAMES
2d00a04c0b77   ubuntu    "/bin/bash"   About an hour ago   Exited (137) 3 minutes ago             container1
[root@ip-172-31-38-12 docker_class]#
[root@ip-172-31-38-12 docker_class]# docker images
REPOSITORY   TAG       IMAGE ID       CREATED       SIZE
tomcat       latest    2362f0cdbf14   3 weeks ago   474MB
ubuntu       latest    58db3edaf2be   4 weeks ago   77.8MB
Note: Here containers ll be deleted but not the images. If you want to delete the images, you can delete them separatly 

-- delete docker image

docker rmi -f <image-name>
[root@ip-172-31-38-12 docker_class]# docker rmi -f tomcat
Untagged: tomcat:latest
Untagged: tomcat@sha256:9e2525bd79c5386c9bd9ba56fe450263d7af605e41db9fead44e1969379b588a
Deleted: sha256:2362f0cdbf14867a1c1ef2e1cc8dc4e78c4f8b66351acdbe71c8ab938e54f364
Deleted: sha256:301da3f7c3d21a8f2b8277a503094c073f8590d50aa14d3ff61474a408b24173
Deleted: sha256:8a77a541c44a41c746957cffbfae4371460b1f3fb830e1efdafc54851410c95f
Deleted: sha256:193b5f6e1d63da1e1e77210f6eaf54ad85e74da97924e0c9a778972bdc04337b
Deleted: sha256:946053b8886e3d663150c166cac63e94978ea8c29f087da3154d64f5a66a56ce
Deleted: sha256:2a6cefd88a47e238c7f3353ceccb865862bf9a8e490320cc781daa7085d041ca
Deleted: sha256:f773875b27ea4af5d222542ae85c25c34b50ae09a6b620ccf7c5198ed1a3aca8
[root@ip-172-31-38-12 docker_class]#

-- Creating an image from an existing container

(Just like take backup of an existing container)

[root@ip-172-31-38-12 docker_class]# docker ps -a
CONTAINER ID   IMAGE     COMMAND       CREATED             STATUS         PORTS     NAMES
2d00a04c0b77   ubuntu    "/bin/bash"   About an hour ago   Up 2 seconds             container1
[root@ip-172-31-38-12 docker_class]#
[root@ip-172-31-38-12 docker_class]# docker attach container1
root@2d00a04c0b77:/#
root@2d00a04c0b77:/# apt-get update -y

Here, we are inside the container and we updated the image first before creating the image
before that we can do some chages in container. Then we can take backup and later when we restore, then we can verify whether they are avialble or not

-- To take image backup

docker commit <source-container-name>

-- add tag to image

docker tag <image-id> <tag-name>

Assignment#2

Take a image of an running container and create one more container and verify all changes are in it or not.


root@2d00a04c0b77:/# cd /tmp
root@2d00a04c0b77:/tmp# mkdir workfiles
root@2d00a04c0b77:/tmp# cd workfiles/
root@2d00a04c0b77:/tmp/workfiles# touch myfile1 myfile2 myfile3
root@2d00a04c0b77:/tmp/workfiles# read escape sequence
[root@ip-172-31-38-12 docker_class]# docker ps -a
CONTAINER ID   IMAGE     COMMAND       CREATED             STATUS         PORTS     NAMES
2d00a04c0b77   ubuntu    "/bin/bash"   About an hour ago   Up 7 minutes             container1
[root@ip-172-31-38-12 docker_class]#
[root@ip-172-31-38-12 docker_class]# docker commit container1
sha256:a5203026bd0ca03bc93715ea66e657c4b5c76c71aef6aa11a4a3e4f8ff57c2e8
[root@ip-172-31-38-12 docker_class]# docker images
REPOSITORY   TAG       IMAGE ID       CREATED         SIZE
<none>       <none>    a5203026bd0c   7 seconds ago   119MB
ubuntu       latest    58db3edaf2be   4 weeks ago     77.8MB
[root@ip-172-31-38-12 docker_class]# docker tag a5203026bd0c sampleimage
[root@ip-172-31-38-12 docker_class]# docker images
REPOSITORY    TAG       IMAGE ID       CREATED              SIZE
sampleimage   latest    a5203026bd0c   About a minute ago   119MB
ubuntu        latest    58db3edaf2be   4 weeks ago          77.8MB
[root@ip-172-31-38-12 docker_class]# docker run -it --name container22 sampleimage /bin/bash
root@120fee2c9008:/# cd /tmp
root@120fee2c9008:/tmp# ls -l
total 0
drwxr-xr-x 2 root root 51 Feb 23 18:09 workfiles
root@120fee2c9008:/tmp# cd workfiles/
root@120fee2c9008:/tmp/workfiles# ls -l
total 0
-rw-r--r-- 1 root root 0 Feb 23 18:09 myfile1
-rw-r--r-- 1 root root 0 Feb 23 18:09 myfile2
-rw-r--r-- 1 root root 0 Feb 23 18:09 myfile3
root@120fee2c9008:/tmp/workfiles#

Here we saw, all changes are also available in new container what we created from image backup.