Docker workshop conducted at Bridgei2i with slides updated from CodeOps

1. Making “Elephants” Dance
Runcy
OommenSlides: http://codeops.tech

3. What is Docker?
Docker is an open-source project that automates the deployment of
applications inside software containers.

4. What is Docker?
“an open platform for developers and sysadmins to build, ship, and run
distributed applications”

5. Why Docker?

6. Why Docker?
“Docker containers wrap a piece of software in a complete
filesystem that contains everything needed to run: code,
runtime, system tools, system libraries – anything that can
be installed on a server. This guarantees that the software
will always run the same, regardless of its environment.”
source: https://www.docker.com/what-docker

7. Why Docker?

8. VMs vs. Docker

9. VMs vs. Docker

10. Docker accesses virtualisation features of
Linux

11. Getting Started

12. Essential Docker components

14. Can I install Docker from
commandline?
Yes! from get.docker.com

16. Finding Docker version
$ docker version

17. Finding details of a Docker
installation
$ docker info

18. How to do “hello world” in
Docker?
$ docker run docker/whalesay cowsay Hello World

19. How to do “Hello World” in
Docker?
$ docker run docker/whalesay cowsay "Hello world"
Runs a command
in a new container
Base image for
creating the container
Command name to
run within the container
Argument to the
“cowsay” command

20. How to do “hello world” in
Docker?
$ docker run -it hello-world

21. How to get help on commands to
use?
$ docker --help

22. Docker commands look like Linux commands - so
familiarity with Linux commands can really help to get
up to speed quickly with Docker.

23. Docker Images
“Images are blueprints for containers”

24. How to get list of images?
$ docker images

25. How to search for an image?
$ docker search <image_name>

26. How to get an image?
$ docker pull <image_name>
In my case fedora image was
already pulled. If it were not there,
Docker would have pulled it afresh

27. Choose smaller images
❖ Example: Alpine vs. Fedora (5 MB vs. 205 MB)
alpine latest 4e38e38c8ce0 4 weeks ago 4.799 MB
fedora latest f9873d530588 4 weeks ago 204.4 MB
❖ Prefer choosing a smaller base image that provides
equivalent functionality (for your requirement) instead of
choosing a larger one

28. How to get details of an
image?
$ docker inspect <image_name>

29. How to see “layers” in an image?
$ docker history <image_name>
Each of these lines are layers and
the size column shows the exact size
of each layer in the image

30. How can I load and store
images?
$ docker save <image_name> -o <filename.tar>
$ docker load –i <filename.tar>

31. How do I delete an image?
$ docker rmi <image-tag>

32. How to delete all docker images?
$ docker rmi $(docker images -q)
docker images -q
lists all image ids
❖ Avoid “Image Sprawl”
❖ Remove unused images and release disk
space

33. How to find “dangling
images”?
$ docker images -f "dangling=true"
❖ Remove “dangling images” using the command below:
$ docker rmi $(docker images -f "dangling=true" -q)

34. Docker Containers

35. How to get list of containers?
$ docker ps -a

36. How to run a container?
$ docker run OPTIONS <image-tag> CMD ARGS
$ docker run fedora /bin/echo 'Hello world'
Image name Command argument
Command name

37. How to run a container
interactively?
$ docker run –i -t fedora /bin/bash
Interactive
Run in terminal

38. Cobb’s Totem - The Top

39. Running a container - Totem?

40. How to run a container in the
background?
$ docker run -d alpine /bin/sh -c "while true; do echo current date and time is: $(date); sleep 10; done"
Detach

41. How to expose/map a port?
$ docker inspect c7ada3308269 | grep Port
$ docker run –d –p 80:80 nginx
Mapped port - nginx
host port (on which this command is run)

42. Using Nginx
Type http://localhost:80 in your browser window

43. How to expose a port?
$ docker run -d -p 80 --name mynginx
nginx
$ docker inspect mynginx | grep
Port
randomly assigned and mapped
port number (by docker)
host port; since no explicit mapped
port is provided, a random port is
assigned

44. How to expose all exposed
ports?
$ docker run -d -P --name mynginx
nginx
$ docker port
mynginx
-P publishes all exposed ports to random ports

45. Exposing ports
$ docker run -d -p 80 --name nginx1 nginx
d415758906dccc07aae319fc438c825e878ea00ffd58551c63d5c41fd39e4153
$ docker port nginx1
80/tcp -> 0.0.0.0:32769
Maps the port 80 from
container to a random port in
the host
$ docker run -d -p 80:80 --name nginx2 nginx
4d7c26218b440d054d33799b7be1174254db50550254211d739f9403ca4092e9
$ docker port nginx2
80/tcp -> 0.0.0.0:80
Maps the port 80 from
container to port 80 in the host
$ docker run -d -p 80:80 -p 443:443 --name nginx3 nginx
2cfde425380601479aaf5e33a9b1fc09111d84b49595c33f509c00ad2cafc12d
$ docker port nginx3
80/tcp -> 0.0.0.0:80
443/tcp -> 0.0.0.0:443
Maps the container ports 80
and 443 to the same port nos.
in the host
$ docker run -d -P --name nginx4 nginx
8e5fadfbcf5f3145909aed3219738535ad81e534153d5958fbec07f9e9c49e67
$ docker port nginx4
443/tcp -> 0.0.0.0:32770
80/tcp -> 0.0.0.0:32771
Maps the container ports 80
and 443 to random port nos. in
the host
The exposed ports in “nginx:latest” are “443/tcp" and “80/tcp”

46. How to attach to a running
container?
$ docker attach <container_id>
$ docker run –d ubuntu /bin/sh -c "while true; do echo current date and time is: $(date); sleep 10; done"
short for “—detach” and it runs
container in the background
The “attach” command attaches to a running container

47. How to detach from a running container (without
exiting)?
From docker documentation
# To detach the tty without exiting the shell,
# use the escape sequence Ctrl-p + Ctrl-q

48. How to get list of containers?
$ docker ps

49. How do I see all the
containers?
$ docker ps -a

50. Explicitly remove exited
containers
❖ Explicitly use "rm" to remove the container from the file
system - otherwise, even if the container exits, it is not
cleaned up yet (and will hog memory).

51. How do I remove a container?
$ docker stop <container_id>
You have to first stop a
container before trying
to remove it
$ docker rm <container_id>

52. How to remove all the
containers?
$ docker stop $(docker ps -a -q)
$ docker rm $(docker ps -a –q)
Note how the output
shows no containers

53. How to debug on a running
container?
$ docker exec –it <container_id> <cmd>

54. Using nginx
Nginx exposes ports 80; -P maps them
randomly in the custom ports range
$ docker run –d –name mynginx –P nginx

55. Using nginx - Example
$ cat Dockerfile
FROM nginx:latest
MAINTAINER Runcy Oommen
ADD ./index.html /usr/share/nginx/html/index.html
EXPOSE 80
$ cat index.html
<h1> welcome to Dockerizing apps! <h1>
$ docker build .
Sending build context to Docker daemon 3.072 kB
// output cropped ...
Removing intermediate container b043a75a4e1c
Successfully built 1aae04309f8b
$ docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
<none> <none> 1aae04309f8b 6 seconds ago 182.8 MB
$ docker run -p 80:80 -d 1aae04309f8b
984c179231188445289e70d854250e4e981b77a899208360db4466e73930be42
$ curl localhost:80
<h1> welcome to Dockerizing apps! <h1>
Type “localhost:80” in
the browser address bar

56. How do I run a C program?
$ cat Dockerfile
FROM gcc:latest
MAINTAINER Runcy Oommen version: 0.1
COPY . /usr/src/mycapp
WORKDIR /usr/src/mycapp
RUN gcc -o first first.c
CMD ["./first"]
$ cat first.c
#include <stdio.h>
int main() { printf("hello worldn"); }
$ docker build . –t "mycapp:latest"
Sending build context to Docker daemon 3.072
kB
Step 1 : FROM gcc:latest
---> a0b516dc1799
// .. steps cropped...
Successfully built f99e7f18fa42
$ docker run -it mycapp
hello world

57. How do I run a Java
program?$ cat Dockerfile
FROM java:latest
COPY . /usr/src/
WORKDIR /usr/src/
RUN javac hello.java
CMD ["java", "hello"]
$ cat hello.java
class hello {
public static void main(String []args) {
System.out.println("hello world");
}
}
$ docker build . –t "myjavaapp:latest"
Sending build context to Docker daemon 3.072 kB
Step 1 : FROM java:latest
---> 264282a59a95
// intermediate steps cropped
Successfully built 0d7a3a12ba9d
$ docker run myjavaapp
hello world

58. Beware of “container
sprawl”
❖ Application broken to run in “too many containers“ can be
difficult to deal with!
“Breaking deployments into more functional discrete
parts is smart, but that means we have MORE
PARTS to manage. There's an inflection point
between separation of concerns and sprawl.”
-- Rob Hirschfeld
(OpenStack Foundation board member)

59. Building images using
Dockerfile

60. Different ways to create
images
docker commit Build an image from a container
docker build
Create an image from a Dockerfile by executing the
build steps given in the file
docker import
Create a base image by importing from a tarball.
[import is mainly used for creating base-images; first
two options are widely used]

61. Dockerfile - key instructions
FROM
The base image for building the new docker image; provide “FROM scratch” if
it is a base image itself
MAINTAINER The author of the Dockerfile and the email
RUN Any OS command to build the image
CMD
Specify the command to be started when the container is run; can be
overridden by the explicit argument when providing docker run command
ADD Copies files or directories from the host to the container in the given path
EXPOSE Exposes the specified port to the host machine

62. Docker Volumes

63. Docker volume commands
Command Description
docker volume create Create a volume
docker volume inspect
Display detailed information on one
or more volumes
docker volume ls List the available volumes
docker volume rm Remove one or more volumes

64. Commands for Docker
volumes
$ docker volume create --name myvolume
myvolume
$ docker volume ls
local myvolume
$ docker volume inspect myvolume
[
{
"Name": "myvolume",
"Driver": "local",
"Mountpoint": "/var/lib/docker/volumes/myvolume/_data",
"Labels": {},
"Scope": "local"
}
]
$ docker volume rm myvolume
myvolume

65. How to persist data?
$ docker run -v /volumetesting --name="persistdata" alpine /bin/sh -c "echo testing
persistence with volumes > /volumetesting/textfile.txt”
$ docker run --volumes-from=persistdata alpine /bin/sh -c "cat /volumetesting/textfile.txt"
testing persistence with volumes
Use -v option to “mount volumes”

66. Removing volumes
$ docker volume rm <volume_name>

67. Removing containers with
volumes
❖ When the container is removed, the volumes will not be
removed. If the volumes also need to be removed, you
have to use the -v option
$ docker rm –v <sha256_hash>

68. Clean up volumes
❖ You can “clean up” the volumes if you aren't using them.
$ docker volume rm $(docker volume ls -q)

69. Docker Compose

70. docker-compose commands
Command Description
docker-compose up (Re)build services
docker-compose kill Kill the containers
docker-compose logs Show the logs of the containers
docker-compose down
Stop and remove images, containers, volumes
and networks
docker-compose rm Remove stopped containers

71. Creating multiple Docker
containers
Step 1. Create a docker-compose.yml file
Step 2. Execute “docker-compose up -d”
Step 3. Execute “docker-compose logs” from another shell (but from same dir)
Step 4. Execute “docker-compose down”

72. Docker Networking

73. Getting the ip address of a
container
$ docker inspect --format '{{ .NetworkSettings.IPAddress }}' fervent_sinoussi
172.17.0.6
$ docker attach fervent_sinoussi
root@856aed6a92f1:/# ip addr
// ...
92: eth0@if93: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default
link/ether 02:42:ac:11:00:06 brd ff:ff:ff:ff:ff:ff
inet 172.17.0.6/16 scope global eth0
valid_lft forever preferred_lft forever
inet6 fe80::42:acff:fe11:6/64 scope link
valid_lft forever preferred_lft forever
root@856aed6a92f1:/# cat /etc/hosts
// ...
172.17.0.6 856aed6a92f1
root@856aed6a92f1:/#
There are many ways to get the IP address of a container:
1. Use the docker inspect command
2. Use ip addr command from the container’s shell
3. Use “cat /etc/hosts” and check the entry for the container

74. How to get port mappings of a
container?
$ docker port <container_id>

75. Three kinds of networks
$ docker network ls
By default, containers are
added to the bridge network.
You can see the containers in
bridge network here

76. Docker network commands
Command Description
docker network connect Connect a container to a network
docker network create Create a network
docker network disconnect
Disconnect a container from a
network
docker network inspect
Display detailed information on one
or more networks
docker network ls List networks
docker network rm Remove one or more networks

77. Docker security

78. Docker security
“One primary risk with running Docker containers is that the default
set of capabilities and mounts given to a container may provide
incomplete isolation, either independently, or when used in
combination with kernel vulnerabilities”
Source: https://docs.docker.com/engine/security/security/

79. Docker workbench for
security
git clone https://github.com/docker/docker-bench-security.git
cd docker-bench-security
sh docker-bench-security.sh
git clone https://github.com/docker/docker-bench-security.git
cd docker-bench-security
docker-compose run --rm docker-bench-security
OR
❖ Use the free Docker Workbench For Security to check for
violations of security best practices

80. Docker workbench for
security

81. Monitoring Docker

82. Stats for all running
containers
$ docker stats
Displays resource utilisation (cpu,
memory, etc) details; automatically
updated when details change

83. Stats for a specific Docker
$ docker stats <CONTAINTER_ID>

84. Other Topics

85. ‘RunC’ container runtime
RunC is the name of the container runtime used by Docker
It is part of OCI (Open Container Initiative)
https://runc.io/

86. Can I use GUI instead of command-
line?
Use “kitematic” (https://github.com/docker/kitematic)

87. Crazy stuff: Docker in
Docker!!
$ docker run --privileged -d docker:dind"
“docker:dind” is the official “Docker In Docker image”
See: https://github.com/jpetazzo/dind

88. Myths and Misconceptions

89. Docker *completely* replaces
VMs

90. Containers AND VMs

91. Docker is *completely*
portable
There are limitations to portability with Docker (depending on
what you mean by “portable”).
For example, you can run a Windows Docker container only on
Windows and run a Linux Docker container only on Linux (and
not vice versa).
Build once, run anywhere - but conditions apply!

92. “Management says we need
Docker, so let’s use it”

93. Quick Ref

94. Docker commands

95. Docker commands

96. Source: http://zeroturnaround.com/wp-content/uploads/2016/03/Docker-cheat-sheet-by-RebelLabs.png

97. Where to learn more?

98. Relevant URLs
❖ Docker resources list: https://github.com/hangyan/docker-resources
❖ Self-learning courses: https://training.docker.com/
❖ Detailed documentation: https://docs.docker.com/
❖ Various presentations: http://container.training
❖ SE-Radio Episode 217: James Turnbull on Docker

99. DOCKER: UP &
RUNNING➤ Covers how to develop, test,
debug, ship, scale, and
support with Docker from
DevOps perspective
➤ We liked the useful tips;
examples:
➤ “Maximize robustness with fast
startup and graceful shutdown.”
➤ “Explicitly declare and isolate
dependencies.”
➤ “Strictly separate build and run
stages.”
http://amzn.com/1491917571
“Docker: Up & Running”, Karl Matthias, Sean P. Kane, O'Reilly Media; 1 edition (July 3, 2015)

100. THE DOCKER
BOOK➤ Interesting sub-title:
“Containerization is the new
virtualization”.
➤ From James Turnbull (CTO at
Kickstarter and Advisor at
Docker)
➤ Useful to get comfortable with
core concepts of Docker
➤ Useful for developers,
operations staff (and DevOps),
and SysAdmins
➤ Supporting website:
http://dockerbook.com/
http://www.amazon.in/dp/B00LRROTI4
The Docker Book, James Turnbull, Amazon Digital South Asia Services, July 2014

101. DOCKER
COOKBOOK➤ Contents written in recipe
format (Problem, Solution,
Discussion)
➤ Useful because we can look for
solutions to the problems that we
face when using Docker
➤ What we like: it covers topics
that are not covered well in
other books including
Kubernetes, Docker
ecosystem tools, monitoring
Docker, and application use
cases (CI, CD)
http://amzn.com/149191971X
“Docker Cookbook”, Sébastien Goasguen, O'Reilly Media, 2015

102. ❖ Book organized into
three parts:
❖ Background and Basics
❖ The Software Lifecycle with
Docker
❖ Tools and Techniques
❖ Useful example: Walks
you through the steps to
develop and deploy web
applications with Docker
❖ Though the book
touches upon basics, it
covers more advanced
topicshttp://amzn.com/1491915765
Using Docker: Developing and Deploying Software with Containers, Adrian Mouat, O'Reilly Media, 2016
USING
DOCKER

103. Meetups
http://www.meetup.com/Container-Developers-Meetup-Bangalore/
http://www.meetup.com/CloudOps-Meetup-Bangalore/
http://www.meetup.com/Bangalore-SDN-IoT-NetworkVirtualization-Enthusiasts/
http://www.meetup.com/SoftwareArchitectsBangalore/

104. THANK YOU!
Q &
A