Introduction to Docker

1. DOCKER
[ Docker ]
Todo lo que quiso saber sobre Docker y seguramente ya tuvo oportunidad de escuchar
César Capillas <cesar at zylk.net>

2. DOCKER
This talk contains:
● Intro
● Docker engine and definitions
● How to use Docker Images
● How to create Docker Images
● Hands on Docker
● Advanced concepts: docker-compose, portainer

3. DOCKER
A container (what is this ?)
● It is an operating system process, that provides:
● A standarized packaging for software and dependencies
● Isolation of apps from each other
● It is not a virtual machine, but it is often compared.
● It provides isolation in terms of:
● Network, Process, User…
● One important feature is that data is ephemeral by default

4. DOCKER
A container (what is this ?)
https://www.altexsoft.com/blog/docker-pros-and-cons/

5. DOCKER
Benefits
● Lightweight / Speed
● No OS to boot applications online in seconds
→
● Highly Portable
● Ability to move between infrastructure
● Easily and quickly provisionable
● Real time provisioning
● Efficiency:
● Less OS overhead
● Native system performance

6. DOCKER
Docker Intro

7. DOCKER
The Docker engine
● It’s a client-server app for running containers
● A server engine (process) with a daemon process called
dockerd
– It provides a REST API for talking with docker
● A command line interface docker (CLI):
– It runs containers
– It is able to manage network and volumes (storage)

8. DOCKER
The Docker engine
Learning Docker – Packt Publishing

9. DOCKER
The Docker family
● Two versions:
● Docker Community Edition
– Free, community-supported product for delivering a
container solution
● Docker Enterprise Edition
– Subscription based, commercially supported for
delivering a secure software supply chain

10. DOCKER
The Docker basics
● Image: Read-only template with instructions for creating a
Docker container.
● Container: Runnable instance of an image.
● Data Volume: Storage folder inside or outside of an image.
● Network: Network interface to connect the container to
default network.

11. DOCKER
Docker architecture

12. DOCKER
Sharing images
● Docker Registry
● You obtain Docker Images from a public (or private)
registry (repository of images)
● When building an image, it is only available in local
● Then you may need to push to a registry
– Docker Hub
– Nexus 3
● Once shared, other people can pull the image

13. DOCKER
Creating images
● Using “Dockerfile”
● FROM Desde qué imagen parto
→
● ENV Definir variables de entorno
→
● ADD Añadir un archivo local en la imagen
→
● COPY
● RUN
● CMD

14. DOCKER
[ Hands on ]
$ mkdir work
$ cd work
$ git clone https://zgit.zylk.net/alfresco/imasd/dx-dockerlab.git
$ cd dx-dockerlab

15. DOCKER
Hands on
0)Prerrequisites (install docker environment)
1)Package and build a custom app with Docker
2)Remembering Tomcat (Revenge)
3)Use commercial databases with Docker (SQL Server)
4)Using docker-compose
5)Docker resources for Apache SOLR
6)Docker resources for Liferay
7)Docker resources for Alfresco

16. DOCKER
Example 1: Deploying a war in Tomcat
FROM tomcat:8.0-alpine
ADD apps/jolokia.war /usr/local/tomcat/webapps/
EXPOSE 8080
CMD ["catalina.sh", "run"]
# Compilo la custom image con el fichero Dockerfile
$ docker build -t myjolokia .
# Creo el contenedor y lo ejecuto en foreground
$ docker run -p 8888:8080 myjolokia

17. DOCKER
Common commands in Docker
$ docker -v
Docker version 19.03.6, build 369ce74a3c
# Para ver tus imágenes locales
$ docker images
# Para ver los containers-id’s que se estan ejecutando
$ docker ps
$ docker ps -a
# Para ejecutar una imagen de docker en background
$ docker run -d <docker-image>
# Para ver los logs de un container
$ docker logs -f <container-id>
# Para inspeccionar el container que estás ejecutando
$ docker exec -it <container-id> /bin/bash
# Para buscar imágenes en Docker Hub
$ docker search tomcat
# Para descargar una imagen
$ docker pull mcr.microsoft.com/mssql/server:2017-latest

18. DOCKER
Example 2: Remembering Tomcat
● Change server.xml configuration file in Tomcat to work in
8998 port instead of default 8080.
● Change in Dockerfile the corresponding port nating.
● 8888 8998
→
● Customize JVM options in setenv.sh to set Memory Heap
● -Xmx1024m
● Check Tomcat logs
● How to set Docker machine in background ?

19. DOCKER
Example 2: Remembering Tomcat
FROM tomcat:8.0-alpine
ADD config/server.xml /usr/local/tomcat/conf/server.xml
ADD config/setenv.sh /usr/local/tomcat/bin/
ADD apps/jolokia.war /usr/local/tomcat/webapps/
EXPOSE 8998
CMD ["catalina.sh", "run"]
# Compilo la custom image con el fichero Dockerfile
$ docker build -t myjolokia2 .
# Ejecuto el docker en background
$ docker run -d -p 8888:8998 --name=mytomcat8 myjolokia2

20. DOCKER
Example 3: Using commercial databases
$ docker pull mcr.microsoft.com/mssql/server:2017-latest
$ docker run -d -e "ACCEPT_EULA=Y" -e "MSSQL_SA_PASSWORD=7y1K7y1K!" -p
1433:1433 --name sqlserver2017 --hostname sqlserver2017 -d
mcr.microsoft.com/mssql/server:2017-latest
# First we can try to check if the default port is available:
$ nc -v localhost 1433
Connection to localhost 1433 port [tcp/ms-sql-s] succeeded!

21. DOCKER
An example: Using MS-SQLServer
# In the following, we are going to create a database for Alfresco. A
possibility is to run sqlcmd utility inside docker machine:
$ docker exec -it sqlserver2017 "bash"
root@de2f9e36fd46:/# /opt/mssql-tools/bin/sqlcmd -S localhost -U SA -P
'7y1K7y1K!'
1> CREATE DATABASE alfresco6
2> SELECT Name from sys.Databases
3> GO
master
tempdb
model
msdb
alfresco6
1> ALTER DATABASE alfresco6 SET ALLOW_SNAPSHOT_ISOLATION ON;
2> GO
1> QUIT

22. DOCKER
[ More advanced concepts ]

23. DOCKER
Composing images with Docker Compose
● Docker Compose
● Provides the composition of a defined setup with
several Docker images.
● It uses a YAML file (docker-compose.yml)
● It defines, networks, ports, services, enviroment
variables…
● $ docker-compose up

24. DOCKER
Example 4:
●
Define local volume to preserve tomcat logs in local.
● Set mem_limit for this service
● Set JVM variables and db.driver in JAVA_OPTS
●
Add extra_hosts for connecting to external mysql (sqldev host)

25. DOCKER
Example 4:
●
What is the problem in this compose ?
version: '3.1'
services:
tomcat:
image: tomcat:8.0-alpine
ports:
- 8888:8080
volumes:
- ./logs:/usr/local/tomcat/logs
mem_limit: 1500m
environment:
JAVA_OPTS: "
-Ddb.driver=org.gjt.mm.mysql.Driver
-Xms512m -Xmx1024m
"
extra_hosts:
- "sqldev.zylk.net:192.168.1.100"

26. DOCKER
SOLR Docker Resources
● https://solr.apache.org/guide/solr/latest/deployment-guide/solr-in-
docker.html

27. DOCKER
Liferay Docker Resources
● Leveraging Docker:
● https://help.liferay.com/hc/en-us/articles/360022307392-
Leveraging-Docker
● https://hub.docker.com/r/liferay/portal

28. DOCKER
Alfresco Docker Resources
● ACS Community Deployment
● https://github.com/Alfresco/acs-community-deployment
● Docker Installer
● https://github.com/Alfresco/alfresco-docker-installer

29. DOCKER
Using Portainer for docker management
● Making Docker Management Easy
● https://www.portainer.io/

30. DOCKER
Managing Images
● A Docker Swarm node to manage remotely Docker
containers.
● Provides a graphical interface for creating and executing
docker images via Docker Compose.
● It is able to use a local registry (Nexus) for custom Docker
images.

31. DOCKER
Common commands for Docker Swarm
$ docker -v
Docker version 19.03.6, build 369ce74a3c
$ export DOCKER_HOST=tcp://dockyard.zylk.net:2376
#$ unset $DOCKER_HOST
$ docker stack ls
$ docker stack deploy -c docker-compose.yml icingalf
$ docker stack rm icingalf
$ docker ps
$ docker ps --filter="name=cas"
$ docker ps --format="{{.Names}}" | sort
$ docker exec -it <container-id> /bin/bash
$ docker logs -f <TAB>

32. DOCKER
Devops Lifecycle with Docker

33. DOCKER
Zylk for reading (Blog Post)
● Using MS-SQLServer with a docker container for developing (outdated)
●
https://www.zylk.net/es/web-2-0/blog/-/blogs/using-docker-image
s-for-enterprise-databases-with-alfresco
● Managing docker images for generating production infrastructure
● https://www.zylk.net/es/web-2-0/blog/-/blogs/managing-docker-i
mages-for-generating-production-infrastructure
● Testing new features on products with Dockerfiles
● https://www.zylk.net/es/web-2-0/blog/-/blogs/testing-new-feature
s-in-elastic-search-7-with-docker
●
Analyzing logs with Elastic and Docker.
● https://www.zylk.net/es/web-2-0/blog/-/blogs/analyzing-tomcat-lo
g-access-data-with-docker-elk-resources

34. DOCKER
External Links
● https://docs.docker.com
● https://hub.docker.com
● https://github.com/docker/community

35. DOCKER
[ Thanks ]