Docker. First steps. Hack_n_Tell from our DevOps Engineer Alex Vacyliev

1. Campaign
proposal
Docker.
First steps.
Hack‘n’Tell

2. Docker against VM’s
- Docker container isn’t a VM
- Docker provides an additional
layer of abstraction of
operating-system-level
virtualization.
- Avoiding the overhead of starting
and maintaining virtual machines
(VMs).
- Provides resource isolation and
allocation benefits, but functions
differently because containers
virtualize the operating system
instead of hardware.
Hack‘n’Tell

3. Docker components
Docker consists of:
- A server which is a type of
long-running program called a
daemon process (the dockerd
command).
- A REST API which specifies
interfaces that programs can use
to talk to the daemon and instruct
it what to do.
- A command line interface (CLI)
client (the docker command).
Hack‘n’Tell

4. Docker installation
Your best choice:
https://www.docker.com/community-edition#/download
If you are on Linux (not prod):
https://get.docker.com/
Windows 10 Pro - your best friend.
Mac OS also supported.
Docker CE, Docker EE, Clouds, etc.
Hack‘n’Tell

5. Docker basic workflow Hack‘n’Tell
- Docker host - bare-metal or
virtual machine where Docker is
installed
- Client - command line interface to
communicate Docker daemon
(may or may not be installed on
the same machine as Docker
daemon).
- Registry - docker image storage
(docker hub, or private storage).
- Image - immutable file, snapshot
of a container.

6. Docker usage scenarios Hack‘n’Tell
- Setup local service - DB, queue,
portal, etc.
- Test your code - check how your
code works on different versions
of language without installing it on
host machine.
- Delivery - prepare and ship image
with preinstalled something (local
system, clouds).

7. Docker usage example 1 Hack‘n’Tell
- Setup local postgres service
docker run --name local-postgres -e POSTGRES_PASSWORD=mysecretpassword -d postgres

8. Docker usage example 2 Hack‘n’Tell
- Setup local wordpres & DB
1) docker run -e MYSQL_ROOT_PASSWORD=XXX -e MYSQL_USER=wpuser -e MYSQL_PASSWORD=XXX -e
MYSQL_DATABASE=wordpress_db -v wpdatabase:/var/lib/mysql --name wordpressdb -d mysql
2) docker run -e WORDPRESS_DB_USER=wpuser -e WORDPRESS_DB_PASSWORD=XXX -e WORDPRESS_DB_NAME=wordpress_db
-p 8081:80 -v wordpress:/var/www/html --link wordpressdb:mysql --name wpcontainer -d wordpress

9. Docker usage example 2 Hack‘n’Tell
- Check your node js script in different versions
docker run -it --rm --name continer-script -p 8080:8080 -v
/path/to/your/code/folder/on/host:/usr/src/app -w /usr/src/app node:4 node
your-daemon-or-script.js

10. Docker container not persistent Hack‘n’Tell
- All container images consist of
layers.
- Layers are created via image build
process and they are immutable.
- Container is a new read-write not
persistent layer on top of the
image.
- After container stopped - all
changes inside it will be reset to
the base image state.
- Container state can be saved to
image via command commit
(better not to do this)

11. Docker usage
Command line Purpose Example
docker pull <image name> Pull image from registry to host docker pull node:latest
docker run <image name> Run container from image docker run ngnix
docker ps
Show all running containers (look here for
container id)
docker ps
docker stop <container id> Stop running container docker stop 4e2802901fd7
docker rm <container id> Remove container docker rm 4e2802901fd7
docker images
Show all images present on host (look here
for image id)
docker images
docker rmi <image id> Remove image from the host docker rmi 3f44455b8f57
docker logs <container id> Logs from container stdout docker logs 4e2802901fd7
docker exec -it <container id>
<command>
Execute command inside container and show
stdout
docker exec -it 4e2802901fd7 ls -l /tmp
Hack‘n’Tell

12. Docker useful links Hack‘n’Tell
- https://hub.docker.com/ - image
storage
- https://docs.docker.com/ -
documentation, tutorials, api,
etc.
- https://labs.play-with-docker.co
m/ - playground, tutorials
(docker hub registration
required)
- https://docs.docker.com/develo
p/ - good place to continue from
this point

13. THANK YOU
avasyliev@intersog.com