Post List - ict.ken.be

Docker

Categories: Docker

How

Kernel Namespaces - Isolation
Control Groups (cgroups) - Resource Utilization
Capabilities - Privilege Partitioning
Every container gets its own writable top layer
One process per container, but we can run multiple processes

Who & What

dotCloud - Solomon Hykes
docker witten in Golang started by using LXC (evolved into libcontainer)

Getting started

For windows 2008R2 install docker from:

Documentation at https://docs.docker.com/

Browse images at https://hub.docker.com/explore/

Commands for quickstart terminal

docker-machine
docker-machine ip
docker-machine ls
docker-machine env
docker --help
docker info
docker run hello-world
docker images
docker ps -a
docker rm distracted_minksy
docker rmi c54a2
docker run container-name
docker run -d -p 80:80 container-name:mayor.minor
docker run container-name --cpu-shares=1024 --memory=1g
docker stop c54
docker stop $(docker ps -a -q)
docker inspect c54 | grep Pid
docker top container-name
docker kill -s docker
docker run ubuntu /bin/bash -c "echo 'some line in a file' > /tmp/some-file"
docker commit container-name custom-image
docker history custom-image
docker save -o /tmp/custom-image.tar custom-image
tar -tf /tmp/custom-image.tar
docker load -i /tmp/custom-image.tar
docker network create --driver bridge customisolatednetwork
docker run -d --net=customisolatednetwork container-name
docker logs container-name
docker --debug ps
docker-compose build
docker-compose build --no-cache
docker-compose up -d
docker-compose logs
docker-compose down

Portmapping: /var/lib/docker/containers/[hashofthe_container]/hostconfig.json

Shortcut Keys

Exit container without killing it: ctrl + P + Q

Shell

docker attach
ssh
docker-enter 8b
docker exec -it 8b /bin/bash
docker run -v /usr/local/bin:/target jpetazzo/nsenter
nsenter -m -u -n -p -i -t /bin/bash

Dockerfile

https://docs.docker.com/engine/reference/builder/
each instruction creates a new layer (eg. RUN, CMD, MAINTAINER)
only last cmd will be executed (even if it is on cmdline)
CMD will add "/bin/sh -c"
ENTRYPOINT will take the cmdline arguments

docker build -t hellonginx:0.1 .
docker build -f custom.dockerfile -t kenowi/custom
docker run hello printechothismessage

Volumes

Store data in directory on host

docker run -it -v /test-dir --name=testvolume ubuntu:15.04 /bin/bash
docker run -it --volumes-from=testvolume ubuntu:15.04 /bin/bash
docker run -v /data-dir-host:/data-dir-container
docker rm -v testvolume

Networking

apt-get install bridge-utils
brctl show docker0
cat /etc/resolv.conf
docker run --dns=8.8.4.4 --name=dnstest my-image
docker port containername
docker run -d -p 192.168.56.50:5000:80/udp --name=overudp my-image
docker run -d -P my-image
docker run --name=src -d my-image
docker run --name=dst --link=src:alias-src -it ubuntu:15.04 /bin/bash
env | grep ALI
cat /etc/hosts

Registry

hub.docker.com
docker tag imageid kenowi/custom
docker push kenowi/custom:1.0
docker pull kenowi/custom:1.0
docker run -d -p 5000:5000 registry

Docker on Ubuntu

sudo su
uname -a
apt-get update
apt-get install -y docker.iodo
service docker.io status
docker -v
docker version
docker info
ls -l /run
cat etc/group
sudo gpasswd -a my-user docker
logout
docker run -it ubuntu /bin/bash
exit
netstat -tlp
service docker stop
docker -H 192.168.56.50:2375 -d &
docker -H 192.168.56.50:2375 -H unix:///var/run/docker.sock -d &
ls -l /var/lib/docker/aufs/diff/
docker start ff7
docker attach ff7
alias dps="docker ps"
service docker stop
docker -d -l debug &

Docker on CentOS

yum install -y docker
systemctl start docker.service
systemctl status docker.service
export DOCKER_HOST="tcp://192.168.56.50:2375"
export DOCKER_HOST=
ps -elf
cat /etc/hosts
ip a
cat /etc/redhat-release
yum check-update
yum install -y vim
vim /tmp/testfile
:wq

Docker and Fedora

docker run -it fedora /bin/bash
docker pull -a fedora
docker images fedora
pstree
man
iostat

Docker and CoreOS

docker pull coreos/etcd

Selenium

https://github.com/SeleniumHQ/docker-selenium

https://hub.docker.com/u/selenium/

docker run -d ‐‐name selenium-hub -p 4444:4444 selenium/hub
docker run -d -P ‐‐link selenium-hub:hub selenium/node-chrome
docker run -d -P ‐‐link selenium-hub:hub selenium/node-firefox

docker-compose.yml

seleniumhub: image: selenium/hub ports: - 4444:4444

firefoxnode: image: selenium/node-firefox ports: - 5900 links: - seleniumhub:hub

chromenode: image: selenium/node-chrome ports: - 5900 links: - seleniumhub:hub

docker-compose up -d
docker-compose scale chromenode=3

NGinx

docker pull kitematic/hello-world-nginx

Gitlab

sudo docker run --detach \ --hostname gitlab.example.com \ --publish 443:443 --publish 80:80 --publish 22:22 \ --name gitlab \ --restart always \ --volume /srv/gitlab/config:/etc/gitlab \ --volume /srv/gitlab/logs:/var/log/gitlab \ --volume /srv/gitlab/data:/var/opt/gitlab \ gitlab/gitlab-ce:latest
docker run gitlab/gitlab-ce

More

First Docker preview ever: https://www.youtube.com/watch?v=wW9CAH9nSLs
https://github.com/DanWahlin/Angular2-RESTfulService
https://app.pluralsight.com/player?course=docker-deep-dive&author=nigel-poulton&name=docker-deep-dive-m0&clip=0&mode=live
phusion/baseimage

Deprecated

docker images --tree

Comments

Selenium Unable to cast object of type 'System.String' to type 'System.Collections.Generic.Dictionary

Categories: Testing

When using Selenium remember that if you are connecting to a linux grid the url for the remote driver is case sensitive.

Mostly when you get this error it is because the url to the grid is wrong !

eg. http://192.168.99.100:4444/wd/hub

System.InvalidCastException

Unable to cast object of type 'System.String' to type 
'System.Collections.Generic.Dictionary`2[System.String,System.Object]'.
 at OpenQA.Selenium.Remote.RemoteWebDriver.StartSession(ICapabilities desiredCapabilities)
 at OpenQA.Selenium.Remote.RemoteWebDriver..ctor(ICommandExecutor commandExecutor, ICapabilities desiredCapabilities)
 at OpenQA.Selenium.Remote.RemoteWebDriver..ctor(Uri remoteAddress, ICapabilities desiredCapabilities)
 at ken.Selenium.Errors.SeleniumTests.ShouldHaveNoJavascriptErrors(String url) in d:\Sources.Sandbox\Ken\ken.Selenium.Errors\...\SeleniumTests.cs:line 79