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Dockerfile

Install VirtualBox

sudo apt-get update
sudo apt-get install virtualbox

This computer doesn't have VT-X/AMD-v enabled. Enabling it in the BIOS is mandatory

  • FIX: VM-->Settings--->Processor-->Enable "Virtualize Intel VT-x/EPT "...

Docker machine

docker-machine create --driver=virtualbox default
  • Check that Docker-host succesfully created
docker-machine ls
  • For export variables into current shell use
eval $(docker-machine env)

Repo structure

Image build

  • Now we are ready to build our image
    • Execute command
      • Dot in the end is must, it points to the path to the Docker-context
      • Flag -t defines tag for the built image
docker build -t app:latest .
  • Check the result
docker images -a

Start a container

  • Pefect, now it is possible to run our container with command
docker run --name app -d --network=host app:latest
  • Check the result
docker-machine ls

Docker hub

  • Download our image into docker hub for using in the future
docker tag app:latest <your_dockerhub_account>/app:1.0

See example

Docker Compose

Docker Practice 3

Networking in Docker

  • none
  • host
  • bridge

None network driver

  • Let's start the container using the none-driver.
  • We use joffotron/docker-net-tools as an image.
  • We do this to save time and effort.
    • It already includes the necessary utilities for working with the network:
      • the bind-tools;
      • net-tools;
      • and curl packages.
  • The container will start a sleep process with a timer for 100 seconds.
  • After 100 seconds have elapsed, the container will be stopped and removed (--rm flag).

Let's run:

docker run --network none --rm -d --name net_test joffotron/docker-net-tools -c "sleep 100"

Then:

docker exec -ti net_test ifconfig

As a result, we see:

  • that only loopback exists inside the container from network interfaces.
  • the network stack of the container itself works (ping localhost), but without the ability to contact the outside world.
  • This means that you can even run network services inside such a container, but only for local experiments
    • testing;
    • containers for performing one-time tasks;
    • etc.

Host network driver

Let's start the container in the network space of the docker host:

docker run --network host --rm -d --name net_test joffotron/docker-net-tools -c "sleep 100"

Compare the output of the commands:

docker exec -ti net_test ifconfig

And

ifconfig

Run several times (2-4):

docker run --network host -d nginx

What is the result?

Answer --network="bridge" : Connect a container to a network
  • 'bridge': create a network stack on the default Docker bridge
  • 'none': no networking
  • 'container:': reuse another container's network stack
  • 'host': use the Docker host network stack
  • '<network-name>|<network-id>': connect to a user-defined network

    • What did the next command give?

    docker ps
    Answer
  • List containers
  • In this case it will return only the last created container with status 'Up'
  • Previous created containers will be shown with status 'Exited'

    • Why do you think?

    Answer
  • Only last version of the container is relevant

    • Stop all running containers:

    docker kill $(docker ps -q)

    Docker networks

    On the docker-host machine, run the command:

    sudo ln -s /var/run/docker/netns /var/run/netns

    You can now view the currently existing net-namespaces with the command:

    sudo ip netns

    Task: Re-launch containers using the none and host drivers and see how the list of namespaces changes.

    Command below will allow to execute commands in the selected namespace:

    sudo ip netns exec <namespace> <command>

    Example:

    sudo ip netns exec 195847b8dda1 ls

    Microservice app

    This practice uses the microservice version of the application from Docker Practice 2.

    Download the repository from the microservices branch:

    git clone -b microservices https://github.com/yagubern/app.git

    Let's collect images for each service:

    export USER_NAME=<your_login>
cd app/comment
chmod u+x ./docker_build.sh
bash docker_build.sh
cd ../post-py
chmod u+x ./docker_build.sh
bash docker_build.sh
cd ../ui
chmod u+x ./docker_build.sh
bash docker_build.sh

    Bridge network driver

    Create a bridge network in docker (the --driver flag is optional, because the default is bridge):

    docker network create app --driver bridge

    Let's run our app project using a bridge network:

    docker run -d --network=app mongo:3.2
docker run -d --network=app <your-login>/post:latest
docker run -d --network=app <your-login>/comment:latest
docker run -d --network=app -p 127.0.0.1:9292:9292 <your-login>/ui:latest

    Let's go to the address http://127.0.0.1:9292

    Something went wrong…

    In fact, our services refer to each other by dns names written in the code.

    In the current installation, the built-in DNS docker does not know anything about these names.

    The solution to the problem is to assign names or network aliases to containers at startup:

    --name <name> (only 1 name can be specified)
--network-alias <alias-name> (multiple aliases can be specified)

    Stop old copies of containers:

    docker kill $(docker ps -q)

    Let's launch new:

    docker run -d --network=app --network-alias=post_db --network-alias=comment_db mongo:3.2
docker run -d --network=app --network-alias=post <your-login>/post:latest
docker run -d --network=app --network-alias=comment <your-login>/comment:latest
docker run -d --network=app -p 127.0.0.1:9292:9292 <your-login>/ui:latest

    Docker-compose

    • One application consists of many containers / services
    • One container depends on the other
    • Startup order matters
    • docker build / run / create ... (long and long)
    • Standalone utility
    • Declarative description of the docker infrastructure in YAML format
    • Management of multi-container applications
    • Syntax reference: https://docs.docker.com/compose/compose-file/

    Plan

    • Build app images using docker-compose
    • Run app with docker-compose

    docker-compose.yml

    • Create a docker-compose.yml file in the project directory.
    • It is important that the ui, comment, post folders are next to each other.

    Note that docker-compose supports

    • Interpolation (substitution) of environment variables.
      • In this case, it is the USERNAME variable.
    • Therefore, before starting, it is necessary to export the values of these environment variables.

    Run:

    export USERNAME=<your-login>
docker-compose up -d
docker-compose ps

    You should see a similar picture in the output:

    docker-compose

    Go to http://127.0.0.1:9292/ and make sure the project is working correctly

    Homework #1

    Add docker-compose.yml so that microservices are launched in 2 bridges as follows:

    That is, so that the ui service does not have access to the database.

    Homework #2

    Parameterize with environment variables:

    • port of publication of the ui service
    • service versions
    • maybe something else at your discretion

    Write the parameterized parameters to a separate file with the .env extension

    Without using the source and export commands, docker-compose must pick up the variables from this file.

    Kubernetes

    kubectl Cheat Sheet

    hosts file

    # <minikube ip> app.com
192.168.49.2 app.com

    Apply manifests

    k apply -f k8s/

    Remove Kubernetes generated items

    k delete -f k8s/
k delete pvc mongo-volume-mongo-statefulset-0

    Get Kubernetes generated items

    k get sc
k get pv
k get pvc
k get sts
k get deploy
k get rs
k get svc
k get ingress
k get endpoints
k get po

    Helm

    Generate helm templates from chart

    helm template chart

    Create helm chart

    helm create chart

    Install helm chart from folder

    helm install app chart/

    Upgrade helm chart

    helm upgrade app chart/

    Get history of helm charts

    helm history app

    Rollback helm chart

    helm rollback app 1

    Uninstall helm chart

    helm uninstall app
k delete pvc mongo-volume-mongo-statefulset-0

    Get helm items

    helm list
helm get manifest wms
helm get manifest wms --revision 1
helm get manifest wms --revision 2

    Get kubernetes items generated by helm

    k get sc
k get pv
k get pvc
k get sts
k get deploy
k get rs
k get svc
k get ingress
k get endpoints
k get po