Participating Events

• Azure Antenna：https://azure.connpass.com/event/77515/

Purpose of Participation

• I was interested in Docker and kubernetes, but didn't touch them much.
• Join to take the first step in handling containers
• If possible, I would like to make good use of containers in the future.

Event Summary

Flow of the day

First half: Overview of containers and Docker Second half: kubernetes

While listening to the explanation, it was a flow to try it hands-on every time.

data

Since it is published, please refer to here for details.

Hands-on content (excerpts from the knowledgeable aspects)

Containers overview

• Containers are the small foundation on which applications run, not virtualization
• Even if you run a container in the centos or ubuntu environment, the actual thing that runs is the host's kernel
• The container ps 1 is the init process. It runs on a completely different pid from the host's point of view.
• Only one container, one type of process should work

merit

1. High portability

   • Improved business continuity
   • Can be staged, developed, and put into production, in the same environment (eliminating environmental differences)
     ⇒ Paas, a little different from serverless (easy development etc.)

2. Efficient use of computer resources

   • Load balancing, even redundancy (k8s)

3. Easy to DevOps ready

   • Infrastructure configuration can also be code-managed
   • How GitHub works with

4. Easy to make and erase

Main usage scenarios

1. Get the application up and running
   • Application servers, Web servers, etc.
2. Make tools and other utilities work
   • Azure's CLI tools are also Docker images, and Python or the right version is packed.

★ The de facto standard for containers is Docker

Docker

Docker commands

The important thing is /var/run/docker.sock Only users with permissions can run docker commands

Docker installation

Note that docker.io Packages # are completely different from docker packages $ sudo apt update && sudo apt install docker.io -y

Find a Docker image

$ docker search *** STARS: Like-like metrics OFFICIAL : / The lack of one is something that the developer put out

: Tag Name

Tags are also important for management If nothing is added, latest is auto-completed

Assign a port for the Docker container on the host

For example, bind host 80 to 80 in the container. This port forwarding is provided by iptables(nat)

Key Docker Commands

$ docker run **** $ docker ps $ docker ps -a $ docker images $ docker pull **** $ docker stop [UUID]

Docker Lifecycle

1. build
   • pull / build
   • commit
   • rm / rmi
2. ship
   • push # Register in registry
3. run
   • run / stop / kill

docker run

$ docker run -it ***** Shell interactive: -it option If the name and tag match, use the image if it is local. If you don't have an image, take it from the remote

docker exec

$ docker exec -it [id] sh Can be in motion as a daemon Often used in debug etc.

Create your own container

  FROM alphine
  MAINTENER なくてもいい
  RUN コマンド  ex) apt install python2 apache2
  CMD ["command"] # メインプロセス docker 起動時の最後のコマンド
    ex) CMD [ "httpd -DFOREGROUND" ]

$ docker build -t myapache2 ./ Cache is used when doing the same work Build a Dockerfile after you change it.

Notes to keep in mind

• Changes in the container are not saved [immutable]
  It should not be used as a database server (it should not be stored in a container)
• Containers and images remain if they are not erased
  $ docker stop # The docker process disappears
  $ docker ps -a What you can see is that there are still containers that have not been started
  Stopped containers remain as they are. The image also remains. Each remains in the path below

    /var/lib/docker/
    /var/lib/docker/image/aufs

• When building a container, the cache is used
  changes may not be reflected unintentionally
• When the host is restarted, the container will not start without permission.
  When docker run, you can run it with the --restart=always option
• The log you want to output is standard output / error output
  Do not put it in the log file
  Run the process you want to run in the main on foreground and not terminate it
  Leave the command prompt in a state where it does not return, do not daemonize
  ⇒ k8s is also designed with this in mind
  • To see standard output and standard error output
    $ docker logs -f [uuid]

alpine linux

Ultra-lightweight Linux optimized for containers Package management tools are apk

 # apk update
 # apk add
 # apk search

Compared to Ubuntu and the like, the size is much smaller The one that came with -alpine when searching for tags is a lighter version. Alpine-based

Docker structure

Docker works with linux 2.6.32-431 and above Use cgroups, namespace, chroot, etc.

I have a base image (like ubuntu) By building, the differencing image is layered on top of each other, When I run, I feel like I'm sticking the literacy layers together.

kubernetes

I'll write about it on a separate page.

impressions

It was a great opportunity to introduce Docker and Kubernetes. There was a lot of content, and I got the impression that it took a little time. The lecturer's explanation was easy to understand and easy to understand. From now on, I will create my own environment and verify various things.