DOCKER 101Raju Gandhi

RAJU GANDHI! " # @LOOSELYTYPED CTO - INTEGRALLIS SOFTWARE

WHY?

BUILD ONCE, RUN ANYWHERE

Image

Registry

Container

pullpush

commit run

WHY?

- Local application development and testing

- Team (and OSS) collaboration

- Ci/Cd

CONTAINERS?

CGROUPS

NAMESPACES

JAILS

CONTAINERS

- A container is a lightweight virtual runtime*

- Share the host kernel

- CPU/Memory/Network/File system isolation

- Own their on hostname, users, networking stack

NAMESPACES

“What you can see”

NAMESPACES

• Isolation of

• Users

• Filesystem

• Process trees

• Network

• IPC

CGROUPS

“What you can use”

CGROUPS

• Limiting/Metering/ACL

• CPU

• Memory

• I/O

• Network

• Device permissions

VM? CONTAINERS?

Server

Host OS

Hypervisor

Guest OS

Libs

App A

Guest OS

Libs

App A*

Guest OS

Libs

App B

VM

Server

Host OS

Docker Engine

Libs

Libs

App A

App A*

App A

App A*

App A

App A*

Server

Host OS

Hypervisor

Guest OS

Libs

App A

Guest OS

Libs

App A*

Guest OS

Libs

App B

VM

Container

Libs

Libs

Libs

Libs

TERMINOLOGY

TERMINOLOGY

- Docker Engine

- Docker client

- Dockerfile

- Docker Machine

- Docker Compose

- Docker Stack

- Docker Swarm

- Docker Hub

INSTALLATION

INSTALLATION

WORKFLOW

client

Dockerfile

Image Registry

Container

build

push

run create start

pull

Modifies

commit

docker engine

WHAT IS A CONTAINER?

Host OS (Kernel)

Base Image

Writeable layer

your changes

Image

Container

Host OS (Kernel)

Base Image

New Layer

commit

Image

Host OS (Kernel)

Base Image

New Layer

Image

run <new-image>

Writeable layer Container

NETWORK

Logical Host Interface

Docker Bridge

Container

docker run -it --net none --rm alpine /bin/sh

Logical Host Interface

Docker Bridge

Container

docker run -it --rm alpine /bin/sh

Container Interface

Logical Host Interface

Docker Bridge

Container

docker run -it --rm -p 8080:8080 alpine /bin/sh

Container Interface

VOLUME

Host filesystem

Container

docker run -it --rm ubuntu /bin/bash

Docker managed space

Host filesystem

Container

docker run -it -v /host/path:/tmp ubuntu /bin/bash

Docker managed space

DOCKER COMPOSE

DOCKER COMPOSE

• A system is usually made up of multiple containers

• Containers depend on each other

• Orchestration

• Single host

DOCKER COMPOSE

• Define multi-container applications in a single file

• Supports scaling, healing

• Single host

serviceB

serviceA

db

Dockerfile

docker-compose.yml

config

Dockerfile

config

Dockerfile

config

depends_on

CONS

CONS

- Orchestration/composition tooling still rudimentary

- Native Docker implementations still buggy

- Most existing monitoring/logging are host centric, not process centric

THANKS!!