Docker

Question 1

What is required for Docker to run on Windows?

Answer 1

At least Win10
or
Hyper-V enabled

Question 2

Dockerfile

Answer 2

FROM ubuntu
Run mkdir tmplogs
RUN apt-get install vim
RUN apt-get install htop

Question 3

Dockerfile - layers?

Answer 3

Each line of the Dockerfile is a layer!

Question 4

Docker image?

Answer 4

A read-only template that forms the foundation of your application

Question 5

Docker Container

Answer 5

a Docker image, when it’s run in a host computer, spawns ta process with its own namespace

Question 6

When container is stopped/killed…?

Answer 6

All changes are lost

Question 7

Ways to mount data?

Answer 7

Volumes, Bind Mounts, tmpfs

Question 8

Docker Registry?

Answer 8

Place to store your Docker images

Question 9

Dockerfile Layers - defined

Answer 9

A FROM instruction that tells Docker what the base image is
An ENV instruction to pass an environment variable
A RUN instruction to run some shell commands (for example, install-
dependent programs not available in the base image)
A CMD or an ENTRYPOINT instruction that tells Docker which executable to
run when a container is started

Question 10

Docker Engine

Answer 10

Docker Engine is the core part of Docker. Docker Engine is a client-server
application that provides the platform, the runtime, and the tooling for building
and managing Docker images, Docker containers, and more.

Question 11

Docker CLI commands (the basics)

Answer 11

docker build
docker pull
docker run
docker exec

Question 12

Docker Compose

Answer 12

Docker Compose is a tool for defining and running multi-container applications

Question 13

Docker Registry (may need authentication)

Answer 13

the registry is hosted on dockerprivate.registry

Question 14

WORKDIR

Answer 14

WORKDIR instruction sets the current working directory for RUN, CMD,
ENTRYPOINT, COPY, and ADD instructions

Question 15

FROM

Answer 15

FROM

As you learned earlier, every image needs to start from a base image

Question 16

ADD & COPY

Answer 16

ADD and COPY instructions seem to do the same—they allow

you to transfer files from the host to the container’s filesystem

Question 17

ADD & COPY - differences

Answer 17

COPY supports
basic copying of files to the container, while ADD has support for features like
tarball auto extraction and remote URL support

Question 18

RUN Command

Answer 18

RUN  (known as the shell form)
RUN ["executable"
,
"parameter 1"
,
" parameter 2"]
(known as the exec form)

Question 19

RUN Example

Answer 19

RUN apt-get update
RUN apt-get install foo
RUN apt-get install bar
RUN apt-get install baz
It’s better to wrap them in a single RUN command:
RUN apt-get update && apt-get install -y \
foo \
bar \
baz

Question 20

CMD & ENTRYPOINT

Answer 20

CMD and ENTRYPOINT instructions define which command is executed when
running a container

Question 21

ENV

Answer 21

The ENV instruction sets the environment variables to the image

Question 22

VOLUME

Answer 22

The VOLUME instruction tells Docker to create a directory on the host and mount
it to a path specified in the instruction.

Question 23

EXPOSE

Answer 23

The EXPOSE instruction tells Docker that the container listens for the specified
network ports at runtime

Question 24

LABEL

Answer 24

The LABEL instruction adds metadata to an image as a key/value pair.

Question 25

Data Persistence

Answer 25

Traditionally, VMs store persistent data, containers do, usually, not

Question 26

Strategies to persist data

Answer 26

mpfs mounts Bind mounts Volumes

Question 27

tmpfs Mounts

Answer 27

The directories mounted in tmpfs appear as a mounted filesystem but are stored in memory, not to persistent storage such as a disk drive.

Question 28

Bind Mounts

Answer 28

In bind mounts, the file/directory on the host machine is mounted into the container.

Question 29

Bind Mount VS. Docker Volume

Answer 29

By contrast, when using a Docker volume, a new directory is created within Docker’s storage directory on the Docker host and the contents of the directory are managed by Docker

Question 30

Preferred flag for Mounting?

Answer 30

--mount

Question 31

Example of Mount | mounting host's home directory, to a directory called 'host-name' within the container

Answer 31

``` docker run -it --name mount-test --mount type=bind,source="$HOME" ,target=/host-home ubuntu bash docker run -it --name mount-test -v $HOME:/host-home ubuntu bash ```

Question 32

Volumes

Answer 32

Docker volumes are the current recommended method of persisting data stored in containers

Question 33

Volume Advantages

Answer 33

Volumes are easier to back up or transfer than bind mounts Volumes work on both Linux and Windows containers Volumes can be shared among multiple containers without problems

Question 34

Docker Volume Commands

Answer 34

``` docker volume create docker volume inspect docker volume ls docker volume prune docker volume rm ```

Question 35

Example Volume command

Answer 35

docker volume create --name=nginx-volume

Question 36

Default Docker Network Drivers

Answer 36

``` bridge host overlay macvlan none ```

Question 37

Bride Network

Answer 37

Allows for containers to communicate together

Question 38

Host Network

Answer 38

Connects containers to the Docker Host

Question 39

Overlay Network

Answer 39

Creates a network spanning multiple docker hosts | primarily used when a cluster of Docker hosts are setup in Swarm mode

Question 40

Macvlan Network

Answer 40

leverage the Linux kernel’s ability to assign multiple | logical addresses based on MAC to a single physical interface

Question 41

None Network

Answer 41

the container has no Network

Question 42

Docker Compose

Answer 42

Simplifies creating Containers for different needs

Question 43

Docker Compose file?

Answer 43

.yml

Question 44

Docker Compose File Versioning

Answer 44

1 2. x 3. x

Question 45

Services

Answer 45

Services is the first root key of the Compose YAML and is the configuration of the container that needs to be created

Question 46

build

Answer 46

The build key contains the configuration options that are applied at build time.

Question 47

context

Answer 47

sets the context to build

Question 48

image

Answer 48

if present, will build the image and name/tag it

Question 49

environment/env_file

Answer 49

stores the keys and values for the build

Question 50

ports

Answer 50

specifies the ports that will be exposed to the port

Question 51

volumes

Answer 51

adds a named volume to the build

Question 52

depends_on

Answer 52

pulls dependency requirements

Question 53

Restart

Answer 53

key that provides the restart policy for the container | By default, set to "no", never restart

Question 54

Docker Compose - build

Answer 54

reads the Compose file, scans for build keys ie docker-compose build

Question 55

Docker Compose - down

Answer 55

``` stops the containers and will proceed to remove containers, volumes, networks dockercompse down(?) ```

Question 56

Docker Compose - exec

Answer 56

lets you run ad hoc commands of any containers

Question 57

Docker Compose - command

Answer 57

docker-compose