docker

Question 1

To run a docker image

Answer 1

press the run button in the UI

Question 2

A docker container is basically

Answer 2

a background process thats running an image. Like a server.

Question 3

An image is

Answer 3

all the code of the OS (binaries, config), the dependencies, and anything you copied in.

Question 4

To create a new image, you need to

Answer 4

create a Dockerfile

Question 5

The FROM section in the Dockerfile defines

Answer 5

which parent image your new image will start from.

Question 6

The EXPOSE section in the Dockerfile defines

Answer 6

the port in your container will be allowed to be proxied to the outside world.

Question 7

To make a docker container accept requests on a particular port, you need to

Answer 7

put EXPOSE 8000 in the dockerfile so it will be permitted to to share that port.
Run the docker image in a container and set a host proxy port which will map to the EXPOSE port.

Question 8

For development, to get updates to project files to get seen by the docker image, you need to use

Answer 8

a volume

Question 9

a volume is

Answer 9

a path to a directory that your container will be able to access in real time from your main computer in its container. A portal.

Question 10

A dockerfile is basically

Answer 10

the list of instructions for creating a new docker image

Question 11

Before deploying, you must

Answer 11

remove your volume and create a new image with the files actually copied into the image.

Question 12

Volumes do not

Answer 12

save into the image.

Question 13

The COPY section in the dockerfile defines

Answer 13

files to copy from the local computer to the container computer.

e.g. COPY myDir /myContainerDir

Question 14

The CMD section in the dockerfile defines

Answer 14

a command you want to run in the container’s WORKDIR
Must be a list of arguments
e.g. CMD [‘echo’, ‘string’]

Question 15

the WORKDIR section in the dockerfile defines the

Answer 15

folder that you want docker to create and cd into so it is the working directory. Basically mkdir my_directory and cd my_directory combined.
CMD commands will run in the WORKDIR

Question 16

the ADD section in the dockerfile defines

Answer 16

a file that you want copied into the image

Question 17

ADD and COPY are the same except

Answer 17

ADD can also accept a URL

Question 18

A base image is

Answer 18

the first image in a lineage of parent images

Question 19

Simplest example app

Answer 19

Copied separately from main.py because each step creates a cache

• Dockerfile
  FROM python:3.9-slim-buster
  WORKDIR /my_app
  COPY requirements.txt .
  RUN [“pip”, “install”, “-r”, “requirements.txt”]
  COPY main.py .
  EXPOSE 8000
  CMD [“python”, “main.py”]
• main.py
  from flask import Flask

app = Flask(__name__)

@app.get(“/”)
def index():
return “<h1>Hello, world!</h1>”

if __name__ == “__main__”:
app.run(host=”0.0.0.0”, port=8000)

• requirements.txt
  Flask==3.0.3

Then build the image
docker build -t my_image_name ./path/to/project_dir

And run it from docker desktop using a proxy host port