Overview

Entire project reference is here, and here is the GitHub repo.

Here we are trying to cover Docker basic in a use case of setting up something, from pulling, run, exec and many others.

Pull

Ref: Docker Pull

Generic usage would be:

$ docker pull [image:tag]

By default it will connect to the Dockerhub registry. if we are gonna pull from, specific repo or registry, say registry.doggonebead.xyz:5000 for image named db:latest, then it shall be:

$ docker pull registry.doggonebad.xyz:5000/db:latest, however we might need to perform docker login first.

Run

Ref: Docker Run

Run an image in a new container.

Typical usage:

$ docker run [OPTIONS] IMAGE [COMMAND] [ARG...]

If you have a image from alpine:latest then to run it simply by:

$ docker run -d -t --name alpinehome alpine:latest

Here are each flags/options mean:

• -d or --detach: Run container in background and print container ID
• -t or --tty: Run container with connected stdout, hence if you want an echo command to be shown, this is needed.
• --name: To rename the container into something you prefer.

Exec

Ref: Docker Exec

To run a command inside already running container.

Typical usage:

$ docker exec [OPTIONS] CONTAINER [COMMAND] [ARG...]

From Run above, we can just run a command sh which means, to run shell inside the alpinehome container:

$ docker exec -it alpinehome sh.

yanua in ~ λ docker exec -it alpinehome sh
/ # whoami
root
/ # ls
bin    etc    lib    mnt    proc   run    srv    tmp    var
dev    home   media  opt    root   sbin   sys    usr
/ #

Very neat!

Stop

Ref: Docker Stop

Stop one or more running containers

Typical usage:

$ docker stop [OPTIONS] CONTAINER [CONTAINER..]

The main process inside the CONTAINER will receive SIGTERM,a nd after a grace period, SIGKILL. The first signal can be changed with the STOPSIGNAL instruction in the container's Dockerfile, or the --stop-signal option to docker run.

Volume

Ref: Docker Volumes

Volumes are preferred mechanism for persistent data storage used by all containers to dump files.

Dockerfile

Workdir

WORKDIR by default is always created, but if explicitly specified by users, will be used subsequently.

For this example Dockerfile:

# Python base image
FROM python:3.9.4-slim

# set the work directory
WORKDIR /app

# copy pip-dependencies to WORKDIr
COPY requirements.txt .
RUN pip install -r requirements.txt

# copy project
COPY . .

WORKDIR is specified into /app directory inside the container. Hence, all dockerfile operations following this command, will use the WORKDIR as relative path :).

To-Do

Some lists of to-do:

• Create CI/CD template, probably with Gitlab
• 100% code linting, probably with Black. Should be part of point above.
• 100% coverage test. Should be part of point 1.