INTRO TO DOCKER

Terminology:

• Image is the blueprint for building, template
• Container is the running copy of the template

Analogy: image is the cookie recipe, container is the cookie (u/Xendrak:reddit)

We will go over:

• pulling docker images
• running docker containers
• building with dockerfiles
• running home-made docker image

1. Install Docker:

• Windows install
• Ubuntu Install
• Mac install

Verify install with the docker command in terminal. You should see available commandsflast

2. Run your first Docker container

docker run hello-world

the docker image in pulled from docker hub and it is built and run

3. Build your own container

docker pull alpine

check containers on system docker image ls lists images on system

• the container exists on local system, but is not running.

to run

docker run --name sample-docker -it alpine

the 'it' flag is for "interactive terminal" you are now in a running docker container CONGRADULATIONS

To leave

exit

No changes to system persist

it is possible to save system changes with the docker commit command Example:

• make a new dir and file in a running docker image
• exit docker image
• use docker ps -a command to see running images
• docker commit [CONTAINTER ID] [new_image_name] will make a new image with the saved changes

THIS IS NOT THE PREFERED METHOD TO SET CONTAINER. IT IS RECOMMENDED TO USE DOCKERFILES

4. DOCKERFILES and the fun begins

1. clone this repository into your docker-enabled system
2. cd into directory where dockerfile resides

dockerfile explained

3. docker build -t flask-sample:latest .

• builds the docker image from the docker file.
• -t flag is to tag image (useful for versioning)
• DONT FORGET THE '.' at the end (I often miss this)

4. You see the docker layers being built.

You should see

Successfully built ########

Successfully tagged flask-sample:latest

5. Now the home-made docker image is ready to run.

RUN

docker run -d -p 5000:5000 flask-sample

• -d flag is detached, does not run in same terminal
• -p flag sets ports for docker and host machine

now if you go to https://localhost:5000 you should see the running flask app

YOU CAN MAKE CHANGES IN THE DOCKERFILE and FLASK APP, when you rebuild it will only make changes to layers that need changes

Docker github has some great resources to learn more

DOCKER LABS