Docker Workshop

First, create a file called Dockerfile in your current folder with this as the contents:

FROM stackbrew/ubuntu:14.04
RUN apt-get update

This is a really basic Dockerfile that can be used to create a Docker image.

$ docker build -t workshop .
Sending build context to Docker daemon  2.56 kB
Sending build context to Docker daemon 
Step 0 : FROM stackbrew/ubuntu:14.04
 ---> ad892dd21d60
Step 1 : RUN apt-get update
 ---> Using cache
 ---> 825917f07e67
Successfully built 825917f07e67

Now, run it a second time. Faster huh? Docker will cache Dockerfile steps!

Lets add a few more things:

FROM stackbrew/ubuntu:14.04
RUN apt-get update
RUN apt-get install -y cowsay

Now lets rebuilding and try running this image with some commands:

$ docker build -t workshop .
...
$ docker run -i -t workshop /usr/games/cowsay hello there!
...

As we keep adding to the Dockerfile you can see the steps are being cached. Caching occurs when step actions do not change. Pay close attention to ording of steps.

Next lets try adding local files. Create a file called myfile.txt in the current directory with this as the contents:

1
2
3

Now add the last line to your Dockerfile:

FROM stackbrew/ubuntu:14.04
RUN apt-get update
RUN apt-get install -y cowsay
ADD myfile.txt /app/

Now, lets see the container have access to it:

$ docker run -i -t workshop cat /app/myfile.txt
...

Exercises

Using our workshop tag, build a new Dockerfile that uses this tag as the base
How can you add a whole folder to the image?

Docker Workshop

Building and using images

Exercises