Building an Image from a Dockerfile

Once you have a Dockerfile, you can tell docker to build it by running the following command:

docker build -t tag-name -f path/to/Dockerfile.extension path/to/build/context
docker build -t clowder -f ./Dockerfile.clowder .

Tagging an Image

Tags are nice for saving a "snapshot" of an image, to make it easily runnable later. This is similar to using Git tags for new releases.

docker tag image-name [repository/]new-image-name[:tag-name]
docker tag clowder ndslabs/clowder:0.9.1


NOTE: Don't forget to push your new tag up to Docker Hub!

Writing a Dockerfile

Docker images are built from files called Dockerfiles.

A simple Dockerfile example can be found below:

# Use centos66 as the base image for this build
FROM    centos:centos6
# Enable Extra Packages for Enterprise Linux (EPEL) for CentOS
RUN     yum install -y epel-release
# Install Node.js and npm
RUN     yum install -y nodejs npm
# Copy files from the host into the container
COPY package.json /src/package.json
# Run 'npm install' to install dependencies
RUN cd /src; npm install --production
# Tell Docker we plan to use this port
EXPOSE  8080
# Specify the default command for when the container runs
CMD ["node", "/src/index.js"]
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