Images

Basic Dockerfile example#

LABEL maintainer="Yaroslav Grebnov" version="1.0"
FROM nginx:alpine
COPY nginx.conf /etc/nginx/nginx.conf

Multistage build Dockerfile example#

Create an image from scratch using Dockerfile#

Create an image using docker commit#

Use variables in Dockerfile#

Variables in Dockerfile to be used during image building

ARG

Not cached

Variables in Dockerfile to be used during container running

ENV

Cached

Variables in Dockerfile to be used during both, image building and container running

ARG var ENV var=${var}

Variable expansion in Dockerfile

COPY {var,,}

Build an image using Dockerfile#

Build an image an push it to registry#

Check how an image was built#

Remove dangling images#

docker rmi $(docker image ls -f "dangling=true" -q)

Command explantion:

• docker image ls lists images
• -f stands for filter. So, -f "dangling=true" selects only the dangling images
• -q stands for quiet, which means that only the images IDs (hashes) are returned
• docker rmi removes a list of selected images