I was helping a customer build some customized automation tasks using vRealize Automation Codestream. These tasks required the use of a container image with certain tools installed, usually we can include a CI task to download the tools into the container image on the fly. However, my customer’s environment is offline, so I needed to provide them a container image with everything installed by default.

Before we dive into the process of running a container and committing the changes, it is recommended where possible to create a new docker file that would build your docker image as needed with the associated commands such as the below:

FROM node:12-alpine
RUN apk add --no-cache python g++ make
WORKDIR /app
COPY . .
RUN yarn install --production
CMD ["node", "src/index.js"]

Committing changes to a container image in this way can cause the image to become bloated. But sometimes there’s a need to do just do it this way.

Prerequisites

• Docker installed

Pull the image you want to update

docker pull {image location/name}

Check your images and get the ID

docker images

For the next command, we will need the Image ID.

Run your image as an active container

docker run -it {Image_ID} /bin/bash

This will then drop you into the tty of the running container.

Modify your container

Continue reading Using Docker to update and commit to a container image →