Caching Issue 2: Unnecessary Gem Installs
Imagine that we want to make a change to our README.md file. Open this file in an editor, and replace the Rails default version with the following:
| | # README |
| | |
| | This is a sample Rails application from Docker for Rails Developers (PragProg). |
| | It was generated using Docker without Ruby installed on the local machine. |
| | |
| | We're using the app to discover the wonderful world of Rails with Docker. |
Now let’s try something. What happens if we rebuild our image:
| | $ docker build -t railsapp . |
| | Sending build context to Docker daemon 102.9kB |
| | Step 1/6 : FROM ruby:2.6 |
| | ---> f28a9e1d0449 |
| | Step 2/6 : RUN apt-get update -yqq && apt-get install -yqq --no-install- |
| | recommends nodejs |
| | ---> |
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