bash, dev containers

Shipping user friendly bash scripts with your Dev Container

Avatar of author Kees C. Bakker To profile Kees C. Bakker Written by Kees C. Bakker, written on , 2 minute read.

Currently I'm working on a small WordPress plugin that does syntax highlighting. I have the need to ship some maintenance scripts with my Dev Containers. I want some aliases to interact with the scripts (instead of calling them through /scripts/actions.sh. This solution uses a Bash startup file and a custom Dockerfile.

The idea

My first thought is to copy the scripts to the Dockerfile as expose them like that. I don't like this solution, as it makes our scripts static. In a "native" situation we would also be able to edit and execute the scripts. We want this experience in our Dev Containers as well.

My second thought is a startup script. I already use a startup.sh script to set some container-wide settings. Adding script aliases to the startup will not work, as the terminal session starts in parallel with the startup script.

Solution: let's ship a bash startup file that makes the scripts executable and aliases them for the user.

.bashrc

The startup file should do the following:

  1. Extract the name of the workspace.
  2. Add the scripts directory to the PATH.
  3. Make the scripts in the directory executable.
  4. Alias a script (in our case release.sh as release).
  5. Let the user know how to use the alias.

Let's create a .bashrc file in our .devcontainer directory:

# figure out workspace  
export WORKSPACE_NAME=$(pwd | awk -F'/' '{for(i=1;i<=NF;i++) if ($i == "workspaces") {print $(i+1); exit}}') 
export WORKSPACE_SCRIPT_PATH="/workspaces/$WORKSPACE_NAME/scripts" 
 
# make scripts executable 
pushd $WORKSPACE_SCRIPT_PATH > /dev/null 
sudo chmod +x *.sh 
popd > /dev/null 
 
export PATH="$PATH:$WORKSPACE_SCRIPT_PATH" 
 
# make aliases for easy execution 
# alias script_name='script_name.sh' 
alias release='release.sh' 
 
# let the user know 
echo "" 
echo "To release a new version do:" 
echo "" 
echo "\$ release [patch|minor|major]" 
echo ""

Dockerfile

Let's copy the file to our docker file:

# Start with the same base image
FROM mcr.microsoft.com/devcontainers/php:0-8.2

# Copy bash profile, if you copy it directly
# you'll lose your colors :-(
COPY ./.bashrc /tmp/.bashrc
RUN cat /tmp/.bashrc >> /home/vscode/.bashrc && \
    rm /tmp/.bashrc

When we now run the dev container we see:

Output of the terminal showing the information set by the profile.
Output of the terminal showing the information set by the profile.

Final thoughts

Easy peasy. If you want to look at the code, please check out the Dev Container directory on GitHub: github.com/KeesCBakker/ktt-wp-code/tree/main/.devcontainer.

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