ht-docker-node/image_support_files

Image Support Files

This directory contains helper scripts that are copied into the Docker image during build to enable NVM functionality.

Files

bash-with-nvm

Purpose: Wrapper script for Dockerfile RUN commands

Usage: Set as SHELL directive in Dockerfile

SHELL ["/usr/local/bin/bash-with-nvm"]

What it does:

• Sources nvm before executing each Dockerfile RUN command
• Enables direct usage of nvm commands without manual sourcing
• Example: RUN nvm install 18 works without bash -c "source ..."

Location in image: /usr/local/bin/bash-with-nvm

How it works:

1. Exports NVM_DIR environment variable
2. Sources $NVM_DIR/nvm.sh to load nvm functions
3. Executes the command passed to it via eval "$@"

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docker-entrypoint.sh

Purpose: ENTRYPOINT script for runtime nvm support

Usage: Set as ENTRYPOINT in Dockerfile

ENTRYPOINT ["/usr/local/bin/docker-entrypoint.sh"]

What it does:

• Makes nvm available in docker run ... bash -c commands
• Enables nvm in CI/CD workflow scripts
• Passes through non-bash commands unchanged

Location in image: /usr/local/bin/docker-entrypoint.sh

How it works:

1. Loads nvm in the entrypoint environment
2. Detects if command is bash -c ...
3. If yes: Injects source /etc/bash.bashrc before the user's command
4. If no: Executes command as-is with exec "$@"

Examples:

• docker run image bash -c "nvm install 18" → nvm is available
• docker run image node --version → Passes through to node binary
• CI/CD: run: nvm install 19 → Works automatically

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Why These Scripts Are Needed

The Problem:

• nvm is a bash function, not a binary executable
• It must be sourced into each shell session
• Docker RUN commands and bash -c don't automatically source it

The Solution:

1. bash-with-nvm: Makes Dockerfile RUN commands work
2. docker-entrypoint.sh: Makes runtime bash -c commands work
3. /etc/bash.bashrc (configured in Dockerfile): Makes interactive shells work

Together, these provide seamless nvm access in all contexts.

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Maintenance

Modifying the scripts:

1. Edit the file in this directory
2. Rebuild the Docker image
3. Test with both docker build and docker run scenarios

Testing checklist:

• RUN nvm install 18 works in Dockerfile
• docker run image bash -c "nvm install 18" works
• docker run image node --version still works (fallback)
• CI/CD workflows can use nvm commands

Debugging:

• View script in running container: docker run image cat /usr/local/bin/bash-with-nvm
• Test entrypoint manually: docker run --entrypoint /bin/bash image -c "nvm --version"