npm install uses wrong package

[itajaja]

I have the following weird combination that leads to unexpected results.

I am running docker on Windows, and in my package.json there is a dependency to phantomjs which install a different executable depending on the environment is in: if it's on windows it downloads a windows executable, if it's on linux it downloads a linux executable. Apparently, the npm install command is run in my windows environment, or it caches the windows packages, Since if I enter the docker image bash and I ls into the node_modules phantomjs folder, I see the windows executable. If I do

rm node_modules -r
npm install

inside the docker container bash it installs the correct phantomjs executable. Is it true that the npm install run during docker build depends on the host environment and not the container environment? This could explain why, otherwise could be a caching problem... Can someone shed some light?

[tianon]

Interesting -- this is actually the very reason why the ruby image changes the default location for ".bundle" to not be in the application directory ( https://github.com/docker-library/ruby/blob/de0bb696964c7ab9b947b1f46993dab484eca259/2.2/Dockerfile#L28-L33). I wonder if NPM has a similar option? Otherwise, your best bet is going to be adding "node_modules" to ".dockerignore" in your application directory next to your "Dockerfile".

[itajaja]

building with --no-cache=true and dockerignoring the node_modules worked! A question: I thought that in absence of a .dockerignore file, docker would use the .gitignore file. Is that untrue?

[tianon]

Yeah, that's untrue, unless you explicitly symlink ".dockerignore" to your ".gitignore".

[itajaja]

thanks for the clarification, I might have been confused by something else, maybe by how npm and npmignore work :)