Replace onbuild with alpine in Dockerfile example

[chchrist]

Since onbuild is deprecated it should not be in the Dockerfile example.

[chorrell]

I don't agree with choosing the alpine variant for the example. The reasoning is, more or less, spell out in https://github.com/nodejs/docker-node#nodealpine

It would also be better to encourage people to pin to a major or major-minor version, such as node:8 or node:8.2. Blindly pulling in the latest node image is not really a good idea.

Also, most of the example text for that section assumes the onbuild variant is being used so this would be inaccurate:

The image assumes that your application has a file named package.json listing its dependencies and defining its start script.

It would probably be better to replace the whole Create a Dockerfile in your Node.js app project section with a sane example that does similar things to what onbuild used to do.

[chorrell]

And we'd want to make sure any doc changes also land on https://hub.docker.com/_/node/ via a PR to https://github.com/docker-library/docs

[SimenB]

I don't agree with choosing the alpine variant for the example. The reasoning is, more or less, spell out in https://github.com/nodejs/docker-node#nodealpine

I have yet to hit anything using alpine that behaved differently. Why shouldn't the smallest image be recommended?

I suppose if it's aimed at beginners in Docker, but then I'd rather point to some other documentation (and document the caveats that come with using alpine, ref #384).

It would also be better to encourage people to pin to a major or major-minor version, such as node:8 or node:8.2. Blindly pulling in the latest node image is not really a good idea.

Agreed.

[Starefossen]

I suggest changing the example more in line of this one:

FROM node:8

WORKDIR /usr/src/app

ADD package.json /usr/src/app
RUN npm install
ADD . /usr/src/app

CMD ["node" "index.js"]

[Starefossen]

It would also be better to encourage people to pin to a major or major-minor version, such as node:8 or node:8.2. Blindly pulling in the latest node image is not really a good idea.

I do not agree with this statement. It is the Node.js Foundation's policy to strictly follow Semantic Versioning which means that feature and patch versions are safe with regards to incompatible or breaking changes.

Keep in mind that minor versions no longer receives patches when the next minor version is released.

[pesho]

feature and patch versions are safe with regards to incompatible or breaking changes

Usually yes, but there have been breakages in all components that we ship (Node, NPM, Yarn). I personally wouldn't base a production image on anything else than a strictly specified version (MAJOR.MINOR.PATCH).

[llb4ll]

How about using latest with a comment to change it to a specific major.minor version: #478

[llb4ll]

Pull request that specifies the current LTS as base image in the Dockerfile example: #482

[SimenB]

Closed in #482 (although we should expand on the instructions, as mentioned there. PR welcome!)