Which docker base image to use in the Dockerfile?

Question

I'm having a web application, which consists of two projects:

• using VueJS as a front-end part;
• using ExpressJS as a back-end part;

I now need to docker-size my application using a docker, but I'm not sure about the very first line in my docker files (which is referring to the used environment I guess, source).

What I will need to do now is separate docker images for both projects, but since I'm very new to this, I can't figure out what should be the very first lines for both of the Dockerfiles (in both of the projects).

I was developing the project in Windows 10 OS, where I'm having node version v8.11.1 and expressjs version 4.16.3.

I tried with some of the versions which I found (as node:8.11.1-alpine) but what I got a warning: `

SECURITY WARNING: You are building a Docker image from Windows against a non-Windows Docker host.

Which made me to think that I should not only care about node versions, instead to care about OS as well. So not sure which base images to use now.

Answer 1

node:8.11.1-alpine is a perfectly correct tag for a Node image. This particular one is based on Alpine Linux - a lightweight Linux distro, which is often used when building Docker images because of it's small footprint.

If you are not sure about which base image you should choose, just read the documentation at DockerHub. It lists all currently supported tags and describes different flavours of the Node image ('Image Variants' section).

Quote:

Image Variants

The node images come in many flavors, each designed for a specific use case.

node:<version>

This is the defacto image. If you are unsure about what your needs are, you probably want to use this one. It is designed to be used both as a throw away container (mount your source code and start the container to start your app), as well as the base to build other images off of. This tag is based off of buildpack-deps. buildpack-deps is designed for the average user of docker who has many images on their system. It, by design, has a large number of extremely common Debian packages. This reduces the number of packages that images that derive from it need to install, thus reducing the overall size of all images on your system.

node:<version>-alpine

This image is based on the popular Alpine Linux project, available in the alpine official image. Alpine Linux is much smaller than most distribution base images (~5MB), and thus leads to much slimmer images in general.

This variant is highly recommended when final image size being as small as possible is desired. The main caveat to note is that it does use musl libc instead of glibc and friends, so certain software might run into issues depending on the depth of their libc requirements. However, most software doesn't have an issue with this, so this variant is usually a very safe choice. See this Hacker News comment thread for more discussion of the issues that might arise and some pro/con comparisons of using Alpine-based images.

To minimize image size, it's uncommon for additional related tools (such as git or bash) to be included in Alpine-based images. Using this image as a base, add the things you need in your own Dockerfile (see the alpine image description for examples of how to install packages if you are unfamiliar).

node:<version>-onbuild

The ONBUILD image variants are deprecated, and their usage is discouraged. For more details, see docker-library/official-images#2076.

While the onbuild variant is really useful for "getting off the ground running" (zero to Dockerized in a short period of time), it's not recommended for long-term usage within a project due to the lack of control over when the ONBUILD triggers fire (see also docker/docker#5714, docker/docker#8240, docker/docker#11917).

Once you've got a handle on how your project functions within Docker, you'll probably want to adjust your Dockerfile to inherit from a non-onbuild variant and copy the commands from the onbuild variant Dockerfile (moving the ONBUILD lines to the end and removing the ONBUILD keywords) into your own file so that you have tighter control over them and more transparency for yourself and others looking at your Dockerfile as to what it does. This also makes it easier to add additional requirements as time goes on (such as installing more packages before performing the previously-ONBUILD steps).

node:<version>-slim

This image does not contain the common packages contained in the default tag and only contains the minimal packages needed to run node. Unless you are working in an environment where only the node image will be deployed and you have space constraints, we highly recommend using the default image of this repository.