Sometime size does matter, for Godzilla of course but also for Docker images. I came across an interesting article this week-end about a 2 week experience with Docker to see if it was production ready and a follow-up by Nicolas De Loof.
One of Frédéric de Villamil’s concerns was the size of the Docker images: your container will most likely weight more than 1GB which seems true as you’ll need to include a Linux distro in your images. In order to mitigate this, Nicolas suggested to start from an images based on Busybox rather than Debian or Ubuntu for instances David’s Java8.
Java 8 Images
At the moment there are a couples of base images for Java 8 applications out there. I guess the most popular are dockerfile/java and the official one. Let’s have a look at those images.
| Image | From | Size |
|---|---|---|
| dockerfile/java:oracle-java8 | dockerfile/ubuntu | 917.7 MB |
| java:8 | debian:experimental | 692.2 MB |
| dgageot/java8 | dgageot/busybox-ubuntu | 201.7 MB |
The size difference is quite significant as we have a 3.5 or 4.5 factor between the lightweight Java image and the regular ones. Even if you add a 100MB application to this base images you’ll still have at least a 2.5 size factor in favor of the lightweight image.
Caveat
Since David’s image is very small many things won’t be included. For instance there is no package manager, no JDK but only a JRE (with tools.jar), etc. Depending on your application you might need to add some extra contents.