#365 Upgrade base image to JRE 17

[vovtz]

#365 In the first place for security concerns, but also to diminish the total image size and get some free performance improvements, upgrade to JRE 17 base image.

[vovtz]

#365

[cstettler]

Hi @vovtz, thank you for your pull request and sorry for the late reply. I locally built the Docker image based on your changes, but I end up with a much larger image for the Confluence Publisher compared to the current version:

Based on openjdk:8-jre-alpine         170MB
Based on openjdk:17.0.2-slim-bullseye 556MB

Is this to be expected? Do you see any chance to reduce the resulting image size while still moving to JRE 17? Thank you for your efforts!

[vovtz]

Is this to be expected? Do you see any chance to reduce the resulting image size while still moving to JRE 17? Thank you for your efforts!

Not really, the size difference between those base images is much smaller:

• OpenJDK 17 Alpine: 181.71 MB
• OpenJDK 17 Bullseye Slim: 210.63 MB

[vovtz]

The precise version I used, OpenJDK 17.0.2 Bullseye Slim, has the same size: 210.63 MB.

[vovtz]

Uncompressed, the sizes are (with between parentheses the size after having installed the necessary dependencies, GraphViz and the DejaVu TrueType font):

• OpenJDK 17 Alpine: 326 MB (369 MB)
• OpenJDK 17.0.2 Bullseye Slim: 408 MB (508 MB)

More importantly, the Alpine image didn’t receive updates for 15 months and therefore still contains a multitude of known vulnerabilities.