Require default-jdk-headless

[openhab]

Require default-jdk-headless

[ThomDietrich]

I know, I've written the docs sentence saying so 😸

Okay then. The whole situation is pretty silly.

[ThomDietrich]

Good idea! Are you fixed on default-jdk-headless? Zulu doesn't seem to provide this virtual package.

[BClark09]

Ah good catch, also default-jdk-headless may not install java 8 at all! I should be able to depend on the following to cover all:

java8-jdk | java8-sdk-headless | java8-sdk | java8-runtime-headless

That said, it shouldn't depend on java 8 but recommend it instead. That way, those who have installed java manually would not have issues.

[ThomDietrich]

Great, seems to cover all the big three, looking at the Provides of all of them maybe you want to also add java8-runtime (of the Java 8 packages Zulu only provides java8-jdk and java8-runtime).

Recommends seems like a good choice 👍

[BClark09]

Eek, looks like these virtual packages are a mess.

java9* virtual package provides java8* virtual packages, so if you recommend or depend on the above then it will automatically choose to install java 9, which is incompatible with openHAB 2. What's worse is that there seems to be no way of specifying a maximum version for these virtual packages.

I understand java8 containing java7 virtual packages, Java 8 is fairly backwards compatible. Java 9 however is not.

Related: https://bugs.launchpad.net/ubuntu/+source/openjdk-9/+bug/1584118

[ThomDietrich]

Okay... wow, this is the key problem:

it is technically correct that java9 does provide a java8-runtime, but java9 isn't even released yet and should definitely not be the default java8-runtime until that time

I agree with the second part but openHAB needs to be properly tested with Java 9 before it can even be considered. Hence that should not be an option at all. The first part makes sense but totally messes with the initial idea.

What's your suggestion? Recommends: zulu-embedded-8 | oracle-java8-jdk | openjdk-8-jre-headless

[BClark09]

openHAB fails to start on openjdk-9, but that is a problem for another day.

Since oracle-java8-jdk is a provided by oracle-java9-installer I think it'll have to be oracle-java8-installer specifically.

[BClark09]

One last use case, someone has manually installed oracle linux, and then tries to install openHAB2.

Even with recommends it'll install openjdk, which would be less stable. Is this something that we should seek to avoid?

[BClark09]

I know, I've written the docs sentence saying so 😸

Haha, sorry. I should really read the changes more often ;)