Do not fetch plugin-versions eagerly

[daniel-beck]

plugin-installation-manager-tool/plugin-management-library/src/main/java/io/jenkins/tools/pluginmanager/impl/PluginManager.java

Line 794 in e71682a

pluginInfoJson = getJson(cfg.getJenkinsPluginInfo(), "plugin-versions");

looks like this file is retrieved even when it's not needed. This should be fixed to reduce bandwidth waste, every call is 10MB.

[timja]

We use it almost every time I think, if any plugin isn't the latest version we use it to get the checksum.

This is cached for 1 hour.

[daniel-beck]

if any plugin isn't the latest version

How likely is this? Do you check the update-center.json for the version first, or is an explicitly specified version enough to go through here, even if it's the latest?

This is cached for 1 hour.

I suggest this caches until content changes (If-Modified-Since).

Plus I see requests from the same IP address every 5 minutes. Is that someone building the same Docker image every 5 minutes?

[hp77-creator]

This is cached for 1 hour.

How is this implemented, I mean the duration of 1 hr if you don't mind?

[timja]

https://github.com/jenkinsci/plugin-installation-manager-tool/blob/master/plugin-management-library/src/main/java/io/jenkins/tools/pluginmanager/impl/CacheManager.java