Hudson: What is a good way to store a variable between the two job runs?

Question

I have a job which needs to know the ceratin value calculated by the previous job run.

Is there a way to store it in the Hudson/Jenkins environment?

E.g., I can write something like next in a shell script action:

XXX=`cat /hardcoded/path/xxx`
#job itself
echo NEW_XXX > /hardcoded/path/xxx

But is there a more reliable approach?

Answer 1

A few options:

• Store the data in the workspace. If the data isn't critical (i.e. it's ok to nuke it when the workspace is nuked) that should be fine. I only use this to cache expensive-to-compute data such as prebuilt library dependancies.
• Store the data in some fixed location in the filesystem. You'll make jenkins less self-contained and thus make migrations+backups more complex - but probably not by much; especially if you store the data in some custom user-subdirectory of jenkins. parallel builds will also be tricky, and distributed builds likely impossible. Jenkins has a userContent subdirectory you could use for this - that way the file is at least part of the jenkins install and thus more easily migrated or backed up. I do this for the (rather large) code coverage trend files for my builds.
• Store the data on a different machine (e.g. a database). This is more complicated to set up, but you're less dependant on the local machine's details, and it's probably easier to get distributed and parallel builds working. I've done this to maintain a live changelog.
• Store the data as a build artifact. This means looking at previous build's artifacts. It's safe and repeatable, and because Uri's are used to access such artifacts, OK for distributed builds too. However, you need to deal with failed builds (should you look back several versions? start from scratch?) and you'll be storing many copies, which is just fine if it's 1KB but less fine if it's 1GB. Another downside here is that you'll probably need to open up jenkin's security settings quite far to allow annonymous access to artifacts (since you're just downloading from a uri).

The appropriate solution will depend on your situation.

Answer 2

I would pass the variable from the first job to the second as a parameter in a parameterized build. See this question for more info on how to trigger a parameterized build from another build.