Configurable digest algorithm

[jaredjennings]

Let the admin configure in puppet.conf which digest algorithm to use for file resources. I think these changes fulfill https://projects.puppetlabs.com/issues/8120.

[slippycheeze]

Please see the discussion at https://projects.puppetlabs.com/issues/8120

[slippycheeze]

I am following this up internally to see what the next steps are on this, since it is important, but difficult and hard to roll out as the code was.

[slippycheeze]

We are still working to figure out the right direction to take here. Sorry this is lingering for so long. :(

[jaredjennings]

That's fine. I know that the migration concerns are huge in the general case.

I haven't looked at this for a bit, so I've gotten blurry on how the filebucket works, but could you look through the whole thing, determine which bucket entries are digested using the old algorithm, and re-digest them, placing the results in the bucket? Would that be one possible step?

[slippycheeze]

@jaredjennings - yeah, migrating a filebucket isn't actually that hard, and we could just have a fsck equivalent that rebuilt with the current digest. More of the challenges are, eg, supporting older agents, and other places that hard-code or assume MD5. Those won't change, so we will still have things submit filebucket content under an MD5 hash, for example.

[jaredjennings]

I'm not sure whether this is the right way to do it, but I've made a new topic branch configurable-digest-algorithm-aug2012 from a more recent commit of the master branch, and cherrypicked the configurable-digest-algorithm changes into it, so that configurable-digest-algorithm-aug2012 should merge much more cleanly into the trunk as it is these days. Accordingly I am closing this pull request.

[jaredjennings]

The branch configurable-digest-algorithm-aug2012 is gravely wrong. The branch configurable-digest-algorithm-14aug2012 contains what configurable-digest-algorithm-aug2012 should have contained.