Interdiff web service

[sun]

Lacking proper support/usage of branches/patch-serials, other Drupal core contributors/reviewers become more and more mad of asking everyone for interdiffs - even for the most silly patches.

Objective

• Create an interdiff web service on dreditor.org.
• Preferably in node.js or perhaps even proxied into bash/shell (just not PHP, please).

→ Instead of manually creating interdiffs, generate them automatically.

Dreditor needs to expose links, but that's a different topic.

Requirements

• Unless internal mechanics of interdiff are re-implemented differently:
  • interdiff binary (GNU diffutils)
  • git clone of Drupal core
  • diff binary (fallback)

API

Synopsis:

/interdiff?old=<uri>&new=<uri>[&timestamp=<unix_timestamp>]

Parameters:

• old: URI to first diff file.
• new: URI to second diff file.
• timestamp: Optional git repository checkout date (typically post date of new). If omitted, checkout defaults to now/latest HEAD.

Logic:

1. Checkout HEAD@{"$timestamp"}
2. curl $old > old.patch
3. curl $new > new.patch
4. interdiff old.patch new.patch && pass-through output (as-is)
5. || fall back to diff -up0 old.patch new.patch (diff of diffs)

---

Creating this issue "ahead of time". Didn't study yet whether it would be feasible to re-implement interdiff in pure JS. (Theoretically not much harder than "formatting" a diff, but not verified.)

[markhalliwell]

Interesting idea. I wouldn't be opposed to this, just have a few questions:

1. Is this really necessary? Shouldn't we instead direct people to create these themselves, in a tool such as https://www.drupal.org/project/drush_iq?
2. How do you envision making this new "service" visible in Dreditor's UI?
3. I'm a little hesitant on having to pull core's HEAD each time (it's massive). I am assuming that we should just pull once initially and then pull again to ensure we're on latest HEAD before each checkout?
4. Semi-related to the above. In reading http://linux.die.net/man/1/interdiff, is a checkout of the repo actually necessary for interdiff to work? It sounds like it's just a diff between two existing files.

xref: https://www.drupal.org/node/1798362

[star-szr]

Why not incorporate this functionality into the d.o infrastructure? Then I could see these automagic interdiffs on my phone, too.

[markhalliwell]

Agreed, I think that would be the ultimate goal for sure. Until then though I can kind of see why @sun would want this though in the interim, even if just prototyping for d.o.

[star-szr]

For sure, it just had to be said :) carry on.