[Foresight-devel] Pre-update script maintenance (was: pinned kerneloops)

[Michael Tharp]

Ken VanDine wrote:
 > Good point, pulling from hg might be nice too.  However, rss means
 > someone has to make the conscience decision to publish the scripts

RSS doesn't seem like a really good fit here since you'd have to 
post-process it on the client side. With hg, you could just point 
clients at a particular file in the repository and fetch it with wget or 
curl or python's urllib.

> This could be accomplished with a mercurial tag or using a separate branch
> and merging over to the main branch when they are to be released.

Branch would be best here; tags are supposed to represent a fixed point 
in time even though you can technically "move" them.

The problem with mercurial though is that the HTTP approach only works 
for a single file and it's slow since the CGI script has to conjure up 
the contents of the file on the fly.

Here's my suggestion: have a hg tree with many scripts so that it's easy 
to maintain. Keep it in the usual location, on hg.foresightlinux.org. 
Then, make a checkout of it on a webserver somewhere, and configure it 
with commit hooks so that whenever anything is pushed to it (the 
checkout, not the main repo), it updates and concatenates all the 
scripts together into a single static script. The static script would 
then be the file that clients fetch and execute before updating. The 
number of people with access to the webserver could be a subset of the 
people with hg access, and whoever does the push has an opportunity to 
test them before doing so.

You could have a script like:
---snip---
#!/bin/bash
hg up -C tip
cat preupdate/*.sh >/srv/www/foobar/preupdate.sh.tmp
mv /srv/www/foobar/preupdate.sh.tmp /srv/www/foobar/preupdate.sh
---snip---
and make that the "changegroup" hook (I think), and it should keep 
itself up to date and rebuild the script whenever anything is pushed to 
it. Naturally, we'd want to sign the resulting script with PGP and 
verify it on the client side, or something along those lines, to prove 
to the tinfoil-hat types (including me) that the script probably isn't evil.

-- m. tharp