Merge ~cjwatson/turnip:cgit-timeout into turnip:master

[Colin Watson]

Time out cgit processes

We don't want these to hang around forever if something is going wrong.
cgit can legitimately take a while to render large files, so I started
out with a relatively lenient value of 30 seconds and we can see how
things look in practice.

[Jonathan Hartley (tartley)]

For my education: This is the kind of change that isn't amenable to unit tests, but could be amenable to end-to-end tests, of a kind I think that we don't have any of, around this bit of code. Is that correct?

Are there reasons we don't have them that I ought to know about, other than the generic 'It's hard and might not be worth the effort" ?

I'm only asking for my education, no judgement! :-)

Thank you!

review: Approve

[Colin Watson (cjwatson)]

We indeed don't have end-to-end tests of this sort of thing at present. It's certainly doable in principle but as you say would be a very considerable amount of effort, as well as being slow to run because deploying the full stack with Juju takes quite a while. At the moment it isn't clear that it would repay the investment.

diff --git a/charm/turnip-pack-frontend-http/config.yaml b/charm/turnip-pack-frontend-http/config.yaml
index 31f0476..56cac33 100644
--- a/charm/turnip-pack-frontend-http/config.yaml
+++ b/charm/turnip-pack-frontend-http/config.yaml
@@ -35,6 +35,10 @@ options:
     type: string
     default: ''
     description: Base64 encoded cgit session secret.
+  cgit_timeout:
+    type: int
+    default: 30
+    description: Time out cgit processes after this many seconds.
   virtinfo_endpoint:
     type: string
     default: http://localhost:6543/githosting
diff --git a/charm/turnip-pack-frontend-http/templates/cgitwrap.j2 b/charm/turnip-pack-frontend-http/templates/cgitwrap.j2
index 7d1fcd2..0a0bdb9 100644
--- a/charm/turnip-pack-frontend-http/templates/cgitwrap.j2
+++ b/charm/turnip-pack-frontend-http/templates/cgitwrap.j2
@@ -1,5 +1,5 @@
 #! /bin/sh
 set -e
 
-exec sudo -u {{ cgit_user }} /usr/lib/cgit/cgit.cgi "$@"
+exec timeout --kill-after=15 {{ cgit_timeout }} sudo -u {{ cgit_user }} /usr/lib/cgit/cgit.cgi "$@"