preinstall packages for charms

[Mark Mims]

hooks can't be written in any language not already installed in bare cloud images.

We can fix this a number of ways... I prefer adding an optional 'preinstall_packages' key or a 'package-dependencies' key into the metadata for a charm.

[William Reade (fwereade)]

Now that hooks are serialized per-unit, "apt-get install" in "install" hooks shouldn't be a problem.

[Tim Penhey (thumper)]

So, if the install hook was written in bash, it may look something like:

#!/bin/bash
apt-get install -y ruby
call-install-ruby-script.rb

Can someone see if that works? Perhaps the script needs a path?

[Mark Mims (mark-mims)]

Yeah, seemed to work fine with an install hook of

    #!/bin/bash
    apt-get -y install -qq ruby
    exec hooks/install.rb

with the rest of the hooks written directly in ruby... tested with

    lp:~mark-mims/charms/precise/ruby/trunk

which gives me a log like:

    http://paste.ubuntu.com/6094884/

could probably even do something like:

    #!/bin/bash
    apt-get -y install -qq ruby && ruby -x << EOF
    puts "ruby stuff here"
    EOF

but it'd be nice to have the ruby packages already installed before the install script is run.

[Dave Cheney (dave-cheney)]

I think wishlist is the appropriate status, there are a lot of workarounds available and most of them aren't so horrid.