[Blueprint servercloud-s-juju-charmhelper2] Charm Helper 2 - Declarative Charming

[Marco Ceppi]

Blueprint changed by Marco Ceppi:

Whiteboard changed:
- [USER STORIES] 
+ [USER STORIES]
+ 
+ Rodrigo is a new charm writer and needs tools to solve problems other
+ authors have already solved in their charms.
+ 
+ Dora is a seasoned charmer that has common functions she wants to
+ publish and share with other authors
+ 
+ Ricardo has written charms before and wants to know what shared
+ functions are available for charms
+ 
+ Lucy is rewriting several hooks to another language and needs to know
+ what helpers exist in that language
+ 
+ Bruce wants to review what parameters a helper function accepts and what
+ the expected output is
+ 
  [ASSUMPTIONS]
+ 
+ 
  [RISKS]
+ 
+ - It'll be difficult for some functions to create a comperable cross-
+ language function
+ 
  [IN SCOPE]
+ 
  [OUT OF SCOPE]
+ 
  [USER ACCEPTANCE]
+ 
  [RELEASE NOTE/BLOG]
  
  --- UDS Discussion ---
  
  We've learned a lot since the creation of charm helper. Debian packagers  took 7 iterations before boiling all of debhelper's goodness into a  declarative system. We can learn from them, and get there in our second  iteration.
  Discussion:
  Charm-helper is not easily discoverable, poorly documented, and not as awesome as it could be.
  dannf likes to write makefiles
  sources list
  config settings with meaning
  want common things to go in a declarative charm
  get rid of copied lib files/folder
  Maintain charm-helper seperately from juju, calling it at the top of the hook vs included in juju trunk
  What happens during upgrade-charm or if a pakcage gets removed?
  Juju can't help with leader election across units of a service, but charm-helper could)
  Work:
  - describe how to handle lifecycle changes for packages in charm-helper/packages (also thinkof: upgrade-charm)
  - install packages
  - debconf preseeding too
  - templating and/or building config files with dotd/concat partials (erb_template _and_ cheetah_template helpers)?
  - remote_files
  - deploy from {distro,ppa,upstream?} ?
  - Manage config files (dynamic, static, etc)
  - Sanitize relation settings (potential risk of SQL Ejection, highjacking, terror)
  - Plugin based for easy extension of charm-helper
  - leader election (perhaps somewhere other than charmhelper)
  - private files (SSL certs) ... no clue...
  - Collaborate on files that no charm "owns"

-- 
Charm Helper 2 - Declarative Charming
https://blueprints.launchpad.net/ubuntu/+spec/servercloud-s-juju-charmhelper2