erb sudoers iterate over hash of arrays - ruby

Question

I try to generate sudoers file dynamically via puppet. Here i have hieradata like this:
---
sudoparameters:
cmnd_aliases:
CMND_ALIAS_A:
- /path/to/command_a *
- /path/to/command_b *
CMND_ALIAS_B:
- /path/to/command_c
- /path/to/command_d *
runas_aliases:
RUNAS_ALIAS_A:
- runas_user_a, runas_user_b
RUNAS_ALIAS_B:
- runas_user_a, runas_user_c
defaults:
- user!authenticate
- user!systlog
commands:
- user ALL=(root) NOPASSWD:/usr/sbin/puppetd --test agent --server=*
- user ALL=(root) NOPASSWD:/usr/bin/lsof -a *
- user ALL=(RUNAS_ALIAS_A) NOPASSWD: CMND_ALIAS_A
And an erb template like this:
<% #sudoparameters['cmnd_aliases'].each do |cmnd_alias| -%>
Cmnd_Alias <%= cmnd_alias %> <%= cmnd_alias.map { |path| path.join(', ') } %>
<% end -%>
<% #sudoparameters['runas_aliases'].each do |runas_alias| -%>
Runas_Aliases <%= runas_alias %> <%= runas_alias.map { |path| path.join(', ') } %>
<% end -%>
<% #sudoparameters['defaults'].each do |default| -%>
Defaults:<%= default %>
<% end -%>
<% #sudoparameters['commands'].each do |command| -%>
<%= command %>
<% end -%>
My approach to iterate over the cmnd_aliases and runas_aliases doesn't work. How can i accomplish it to generate a comma seperatet list für Cmnd_Aliases and Runas_Aliases if these arrays exists in sudoparameter hash?
Cheers
Christian

Answer 1

To solve the issue i wrapped the each blocks into:
<% if (#sudoparameters['cmnd_aliases'] != nil) then -%>
<% #sudoparameters['cmnd_aliases'].each do |cmnd_alias| -%>
Cmnd_Alias <%= cmnd_alias %> <%= cmnd_alias.map { |path| path.join(', ') } %>
<% end -%>
<% end -%>
But for now the cmnd_alias.mapdoesn't work as expected. i get the following error.
Detail: undefined method `join' for "CMND_ALIAS_A":String
To solve that i save key and value to different vars and apply the join directly to the values.
<% if (#sudoparameters['cmnd_aliases'] != nil) then -%>
<% #sudoparameters['cmnd_aliases'].each do |cmnd_alias_key, cmnd_alias_value| -%>
Cmnd_Alias <%= cmnd_alias_key %> <%= cmnd_alias_value.join(', ') %>
<% end -%>
<% end -%>
<% if (#sudoparameters['runas_aliases'] != nil) then -%>
<% #sudoparameters['runas_aliases'].each do |runas_alias_key, runas_alias_value| -%>
Runas_Aliases <%= runas_alias_key %> <%= runas_alias_value.join(', ') %>
<% end -%>
<% end -%>
<% if (#sudoparameters['defaults'] != nil) then -%>
<% #sudoparameters['defaults'].each do |default| -%>
Defaults:<%= default %>
<% end -%>
<% end -%>
<% #sudoparameters['commands'].each do |command| -%>
<%= command %>
<% end -%>

Answer 2

If some values in your Hash are nil, you can use this syntax :
<% (#sudoparameters['cmnd_aliases'] || {}).each do |cmnd_alias_key, cmnd_alias_values| -%>
Cmnd_Alias <%= cmnd_alias_key %> <%= cmnd_alias_values.join(', ') %>
<% end -%>
a || b syntax is helpful to avoid undefined method errors :
{:a => :b} || {}
#=> {:a => :b}
nil || {}
#=> {}
Finally, if cmnd_alias_value is an Array, it should be written as a plural : cmnd_alias_values. It's not a must, but it might make your code a bit easier to understand.