Merge ~cjwatson/lp-codeimport:charm-fix-part-name into lp-codeimport:master

[Colin Watson]

charm: Add type/description to overridden install_sources/install_keys

Copied from `layer-apt/config.yaml`. `charmcraft` seems to be a bit pickier about this nowadays and is failing if we try to override just the default values.

[Guruprasad (lgp171188)]

LGTM 👍

review: Approve

diff --git a/charm/lp-codeimport/config.yaml b/charm/lp-codeimport/config.yaml
index 9b38fb9..7bffb34 100644
--- a/charm/lp-codeimport/config.yaml
+++ b/charm/lp-codeimport/config.yaml
@@ -87,8 +87,26 @@ options:
       the nrpe subordinate charm to set up /etc/rsyncd.conf properly.
   # layer-apt
   install_sources:
+    type: string
     default: |
       - ppa:launchpad/ppa
+    description: >
+      List of extra apt sources, per charm-helpers standard
+      format (a yaml list of strings encoded as a string). Each source
+      may be either a line that can be added directly to
+      sources.list(5), or in the form ppa:<user>/<ppa-name> for adding
+      Personal Package Archives, or a distribution component to enable.
   install_keys:
+    type: string
     default: |
       - null  # PPA keys securely added via Launchpad.
+    description: >
+      List of signing keys for install_sources package sources, per
+      charmhelpers standard format (a yaml list of strings encoded as
+      a string). The keys should be the full ASCII armoured GPG public
+      keys. While GPG key ids are also supported and looked up on a
+      keyserver, operators should be aware that this mechanism is
+      insecure. null can be used if a standard package signing key is
+      used that will already be installed on the machine, and for PPA
+      sources where the package signing key is securely retrieved from
+      Launchpad.