__debian_backports -> __apt_backports; add wider os support

As discussed in the chat, this type now supports a broader list of OSes
which it supports backports for. Because of this, it was renamed to
something more generic. "apt" should fit in.

cdist/conf/type/__apt_backports/man.rst

@@ -3,13 +3,13 @@ cdist-type__debian_backports(7)
 
 NAME
 ----
-cdist-type__debian_backports - Install backports for Debain systems
+cdist-type__apt_backports - Install backports
 
 
 DESCRIPTION
 -----------
-This singleton type installs backports for the current Debian version.
-It aborts if backports are not supported for the specified os or no
+This singleton type installs backports for the current OS release.
+It aborts if backports are not supported for the specified OS or no
 version codename could be fetched (like Debian unstable).
 
 
@@ -27,8 +27,8 @@ state
     Will be directly passed to :strong:`cdist-type__apt_source`\ (7).
 
 mirror
-    The mirror to fetch the backports from. Will defaults to the Debian default
-    `<http://deb.debian.org/debian/>`_.
+    The mirror to fetch the backports from. Will defaults to the generic
+    mirror of the current OS.
 
     Will be directly passed to :strong:`cdist-type__apt_source`\ (7).
 
@@ -49,12 +49,12 @@ EXAMPLES
 .. code-block:: sh
 
    # setup the backports
-   __debian_backports
-   __debian_backports --state absent
-   __debian_backports --state present --mirror "http://ftp.de.debian.org/debian/"
+   __apt_backports
+   __apt_backports --state absent
+   __apt_backports --state present --mirror "http://ftp.de.debian.org/debian/"
 
    # update
-   require="__debian_backports" __apt_update_index
+   require="__apt_backports" __apt_update_index
 
    # install a backports package
    # currently for the buster release backports
@@ -70,6 +70,15 @@ Aborts if no distribuition codename could be detected. This is common for the
 unstable distribution, but there is no backports repository for it already.
 
 
+CAVEATS
+-------
+For Ubuntu, it setup all componenents for the backports repository: ``main``,
+``restricted``, ``universe`` and ``multiverse``. The user may not want to
+install proprietary packages, which will only be installed if the user
+explicitly uses the backports target-release. The user may change this behavior
+to install backports packages without the need of explicitly select it.
+
+
 SEE ALSO
 --------
 `Official Debian Backports site <https://backports.debian.org/>`_

cdist/conf/type/__apt_backports/manifest

@@ -1,5 +1,5 @@
 #!/bin/sh -e
-# __debian_backports/manifest
+# __apt_backports/manifest
 #
 # 2020 Matthias Stecher (matthiasstecher at gmx.de)
 #
@@ -23,18 +23,34 @@
 #
 
 
+# Get the distribution codename by /etc/os-release.
+#  is already executed in a subshell by string substitution
+#  lsb_release may not be given in all installations
+codename_os_release() {
+    # shellcheck disable=SC1090
+    . "$__global/explorer/os-release"
+    printf "%s" "$VERSION_CODENAME"
+}
+
 # detect backport distribution
 os="$(cat "$__global/explorer/os")"
 case "$os" in
     debian)
-        # distribution codename from /etc/os-release
-        # lsb_release may not be given in all debian installations
-        dist="$(
-            # shellcheck disable=SC1090
-            . "$__global/explorer/os-release"
-            printf "%s" "$VERSION_CODENAME"
-        )"
+        dist="$( codename_os_release )"
+        components="main"
+        mirror="http://deb.debian.org/debian/"
+        ;;
+    devuan)
+        dist="$( codename_os_release )"
+        components="main"
+        mirror="http://deb.devuan.org/merged"
         ;;
+    ubuntu)
+        dist="$( codename_os_release )"
+        components="main restricted universe multiverse"
+        mirror="http://archive.ubuntu.com/ubuntu"
+        ;;
+
     *)
         printf "Backports for %s are not supported!\n" "$os" >&2
         exit 1
@@ -50,11 +66,16 @@ fi
 
 # parameters
 state="$(cat "$__object/parameter/state")"
-mirror="$(cat "$__object/parameter/mirror")"
+
+# mirror already set for the os, only override user-values
+if [ -f "$__object/parameter/mirror" ]; then
+    mirror="$(cat "$__object/parameter/mirror")"
+fi
+
 
 # install the given backports repository
 __apt_source "${dist}-backports" \
     --state "$state" \
     --distribution "${dist}-backports" \
-    --component main \
+    --component "$components" \
     --uri "$mirror"

cdist/conf/type/__debian_backports/parameter/default/mirror

@@ -1 +0,0 @@
-http://deb.debian.org/debian/