__prometheus_{server,alertmanager}: use os_version instead of lsb_release

works without the `lsb-release` package and actually seems to be more reliable, even though it is inconsistent between debian and devuan

cdist/conf/type/__prometheus_alertmanager/manifest

@@ -17,22 +17,18 @@ storage_path="$(cat "$__object/parameter/storage-path")"
 require_pkg=""  # what to require if I want to require "the package"
 if [ -f "$__object/parameter/install-from-backports" ]; then
 	os=$(cat "$__global/explorer/os")
-	lsb_codename=$(cat "$__global/explorer/lsb_codename")
+	os_version=$(cat "$__global/explorer/os_version")
 
 	case $os in
 		devuan)
-			if [ -z "$lsb_codename" ]; then
-				echo "Command `lsb_release` not functional -- is package `lsb-release` installed?" >&2
-				exit 1
-			fi
-			[ "$lsb_codename" = "n/a" ] && lsb_codename='ascii'  # TODO this is a devuan bug that should be fixed soon => remove when no longer needed
-			__apt_source backports --uri http://auto.mirror.devuan.org/merged --distribution $lsb_codename-backports --component main
-			require="$require __apt_source/backports" __package_apt prometheus-alertmanager --target-release $lsb_codename-backports
+			[ "$os_version" = "ascii/ceres" ] && os_version='ascii'  # "ascii" used in the repo URLs
+			__apt_source backports --uri http://auto.mirror.devuan.org/merged --distribution $os_version-backports --component main
+			require="$require __apt_source/backports" __package_apt prometheus-alertmanager --target-release $os_version-backports
 			require_pkg="__package_apt/prometheus-alertmanager"
 		;;
 		*)
-			echo "--install-from-backports is only supported on Devuan -- ignoring" >&2
-			echo "send a pull request if you require it" >&2
+			echo "--install-from-backports is only supported on Devuan -- ignoring." >&2
+			echo "Send a pull request if you require it." >&2
 		;;
 	esac
 else

cdist/conf/type/__prometheus_server/manifest

@@ -20,22 +20,18 @@ rule_files="$(cat "$__object/parameter/rule-files")"
 require_pkg=""  # what to require if I want to require "the package"
 if [ -f "$__object/parameter/install-from-backports" ]; then
 	os=$(cat "$__global/explorer/os")
-	lsb_codename=$(cat "$__global/explorer/lsb_codename")
+	os_version=$(cat "$__global/explorer/os_version")
 
 	case $os in
 		devuan)
-			if [ -z "$lsb_codename" ]; then
-				echo "Command `lsb_release` not functional -- is package `lsb-release` installed?" >&2
-				exit 1
-			fi
-			[ "$lsb_codename" = "n/a" ] && lsb_codename='ascii'  # TODO this is a devuan bug that should be fixed soon => remove when no longer needed
-			__apt_source backports --uri http://auto.mirror.devuan.org/merged --distribution $lsb_codename-backports --component main
-			require="$require __apt_source/backports" __package_apt prometheus --target-release $lsb_codename-backports
+			[ "$os_version" = "ascii/ceres" ] && os_version='ascii'  # "ascii" used in the repo URLs
+			__apt_source backports --uri http://auto.mirror.devuan.org/merged --distribution $os_version-backports --component main
+			require="$require __apt_source/backports" __package_apt prometheus --target-release $os_version-backports
 			require_pkg="__package_apt/prometheus"
 		;;
 		*)
-			echo "--install-from-backports is only supported on Devuan -- ignoring" >&2
-			echo "send a pull request if you require it" >&2
+			echo "--install-from-backports is only supported on Devuan -- ignoring." >&2
+			echo "Send a pull request if you require it." >&2
 		;;
 	esac
 else