Add support for SUSE distributions using DNF

SUSE distributions are able to use the DNF package manager with tracer
through the plugin, so we should have support for it.

SUSE distributions also relocate the persistent state data from /var/lib
to /usr/lib/sysimage for the Btrfs system snapshot setup.

tracer/packageManagers/dnf.py

@@ -21,7 +21,7 @@
 import os.path
 
 from tracer.resources.system import System
-if System.distribution() in ["rhel", "fedora", "mageia"]:
+if System.distribution() in ["rhel", "fedora", "mageia", "suse"]:
 
 	import subprocess
 	from tracer.packageManagers.rpm import Rpm
@@ -30,14 +30,22 @@ class Dnf(Rpm):
 
 		def __init__(self, **kwargs):
 			super(Dnf, self).__init__(**kwargs)
-			if os.path.exists('/var/lib/dnf/history.sqlite'):
+			if os.path.exists('/usr/lib/sysimage/dnf'):
+				self.opts['sysimage_persistdir'] = True
+			if os.path.exists('/usr/lib/sysimage/dnf/history.sqlite') or os.path.exists('/var/lib/dnf/history.sqlite'):
 				self.opts['modern_swdb'] = True
 
 		@property
 		def history_path(self):
 			if self.opts.get('modern_swdb'):
-				return '/var/lib/dnf/history.sqlite'
-			return '/var/lib/dnf/history/'
+				if self.opts.get('sysimage_persistdir'):
+					return '/usr/lib/sysimage/dnf/history.sqlite'
+				else:
+					return '/var/lib/dnf/history.sqlite'
+			if self.opts.get('sysimage_persistdir'):
+				return '/usr/lib/sysimage/dnf/history/'
+			else:
+				return '/var/lib/dnf/history/'
 
 		def package_files(self, pkg_name):
 			if self._is_installed(pkg_name):

tracer/resources/system.py

@@ -42,7 +42,7 @@ def distribution():
 		if os.path.isfile("/etc/os-release"):
 			with open("/etc/os-release") as os_release_file:
 				os_release_data = {}
-				distros = ["gentoo", "debian", "rhel", "centos", "ol", "mageia", "arch", "archarm", "fedora"]
+				distros = ["gentoo", "debian", "rhel", "centos", "ol", "mageia", "arch", "archarm", "fedora", "suse"]
 
 				# Remove empty lines and trailing spaces
 				lines = [line.rstrip() for line in os_release_file if line.rstrip()]
@@ -85,6 +85,7 @@ def get_instance(pair):
 				("tracer.packageManagers.dnf", "Dnf"),
 				("tracer.packageManagers.yum", "Yum"),
 			],
+			"suse":  [("tracer.packageManagers.dnf", "Dnf")],
 		}
 
 		distro = System.distribution()