diff --git a/cdist/argparse.py b/cdist/argparse.py
index 88759d7b..cadac39a 100644
--- a/cdist/argparse.py
+++ b/cdist/argparse.py
@@ -533,10 +533,10 @@ def parse_and_configure(argv, singleton=True):
 
     log = logging.getLogger("cdist")
 
-    log.verbose("version %s" % cdist.VERSION)
-    log.trace('command line args: {}'.format(cfg.command_line_args))
-    log.trace('configuration: {}'.format(cfg.get_config()))
-    log.trace('configured args: {}'.format(args))
+    log.verbose("version %s", cdist.VERSION)
+    log.trace('command line args: %s', cfg.command_line_args)
+    log.trace('configuration: %s', cfg.get_config())
+    log.trace('configured args: %s', args)
 
     check_beta(vars(args))
 
diff --git a/cdist/config.py b/cdist/config.py
index 19d5bd70..d6fec55f 100644
--- a/cdist/config.py
+++ b/cdist/config.py
@@ -273,15 +273,15 @@ class Config:
                     host_tags = None
             host_base_path, hostdir = cls.create_host_base_dirs(
                 host, base_root_path)
-            log.debug("Base root path for target host \"{}\" is \"{}\"".format(
-                host, host_base_path))
+            log.debug("Base root path for target host \"%s\" is \"%s\"",
+                      host, host_base_path)
 
             hostcnt += 1
             if args.parallel:
                 pargs = (host, host_tags, host_base_path, hostdir, args, True,
                          configuration)
-                log.trace(("Args for multiprocessing operation "
-                           "for host {}: {}".format(host, pargs)))
+                log.trace("Args for multiprocessing operation for host %s: %s",
+                          host, pargs)
                 process_args.append(pargs)
             else:
                 try:
@@ -298,10 +298,10 @@ class Config:
             except cdist.Error:
                 failed_hosts.append(host)
         elif args.parallel:
-            log.trace("Multiprocessing start method is {}".format(
-                multiprocessing.get_start_method()))
-            log.trace(("Starting multiprocessing Pool for {} "
-                       "parallel host operation".format(args.parallel)))
+            log.trace("Multiprocessing start method is %s",
+                      multiprocessing.get_start_method())
+            log.trace("Starting multiprocessing Pool for %d parallel host"
+                      " operation", args.parallel)
 
             results = mp_pool_run(cls.onehost,
                                   process_args,
@@ -396,16 +396,13 @@ class Config:
 
             remote_exec, remote_copy, cleanup_cmd = cls._resolve_remote_cmds(
                 args)
-            log.debug("remote_exec for host \"{}\": {}".format(
-                host, remote_exec))
-            log.debug("remote_copy for host \"{}\": {}".format(
-                host, remote_copy))
+            log.debug("remote_exec for host \"%s\": %s", host, remote_exec)
+            log.debug("remote_copy for host \"%s\": %s", host, remote_copy)
 
             family = cls._address_family(args)
-            log.debug("address family: {}".format(family))
+            log.debug("address family: %s", family)
             target_host = cls.resolve_target_addresses(host, family)
-            log.debug("target_host for host \"{}\": {}".format(
-                host, target_host))
+            log.debug("target_host for host \"%s\": %s", host, target_host)
 
             local = cdist.exec.local.Local(
                 target_host=target_host,
@@ -474,8 +471,8 @@ class Config:
         """Do what is most often done: deploy & cleanup"""
         start_time = time.time()
 
-        self.log.info("Starting {} run".format(
-            'dry' if self.dry_run else 'configuration'))
+        self.log.info("Starting %s run",
+                      'dry' if self.dry_run else 'configuration')
 
         self._init_files_dirs()
 
@@ -493,9 +490,9 @@ class Config:
         self._remove_files_dirs()
 
         self.local.save_cache(start_time)
-        self.log.info("Finished {} run in {:.2f} seconds".format(
+        self.log.info("Finished %s run in %.2f seconds",
                       'dry' if self.dry_run else 'successful',
-                      time.time() - start_time))
+                      time.time() - start_time)
 
     def cleanup(self):
         self.log.debug("Running cleanup commands")
@@ -519,8 +516,8 @@ class Config:
                 self.local.object_path, self.local.type_path,
                 self.local.object_marker_name):
             if cdist_object.cdist_type.is_install:
-                self.log.debug(("Running in config mode, ignoring install "
-                                "object: {0}").format(cdist_object))
+                self.log.debug("Running in config mode, ignoring install "
+                               "object: %s", cdist_object)
             else:
                 yield cdist_object
 
@@ -565,8 +562,7 @@ class Config:
         return objects_changed
 
     def _iterate_once_parallel(self):
-        self.log.debug("Iteration in parallel mode in {} jobs".format(
-            self.jobs))
+        self.log.debug("Iteration in parallel mode in %d jobs", self.jobs)
         objects_changed = False
 
         cargo = []
@@ -588,8 +584,8 @@ class Config:
             self.object_prepare(cargo[0])
             objects_changed = True
         elif cargo:
-            self.log.trace("Multiprocessing start method is {}".format(
-                multiprocessing.get_start_method()))
+            self.log.trace("Multiprocessing start method is %s",
+                           multiprocessing.get_start_method())
 
             self.log.trace("Multiprocessing cargo: %s", cargo)
 
@@ -603,9 +599,8 @@ class Config:
                                 "sequentially"))
                 self.explorer.transfer_type_explorers(cargo_types.pop())
             else:
-                self.log.trace(("Starting multiprocessing Pool for {} "
-                                "parallel types explorers transferring".format(
-                                    nt)))
+                self.log.trace("Starting multiprocessing Pool for %d "
+                               "parallel types explorers transferring", nt)
                 args = [
                     (ct, ) for ct in cargo_types
                 ]
@@ -614,8 +609,8 @@ class Config:
                 self.log.trace(("Multiprocessing for parallel transferring "
                                 "types' explorers finished"))
 
-            self.log.trace(("Starting multiprocessing Pool for {} parallel "
-                            "objects preparation".format(n)))
+            self.log.trace("Starting multiprocessing Pool for %d parallel "
+                           "objects preparation", n)
             args = [
                 (c, False, ) for c in cargo
             ]
@@ -667,10 +662,10 @@ class Config:
                 self.object_run(chunk[0])
                 objects_changed = True
             elif chunk:
-                self.log.trace("Multiprocessing start method is {}".format(
-                    multiprocessing.get_start_method()))
-                self.log.trace(("Starting multiprocessing Pool for {} "
-                               "parallel object run".format(n)))
+                self.log.trace("Multiprocessing start method is %s",
+                               multiprocessing.get_start_method())
+                self.log.trace("Starting multiprocessing Pool for %d "
+                               "parallel object run", n)
                 args = [
                     (c, ) for c in chunk
                 ]
@@ -794,9 +789,9 @@ class Config:
     def object_prepare(self, cdist_object, transfer_type_explorers=True):
         """Prepare object: Run type explorer + manifest"""
         self._handle_deprecation(cdist_object)
-        self.log.verbose("Preparing object {}".format(cdist_object.name))
-        self.log.verbose(
-            "Running manifest and explorers for " + cdist_object.name)
+        self.log.verbose("Preparing object %s", cdist_object.name)
+        self.log.verbose("Running manifest and explorers for %s",
+                         cdist_object.name)
         self.explorer.run_type_explorers(cdist_object, transfer_type_explorers)
         try:
             self.manifest.run_type_manifest(cdist_object)
@@ -810,13 +805,13 @@ class Config:
     def object_run(self, cdist_object):
         """Run gencode and code for an object"""
         try:
-            self.log.verbose("Running object " + cdist_object.name)
+            self.log.verbose("Running object %s", cdist_object.name)
             if cdist_object.state == core.CdistObject.STATE_DONE:
                 raise cdist.Error(("Attempting to run an already finished "
-                                   "object: %s"), cdist_object)
+                                   "object: {}").format(cdist_object))
 
             # Generate
-            self.log.debug("Generating code for %s" % (cdist_object.name))
+            self.log.debug("Generating code for %s", cdist_object.name)
             cdist_object.code_local = self.code.run_gencode_local(cdist_object)
             cdist_object.code_remote = self.code.run_gencode_remote(
                 cdist_object)
@@ -825,20 +820,20 @@ class Config:
 
             # Execute
             if cdist_object.code_local or cdist_object.code_remote:
-                self.log.info("Processing %s" % (cdist_object.name))
+                self.log.info("Processing %s", cdist_object.name)
             if not self.dry_run:
                 if cdist_object.code_local:
-                    self.log.trace("Executing local code for %s"
-                                   % (cdist_object.name))
+                    self.log.trace("Executing local code for %s",
+                                   cdist_object.name)
                     self.code.run_code_local(cdist_object)
                 if cdist_object.code_remote:
-                    self.log.trace("Executing remote code for %s"
-                                   % (cdist_object.name))
+                    self.log.trace("Executing remote code for %s",
+                                   cdist_object.name)
                     self.code.transfer_code_remote(cdist_object)
                     self.code.run_code_remote(cdist_object)
 
             # Mark this object as done
-            self.log.trace("Finishing run of " + cdist_object.name)
+            self.log.trace("Finishing run of %s", cdist_object.name)
             cdist_object.state = core.CdistObject.STATE_DONE
         except cdist.Error as e:
             raise cdist.CdistObjectError(cdist_object, e)
diff --git a/cdist/core/cdist_type.py b/cdist/core/cdist_type.py
index c0329c8a..274de989 100644
--- a/cdist/core/cdist_type.py
+++ b/cdist/core/cdist_type.py
@@ -82,9 +82,9 @@ class CdistType:
                 yield cls(base_path, name)
             except InvalidTypeError as e:
                 # ignore invalid type, log warning and continue
-                msg = "Ignoring invalid type '%s' at '%s' defined at '%s'" % (
-                    e.type_path, e.type_absolute_path, e.source_path)
-                cls.log.warning(msg)
+                cls.log.warning("Ignoring invalid type '%s' at '%s' defined"
+                                " at '%s'", e.type_path, e.type_absolute_path,
+                                e.source_path)
                 # remove invalid from runtime conf dir
                 os.remove(e.type_absolute_path)
 
diff --git a/cdist/core/explorer.py b/cdist/core/explorer.py
index a3baa959..caa12a7d 100644
--- a/cdist/core/explorer.py
+++ b/cdist/core/explorer.py
@@ -131,18 +131,17 @@ class Explorer:
             self._run_global_explorer(explorer, out_path)
 
     def _run_global_explorers_parallel(self, out_path):
-        self.log.debug("Running global explorers in {} parallel jobs".format(
-            self.jobs))
-        self.log.trace("Multiprocessing start method is {}".format(
-            multiprocessing.get_start_method()))
-        self.log.trace(("Starting multiprocessing Pool for global "
-                       "explorers run"))
+        self.log.debug("Running global explorers in %s parallel jobs",
+                       self.jobs)
+        self.log.trace("Multiprocessing start method is %s",
+                       multiprocessing.get_start_method())
+        self.log.trace("Starting multiprocessing Pool for global explorers"
+                       " run")
         args = [
             (e, out_path, ) for e in self.list_global_explorer_names()
         ]
         mp_pool_run(self._run_global_explorer, args, jobs=self.jobs)
-        self.log.trace(("Multiprocessing run for global explorers "
-                        "finished"))
+        self.log.trace("Multiprocessing run for global explorers finished")
 
     # logger is not pickable, so remove it when we pickle
     def __getstate__(self):
@@ -184,15 +183,14 @@ class Explorer:
         in the object.
 
         """
-        self.log.verbose("Running type explorers for {}".format(
-            cdist_object.cdist_type))
+        self.log.verbose("Running type explorers for %s",
+                         cdist_object.cdist_type)
         if transfer_type_explorers:
             self.log.trace("Transferring type explorers for type: %s",
                            cdist_object.cdist_type)
             self.transfer_type_explorers(cdist_object.cdist_type)
         else:
-            self.log.trace(("No need for transferring type explorers for "
-                            "type: %s"),
+            self.log.trace("No need for transferring type explorers for %s",
                            cdist_object.cdist_type)
         self.log.trace("Transferring object parameters for object: %s",
                        cdist_object.name)
@@ -236,8 +234,8 @@ class Explorer:
            remote side."""
         if cdist_type.explorers:
             if cdist_type.name in self._type_explorers_transferred:
-                self.log.trace(("Skipping retransfer of type explorers "
-                                "for: %s"), cdist_type)
+                self.log.trace("Skipping retransfer of type explorers for: %s",
+                               cdist_type)
             else:
                 source = os.path.join(self.local.type_path,
                                       cdist_type.explorer_path)
diff --git a/cdist/core/manifest.py b/cdist/core/manifest.py
index 390340d4..3148d66c 100644
--- a/cdist/core/manifest.py
+++ b/cdist/core/manifest.py
@@ -161,7 +161,7 @@ class Manifest:
             raise NoInitialManifestError(initial_manifest, user_supplied)
 
         message_prefix = "initialmanifest"
-        self.log.verbose("Running initial manifest " + initial_manifest)
+        self.log.verbose("Running initial manifest %s", initial_manifest)
         which = "init"
         if self.local.save_output_streams:
             stderr_path = os.path.join(self.local.stderr_base_path, which)
diff --git a/cdist/emulator.py b/cdist/emulator.py
index f1db862e..f09c282d 100644
--- a/cdist/emulator.py
+++ b/cdist/emulator.py
@@ -107,8 +107,8 @@ class Emulator:
             self.record_requirements()
             self.record_auto_requirements()
             self.record_parent_child_relationships()
-            self.log.trace("Finished %s %s" % (
-                self.cdist_object.path, self.parameters))
+            self.log.trace("Finished %s %s", self.cdist_object.path,
+                           self.parameters)
 
     def __init_log(self):
         """Setup logging facility"""
@@ -170,7 +170,7 @@ class Emulator:
 
         # And finally parse/verify parameter
         self.args = parser.parse_args(self.argv[1:])
-        self.log.trace('Args: %s' % self.args)
+        self.log.trace('Args: %s', self.args)
 
     def init_object(self):
         # Initialize object - and ensure it is not in args
@@ -241,8 +241,8 @@ class Emulator:
                 raise cdist.Error(errmsg)
         else:
             if self.cdist_object.exists:
-                self.log.debug(('Object %s override forced with '
-                                'CDIST_OVERRIDE'), self.cdist_object.name)
+                self.log.debug('Object %s override forced with CDIST_OVERRIDE',
+                               self.cdist_object.name)
                 self.cdist_object.create(True)
             else:
                 self.cdist_object.create()
@@ -260,8 +260,8 @@ class Emulator:
             parent = self.cdist_object.object_from_name(__object_name)
             parent.typeorder.append(self.cdist_object.name)
             if self._order_dep_on():
-                self.log.trace(('[ORDER_DEP] Adding %s to typeorder dep'
-                                ' for %s'), depname, parent.name)
+                self.log.trace('[ORDER_DEP] Adding %s to typeorder dep for %s',
+                               depname, parent.name)
                 parent.typeorder_dep.append(depname)
         elif self._order_dep_on():
             self.log.trace('[ORDER_DEP] Adding %s to global typeorder dep',
@@ -301,16 +301,14 @@ class Emulator:
         try:
             cdist_object = self.cdist_object.object_from_name(requirement)
         except core.cdist_type.InvalidTypeError as e:
-            self.log.error(("%s requires object %s, but type %s does not"
-                            " exist. Defined at %s" % (
-                                self.cdist_object.name,
-                                requirement, e.name, self.object_source)))
+            self.log.error("%s requires object %s, but type %s does not"
+                           " exist. Defined at %s", self.cdist_object.name,
+                           requirement, e.name, self.object_source)
             raise
         except core.cdist_object.MissingObjectIdError:
-            self.log.error(("%s requires object %s without object id."
-                            " Defined at %s" % (self.cdist_object.name,
-                                                requirement,
-                                                self.object_source)))
+            self.log.error("%s requires object %s without object id."
+                           " Defined at %s", self.cdist_object.name,
+                           requirement, self.object_source)
             raise
 
         self.log.debug("Recording requirement %s for %s",
@@ -380,10 +378,9 @@ class Emulator:
                         self.env['require'] += " " + lastcreatedtype
                 else:
                     self.env['require'] = lastcreatedtype
-                self.log.debug(("Injecting require for "
-                                "CDIST_ORDER_DEPENDENCY: %s for %s"),
-                               lastcreatedtype,
-                               self.cdist_object.name)
+                self.log.debug("Injecting require for"
+                               " CDIST_ORDER_DEPENDENCY: %s for %s",
+                               lastcreatedtype, self.cdist_object.name)
             except IndexError:
                 # if no second last line, we are on the first type,
                 # so do not set a requirement
@@ -391,7 +388,7 @@ class Emulator:
 
         if "require" in self.env:
             requirements = self.env['require']
-            self.log.debug("reqs = " + requirements)
+            self.log.debug("reqs = %s", requirements)
             for requirement in self._parse_require(requirements):
                 # Ignore empty fields - probably the only field anyway
                 if len(requirement) == 0:
diff --git a/cdist/exec/local.py b/cdist/exec/local.py
index e0aab190..6713cd13 100644
--- a/cdist/exec/local.py
+++ b/cdist/exec/local.py
@@ -154,8 +154,8 @@ class Local:
         with open(self.object_marker_file, 'w') as fd:
             fd.write("%s\n" % self.object_marker_name)
 
-        self.log.trace("Object marker %s saved in %s" % (
-            self.object_marker_name, self.object_marker_file))
+        self.log.trace("Object marker %s saved in %s",
+                       self.object_marker_name, self.object_marker_file)
 
     def _init_cache_dir(self, cache_dir):
         home_dir = cdist.home_dir()
@@ -289,14 +289,12 @@ class Local:
         return cache_subpath
 
     def save_cache(self, start_time=time.time()):
-        self.log.trace("cache subpath pattern: {}".format(
-            self.cache_path_pattern))
+        self.log.trace("cache subpath pattern: %s", self.cache_path_pattern)
         cache_subpath = self._cache_subpath(start_time,
                                             self.cache_path_pattern)
-        self.log.debug("cache subpath: {}".format(cache_subpath))
+        self.log.debug("cache subpath: %s", cache_subpath)
         destination = os.path.join(self.cache_path, cache_subpath)
-        self.log.trace(("Saving cache: " + self.base_path + " to " +
-                        destination))
+        self.log.trace("Saving cache %s to %s", self.base_path, destination)
 
         if not os.path.exists(destination):
             shutil.move(self.base_path, destination)
@@ -332,7 +330,7 @@ class Local:
 
         # Iterate over all directories and link the to the output dir
         for conf_dir in self.conf_dirs:
-            self.log.debug("Checking conf_dir %s ..." % (conf_dir))
+            self.log.debug("Checking conf_dir %s ...", conf_dir)
             for sub_dir in CONF_SUBDIRS_LINKED:
                 current_dir = os.path.join(conf_dir, sub_dir)
 
@@ -350,7 +348,7 @@ class Local:
                     if os.path.exists(dst):
                         os.unlink(dst)
 
-                    self.log.trace("Linking %s to %s ..." % (src, dst))
+                    self.log.trace("Linking %s to %s ...", src, dst)
                     try:
                         os.symlink(src, dst)
                     except OSError as e:
diff --git a/cdist/exec/remote.py b/cdist/exec/remote.py
index e5af2f34..ea85da4c 100644
--- a/cdist/exec/remote.py
+++ b/cdist/exec/remote.py
@@ -176,19 +176,19 @@ class Remote:
                 # create archive
                 tarpath, fcnt = autil.tar(source, self.archiving_mode)
                 if tarpath is None:
-                    self.log.trace(("Files count {} is lower than {} limit, "
-                                    "skipping archiving").format(
-                                        fcnt, autil.FILES_LIMIT))
+                    self.log.trace("Files count %d is lower than %d limit, "
+                                   "skipping archiving",
+                                   fcnt, autil.FILES_LIMIT)
                 else:
-                    self.log.trace(("Archiving mode, tarpath: %s, file count: "
-                                    "%s"), tarpath, fcnt)
+                    self.log.trace("Archiving mode, tarpath: %s, file count: "
+                                   "%s", tarpath, fcnt)
                     # get archive name
                     tarname = os.path.basename(tarpath)
                     self.log.trace("Archiving mode tarname: %s", tarname)
                     # archive path at the remote
                     desttarpath = os.path.join(destination, tarname)
-                    self.log.trace(
-                        "Archiving mode desttarpath: %s", desttarpath)
+                    self.log.trace("Archiving mode desttarpath: %s",
+                                   desttarpath)
                     # transfer archive to the remote side
                     self.log.trace("Archiving mode: transferring")
                     self._transfer_file(tarpath, desttarpath)
diff --git a/cdist/install.py b/cdist/install.py
index 7c894fe5..d077baef 100644
--- a/cdist/install.py
+++ b/cdist/install.py
@@ -47,4 +47,4 @@ class Install(cdist.config.Config):
                 yield cdist_object
             else:
                 self.log.debug("Running in install mode, ignoring non install"
-                               "object: {0}".format(cdist_object))
+                               "object: %s", cdist_object)
diff --git a/cdist/inventory.py b/cdist/inventory.py
index 0387f326..106052a2 100644
--- a/cdist/inventory.py
+++ b/cdist/inventory.py
@@ -92,7 +92,7 @@ class Inventory:
         self.init_db()
 
     def init_db(self):
-        self.log.trace("Init db: {}".format(self.db_basedir))
+        self.log.trace("Init db: %s", self.db_basedir)
         if not os.path.exists(self.db_basedir):
             os.makedirs(self.db_basedir, exist_ok=True)
         elif not os.path.isdir(self.db_basedir):
@@ -182,9 +182,9 @@ class Inventory:
         configuration = cfg.get_config(section='GLOBAL')
         determine_default_inventory_dir(args, configuration)
 
-        log.debug("Using inventory: {}".format(args.inventory_dir))
-        log.trace("Inventory args: {}".format(vars(args)))
-        log.trace("Inventory command: {}".format(args.subcommand))
+        log.debug("Using inventory: %s", args.inventory_dir)
+        log.trace("Inventory args: %s", vars(args))
+        log.trace("Inventory command: %s", args.subcommand)
 
         if args.subcommand == "list":
             c = InventoryList(hosts=args.host, istag=args.tag,
@@ -237,16 +237,16 @@ class InventoryList(Inventory):
     def _do_list(self, it_tags, it_hosts, check_func):
         if (it_tags is not None):
             param_tags = set(it_tags)
-            self.log.trace("param_tags: {}".format(param_tags))
+            self.log.trace("param_tags: %s", param_tags)
         else:
             param_tags = set()
         for host in it_hosts:
-            self.log.trace("host: {}".format(host))
+            self.log.trace("host: %s", host)
             tags = self._get_host_tags(host)
             if tags is None:
-                self.log.debug("Host \'{}\' not found, skipped".format(host))
+                self.log.debug("Host \'%s\' not found, skipped", host)
                 continue
-            self.log.trace("tags: {}".format(tags))
+            self.log.trace("tags: %s", tags)
             if check_func(tags, param_tags):
                 yield host, tags
 
@@ -308,11 +308,11 @@ class InventoryHost(Inventory):
 
     def _action(self, host):
         if self.action == "add":
-            self.log.debug("Adding host \'{}\'".format(host))
+            self.log.debug("Adding host \'%s\'", host)
         elif self.action == "del":
-            self.log.debug("Deleting host \'{}\'".format(host))
+            self.log.debug("Deleting host \'%s\'", host)
         hostpath = self._host_path(host)
-        self.log.trace("hostpath: {}".format(hostpath))
+        self.log.trace("hostpath: %s", hostpath)
         if self.action == "add" and not os.path.exists(hostpath):
             self._new_hostpath(hostpath)
         else:
@@ -372,23 +372,23 @@ class InventoryTag(Inventory):
             print("Host \'{}\' does not exist, skipping".format(host),
                   file=sys.stderr)
             return
-        self.log.trace("existing host_tags: {}".format(host_tags))
+        self.log.trace("existing host_tags: %s", host_tags)
         if self.action == "del" and self.all:
             host_tags = set()
         else:
             for tag in self.input_tags:
                 if self.action == "add":
-                    self.log.debug("Adding tag \'{}\' for host \'{}\'".format(
-                        tag, host))
+                    self.log.debug("Adding tag \'%s\' for host \'%s\'",
+                                   tag, host)
                     host_tags.add(tag)
                 elif self.action == "del":
-                    self.log.debug("Deleting tag \'{}\' for host "
-                                   "\'{}\'".format(tag, host))
+                    self.log.debug("Deleting tag \'%s\' for host \'%s\'",
+                                   tag, host)
                     if tag in host_tags:
                         host_tags.remove(tag)
-        self.log.trace("new host tags: {}".format(host_tags))
+        self.log.trace("new host tags: %s", host_tags)
         if not self._write_host_tags(host, host_tags):
-            self.log.trace("{} does not exist, skipped".format(host))
+            self.log.trace("%s does not exist, skipped", host)
 
     def run(self):
         if self.allhosts:
diff --git a/cdist/preos.py b/cdist/preos.py
index f8a5dd67..45711a41 100644
--- a/cdist/preos.py
+++ b/cdist/preos.py
@@ -49,7 +49,7 @@ def scan_preos_dir_plugins(dir):
                 c = cm[1]
                 yield from preos_plugin(c)
         except ImportError as e:
-            log.warning("Cannot import '{}': {}".format(module_name, e))
+            log.warning("Cannot import '%s': %s", module_name, e)
 
 
 def find_preos_plugins():
@@ -102,7 +102,7 @@ class PreOS:
         parser.add_argument('remainder_args', nargs=argparse.REMAINDER)
         args = parser.parse_args(argv[1:])
         cdist.argparse.handle_loglevel(args)
-        log.debug("preos args : {}".format(args))
+        log.debug("preos args : %s", args)
 
         conf_dirs = util.resolve_conf_dirs_from_config_and_args(args)
 
@@ -122,7 +122,7 @@ class PreOS:
                 func_args = [preos, args.remainder_args, ]
             else:
                 func_args = [args.remainder_args, ]
-            log.info("Running preos : {}".format(preos_name))
+            log.info("Running preos : %s", preos_name)
             func(*func_args)
         else:
             raise cdist.Error(
diff --git a/cdist/preos/debootstrap/debootstrap.py b/cdist/preos/debootstrap/debootstrap.py
index a20cdb9c..f1f750ee 100644
--- a/cdist/preos/debootstrap/debootstrap.py
+++ b/cdist/preos/debootstrap/debootstrap.py
@@ -166,7 +166,7 @@ class Debian:
             args.pxe_boot_dir = os.path.realpath(args.pxe_boot_dir)
 
         cdist.argparse.handle_loglevel(args)
-        log.debug("preos: {}, args: {}".format(cls._preos_name, args))
+        log.debug("preos: %s, args: %s", cls._preos_name, args)
         try:
             env = vars(args)
             new_env = {}
@@ -190,27 +190,30 @@ class Debian:
             env = new_env
             env.update(os.environ)
             cls.update_env(env)
-            log.debug("preos: {} env: {}".format(cls._preos_name, env))
+            log.debug("preos: %s env: %s", cls._preos_name, env)
+
+            if log.getEffectiveLevel() <= logging.INFO:
+                info_msg = ["Running preos: {}, suite: {}, arch: {}".format(
+                    cls._preos_name, args.suite, args.arch), ]
+                if args.mirror:
+                    info_msg.append("mirror: {}".format(args.mirror))
+                if args.script:
+                    info_msg.append("script: {}".format(args.script))
+                if args.bootstrap:
+                    info_msg.append("bootstrapping")
+                if args.configure:
+                    info_msg.append("configuring")
+                if args.pxe_boot_dir:
+                    info_msg.append("creating PXE")
+                if args.drive:
+                    info_msg.append("creating bootable drive")
+                log.info(info_msg)
+
             cmd = os.path.join(cls._files_dir, "code")
-            info_msg = ["Running preos: {}, suite: {}, arch: {}".format(
-                cls._preos_name, args.suite, args.arch), ]
-            if args.mirror:
-                info_msg.append("mirror: {}".format(args.mirror))
-            if args.script:
-                info_msg.append("script: {}".format(args.script))
-            if args.bootstrap:
-                info_msg.append("bootstrapping")
-            if args.configure:
-                info_msg.append("configuring")
-            if args.pxe_boot_dir:
-                info_msg.append("creating PXE")
-            if args.drive:
-                info_msg.append("creating bootable drive")
-            log.info(info_msg)
-            log.debug("cmd={}".format(cmd))
+            log.debug("cmd=%s", cmd)
             subprocess.check_call(cmd, env=env, shell=True)
         except subprocess.CalledProcessError as e:
-            log.error("preos {} failed: {}".format(cls._preos_name, e))
+            log.error("preos %s failed: %s", cls._preos_name, e)
 
 
 class Ubuntu(Debian):
diff --git a/cdist/scan/scan.py b/cdist/scan/scan.py
index b1d0e9e1..9a0bcc52 100644
--- a/cdist/scan/scan.py
+++ b/cdist/scan/scan.py
@@ -94,7 +94,7 @@ class Trigger(object):
 
     def trigger(self, interface):
         packet = IPv6(dst=f"ff02::1%{interface}") / ICMPv6EchoRequest()
-        log.debug(f"Sending request on {interface}")
+        log.debug("Sending request on %s", interface)
         send(packet, verbose=self.verbose)
 
 
@@ -114,7 +114,7 @@ class Scanner(object):
     def handle_pkg(self, pkg):
         if ICMPv6EchoReply in pkg:
             host = pkg['IPv6'].src
-            log.verbose(f"Host {host} is alive")
+            log.verbose("Host %s is alive", host)
 
             dir = os.path.join(self.outdir, host)
             fname = os.path.join(dir, "last_seen")
diff --git a/cdist/util/ipaddr.py b/cdist/util/ipaddr.py
index 95ca74ee..d9e5f498 100644
--- a/cdist/util/ipaddr.py
+++ b/cdist/util/ipaddr.py
@@ -42,8 +42,7 @@ def resolve_target_host_name(host, family=0):
         # gethostbyaddr returns triple
         # (hostname, aliaslist, ipaddrlist)
         host_name = socket.gethostbyaddr(ip_addr)[0]
-        log.debug("derived host_name for host \"{}\": {}".format(
-            host, host_name))
+        log.debug("derived host_name for host \"%s\": %s", host, host_name)
     except (socket.gaierror, socket.herror) as e:
         # in case of error provide empty value
         host_name = ''
@@ -54,8 +53,7 @@ def resolve_target_fqdn(host):
     log = logging.getLogger(host)
     try:
         host_fqdn = socket.getfqdn(host)
-        log.debug("derived host_fqdn for host \"{}\": {}".format(
-            host, host_fqdn))
+        log.debug("derived host_fqdn for host \"%s\": %s", host, host_fqdn)
     except socket.herror as e:
         # in case of error provide empty value
         host_fqdn = ''