nixvirt-module-helper: only redefine the config when the settings is new

modules.nix

@@ -122,7 +122,7 @@ let
                 jsonFile = packages.writeText "nixvirt module script" (builtins.toJSON opts);
                 verboseFlag = if cfg.verbose then "-v" else "";
               in
-              "${moduleHelperFile} ${verboseFlag} --connect ${connection} ${jsonFile}\n";
+              "${moduleHelperFile} ${verboseFlag} --statedir /var/lib/nixvirt --connect ${connection} ${jsonFile}\n";
 
             extraPackages = [ packages.qemu-utils ] ++ (if cfg.swtpm.enable then [ packages.swtpm ] else [ ]);
             extraPaths = concatStrMap (p: "${p}/bin:") extraPackages;

tool/nixvirt-module-helper

@@ -1,19 +1,49 @@
 #!/usr/bin/python3
-import sys, argparse, uuid, lxml.etree, json, libvirt, nixvirt
+import sys, argparse, uuid, lxml.etree, json, libvirt, nixvirt, os
 
 parser = argparse.ArgumentParser(prog='nixvirt-module-helper',description='Define and control a collection of libvirt objects idempotently.')
 parser.add_argument('-v', '--verbose', action='store_true', help='report actions to stderr')
 parser.add_argument('--connect', action='store', required=True, metavar='URI', help='connection URI (e.g. qemu:///session)')
+parser.add_argument('--statedir', action='store', required=True, metavar='PATH', help='state dir (e.g. /var/lib/nixvirt)')
 parser.add_argument('settingspath', action='store', metavar='PATH', help='path to JSON file of settings')
 args = parser.parse_args()
+types = [("network","networks"),("pool","pools"),("domain","domains")]
+
+if not os.path.exists(args.statedir):
+    os.makedirs(args.statedir)
 
 with open(args.settingspath,"r") as f:
-    settings = json.load(f)
+    newSettings = json.load(f)
+
+# save newSettings as json since we will edit it
+newSettingsStr = json.dumps(newSettings)
+
+oldSettingsPath = os.path.join(args.statedir, "oldsettings.json")
+if os.path.isfile(oldSettingsPath):
+    with open(oldSettingsPath, "r") as f:
+        oldSettings = json.load(f)
+else:
+    oldSettings = {}
+
+settings = {}
+
+for (type,key) in types:
+    newItemlist = newSettings.get(key)
+    oldItemlist = oldSettings.get(key)
+    if newItemlist is None or oldItemlist is None:
+        continue
+    else:
+        for newItem in newItemlist:
+            # tag it with "unchanged"
+            if oldItemlist.__contains__(newItem):
+                newItem["unchanged"] = True
+    settings[key] = newItemlist
+
 
 class TypeSpec:
     def __init__(self,session,type,itemlist):
         self.oc = nixvirt.getObjectConnection(session,type)
-        self.specList = [nixvirt.ObjectSpec.fromDefinitionFile(self.oc,item["definition"],item.get("active"),item) for item in itemlist]
+        self.specList = [nixvirt.ObjectSpec.fromDefinitionFile(self.oc,item["definition"],item.get("active"),item.get("unchanged"),item) for item in itemlist]
 
     def deleteOld(self):
         allObjects = self.oc.getAll()
@@ -39,8 +69,6 @@ class TypeSpec:
 try:
     session = nixvirt.Session(args.connect,args.verbose)
 
-    types = [("network","networks"),("pool","pools"),("domain","domains")]
-
     session.vreport("Examining settings")
     typeSpecs = []
     for (type,key) in types:
@@ -68,6 +96,10 @@ try:
     for typeSpec in typeSpecs:
         typeSpec.setActive()
 
+    # save the new Settings
+    with open(oldSettingsPath, "w") as f:
+        f.write(newSettingsStr)
+
     session.vreport("Done")
 
 except nixvirt.NixVirtError as err:

tool/nixvirt.py

@@ -309,7 +309,7 @@ def defineExtra(self,extra):
 # what we want for an object
 class ObjectSpec:
 
-    def __init__(self,oc,specUUID = None,specName = None,specDefXML = None,active = None,extra = None):
+    def __init__(self,oc,specUUID = None,specName = None,specDefXML = None,active = None, unchanged = None, extra = None):
         if specUUID is not None:
             self.subject = oc.fromUUIDOrNone(specUUID)
         elif specName is not None:
@@ -327,6 +327,7 @@ def __init__(self,oc,specUUID = None,specName = None,specDefXML = None,active =
         self.specName = specName
         self.specUUID = specUUID
         self.active = active
+        self.unchanged = unchanged
         self.extra = extra
 
     def vreport(self,msg):
@@ -338,20 +339,22 @@ def fromUUID(oc,specUUID,active):
     def fromName(oc,specName,active):
         return ObjectSpec(oc,specName = specName,active = active)
 
-    def fromDefinition(oc,specDefXML,active,extra = None):
+    def fromDefinition(oc,specDefXML,active,unchanged,extra = None):
         specDefETree = xmlToETree(specDefXML)
         specUUID = uuid.UUID(specDefETree.find("uuid").text).bytes
         specName = specDefETree.find("name").text
         fixedDefETree = oc._fixDefinitionETree(specUUID,specDefETree)
         if fixedDefETree is not None:
             specDefXML = eTreeToXML(fixedDefETree)
-        return ObjectSpec(oc,specUUID = specUUID,specName = specName,specDefXML = specDefXML,active = active, extra = extra)
+        return ObjectSpec(oc,specUUID = specUUID,specName = specName,specDefXML = specDefXML,active = active, unchanged = unchanged, extra = extra)
 
-    def fromDefinitionFile(oc,path,active,extra = None):
+    def fromDefinitionFile(oc,path,active,unchanged,extra = None):
         specDefXML = oc.getFile(path)
-        return ObjectSpec.fromDefinition(oc,specDefXML,active, extra = extra)
+        return ObjectSpec.fromDefinition(oc,specDefXML,active,unchanged,extra = extra)
 
     def define(self):
+        if self.unchanged:
+            return
         if self.specDefXML is not None:
             if self.subject is not None:
                 oldDefETree = self.subject.descriptionETree()
@@ -377,8 +380,12 @@ def define(self):
                 self.subject = self.oc._fromXML(self.specDefXML)
 
     def defineExtra(self):
+        if self.unchanged:
+            return
         if self.subject is not None:
             self.subject.defineExtra(self.extra)
 
     def setActive(self):
+        if self.unchanged:
+            return
         self.subject.setActive(self.active)