Autotune directory server to use a greater number of files

This changes the system limits for the dirsrv user as well as
configuring DS to allow by default 8192 max files and 64 reserved
files (for replication indexes, etc..).

Fixes: https://fedorahosted.org/freeipa/ticket/464

install/share/Makefile.am

@@ -17,6 +17,7 @@ app_DATA =				\
 	default-keytypes.ldif		\
 	default-pwpolicy.ldif		\
 	delegation.ldif			\
+	ds-nfiles.ldif			\
 	dns.ldif			\
 	kerberos.ldif			\
 	indices.ldif			\

install/share/ds-nfiles.ldif

@@ -0,0 +1,8 @@
+dn: cn=config
+changetype: modify
+replace: nsslapd-maxdescriptors
+nsslapd-maxdescriptors: $NOFILES
+-
+replace: nsslapd-reservedescriptors
+nsslapd-reservedescriptors: 64
+-

ipaserver/install/dsinstance.py

@@ -185,10 +185,7 @@ class DsInstance(service.Service):
         else:
             self.suffix = None
 
-        if fstore:
-            self.fstore = fstore
-        else:
-            self.fstore = sysrestore.FileStore('/var/lib/ipa/sysrestore')
+        self.fstore = sysrestore.FileStore('/var/lib/ipa/sysrestore')
 
 
     def create_instance(self, ds_user, realm_name, fqdn, domain_name,
@@ -239,6 +236,7 @@ class DsInstance(service.Service):
             self.step("creating default HBAC rule allow_all", self.add_hbac)
         self.step("enabling compatibility plugin",
                   self.__enable_compat_plugin)
+        self.step("tuning directory server", self.__tuning)
 
         self.step("configuring directory to start on boot", self.__enable)
 
@@ -532,6 +530,7 @@ class DsInstance(service.Service):
             self.stop()
 
         try:
+            self.fstore.restore_file("/etc/security/limits.conf")
             self.fstore.restore_file("/etc/sysconfig/dirsrv")
         except ValueError, error:
             logging.debug(error)
@@ -603,3 +602,66 @@ class DsInstance(service.Service):
         self.start()
 
         return status
+
+    def tune_nofile(self, num=8192):
+        """
+        Increase the number of files descriptors available to directory server
+        from the default 1024 to 8192. This will allow to support a greater
+        number of clients out of the box.
+        """
+
+        # check limits.conf
+        need_limits = True
+        fd = open("/etc/security/limits.conf", "r")
+        lines = fd.readlines()
+        fd.close()
+        for line in lines:
+            sline = line.strip()
+            if not sline.startswith(self.ds_user):
+                continue
+            if sline.find('nofile') == -1:
+                continue
+            # ok we already have an explicit entry for user/nofile
+            need_limits = False
+
+        # check sysconfig/dirsrv
+        need_sysconf = True
+        fd = open("/etc/sysconfig/dirsrv", "r")
+        lines = fd.readlines()
+        fd.close()
+        for line in lines:
+            sline = line.strip()
+            if not sline.startswith('ulimit'):
+                continue
+            if sline.find('-n') == -1:
+                continue
+            # ok we already have an explicit entry for file limits
+            need_sysconf = False
+
+        #if sysconf or limits are set avoid messing up and defer to the admin
+        if need_sysconf and need_limits:
+            self.fstore.backup_file("/etc/security/limits.conf")
+            fd = open("/etc/security/limits.conf", "a+")
+            fd.write('%s\t\t-\tnofile\t\t%s\n' % (self.ds_user, str(num)))
+            fd.close()
+
+            fd = open("/etc/sysconfig/dirsrv", "a+")
+            fd.write('ulimit -n %s\n' % str(num))
+            fd.close()
+
+        else:
+            logging.info("Custom file limits are already set! Skipping\n")
+            print "Custom file limits are already set! Skipping\n"
+            return
+
+        # finally change also DS configuration
+        # NOTE: dirsrv will not allow you to set max file descriptors unless
+        # the user limits allow it, so we have to restart dirsrv before
+        # attempting to change them in cn=config
+        self.__restart_instance()
+
+        nf_sub_dict = dict(NOFILES=str(num))
+        self._ldap_mod("ds-nfiles.ldif", nf_sub_dict)
+
+    def __tuning(self):
+        self.tune_nofile(8192)