[#104,!290] kea-dhcpv6 now supports fetching config from backends

    Infrastructure has been added to kea-dhcp6 such that it can
    now be configured to fetch full and then periodic updates
    from config backends.

    Merging the actual fetched content will be done under subsequent
    issues.

src/bin/dhcp6
    ctrl_dhcp6_srv.*
        - ControlledDhcpv6Srv::processConfig() - added logic to schedule CB update timer
        - ControlledDhcpv6Srv::cbFetchUpdates() - new callback function for CB updates

    dhcp6_lexer.ll
    dhcp6_parser.yy
        -  Added config-fetch-wait-time

    dhcp6_messages.mes
        -  New log messages

    dhcp6_srv.*
        - Dhcpv6Srv::cb_control_  - new member for config backend access
        - Dhcpv6Srv::inTestMode() - new function to test for unit test mode

    json_config_parser.cc
        - configureDhcp6Server() - invokes full fetch from config backend

src/bin/dhcp6/tests
    config_backend_unittest.cc - new file/tests for config backend testing
    config_parser_unittest.cc - updated
    get_config_unittest.cc - rebuild tests
    kea_controller_unittest.cc - added CB control/timer tests

src/lib/dhcpsrv/
    dhcpsrv_messages.mes - added log message
	cb_ctl_dhcp6.* - new files that provide v6 impl of config backend controller

doc/examples/kea6/all-keys-current.json - added config-fetch-wait-time

6 files changed, 146 insertions, 2 deletions

diff --git a/src/lib/dhcpsrv/Makefile.am b/src/lib/dhcpsrv/Makefile.am
index 4c862958ff..ab5b800333 100644
--- a/src/lib/dhcpsrv/Makefile.am
+++ b/src/lib/dhcpsrv/Makefile.am
@@ -68,6 +68,7 @@ libkea_dhcpsrv_la_SOURCES += cache_host_data_source.h
 libkea_dhcpsrv_la_SOURCES += callout_handle_store.h
 libkea_dhcpsrv_la_SOURCES += cb_ctl_dhcp.h
 libkea_dhcpsrv_la_SOURCES += cb_ctl_dhcp4.cc cb_ctl_dhcp4.h
+libkea_dhcpsrv_la_SOURCES += cb_ctl_dhcp6.cc cb_ctl_dhcp6.h
 libkea_dhcpsrv_la_SOURCES += cfg_4o6.cc cfg_4o6.h
 libkea_dhcpsrv_la_SOURCES += cfg_consistency.cc cfg_consistency.h
 libkea_dhcpsrv_la_SOURCES += cfg_db_access.cc cfg_db_access.h
diff --git a/src/lib/dhcpsrv/cb_ctl_dhcp6.cc b/src/lib/dhcpsrv/cb_ctl_dhcp6.cc
new file mode 100644
index 0000000000..b379e80e18
--- /dev/null
+++ b/src/lib/dhcpsrv/cb_ctl_dhcp6.cc
@@ -0,0 +1,85 @@
+// Copyright (C) 2019 Internet Systems Consortium, Inc. ("ISC")
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#include <config.h>
+#include <dhcpsrv/cb_ctl_dhcp6.h>
+#include <dhcpsrv/cfgmgr.h>
+#include <dhcpsrv/dhcpsrv_log.h>
+
+using namespace isc::data;
+using namespace isc::process;
+
+namespace isc {
+namespace dhcp {
+
+void
+CBControlDHCPv6::databaseConfigApply(const db::BackendSelector& backend_selector,
+                                     const db::ServerSelector& server_selector,
+                                     const boost::posix_time::ptime& lb_modification_time,
+                                     const db::AuditEntryCollection& audit_entries) {
+    // Create the external config into which we'll fetch backend config data.
+    SrvConfigPtr external_cfg = CfgMgr::instance().createExternalCfg();
+
+    // First let's fetch the globals and add them to external config.
+    if (fetchConfigElement(audit_entries, "dhcp6_global_parameter")) {
+        data::StampedValueCollection globals;
+        globals = getMgr().getPool()->getModifiedGlobalParameters6(backend_selector, server_selector,
+                                                                   lb_modification_time);
+        addGlobalsToConfig(external_cfg, globals);
+    }
+
+    // Now we fetch the option definitions and add them.
+    if (fetchConfigElement(audit_entries, "dhcp6_option_def")) {
+        OptionDefContainer option_defs =
+            getMgr().getPool()->getModifiedOptionDefs6(backend_selector, server_selector,
+                                                       lb_modification_time);
+        for (auto option_def = option_defs.begin(); option_def != option_defs.end(); ++option_def) {
+            external_cfg->getCfgOptionDef()->add((*option_def), (*option_def)->getOptionSpaceName());
+        }
+    }
+
+    // Next fetch the options. They are returned as a container of OptionDescriptors.
+    if (fetchConfigElement(audit_entries, "dhcp6_options")) {
+        OptionContainer options = getMgr().getPool()->getModifiedOptions6(backend_selector,
+                                                                          server_selector,
+                                                                          lb_modification_time);
+        for (auto option = options.begin(); option != options.end(); ++option) {
+            external_cfg->getCfgOption()->add((*option), (*option).space_name_);
+        }
+    }
+
+    // Now fetch the shared networks.
+    if (fetchConfigElement(audit_entries, "dhcp6_shared_network")) {
+        SharedNetwork6Collection networks =
+            getMgr().getPool()->getModifiedSharedNetworks6(backend_selector, server_selector,
+                                                           lb_modification_time);
+        for (auto network = networks.begin(); network != networks.end(); ++network) {
+            external_cfg->getCfgSharedNetworks6()->add((*network));
+        }
+    }
+
+    // Next we fetch subnets.
+    if (fetchConfigElement(audit_entries, "dhcp6_subnet")) {
+        Subnet6Collection subnets = getMgr().getPool()->getModifiedSubnets6(backend_selector,
+                                                                            server_selector,
+                                                                            lb_modification_time);
+        for (auto subnet = subnets.begin(); subnet != subnets.end(); ++subnet) {
+            external_cfg->getCfgSubnets6()->add((*subnet));
+        }
+    }
+
+    if (audit_entries.empty()) {
+        CfgMgr::instance().mergeIntoStagingCfg(external_cfg->getSequence());
+
+    } else {
+        CfgMgr::instance().mergeIntoCurrentCfg(external_cfg->getSequence());
+    }
+    LOG_INFO(dhcpsrv_logger, DHCPSRV_CFGMGR_CONFIG6_MERGED);
+}
+
+
+} // end of namespace isc::dhcp
+} // end of namespace isc
diff --git a/src/lib/dhcpsrv/cb_ctl_dhcp6.h b/src/lib/dhcpsrv/cb_ctl_dhcp6.h
new file mode 100644
index 0000000000..4817556540
--- /dev/null
+++ b/src/lib/dhcpsrv/cb_ctl_dhcp6.h
@@ -0,0 +1,50 @@
+// Copyright (C) 2019 Internet Systems Consortium, Inc. ("ISC")
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#ifndef CB_CTL_DHCP6_H
+#define CB_CTL_DHCP6_H
+
+#include <dhcpsrv/cb_ctl_dhcp.h>
+#include <dhcpsrv/config_backend_dhcp6_mgr.h>
+#include <dhcpsrv/srv_config.h>
+
+namespace isc {
+namespace dhcp {
+
+/// @brief Implementation of the mechanisms to control the use of
+/// the Configuration Backends by the DHCPv6 server.
+///
+/// It implements fetching and merging DHCPv6 server configuration from
+/// the database into the staging or current configuration.
+///
+/// @tparam ConfigBackendMgrType Type of the Config Backend Manager used
+/// by the server implementing this class. For example, for the DHCPv6
+/// server it will be @c ConfigBackendDHCPv6Mgr.
+class CBControlDHCPv6 : public CBControlDHCP<ConfigBackendDHCPv6Mgr> {
+protected:
+
+    /// @brief DHCPv6 server specific method to fetch and apply back end
+    /// configuration into the local configuration.
+    ///
+    /// @param backend_selector Backend selector.
+    /// @param server_selector Server selector.
+    /// @param lb_modification_time Lower bound modification time for the
+    /// configuration elements to be fetched.
+    /// @param audit_entries Audit entries fetched from the database since
+    /// the last configuration update. This collection is empty if there
+    /// were no updates.
+    virtual void databaseConfigApply(const db::BackendSelector& backend_selector,
+                                     const db::ServerSelector& server_selector,
+                                     const boost::posix_time::ptime& lb_modification_time,
+                                     const db::AuditEntryCollection& audit_entries);
+};
+
+typedef boost::shared_ptr<CBControlDHCPv6> CBControlDHCPv6Ptr;
+
+} // end of namespace isc::dhcp
+} // end of namespace isc
+
+#endif // CB_CTL_DHCP6_H
diff --git a/src/lib/dhcpsrv/dhcpsrv_messages.cc b/src/lib/dhcpsrv/dhcpsrv_messages.cc
index 0b33bf120e..a45a3b988e 100644
--- a/src/lib/dhcpsrv/dhcpsrv_messages.cc
+++ b/src/lib/dhcpsrv/dhcpsrv_messages.cc
@@ -1,4 +1,4 @@
-// File created from ../../../src/lib/dhcpsrv/dhcpsrv_messages.mes on Tue Mar 19 2019 10:19
+// File created from ../../../src/lib/dhcpsrv/dhcpsrv_messages.mes on Tue Mar 26 2019 13:08
 
 #include <cstddef>
 #include <log/message_types.h>
@@ -14,6 +14,7 @@ extern const isc::log::MessageID DHCPSRV_CFGMGR_ALL_IFACES_ACTIVE = "DHCPSRV_CFG
 extern const isc::log::MessageID DHCPSRV_CFGMGR_CFG_DHCP_DDNS = "DHCPSRV_CFGMGR_CFG_DHCP_DDNS";
 extern const isc::log::MessageID DHCPSRV_CFGMGR_CLEAR_ACTIVE_IFACES = "DHCPSRV_CFGMGR_CLEAR_ACTIVE_IFACES";
 extern const isc::log::MessageID DHCPSRV_CFGMGR_CONFIG4_MERGED = "DHCPSRV_CFGMGR_CONFIG4_MERGED";
+extern const isc::log::MessageID DHCPSRV_CFGMGR_CONFIG6_MERGED = "DHCPSRV_CFGMGR_CONFIG6_MERGED";
 extern const isc::log::MessageID DHCPSRV_CFGMGR_CONFIGURE_SERVERID = "DHCPSRV_CFGMGR_CONFIGURE_SERVERID";
 extern const isc::log::MessageID DHCPSRV_CFGMGR_DEL_SUBNET4 = "DHCPSRV_CFGMGR_DEL_SUBNET4";
 extern const isc::log::MessageID DHCPSRV_CFGMGR_DEL_SUBNET6 = "DHCPSRV_CFGMGR_DEL_SUBNET6";
@@ -245,6 +246,7 @@ const char* values[] = {
     "DHCPSRV_CFGMGR_CFG_DHCP_DDNS", "Setting DHCP-DDNS configuration to: %1",
     "DHCPSRV_CFGMGR_CLEAR_ACTIVE_IFACES", "stop listening on all interfaces",
     "DHCPSRV_CFGMGR_CONFIG4_MERGED", "Configuration backend data has been merged.",
+    "DHCPSRV_CFGMGR_CONFIG6_MERGED", "Configuration backend data has been merged.",
     "DHCPSRV_CFGMGR_CONFIGURE_SERVERID", "server configuration includes specification of a server identifier",
     "DHCPSRV_CFGMGR_DEL_SUBNET4", "IPv4 subnet %1 removed",
     "DHCPSRV_CFGMGR_DEL_SUBNET6", "IPv6 subnet %1 removed",
diff --git a/src/lib/dhcpsrv/dhcpsrv_messages.h b/src/lib/dhcpsrv/dhcpsrv_messages.h
index b9bc955029..3a421e3dd1 100644
--- a/src/lib/dhcpsrv/dhcpsrv_messages.h
+++ b/src/lib/dhcpsrv/dhcpsrv_messages.h
@@ -1,4 +1,4 @@
-// File created from ../../../src/lib/dhcpsrv/dhcpsrv_messages.mes on Tue Mar 19 2019 10:19
+// File created from ../../../src/lib/dhcpsrv/dhcpsrv_messages.mes on Tue Mar 26 2019 13:08
 
 #ifndef DHCPSRV_MESSAGES_H
 #define DHCPSRV_MESSAGES_H
@@ -15,6 +15,7 @@ extern const isc::log::MessageID DHCPSRV_CFGMGR_ALL_IFACES_ACTIVE;
 extern const isc::log::MessageID DHCPSRV_CFGMGR_CFG_DHCP_DDNS;
 extern const isc::log::MessageID DHCPSRV_CFGMGR_CLEAR_ACTIVE_IFACES;
 extern const isc::log::MessageID DHCPSRV_CFGMGR_CONFIG4_MERGED;
+extern const isc::log::MessageID DHCPSRV_CFGMGR_CONFIG6_MERGED;
 extern const isc::log::MessageID DHCPSRV_CFGMGR_CONFIGURE_SERVERID;
 extern const isc::log::MessageID DHCPSRV_CFGMGR_DEL_SUBNET4;
 extern const isc::log::MessageID DHCPSRV_CFGMGR_DEL_SUBNET6;
diff --git a/src/lib/dhcpsrv/dhcpsrv_messages.mes b/src/lib/dhcpsrv/dhcpsrv_messages.mes
index 56a500a5a7..810d695f21 100644
--- a/src/lib/dhcpsrv/dhcpsrv_messages.mes
+++ b/src/lib/dhcpsrv/dhcpsrv_messages.mes
@@ -36,6 +36,11 @@ This is an informational message emitted when the DHCPv4 server has
 successfully merged configuration data retrieved from its configuration
 backends into the current configuration.
 
+% DHCPSRV_CFGMGR_CONFIG6_MERGED Configuration backend data has been merged.
+This is an informational message emitted when the DHCPv6 server has
+successfully merged configuration data retrieved from its configuration
+backends into the current configuration.
+
 % DHCPSRV_CFGMGR_CONFIGURE_SERVERID server configuration includes specification of a server identifier
 This warning message is issued when the server specified configuration of
 a server identifier. If this new configuration overrides an existing