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@@ -85,25 +85,46 @@
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</para>
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<para>
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- If you want to specify logging for one specific library within a
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- daemon, you set the name to
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- <replaceable>daemon.library</replaceable>. For example, the logger
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- used by the code from libdhcpsrv used in kea-dhcp4 binary has the
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- full name of <quote>kea-dhcp4.dhcpsrv</quote>. If there is no entry
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- in Logging for a particular library, it will use the configuration
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- given for the whole daemon.
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+ When diagnosing the problem with the server's operation it is often
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+ desired to use the DEBUG logging level to obtain the verbose output
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+ from the server and libraries it uses. However, high verbosity may
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+ be an overkill for the logging system in cases when the server
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+ is processing high volume traffic. To mitigate this problem, Kea
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+ is using multiple loggers, which can be configured independently
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+ and which are responsible for logging messages from different
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+ functional parts of the server. If the user, trying to diagnose the
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+ problem, has a reasonably high confidence that the problem origins
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+ in a specific function of the server, or the problem is related
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+ to the specific type of operation, he may enable high verbosity
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+ only for the relevant logger, thus limiting the debug messages
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+ to the required minimum.
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</para>
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<para>
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- To illustrate this, suppose you want the dhcpsrv library
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- to log messages of severity DEBUG, and the rest of the
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- DHCPv4 server code to log messages of severity INFO. To achieve
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- this you specify two loggers, one with the name
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- <quote>kea-dhcp4</quote> and severity INFO, and one with
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- the name <quote>kea-dhcp4.dhcpsrv</quote> with severity
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- DEBUG. As there are no entries for other libraries,
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- they will use the configuration for the daemon
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- (<quote>kea-dhcp4</quote>), so giving the desired behavior.
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+ The loggers are associated with a particular library or binary
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+ of Kea. However, each library or binary may (and usually does)
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+ include multiple loggers. For example, the DHCPv4 server binary
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+ contains separate loggers for: packet parsing, for dropped packets,
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+ for callouts etc. Each logger "derives" its configuration from the
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+ root logger. In the typical case, the root logger configuration
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+ is the only logging configuration specified in the configuration
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+ file. Creating a specific configuration for the selected logger,
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+ thus overriding the configuration settings specified in the
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+ root logger configuration, requires putting its configuration
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+ aside of the root logger's configuration with some of the
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+ parameters modified.
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+ </para>
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+
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+ <para>
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+ To illustrate this, suppose you are using the DHCPv4 server
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+ with the root logger <quote>kea-dhcp4</quote> logging at the
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+ INFO level. In order to enable DEBUG verbosity for the DHCPv4
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+ packet drops, you must create configuration entry for the
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+ logger called <quote>kea-dhcp4.bad_packet</quote> and specify
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+ severity DEBUG for this logger. All other configuration
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+ parameters may be omited for this logger if the logger should
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+ use the default values specified in the root logger's
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+ configuration.
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</para>
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<!-- we don't support asterisk anymore.
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@@ -129,21 +150,6 @@
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</para>
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<para>
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- One final note about the naming. When specifying the daemon name
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- within a logger, use the name of the binary file,
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- e.g. <quote>kea-dhcp4</quote> for the DHCPv4 server,
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- <quote>kea-dhcp6</quote> for the DHCPv6 server, etc. When the
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- message is logged, the message will include the name of the process
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- (e.g. <quote>kea-dhcp4</quote>) followed by the specific component
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- in that process, e.g. <quote>hooks</quote>. It is possible to
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- specify either just the process name (<quote>kea-dhcp4</quote>, will
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- apply to everything logged within that process) or process name
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- followed by specific logger,
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- e.g. <quote>kea-dhcp4.hooks</quote>. That will apply only to
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- messages originating from that component.
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- </para>
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-
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- <para>
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Currently defined loggers are:
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</para>
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@@ -158,7 +164,7 @@
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<simpara><command>kea-dhcp4.bad_packet</command> - this is the
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logger used by the DHCPv4 server deamon for logging inbound client
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packets that were dropped or to which the server responded with a
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- NAK. The allows adminstrators to configure a separate log
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+ DHCPNAK. The allows adminstrators to configure a separate log
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output that contains only packet drop and reject entries.</simpara>
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</listitem>
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<listitem>
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@@ -174,8 +180,18 @@
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</listitem>
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<listitem>
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<simpara><command>kea-dhcp4.hooks</command> - this logger is used
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- during DHCPv4 hooks operation, i.e. anything related to user
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- libraries will be logged using this logger.</simpara>
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+ by the hooks framework to log messages related to the execution of
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+ callouts for various hook points. This logger doesn't log messages
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+ which pertain to actions on the server side being the result of
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+ the callout execution, e.g. skipping packet parsing by the server
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+ because the callout has indicated that it has parsed the packet
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+ already.</simpara>
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+ </listitem>
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+ <listitem>
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+ <simpara><command>kea-dhcp4.hostname</command> - this logger is
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+ used by the DHCPv4 server to log messages related to the Client
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+ FQDN and Hostname option processing. It also includes log messages
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+ related to the relevant DNS updates.</simpara>
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</listitem>
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<listitem>
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<simpara><command>kea-dhcp4.hosts</command> - this logger is used
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@@ -184,6 +200,42 @@
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and adding new reservations.</simpara>
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</listitem>
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<listitem>
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+ <simpara><command>kea-dhcp4.lease</command> - this logger is used
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+ by the DHCPv4 server to log messages related to the lease allocation.
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+ These messages are logged for each processed packet. The messages
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+ include detailed information about the allocated or offered leases,
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+ errors during the lease allocation etc.
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+ </simpara>
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+ </listitem>
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+ <listitem>
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+ <simpara><command>kea-dhcp4.options</command> - this logger is
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+ used by the DHCPv4 server to log messages related to processing
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+ of the options in the DHCPv4 messages, i.e. parsing options,
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+ encoding options into on-wire format and packet classification
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+ using options contained in the received packets.</simpara>
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+ </listitem>
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+ <listitem>
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+ <simpara><command>kea-dhcp4.packet</command> - this logger
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+ is mostly used to log messages related to transmission of the DHCPv4
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+ packets, i.e. packet reception and sending a response. Such messages
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+ include the information about the source and destination IP addresses
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+ and interfaces used to transmit packets. This logger is also used
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+ to log messages related to subnet selection, as this selection is
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+ usually based on the IP addresses and/or interface names, which can
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+ be retrieved from the received packet, even before the DHCPv4 message
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+ carried in the packet is parsed.
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+ </simpara>
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+ </listitem>
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+ <listitem>
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+ <simpara><command>kea-dhcp4.server-hook</command> - this logger is
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+ used by the DHCPv4 server to log messages pertaining to the
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+ preparations for the callouts execution by the server and to the
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+ actions taken by the server as a result of the callouts execution.
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+ Note that it is a different logger than the
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+ <command>kea-dhcp4.hooks</command> logger.
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+ </simpara>
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+ </listitem>
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+ <listitem>
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<simpara><command>kea-dhcp6</command> - this is the root logger for
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the DHCPv6 server. All components used by the DHCPv6 server inherit
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the settings from this logger if there is no specialized logger
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@@ -202,8 +254,12 @@
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</listitem>
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<listitem>
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<simpara><command>kea-dhcp6.hooks</command> - this logger is used
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- during DHCPv6 hooks operation, i.e. anything related to user
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- libraries will be logged using this logger.</simpara>
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+ by the hooks framework to log messages related to the execution of
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+ callouts for various hook points. This logger doesn't log messages
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+ which pertain to actions on the server side being the result of
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+ the callout execution, e.g. skipping packet parsing by the server
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+ because the callout has indicated that it has parsed the packet
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+ already.</simpara>
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</listitem>
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<listitem>
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<simpara><command>kea-dhcp6.hosts</command> - this logger is used
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Marcin Siodelski