The following configuration parameters are defined for the Kernel
application. For more information about configuration parameters, see file
app(5).
- connect_all
= true | false:
- If enabled (true), which also is the default, global(3erl)
will actively connect to all nodes that becomes known to it. Note that you
also want to enable prevent_overlapping_partitions in order for
global to ensure that a fully connected network is maintained.
prevent_overlapping_partitions will also prevent inconsistencies in
global's name registration and locking.
The now deprecated command line argument -connect_all
<boolean> has the same effect as the connect_all
configuration parameter. If this configuration parameter is defined, it will
override the command line argument.
- distributed
= [Distrib]:
- Specifies which applications that are distributed and on which nodes they
are allowed to execute. In this parameter:
- *
- Distrib = {App,Nodes} | {App,Time,Nodes}
- *
- App = atom()
- *
- Time = integer()>0
- *
- Nodes = [node() | {node(),...,node()}]
The parameter is described in application:load/2.
- dist_auto_connect
= Value:
- Specifies when nodes are automatically connected. If this parameter is not
specified, a node is always automatically connected, for example, when a
message is to be sent to that node. Value is one of:
- never:
- Connections are never automatically established, they must be explicitly
connected. See net_kernel(3erl).
- once:
- Connections are established automatically, but only once per node. If a
node goes down, it must thereafter be explicitly connected. See
net_kernel(3erl).
- permissions
= [Perm]:
- Specifies the default permission for applications when they are started.
In this parameter:
- *
- Perm = {ApplName,Bool}
- *
- ApplName = atom()
- *
- Bool = boolean()
Permissions are described in application:permit/2.
- logger =
[Config]:
- Specifies the configuration for Logger, except the primary log level,
which is specified with logger_level, and the compatibility with
SASL Error Logging, which is specified with
logger_sasl_compatible.
The logger parameter is described in section Logging in
the Kernel User's Guide.
- logger_level
= Level:
- Specifies the primary log level for Logger. Log events with the same, or a
more severe level, pass through the primary log level check. See section
Logging in the Kernel User's Guide for more information about Logger and
log levels.
Level = emergency | alert | critical | error | warning | notice
| info | debug | all | none
To change the primary log level at runtime, use
logger:set_primary_config(level, Level).
- logger_metadata
= Metadata:
- Specifies primary metadata for log events.
- logger_sasl_compatible
= true | false:
- Specifies if Logger behaves backwards compatible with the SASL error
logging functionality from releases prior to Erlang/OTP 21.0.
If this parameter is set to true, the default Logger
handler does not log any progress-, crash-, or supervisor reports. If the
SASL application is then started, it adds a Logger handler named
sasl, which logs these events according to values of the SASL
configuration parameter sasl_error_logger and
sasl_errlog_type.
See section Deprecated Error Logger Event Handlers and
Configuration in the sasl(7) manual page for information about the SASL
configuration parameters.
See section SASL Error Logging in the SASL User's Guide, and
section Backwards Compatibility with error_logger in the Kernel User's Guide
for information about the SASL error logging functionality, and how Logger
can be backwards compatible with this.
Note:
If this parameter is set to
true,
sasl_errlog_type indicates that
progress reports shall be logged, and the configured primary log level is
notice or more severe, then SASL automatically sets the primary log
level to
info. That is, this setting can potentially overwrite the
value of the Kernel configuration parameter
logger_level. This is to
allow progress reports, which have log level
info, to be forwarded to
the handlers.
- global_groups
= [GroupTuple]:
- Defines global groups, see global_group(3erl). In this
parameter:
- *
- GroupTuple = {GroupName, [Node]} | {GroupName, PublishType,
[Node]}
- *
- GroupName = atom()
- *
- PublishType = normal | hidden
- *
- Node = node()
- inet_default_connect_options
= [{Opt, Val}]:
- Specifies default options for connect sockets, see
inet(3erl).
- inet_default_listen_options
= [{Opt, Val}]:
- Specifies default options for listen (and accept) sockets,
see inet(3erl).
- inet_dist_use_interface
= ip_address():
- If the host of an Erlang node has many network interfaces, this parameter
specifies which one to listen on. For the type definition of
ip_address(), see inet(3erl).
- inet_dist_listen_min
= First
-
inet_dist_listen_max = Last: Defines the First..Last port
range for the listener socket of a distributed Erlang node.
- inet_dist_listen_options
= Opts:
- Defines a list of extra socket options to be used when opening the
listening socket for a distributed Erlang node. See
gen_tcp:listen/2.
- inet_dist_connect_options
= Opts:
- Defines a list of extra socket options to be used when connecting to other
distributed Erlang nodes. See gen_tcp:connect/4.
- inet_parse_error_log
= silent:
- If set, no log events are issued when erroneous lines are found and
skipped in the various Inet configuration files.
- inetrc =
Filename:
- The name (string) of an Inet user configuration file. For details, see
section Inet Configuration in the ERTS User's Guide.
- net_setuptime
= SetupTime:
-
SetupTime must be a positive integer or floating point
number, and is interpreted as the maximum allowed time for each network
operation during connection setup to another Erlang node. The maximum
allowed value is 120. If higher values are specified, 120 is
used. Default is 7 seconds if the variable is not specified, or if the value
is incorrect (for example, not a number).
Notice that this value does not limit the total connection setup
time, but rather each individual network operation during the connection
setup and handshake.
- net_ticker_spawn_options
= Opts:
- Defines a list of extra spawn options for net ticker processes. There
exist one such process for each connection to another node. A net ticker
process is responsible for supervising the connection it is associated
with. These processes also execute the distribution handshake protocol
when setting up connections. When there is a large number of distribution
connections, setting up garbage collection options can be helpful to
reduce memory usage. Default is [link, {priority, max}], and these
two options cannot be changed. The monitor and {monitor,
MonitorOpts} options are not allowed and will be dropped if present.
See the documentation of the erlang:spawn_opt/4 BIF for information
about valid options. If the Opts list is not a proper list, or
containing invalid options the setup of connections will fail.
Note that the behavior described above is only true if the
distribution carrier protocol used is implemented as described in ERTS
User's Guide ➜ How to implement an Alternative Carrier for the Erlang
Distribution ➜ Distribution Module without further alterations. The
implementer of the distribution carrier protocol used, may have chosen to
ignore the net_ticker_spawn_options parameter or altered its
behavior. Currently all distribution modules shipped with OTP do, however,
behave as described above.
- net_tickintensity
= NetTickIntensity:
- Net tick intensity specifies how many ticks to send during a net
tick time period when no other data is sent over a connection to another
node. This also determines how often to check for data from the other
node. The higher net tick intensity, the closer to the chosen net tick
time period the node will detect an unresponsive node. The net tick
intensity defaults to 4. The value of NetTickIntensity
should be an integer in the range 4..1000. If the
NetTickIntensity is not an integer or an integer less than
4, 4 will silently be used. If NetTickIntensity is an
integer larger than 1000, 1000 will silently be used.
Note:
Note that all communicating nodes are expected to use the same
net tick
intensity as well as the same
net tick time .
Warning:
Be careful not to set a too high net tick intensity, since you can overwhelm the
node with work if it is set too high.
- net_ticktime
= NetTickTime:
- Specifies the net tick time in seconds. This is the approximate
time a connected node may be unresponsive until it is considered down and
thereby disconnected.
Net tick time together with net tick intensity determines an
interval TickInterval = NetTickTime/NetTickIntensity. Once every
TickInterval seconds, each connected node is ticked if nothing has
been sent to it during that last TickInterval seconds. A tick is a
small package sent on the connection. A connected node is considered to be
down if no ticks or payload packages have been received during the last
NetTickIntensity number of TickInterval seconds intervals.
This ensures that nodes that are not responding, for reasons such as
hardware errors, are considered to be down.
As the availability is only checked every TickInterval
seconds, the actual time T a node have been unresponsive when
detected may vary between MinT and MaxT, where:
MinT = NetTickTime - NetTickTime / NetTickIntensity
MaxT = NetTickTime + NetTickTime / NetTickIntensity
NetTickTime defaults to 60 seconds and
NetTickIntensity defaults to 4. Thus, 45 < T < 75
seconds.
Note:
Notice that
all communicating nodes are to have the
same
NetTickTime and
NetTickIntensity values specified, as it
determines both the frequency of outgoing ticks and the expected frequency of
incominging ticks.
NetTickTime needs to be a multiple of
NetTickIntensity. If the configured values are not,
NetTickTime will internally be rounded up to the nearest millisecond.
net_kernel:get_net_ticktime() will, however, report net tick time
truncated to the nearest second.
Normally, a terminating node is detected immediately by the
transport protocol (like TCP/IP).
- prevent_overlapping_partitions
= true | false:
- If enabled (true), global will actively prevent overlapping
partitions from forming when connections are lost between nodes. This fix
is enabled by default. If you are about to disable this fix, make sure to
read the global(3erl) documentation about this fix for more
important information about this.
- shutdown_timeout
= integer() | infinity:
- Specifies the time application_controller waits for an application
to terminate during node shutdown. If the timer expires,
application_controller brutally kills application_master of
the hanging application. If this parameter is undefined, it defaults to
infinity.
- sync_nodes_mandatory
= [NodeName]:
- Specifies which other nodes that must be alive for this node to
start properly. If some node in the list does not start within the
specified time, this node does not start either. If this parameter is
undefined, it defaults to [].
- sync_nodes_optional
= [NodeName]:
- Specifies which other nodes that can be alive for this node to
start properly. If some node in this list does not start within the
specified time, this node starts anyway. If this parameter is undefined,
it defaults to the empty list.
- sync_nodes_timeout
= integer() | infinity:
- Specifies the time (in milliseconds) that this node waits for the
mandatory and optional nodes to start. If this parameter is undefined, no
node synchronization is performed. This option ensures that global
is synchronized.
- start_distribution
= true | false:
- Starts all distribution services, such as rpc, global, and
net_kernel if the parameter is true. This parameter is to be
set to false for systems who want to disable all distribution
functionality.
- start_dist_ac
= true | false:
- Starts the dist_ac server if the parameter is true. This
parameter is to be set to true for systems using distributed
applications.
Defaults to false. If this parameter is undefined, the
server is started if parameter distributed is set.
- start_boot_server
= true | false:
- Starts the boot_server if the parameter is true (see
erl_boot_server(3erl)). This parameter is to be set to true
in an embedded system using this service.
- boot_server_slaves
= [SlaveIP]:
- If configuration parameter start_boot_server is true, this
parameter can be used to initialize boot_server with a list of
slave IP addresses:
SlaveIP = string() | atom |
{integer(),integer(),integer(),integer()},
where 0 <= integer() <=255.
Examples of SlaveIP in atom, string, and tuple form:
'150.236.16.70', "150,236,16,70",
{150,236,16,70}.
- start_disk_log
= true | false:
- Starts the disk_log_server if the parameter is true (see
disk_log(3erl)). This parameter is to be set to true in an
embedded system using this service.
- start_pg = true
| false:
-
Starts the default pg scope server (see pg(3erl)) if
the parameter is true. This parameter is to be set to true in
an embedded system that uses this service.
- start_timer
= true | false:
- Starts the timer_server if the parameter is true (see
timer(3erl)). This parameter is to be set to true in an
embedded system using this service.
- shell_history
= enabled | disabled | module():
- Specifies whether shell history should be logged to disk between usages of
erl (enabled), not logged at all (disabled), or a
user-specified module will be used to log shell history. This module
should export load() -> [string()] returning a list of strings
to load in the shell when it starts, and add(iodata()) -> ok.
called every time new line is entered in the shell. By default logging is
disabled.
- shell_history_drop
= [string()]:
- Specific log lines that should not be persisted. For example
["q().", "init:stop()."] will allow to ignore
commands that shut the node down. Defaults to [].
- shell_history_file_bytes
= integer():
- How many bytes the shell should remember. By default, the value is set to
512kb, and the minimal value is 50kb.
- shell_history_path
= string():
- Specifies where the shell history files will be stored. defaults to the
user's cache directory as returned by filename:basedir(user_cache,
"erlang-history").
- shutdown_func
= {Mod, Func}:
- Where:
- *
- Mod = atom()
- *
- Func = atom()
Sets a function that application_controller calls when it
starts to terminate. The function is called as Mod:Func(Reason),
where Reason is the terminate reason for
application_controller, and it must return as soon as possible for
application_controller to terminate properly.
- source_search_rules
= [DirRule] | [SuffixRule] :
-
- *
- DirRule = {ObjDirSuffix,SrcDirSuffix}
- *
- SuffixRule = {ObjSuffix,SrcSuffix,[DirRule]}
- *
- ObjDirSuffix = string()
- *
- SrcDirSuffix = string()
- *
- ObjSuffix = string()
- *
- SrcSuffix = string()
Specifies a list of rules for use by filelib:find_file/2
filelib:find_source/2 If this is set to some other value than the
empty list, it replaces the default rules. Rules can be simple pairs of
directory suffixes, such as {"ebin", "src"},
which are used by filelib:find_file/2, or triples specifying separate
directory suffix rules depending on file name extensions, for example
[{".beam", ".erl", [{"ebin",
"src"}]}, which are used by filelib:find_source/2. Both
kinds of rules can be mixed in the list.
The interpretation of ObjDirSuffix and SrcDirSuffix
is as follows: if the end of the directory name where an object is located
matches ObjDirSuffix, then the name created by replacing
ObjDirSuffix with SrcDirSuffix is expanded by calling
filelib:wildcard/1, and the first regular file found among the
matches is the source file.