icinga2/doc/1-about.md

About Icinga 2

What is Icinga 2?

Icinga 2 is an open source monitoring system which checks the availability of your network resources, notifies users of outages, and generates performance data for reporting.

Scalable and extensible, Icinga 2 can monitor large, complex environments across multiple locations.

Licensing

Icinga 2 and the Icinga 2 documentation are licensed under the terms of the GNU General Public License Version 2, you will find a copy of this license in the LICENSE file included in the source package.

Support

Support for Icinga 2 is available in a number of ways. Please have a look at the support overview page.

Contribute

There are many ways to contribute to Icinga - whether it be sending patches, testing, reporting bugs, or reviewing and updating the documentation. Every contribution is appreciated!

Please get in touch with the Icinga team at https://www.icinga.org/community/.

If you want to help update this documentation please read this howto.

Icinga 2 Development

You can follow Icinga 2's development closely by checking out these resources:

• Development Bug Tracker: How to report a bug?
• Git Repositories: main mirror on icinga.org release mirror at github.com
• Git Checkins Mailinglist
• Development and Users Mailinglists
• #icinga-devel on irc.freenode.net including a Git Commit Bot

For general support questions, please refer to the community support channels.

How to Report a Bug or Feature Request

More details in the Icinga FAQ.

• Register an Icinga account.
• Create a new issue at the Icinga 2 Development Tracker.
• When reporting a bug, please include the details described in the Troubleshooting chapter (version, configs, logs, etc).

What's New

What's New in Version 2.3.5

Changes

• NSClient++ is now bundled with the Windows setup wizard and can optionally be installed
• Windows Wizard: "include " is set by default
• Windows Wizard: Add update mode
• Plugins: Add check_perfmon plugin for Windows
• ITL: Add CheckCommand objects for Windows plugins ("include ")
• ITL: Add CheckCommand definitions for "mongodb", "iftraffic", "disk_smb"
• ITL: Add arguments to CheckCommands "dns", "ftp", "tcp", "nscp"

Features

• Feature 8116: Extend Windows installer with an update mode
• Feature 8180: Add documentation and CheckCommands for the windows plugins
• Feature 8809: Add check_perfmon plugin for Windows
• Feature 9115: Add SHOWALL to NSCP Checkcommand
• Feature 9130: Add 'check_drivesize' as nscp-local check command
• Feature 9145: Add arguments to "dns" CheckCommand
• Feature 9146: Add arguments to "ftp" CheckCommand
• Feature 9147: Add arguments to "tcp" CheckCommand
• Feature 9176: ITL Documentation: Add a link for passing custom attributes as command parameters
• Feature 9180: Include Windows support details in the documentation
• Feature 9185: Add timestamp support for PerfdataWriter
• Feature 9191: Add "mongodb" CheckCommand definition
• Feature 9238: Bundle NSClient++ in Windows Installer
• Feature 9254: Add 'disk_smb' Plugin CheckCommand definition
• Feature 9256: Determine NSClient++ installation path using MsiGetComponentPath
• Feature 9260: Include by default on Windows
• Feature 9261: Add the --load-all and --log options for nscp-local
• Feature 9263: Add support for installing NSClient++ in the Icinga 2 Windows wizard
• Feature 9270: Update service apply for documentation
• Feature 9272: Add 'iftraffic' to plugins-contrib check command definitions
• Feature 9285: Best practices: cluster config sync
• Feature 9297: Add examples for function usage in "set_if" and "command" attributes
• Feature 9310: Add typeof in 'assign/ignore where' expression as example
• Feature 9311: Add local variable scope for *Command to documentation (host, service, etc)
• Feature 9313: Use a more simple example for passing command parameters
• Feature 9318: Explain string concatenation in objects by real-world example
• Feature 9363: Update documentation for escape sequences
• Feature 9419: Enhance cluster/client troubleshooting
• Feature 9420: Enhance cluster docs with HA command_endpoints
• Feature 9431: Documentation: Move configuration before advanced topics

Bugfixes

• Bug 8853: Syntax Highlighting: host.address vs host.add
• Bug 8888: Icinga2 --version: Error showing Distribution
• Bug 8891: Node wont connect properly to master if host is is not set for Endpoint on new installs
• Bug 9055: Wrong timestamps w/ historical data replay in DB IDO
• Bug 9109: WIN: syslog is not an enable-able feature in windows
• Bug 9116: node update-config reports critical and warning
• Bug 9121: Possible DB deadlock
• Bug 9131: Missing ")" in last Apply Rules example
• Bug 9142: Downtimes are always "fixed"
• Bug 9143: Incorrect type and state filter mapping for User objects in DB IDO
• Bug 9161: 'disk': wrong order of threshold command arguments
• Bug 9187: SPEC: Give group write permissions for perfdata dir
• Bug 9205: port empty when using icinga2 node wizard
• Bug 9222: Missing custom attributes in backends if name is equal to object attribute
• Bug 9253: Incorrect variable name in the ITL
• Bug 9255: --scm-installs fails when the service is already installed
• Bug 9258: Some checks in the default Windows configuration fail
• Bug 9259: Disk and 'icinga' services are missing in the default Windows config
• Bug 9268: Typo in Configuration Best Practice
• Bug 9269: Wrong permission etc on windows
• Bug 9324: Multi line output not correctly handled from compat channels
• Bug 9328: Multiline vars are broken in objects.cache output
• Bug 9372: plugins-contrib.d/databases.conf: wrong argument for mssql_health
• Bug 9389: Documentation: Typo
• Bug 9390: Wrong service table attributes in Livestatus documentation
• Bug 9393: Documentation: Extend Custom Attributes with the boolean type
• Bug 9394: Including on Linux fails with unregistered function
• Bug 9399: Documentation: Typo
• Bug 9406: Selective cluster reconnecting breaks client communication
• Bug 9412: Documentation: Update the link to register a new Icinga account

What's New in Version 2.3.4

Changes

• ITL: Check commands for various databases
• Improve validation messages for time periods
• Update max_check_attempts in generic-{host,service} templates
• Update logrotate configuration
• Bugfixes

Features

• Feature 8760: Add database plugins to ITL
• Feature 8803: Agent Wizard: add options for API defaults
• Feature 8893: Improve timeperiod validation error messages
• Feature 8895: Add explanatory note for Icinga2 client documentation

Bugfixes

• Bug 8808: logrotate doesn't work on Ubuntu
• Bug 8821: command_endpoint check_results are not replicated to other endpoints in the same zone
• Bug 8879: Reword documentation of check_address
• Bug 8881: Add arguments to the UPS check
• Bug 8889: Fix a minor markdown error
• Bug 8892: Validation errors for time ranges which span the DST transition
• Bug 8894: Default max_check_attempts should be lower for hosts than for services
• Bug 8913: Windows Build: Flex detection
• Bug 8917: Node wizard should only accept 'y', 'n', 'Y' and 'N' as answers for boolean questions
• Bug 8919: Fix complexity class for Dictionary::Get
• Bug 8987: Fix a typo
• Bug 9012: Typo in graphite feature enable documentation
• Bug 9014: Don't update scheduleddowntime table w/ trigger_time column when only adding a downtime
• Bug 9016: Downtimes which have been triggered are not properly recorded in the database
• Bug 9017: scheduled_downtime_depth column is not reset when a downtime ends or when a downtime is being removed
• Bug 9021: Multiple log messages w/ "Attempting to send notifications for notification object"
• Bug 9041: Acknowledging problems w/ expire time does not add the expiry information to the related comment for IDO and compat
• Bug 9045: Vim syntax: Match groups before host/service/user objects
• Bug 9049: check_disk order of command arguments
• Bug 9050: web.conf is not in the RPM package
• Bug 9064: troubleshoot truncates crash reports
• Bug 9069: Documentation: set_if usage with boolean values and functions
• Bug 9073: custom attributes with recursive macro function calls causing sigabrt

What's New in Version 2.3.3

Changes

• New function: parse_performance_data
• Include more details in --version
• Improve documentation
• Bugfixes

Features

• Feature 8685: Show state/type filter names in notice/debug log
• Feature 8686: Update documentation for "apply for" rules
• Feature 8693: New function: parse_performance_data
• Feature 8740: Add "access objects at runtime" examples to advanced section
• Feature 8761: Include more details in --version
• Feature 8816: Add "random" CheckCommand for test and demo purposes
• Feature 8827: Move release info in INSTALL.md into a separate file

Bugfixes

• Bug 8660: Update syntax highlighting for 2.3 features
• Bug 8677: Re-order the object types in alphabetical order
• Bug 8724: Missing config validator for command arguments 'set_if'
• Bug 8734: startup.log broken when the DB schema needs an update
• Bug 8736: Don't update custom vars for each status update
• Bug 8748: Don't ignore extraneous arguments for functions
• Bug 8749: Build warnings with CMake 3.1.3
• Bug 8750: Flex version check does not reject unsupported versions
• Bug 8753: Fix a typo in the documentation of ICINGA2_WITH_MYSQL and ICINGA2_WITH_PGSQL
• Bug 8755: Fix VIM syntax highlighting for comments
• Bug 8757: Add missing keywords in the syntax highlighting files
• Bug 8762: Plugin "check_http" is missing in Windows environments
• Bug 8763: Typo in doc library-reference
• Bug 8764: Revamp migration documentation
• Bug 8765: Explain processing logic/order of apply rules with for loops
• Bug 8766: Remove prompt to create a TicketSalt from the wizard
• Bug 8767: Typo and invalid example in the runtime macro documentation
• Bug 8769: Improve error message for invalid field access
• Bug 8770: object Notification + apply Service fails with error "...refers to service which doesn't exist"
• Bug 8771: Correct HA documentation
• Bug 8829: Figure out why command validators are not triggered
• Bug 8834: Return doesn't work inside loops
• Bug 8844: Segmentation fault when executing "icinga2 pki new-cert"
• Bug 8862: wrong 'dns_lookup' custom attribute default in command-plugins.conf
• Bug 8866: Fix incorrect perfdata templates in the documentation
• Bug 8869: Array in command arguments doesn't work

What's New in Version 2.3.2

Changes

• Bugfixes

Bugfixes

• Bug 8721: Log message for cli commands breaks the init script

What's New in Version 2.3.1

Changes

• Bugfixes

Please note that this version fixes the default thresholds for the disk check which were inadvertently broken in 2.3.0; if you're using percent-based custom thresholds you will need to add the '%' sign to your custom attributes

Features

• Feature 8659: Implement String#contains

Bugfixes

• Bug 8540: Kill signal sent only to check process, not whole process group
• Bug 8657: Missing program name in 'icinga2 --version'
• Bug 8658: Fix check_disk thresholds: make sure partitions are the last arguments
• Bug 8672: Api heartbeat message response time problem
• Bug 8673: Fix check_disk default thresholds and document the change of unit
• Bug 8679: Config validation fail because of unexpected new-line
• Bug 8680: Update documentation for DB IDO HA Run-Once
• Bug 8683: Make sure that the /var/log/icinga2/crash directory exists
• Bug 8684: Fix formatting for the GDB stacktrace
• Bug 8687: Crash in Dependency::Stop
• Bug 8691: Debian packages do not create /var/log/icinga2/crash

What's New in Version 2.3.0

Changes

• Improved configuration validation

  • Unnecessary escapes are no longer permitted (e.g. ')
  • Dashes are no longer permitted in identifier names (as their semantics are ambiguous)
  • Unused values are detected (e.g. { "-M" })
  • Validation for time ranges has been improved
  • Additional validation rules for some object types (Notification and User)

• New language features

  • Implement a separate type for boolean values
  • Support for user-defined functions
  • Support for conditional statements (if/else)
  • Support for 'for' and 'while' loops
  • Support for local variables using the 'var' keyword
  • New operators: % (modulo), ^ (xor), - (unary minus) and + (unary plus)
  • Implemented prototype-based methods for most built-in types (e.g. [ 3, 2 ].sort())
  • Explicit access to local and global variables using the 'locals' and 'globals' keywords
  • Changed the order in which filters are evaluated for apply rules with 'for'
  • Make type objects accessible as global variables
  • Support for using functions in custom attributes
  • Access objects and their runtime attributes in functions (e.g. get_host(NodeName).state)

• ITL improvements

  • Additional check commands were added to the ITL
  • Additional arguments for existing check commands

• CLI improvements

  • Add the 'icinga2 console' CLI command which can be used to test expressions
  • Add the 'icinga2 troubleshoot' CLI command for collecting troubleshooting information
  • Performance improvements for the 'icinga2 node update-config' CLI command
  • Implement argument auto-completion for short options (e.g. daemon -c)
  • 'node setup' and 'node wizard' create backups for existing certificate files

• Add ignore_soft_states option for Dependency object configuration

• Fewer threads are used for socket I/O

• Flapping detection for hosts and services is disabled by default

• Added support for OpenTSDB

• New Livestatus tables: hostsbygroup, servicesbygroup, servicesbyhostgroup

• Include GDB backtrace in crash reports

• Various documentation improvements

• Solved a number of issues where cluster instances would not reconnect after intermittent connection problems

• A lot of other, minor changes

• DB IDO schema upgrade to 1.13.0 required!

Features

• Feature 3446: Add troubleshooting collect cli command
• Feature 6109: Don't spawn threads for network connections
• Feature 6570: Disallow side-effect-free r-value expressions in expression lists
• Feature 6697: Plugin Check Commands: add check_vmware_esx
• Feature 6857: Run CheckCommands with C locale (workaround for comma vs dot and plugin api bug)
• Feature 6858: Add some more PNP details
• Feature 6868: Disable flapping detection by default
• Feature 6923: IDO should fill program_end_time on a clean shutdown
• Feature 7136: extended Manubulon SNMP Check Plugin Command
• Feature 7209: ITL: Interfacetable
• Feature 7256: Add OpenTSDB Writer
• Feature 7292: ITL: Check_Mem.pl
• Feature 7294: ITL: ESXi-Hardware
• Feature 7326: Add parent soft states option to Dependency object configuration
• Feature 7361: Livestatus: Add GroupBy tables: hostsbygroup, servicesbygroup, servicesbyhostgroup
• Feature 7545: Please add labels in SNMP checks
• Feature 7564: Access object runtime attributes in custom vars & command arguments
• Feature 7610: Variable from for loop not usable in assign statement
• Feature 7700: Evaluate apply/object rules when the parent objects are created
• Feature 7702: Add an option that hides CLI commands
• Feature 7704: ConfigCompiler::HandleInclude* should return an AST node
• Feature 7706: ConfigCompiler::Compile* should return an AST node
• Feature 7748: Redesign how stack frames work for scripts
• Feature 7767: Rename _DEBUG to I2_DEBUG
• Feature 7774: Implement an AST Expression for T_CONST
• Feature 7778: Missing check_disk output on Windows
• Feature 7784: Implement the DISABLE_HOST_SVC_NOTIFICATIONS and ENABLE_HOST_SVC_NOTIFICATIONS commands
• Feature 7793: Don't build db_ido when both MySQL and PostgreSQL aren't enabled
• Feature 7794: Implement an option to disable building the Livestatus module
• Feature 7795: Implement an option to disable building the Demo component
• Feature 7805: Implement unit tests for the config parser
• Feature 7807: Move the cast functions into libbase
• Feature 7813: Implement the % operator
• Feature 7816: Document operator precedence
• Feature 7822: Make the config parser thread-safe
• Feature 7823: Figure out whether Number + String should implicitly convert the Number argument to a string
• Feature 7824: Implement the "if" and "else" keywords
• Feature 7873: Plugin Check Commands: Add icmp
• Feature 7879: Windows agent is missing the standard plugin check_ping
• Feature 7883: Implement official support for user-defined functions and the "for" keyword
• Feature 7901: Implement socket_path attribute for the IdoMysqlConnection class
• Feature 7910: The lexer shouldn't accept escapes for characters which don't have to be escaped
• Feature 7925: Move the config file for the ido-sql features into the icinga2-ido- packages
• Feature 8016: Documentation enhancement for snmp traps and passive checks.
• Feature 8019: Register type objects as global variables
• Feature 8020: Improve output of ToString for type objects
• Feature 8030: Evaluate usage of function()
• Feature 8033: Allow name changed from inside the object
• Feature 8040: Disallow calling strings as functions
• Feature 8043: Implement a boolean sub-type for the Value class
• Feature 8047: ConfigCompiler::HandleInclude should return an inline dictionary
• Feature 8060: Windows plugins should behave like their Linux cousins
• Feature 8065: Implement a way to remove dictionary keys
• Feature 8071: Implement a way to call methods on objects
• Feature 8074: Figure out how variable scopes should work
• Feature 8078: Backport i2tcl's error reporting functionality into "icinga2 console"
• Feature 8096: Document the new language features in 2.3
• Feature 8121: feature enable should use relative symlinks
• Feature 8133: Implement line-continuation for the "console" command
• Feature 8169: Implement additional methods for strings
• Feature 8172: Assignments shouldn't have a "return" value
• Feature 8195: Host/Service runtime macro downtime_depth
• Feature 8226: Make invalid log-severity option output an error instead of a warning
• Feature 8244: Implement keywords to explicitly access globals/locals
• Feature 8259: The check "hostalive" is not working with ipv6
• Feature 8269: Implement the while keyword
• Feature 8277: Add macros host.check_source and service.check_source
• Feature 8290: Make operators &&, || behave like in JavaScript
• Feature 8291: Implement validator support for function objects
• Feature 8293: The Zone::global attribute is not documented
• Feature 8316: Extend disk checkcommand
• Feature 8322: Implement Array#join
• Feature 8371: Add path information for objects in object list
• Feature 8374: Add timestamp support for Graphite
• Feature 8386: Add documentation for cli command 'console'
• Feature 8393: Implement support for Json.encode and Json.decode
• Feature 8394: Implement continue/break keywords
• Feature 8399: Backup certificate files in 'node setup'
• Feature 8410: udp check command is missing arguments.
• Feature 8414: Add ITL check command for check_ipmi_sensor
• Feature 8429: add webinject checkcommand
• Feature 8465: Add the ability to use a CA certificate as a way of verifying hosts for CSR autosigning
• Feature 8467: introduce time dependent variable values
• Feature 8498: Snmp CheckCommand misses various options
• Feature 8515: Show slave lag for the cluster-zone check
• Feature 8522: Update Remote Client/Distributed Monitoring Documentation
• Feature 8527: Change Livestatus query log level to 'notice'
• Feature 8548: Add support for else-if
• Feature 8575: Include GDB backtrace in crash reports
• Feature 8599: Remove macro argument for IMPL_TYPE_LOOKUP
• Feature 8600: Add validator for time ranges in ScheduledDowntime objects
• Feature 8610: Support the SNI TLS extension
• Feature 8621: Add check commands for NSClient++
• Feature 8648: Document closures ('use')

Bugfixes

• Bug 6171: Remove name and return value for stats functions
• Bug 6959: Scheduled start time will be ignored if the host or service is already in a problem state
• Bug 7311: Invalid macro results in exception
• Bug 7542: Update validators for CustomVarObject
• Bug 7576: validate configured legacy timeperiod ranges
• Bug 7582: Variable expansion is single quoted.
• Bug 7644: Unity build doesn't work with MSVC
• Bug 7647: Avoid rebuilding libbase when the version number changes
• Bug 7731: Reminder notifications not being sent but logged every 5 secs
• Bug 7765: DB IDO: Duplicate entry icinga_{host,service}dependencies
• Bug 7800: Fix the shift/reduce conflicts in the parser
• Bug 7802: Change parameter type for include and include_recursive to T_STRING
• Bug 7808: Unterminated string literals should cause parser to return an error
• Bug 7809: Scoping rules for "for" are broken
• Bug 7810: Return values for functions are broken
• Bug 7811: The __return keyword is broken
• Bug 7812: Validate array subscripts
• Bug 7814: Set expression should check whether LHS is a null pointer
• Bug 7815: - operator doesn't work in expressions
• Bug 7826: Compiler warnings
• Bug 7830: - shouldn't be allowed in identifiers
• Bug 7871: Missing persistent_comment, notify_contact columns for acknowledgement table
• Bug 7894: Fix warnings when using CMake 3.1.0
• Bug 7895: Serialize() fails to serialize objects which don't have a registered type
• Bug 7995: Windows Agent: Missing directory "zones" in setup
• Bug 8018: Value("").IsEmpty() should return true
• Bug 8029: operator precedence for % and > is incorrect
• Bug 8041: len() overflows
• Bug 8061: Confusing error message for import
• Bug 8067: Require at least one user for notification objects (user or as member of user_groups)
• Bug 8076: icinga 2 Config Error needs to be more verbose
• Bug 8081: Location info for strings is incorrect
• Bug 8100: POSTGRES IDO: invalid syntax for integer: "true" while trying to update table icinga_hoststatus
• Bug 8111: User::ValidateFilters isn't being used
• Bug 8117: Agent checks fail when there's already a host with the same name
• Bug 8122: Config file passing validation causes segfault
• Bug 8132: Debug info for indexer is incorrect
• Bug 8136: Icinga crashes when config file name is invalid
• Bug 8164: escaped backslash in string literals
• Bug 8166: parsing include_recursive
• Bug 8173: Segfault on icinga::String::operator= when compiling configuration
• Bug 8175: Compiler warnings
• Bug 8179: Exception on missing config files
• Bug 8184: group assign fails with bad lexical cast when evaluating rules
• Bug 8185: Argument auto-completion doesn't work for short options
• Bug 8211: icinga2 node update should not write config for blacklisted zones/host
• Bug 8230: Lexer term for T_ANGLE_STRING is too aggressive
• Bug 8249: Problems using command_endpoint inside HA zone
• Bug 8257: Report missing command objects on remote agent
• Bug 8260: icinga2 node wizard: Create backups of certificates
• Bug 8289: Livestatus operator =~ is not case-insensitive
• Bug 8294: Running icinga2 command as non privilged user raises error
• Bug 8298: notify flag is ignored in ACKNOWLEDGE_*_PROBLEM commands
• Bug 8300: ApiListener::ReplayLog shouldn't hold mutex lock during call to Socket::Poll
• Bug 8307: PidPath, VarsPath, ObjectsPath and StatePath no longer read from init.conf
• Bug 8309: Crash in ScheduledDowntime::CreateNextDowntime
• Bug 8313: Incorrectly formatted timestamp in .timestamp file
• Bug 8318: Remote Clients: Add manual setup cli commands
• Bug 8323: Apply rule '' for host does not match anywhere!
• Bug 8333: Icinga2 master doesn't change check-status when "accept_commands = true" is not set at client node
• Bug 8372: Stacktrace on Endpoint not belonging to a zone or multiple zones
• Bug 8383: last_hard_state missing in StatusDataWriter
• Bug 8387: StatusDataWriter: Wrong host notification filters (broken fix in #8192)
• Bug 8388: Config sync authoritative file never created
• Bug 8389: Added downtimes must be triggered immediately if checkable is Not-OK
• Bug 8390: Agent writes CR CR LF in synchronized config files
• Bug 8397: Icinga2 config reset after package update (centos6.6)
• Bug 8425: DB IDO: Duplicate entry icinga_scheduleddowntime
• Bug 8433: Make the arguments for the stats functions const-ref
• Bug 8434: Build fails on OpenBSD
• Bug 8436: Indicate that Icinga2 is shutting down in case of a fatal error
• Bug 8438: DB IDO {host,service}checks command_line value is "Object of type 'icinga::Array'"
• Bug 8444: Don't attempt to restore program state from non-existing state file
• Bug 8452: Livestatus query on commands table with custom vars fails
• Bug 8461: Don't request heartbeat messages until after we've synced the log
• Bug 8473: Exception in WorkQueue::StatusTimerHandler
• Bug 8488: Figure out why 'node update-config' becomes slow over time
• Bug 8493: Misleading ApiListener connection log messages on a master (Endpoint vs Zone)
• Bug 8496: Icinga doesn't update long_output in DB
• Bug 8511: Deadlock with DB IDO dump and forcing a scheduled check
• Bug 8517: Config parser fails non-deterministic on Notification missing Checkable
• Bug 8519: apply-for incorrectly converts loop var to string
• Bug 8529: livestatus limit header not working
• Bug 8535: Crash in ApiEvents::RepositoryTimerHandler
• Bug 8536: Valgrind warning for ExternalCommandListener::CommandPipeThread
• Bug 8537: Crash in DbObject::SendStatusUpdate
• Bug 8544: Hosts: process_performance_data = 0 in database even though enable_perfdata = 1 in config
• Bug 8555: Don't accept config updates for zones for which we have an authoritative copy of the config
• Bug 8559: check_memory tool shows incorrect memory size on windows
• Bug 8593: Memory leak in Expression::GetReference
• Bug 8594: Improve Livestatus query performance
• Bug 8596: Dependency: Validate *_{host,service}_name objects on their existance
• Bug 8604: Attribute hints don't work for nested attributes
• Bug 8627: Icinga2 shuts down when service is reloaded
• Bug 8638: Fix a typo in documentation