filestream inputedit

This functionality is experimental and may be changed or removed completely in a future release. Elastic will take a best effort approach to fix any issues, but experimental features are not subject to the support SLA of official GA features.

Use the filestream input to read lines from active log files. It is the new, improved alternative to the log input. However, a few feature are missing from it, e.g. multiline or other special parsing capabilities. These missing options are probably going to be added again. We strive to achieve feature parity, if possible.

To configure this input, specify a list of glob-based paths that must be crawled to locate and fetch the log lines.

Example configuration:

filebeat.inputs:
- type: filestream
  paths:
    - /var/log/messages
    - /var/log/*.log

You can apply additional configuration settings (such as fields, include_lines, exclude_lines and so on) to the lines harvested from these files. The options that you specify are applied to all the files harvested by this input.

To apply different configuration settings to different files, you need to define multiple input sections:

filebeat.inputs:
- type: filestream 
  paths:
    - /var/log/system.log
    - /var/log/wifi.log
- type: filestream 
  paths:
    - "/var/log/apache2/*"
  fields:
    apache: true

Harvests lines from two files: system.log and wifi.log.

Harvests lines from every file in the apache2 directory, and uses the fields configuration option to add a field called apache to the output.

Reading files on network shares and cloud providersedit

However, one of the limitations of these data sources can be mitigated if you configure Filebeat adequately.

By default, Filebeat identifies files based on their inodes and device IDs. However, on network shares and cloud providers these values might change during the lifetime of the file. If this happens Filebeat thinks that file is new and resends the whole content of the file. To solve this problem you can configure file_identity option. Possible values besides the default inode_deviceid are path and inode_marker.

Selecting path instructs Filebeat to identify files based on their paths. This is a quick way to avoid rereading files if inode and device ids might change. However, keep in mind if the files are rotated (renamed), they will be reread and resubmitted.

The option inode_marker can be used if the inodes stay the same even if the device id is changed. You should choose this method if your files are rotated instead of path if possible. You have to configure a marker file readable by Filebeat and set the path in the option path of inode_marker.

The content of this file must be unique to the device. You can put the UUID of the device or mountpoint where the input is stored. The following example oneliner generates a hidden marker file for the selected mountpoint /logs: Please note that you should not use this option on Windows as file identifiers might be more volatile.

$ lsblk -o MOUNTPOINT,UUID | grep /logs | awk '{print $2}' >> /logs/.filebeat-marker

To set the generated file as a marker for file_identity you should configure the input the following way:

filebeat.inputs:
- type: filestream
  paths:
    - /logs/*.log
  file_identity.inode_marker.path: /logs/.filebeat-marker

Reading from rotating logsedit

When dealing with file rotation, avoid harvesting symlinks. Instead use the paths setting to point to the original file, and specify a pattern that matches the file you want to harvest and all of its rotated files. Also make sure your log rotation strategy prevents lost or duplicate messages. For more information, see Log rotation results in lost or duplicate events.

Furthermore, to avoid duplicate of rotated log messages, do not use the path method for file_identity. Or exclude the rotated files with exclude_files option.

Prospector optionsedit

The filestream input supports the following configuration options plus the Common options described later.

pathsedit

A list of glob-based paths that will be crawled and fetched. All patterns supported by Go Glob are also supported here. For example, to fetch all files from a predefined level of subdirectories, the following pattern can be used: /var/log/*/*.log. This fetches all .log files from the subfolders of /var/log. It does not fetch log files from the /var/log folder itself. It is possible to recursively fetch all files in all subdirectories of a directory using the optional recursive_glob settings.

Filebeat starts a harvester for each file that it finds under the specified paths. You can specify one path per line. Each line begins with a dash (-).

prospector.scanner.recursive_globedit

Enable expanding ** into recursive glob patterns. With this feature enabled, the rightmost ** in each path is expanded into a fixed number of glob patterns. For example: /foo/** expands to /foo, /foo/*, /foo/*/*, and so on. If enabled it expands a single ** into a 8-level deep * pattern.

This feature is enabled by default. Set prospector.scanner.recursive_glob to false to disable it.

encodingedit

The file encoding to use for reading data that contains international characters. See the encoding names recommended by the W3C for use in HTML5.

Valid encodings:

  • plain: plain ASCII encoding
  • utf-8 or utf8: UTF-8 encoding
  • gbk: simplified Chinese charaters
  • iso8859-6e: ISO8859-6E, Latin/Arabic
  • iso8859-6i: ISO8859-6I, Latin/Arabic
  • iso8859-8e: ISO8859-8E, Latin/Hebrew
  • iso8859-8i: ISO8859-8I, Latin/Hebrew
  • iso8859-1: ISO8859-1, Latin-1
  • iso8859-2: ISO8859-2, Latin-2
  • iso8859-3: ISO8859-3, Latin-3
  • iso8859-4: ISO8859-4, Latin-4
  • iso8859-5: ISO8859-5, Latin/Cyrillic
  • iso8859-6: ISO8859-6, Latin/Arabic
  • iso8859-7: ISO8859-7, Latin/Greek
  • iso8859-8: ISO8859-8, Latin/Hebrew
  • iso8859-9: ISO8859-9, Latin-5
  • iso8859-10: ISO8859-10, Latin-6
  • iso8859-13: ISO8859-13, Latin-7
  • iso8859-14: ISO8859-14, Latin-8
  • iso8859-15: ISO8859-15, Latin-9
  • iso8859-16: ISO8859-16, Latin-10
  • cp437: IBM CodePage 437
  • cp850: IBM CodePage 850
  • cp852: IBM CodePage 852
  • cp855: IBM CodePage 855
  • cp858: IBM CodePage 858
  • cp860: IBM CodePage 860
  • cp862: IBM CodePage 862
  • cp863: IBM CodePage 863
  • cp865: IBM CodePage 865
  • cp866: IBM CodePage 866
  • ebcdic-037: IBM CodePage 037
  • ebcdic-1040: IBM CodePage 1140
  • ebcdic-1047: IBM CodePage 1047
  • koi8r: KOI8-R, Russian (Cyrillic)
  • koi8u: KOI8-U, Ukranian (Cyrillic)
  • macintosh: Macintosh encoding
  • macintosh-cyrillic: Macintosh Cyrillic encoding
  • windows1250: Windows1250, Central and Eastern European
  • windows1251: Windows1251, Russian, Serbian (Cyrillic)
  • windows1252: Windows1252, Legacy
  • windows1253: Windows1253, Modern Greek
  • windows1254: Windows1254, Turkish
  • windows1255: Windows1255, Hebrew
  • windows1256: Windows1256, Arabic
  • windows1257: Windows1257, Estonian, Latvian, Lithuanian
  • windows1258: Windows1258, Vietnamese
  • windows874: Windows874, ISO/IEC 8859-11, Latin/Thai
  • utf-16-bom: UTF-16 with required BOM
  • utf-16be-bom: big endian UTF-16 with required BOM
  • utf-16le-bom: little endian UTF-16 with required BOM

The plain encoding is special, because it does not validate or transform any input.

exclude_linesedit

A list of regular expressions to match the lines that you want Filebeat to exclude. Filebeat drops any lines that match a regular expression in the list. By default, no lines are dropped. Empty lines are ignored.

The following example configures Filebeat to drop any lines that start with DBG.

filebeat.inputs:
- type: filestream
  ...
  exclude_lines: ['^DBG']

See Regular expression support for a list of supported regexp patterns.

include_linesedit

A list of regular expressions to match the lines that you want Filebeat to include. Filebeat exports only the lines that match a regular expression in the list. By default, all lines are exported. Empty lines are ignored.

The following example configures Filebeat to export any lines that start with ERR or WARN:

filebeat.inputs:
- type: filestream
  ...
  include_lines: ['^ERR', '^WARN']

If both include_lines and exclude_lines are defined, Filebeat executes include_lines first and then executes exclude_lines. The order in which the two options are defined doesn’t matter. The include_lines option will always be executed before the exclude_lines option, even if exclude_lines appears before include_lines in the config file.

The following example exports all log lines that contain sometext, except for lines that begin with DBG (debug messages):

filebeat.inputs:
- type: filestream
  ...
  include_lines: ['sometext']
  exclude_lines: ['^DBG']

See Regular expression support for a list of supported regexp patterns.

buffer_sizeedit

The size in bytes of the buffer that each harvester uses when fetching a file. The default is 16384.

message_max_bytesedit

The maximum number of bytes that a single log message can have. All bytes after mesage_max_bytes are discarded and not sent. The default is 10MB (10485760).

Prospector optionsedit

The prospector is running a file system watcher which looks for files specified in the paths option. At the moment only simple file system scanning is supported.

Scanner optionsedit

The scanner watches the configured paths. It scans the file system periodically and returns the file system events to the Prospector.

prospector.scanner.exclude_filesedit

A list of regular expressions to match the files that you want Filebeat to ignore. By default no files are excluded.

The following example configures Filebeat to ignore all the files that have a gz extension:

filebeat.inputs:
- type: filestream
  ...
  prospector.scanner.exclude_files: ['\.gz$']

See Regular expression support for a list of supported regexp patterns.

prospector.scanner.symlinksedit

The symlinks option allows Filebeat to harvest symlinks in addition to regular files. When harvesting symlinks, Filebeat opens and reads the original file even though it reports the path of the symlink.

When you configure a symlink for harvesting, make sure the original path is excluded. If a single input is configured to harvest both the symlink and the original file, Filebeat will detect the problem and only process the first file it finds. However, if two different inputs are configured (one to read the symlink and the other the original path), both paths will be harvested, causing Filebeat to send duplicate data and the inputs to overwrite each other’s state.

The symlinks option can be useful if symlinks to the log files have additional metadata in the file name, and you want to process the metadata in Logstash. This is, for example, the case for Kubernetes log files.

Because this option may lead to data loss, it is disabled by default.

prospector.scanner.check_intervaledit

How often Filebeat checks for new files in the paths that are specified for harvesting. For example, if you specify a glob like /var/log/*, the directory is scanned for files using the frequency specified by check_interval. Specify 1s to scan the directory as frequently as possible without causing Filebeat to scan too frequently. We do not recommend to set this value <1s.

If you require log lines to be sent in near real time do not use a very low check_interval but adjust close.on_state_change.inactive so the file handler stays open and constantly polls your files.

The default setting is 10s.

ignore_olderedit

If this option is enabled, Filebeat ignores any files that were modified before the specified timespan. Configuring ignore_older can be especially useful if you keep log files for a long time. For example, if you want to start Filebeat, but only want to send the newest files and files from last week, you can configure this option.

You can use time strings like 2h (2 hours) and 5m (5 minutes). The default is 0, which disables the setting. Commenting out the config has the same effect as setting it to 0.

You must set ignore_older to be greater than close.on_state_change.inactive.

The files affected by this setting fall into two categories:

  • Files that were never harvested
  • Files that were harvested but weren’t updated for longer than ignore_older

For files which were never seen before, the offset state is set to the end of the file. If a state already exist, the offset is not changed. In case a file is updated again later, reading continues at the set offset position.

The ignore_older setting relies on the modification time of the file to determine if a file is ignored. If the modification time of the file is not updated when lines are written to a file (which can happen on Windows), the ignore_older setting may cause Filebeat to ignore files even though content was added at a later time.

To remove the state of previously harvested files from the registry file, use the clean_inactive configuration option.

Before a file can be ignored by Filebeat, the file must be closed. To ensure a file is no longer being harvested when it is ignored, you must set ignore_older to a longer duration than close.on_state_change.inactive.

If a file that’s currently being harvested falls under ignore_older, the harvester will first finish reading the file and close it after close.on_state_change.inactive is reached. Then, after that, the file will be ignored.

close.*edit

The close.* configuration options are used to close the harvester after a certain criteria or time. Closing the harvester means closing the file handler. If a file is updated after the harvester is closed, the file will be picked up again after prospector.scanner.check_interval has elapsed. However, if the file is moved or deleted while the harvester is closed, Filebeat will not be able to pick up the file again, and any data that the harvester hasn’t read will be lost.

The close.on_state_change.* settings are applied asynchronously to read from a file, meaning that if Filebeat is in a blocked state due to blocked output, full queue or other issue, a file that would be closed regardless.

close.on_state_change.inactiveedit

When this option is enabled, Filebeat closes the file handle if a file has not been harvested for the specified duration. The counter for the defined period starts when the last log line was read by the harvester. It is not based on the modification time of the file. If the closed file changes again, a new harvester is started and the latest changes will be picked up after prospector.scanner.check_interval has elapsed.

We recommended that you set close.on_state_change.inactive to a value that is larger than the least frequent updates to your log files. For example, if your log files get updated every few seconds, you can safely set close.on_state_change.inactive to 1m. If there are log files with very different update rates, you can use multiple configurations with different values.

Setting close.on_state_change.inactive to a lower value means that file handles are closed sooner. However this has the side effect that new log lines are not sent in near real time if the harvester is closed.

The timestamp for closing a file does not depend on the modification time of the file. Instead, Filebeat uses an internal timestamp that reflects when the file was last harvested. For example, if close.on_state_change.inactive is set to 5 minutes, the countdown for the 5 minutes starts after the harvester reads the last line of the file.

You can use time strings like 2h (2 hours) and 5m (5 minutes). The default is 5m.

close.on_state_change.renamededit

Only use this option if you understand that data loss is a potential side effect.

When this option is enabled, Filebeat closes the file handler when a file is renamed. This happens, for example, when rotating files. By default, the harvester stays open and keeps reading the file because the file handler does not depend on the file name. If the close.on_state_change.renamed option is enabled and the file is renamed or moved in such a way that it’s no longer matched by the file patterns specified for the , the file will not be picked up again. Filebeat will not finish reading the file.

Do not use this option when path based file_identity is configured. It does not make sense to enable the option, as Filebeat cannot detect renames using path names as unique identifiers.

WINDOWS: If your Windows log rotation system shows errors because it can’t rotate the files, you should enable this option.

close.on_state_change.removededit

When this option is enabled, Filebeat closes the harvester when a file is removed. Normally a file should only be removed after it’s inactive for the duration specified by close.on_state_change.inactive. However, if a file is removed early and you don’t enable close.on_state_change.removed, Filebeat keeps the file open to make sure the harvester has completed. If this setting results in files that are not completely read because they are removed from disk too early, disable this option.

This option is enabled by default. If you disable this option, you must also disable clean.on_state_change.removed.

WINDOWS: If your Windows log rotation system shows errors because it can’t rotate files, make sure this option is enabled.

close.reader.eofedit

Only use this option if you understand that data loss is a potential side effect.

When this option is enabled, Filebeat closes a file as soon as the end of a file is reached. This is useful when your files are only written once and not updated from time to time. For example, this happens when you are writing every single log event to a new file. This option is disabled by default.

close.reader.timeoutedit

Only use this option if you understand that data loss is a potential side effect. Another side effect is that multiline events might not be completely sent before the timeout expires.

When this option is enabled, Filebeat gives every harvester a predefined lifetime. Regardless of where the reader is in the file, reading will stop after the close.reader.after_interval period has elapsed. This option can be useful for older log files when you want to spend only a predefined amount of time on the files. While close.reader.after_interval will close the file after the predefined timeout, if the file is still being updated, Filebeat will start a new harvester again per the defined scan_frequency. And the close.reader.after_interval for this harvester will start again with the countdown for the timeout.

This option is particularly useful in case the output is blocked, which makes Filebeat keep open file handlers even for files that were deleted from the disk. Setting close.reader.after_interval to 5m ensures that the files are periodically closed so they can be freed up by the operating system.

If you set close.reader.after_interval to equal ignore_older, the file will not be picked up if it’s modified while the harvester is closed. This combination of settings normally leads to data loss, and the complete file is not sent.

When you use close.reader.after_interval for logs that contain multiline events, the harvester might stop in the middle of a multiline event, which means that only parts of the event will be sent. If the harvester is started again and the file still exists, only the second part of the event will be sent.

This option is set to 0 by default which means it is disabled.

clean_*edit

The clean_* options are used to clean up the state entries in the registry file. These settings help to reduce the size of the registry file and can prevent a potential inode reuse issue.

clean_inactiveedit

Only use this option if you understand that data loss is a potential side effect.

When this option is enabled, Filebeat removes the state of a file after the specified period of inactivity has elapsed. The state can only be removed if the file is already ignored by Filebeat (the file is older than ignore_older). The clean_inactive setting must be greater than ignore_older + scan_frequency to make sure that no states are removed while a file is still being harvested. Otherwise, the setting could result in Filebeat resending the full content constantly because clean_inactive removes state for files that are still detected by Filebeat. If a file is updated or appears again, the file is read from the beginning.

The clean_inactive configuration option is useful to reduce the size of the registry file, especially if a large amount of new files are generated every day.

This config option is also useful to prevent Filebeat problems resulting from inode reuse on Linux. For more information, see Inode reuse causes Filebeat to skip lines.

Every time a file is renamed, the file state is updated and the counter for clean_inactive starts at 0 again.

During testing, you might notice that the registry contains state entries that should be removed based on the clean_inactive setting. This happens because Filebeat doesn’t remove the entries until it opens the registry again to read a different file. If you are testing the clean_inactive setting, make sure Filebeat is configured to read from more than one file, or the file state will never be removed from the registry.

clean_removededit

When this option is enabled, Filebeat cleans files from the registry if they cannot be found on disk anymore under the last known name. This means also files which were renamed after the harvester was finished will be removed. This option is enabled by default.

If a shared drive disappears for a short period and appears again, all files will be read again from the beginning because the states were removed from the registry file. In such cases, we recommend that you disable the clean_removed option.

You must disable this option if you also disable close_removed.

backoff.*edit

The backoff options specify how aggressively Filebeat crawls open files for updates. You can use the default values in most cases.

The backoff option defines how long Filebeat waits before checking a file again after EOF is reached. The default is 1s, which means the file is checked every second if new lines were added. This enables near real-time crawling. Every time a new line appears in the file, the backoff value is reset to the initial value. The default is 1s.

backoff.initedit

The maximum time for Filebeat to wait before checking a file again after EOF is reached. After having backed off multiple times from checking the file, the wait time will never exceed max_backoff regardless of what is specified for backoff_factor. Because it takes a maximum of 10s to read a new line, specifying 10s for max_backoff means that, at the worst, a new line could be added to the log file if Filebeat has backed off multiple times. The default is 10s.

Requirement: Set max_backoff to be greater than or equal to backoff and less than or equal to scan_frequency (backoff <= max_backoff <= scan_frequency). If max_backoff needs to be higher, it is recommended to close the file handler instead and let Filebeat pick up the file again.

backoff.maxedit

The maximum time for Filebeat to wait before checking a file again after EOF is reached. After having backed off multiple times from checking the file, the wait time will never exceed max_backoff regardless of what is specified for backoff_factor. Because it takes a maximum of 10s to read a new line, specifying 10s for max_backoff means that, at the worst, a new line could be added to the log file if Filebeat has backed off multiple times. The default is 10s.

Requirement: Set max_backoff to be greater than or equal to backoff and less than or equal to scan_frequency (backoff <= max_backoff <= scan_frequency). If max_backoff needs to be higher, it is recommended to close the file handler instead and let Filebeat pick up the file again.

file_identityedit

Different file_identity methods can be configured to suit the environment where you are collecting log messages.

native
The default behaviour of Filebeat is to differentiate between files using their inodes and device ids.
file_identity.native: ~
path
To identify files based on their paths use this strategy.

Only use this strategy if your log files are rotated to a folder outside of the scope of your input or not at all. Otherwise you end up with duplicated events.

This strategy does not support renaming files. If an input file is renamed, Filebeat will read it again if the new path matches the settings of the input.

file_identity.path: ~
inode_marker
If the device id changes from time to time, you must use this method to distinguish files. This option is not supported on Windows.

Set the location of the marker file the following way:

file_identity.inode_marker.path: /logs/.filebeat-marker

Common optionsedit

The following configuration options are supported by all inputs.

enablededit

Use the enabled option to enable and disable inputs. By default, enabled is set to true.

tagsedit

A list of tags that Filebeat includes in the tags field of each published event. Tags make it easy to select specific events in Kibana or apply conditional filtering in Logstash. These tags will be appended to the list of tags specified in the general configuration.

Example:

filebeat.inputs:
- type: filestream
  . . .
  tags: ["json"]
fieldsedit

Optional fields that you can specify to add additional information to the output. For example, you might add fields that you can use for filtering log data. Fields can be scalar values, arrays, dictionaries, or any nested combination of these. By default, the fields that you specify here will be grouped under a fields sub-dictionary in the output document. To store the custom fields as top-level fields, set the fields_under_root option to true. If a duplicate field is declared in the general configuration, then its value will be overwritten by the value declared here.

filebeat.inputs:
- type: filestream
  . . .
  fields:
    app_id: query_engine_12
fields_under_rootedit

If this option is set to true, the custom fields are stored as top-level fields in the output document instead of being grouped under a fields sub-dictionary. If the custom field names conflict with other field names added by Filebeat, then the custom fields overwrite the other fields.

processorsedit

A list of processors to apply to the input data.

See Processors for information about specifying processors in your config.

pipelineedit

The Ingest Node pipeline ID to set for the events generated by this input.

The pipeline ID can also be configured in the Elasticsearch output, but this option usually results in simpler configuration files. If the pipeline is configured both in the input and output, the option from the input is used.

keep_nulledit

If this option is set to true, fields with null values will be published in the output document. By default, keep_null is set to false.

indexedit

If present, this formatted string overrides the index for events from this input (for elasticsearch outputs), or sets the raw_index field of the event’s metadata (for other outputs). This string can only refer to the agent name and version and the event timestamp; for access to dynamic fields, use output.elasticsearch.index or a processor.

Example value: "%{[agent.name]}-myindex-%{+yyyy.MM.dd}" might expand to "filebeat-myindex-2019.11.01".

publisher_pipeline.disable_hostedit

By default, all events contain host.name. This option can be set to true to disable the addition of this field to all events. The default value is false.