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input-common-file-options.asciidoc

File metadata and controls

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exclude_files

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

The following example configures {beatname_uc} to ignore all the files that have a gz extension:

{beatname_lc}.inputs:
- type: {type}
  ...
  exclude_files: ['\.gz$']

See [regexp-support] for a list of supported regexp patterns.

ignore_older

If this option is enabled, {beatname_uc} 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 {beatname_uc}, 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.

Important
You must set ignore_older to be greater than close_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 {beatname_uc} 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 {beatname_uc}, 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_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_inactive is reached. Then, after that, the file will be ignored.

close_*

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 scan_frequency has elapsed. However, if the file is moved or deleted while the harvester is closed, {beatname_uc} will not be able to pick up the file again, and any data that the harvester hasn’t read will be lost. The close_* settings are applied synchronously when {beatname_uc} attempts to read from a file, meaning that if {beatname_uc} is in a blocked state due to blocked output, full queue or other issue, a file that would otherwise be closed remains open until {beatname_uc} once again attempts to read from the file.

close_inactive

When this option is enabled, {beatname_uc} 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 scan_frequency has elapsed.

We recommended that you set close_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_inactive to 1m. If there are log files with very different update rates, you can use multiple configurations with different values.

Setting close_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, {beatname_uc} uses an internal timestamp that reflects when the file was last harvested. For example, if close_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_renamed
Warning
Only use this option if you understand that data loss is a potential side effect.

When this option is enabled, {beatname_uc} 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_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 path, the file will not be picked up again. {beatname_uc} 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_removed

When this option is enabled, {beatname_uc} 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_inactive. However, if a file is removed early and you don’t enable close_removed, {beatname_uc} 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_removed.

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

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

When this option is enabled, {beatname_uc} 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_timeout
Warning
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, {beatname_uc} gives every harvester a predefined lifetime. Regardless of where the reader is in the file, reading will stop after the close_timeout 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_timeout will close the file after the predefined timeout, if the file is still being updated, {beatname_uc} will start a new harvester again per the defined scan_frequency. And the close_timeout 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 {beatname_uc} keep open file handlers even for files that were deleted from the disk. Setting close_timeout to 5m ensures that the files are periodically closed so they can be freed up by the operating system.

If you set close_timeout 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_timeout 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_*

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

When this option is enabled, {beatname_uc} 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 {beatname_uc} (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 {beatname_uc} resending the full content constantly because clean_inactive removes state for files that are still detected by {beatname_uc}. 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 {beatname_uc} problems resulting from inode reuse on Linux. For more information, see [inode-reuse-issue].

Note
Every time a file is renamed, the file state is updated and the counter for clean_inactive starts at 0 again.
Tip
During testing, you might notice that the registry contains state entries that should be removed based on the clean_inactive setting. This happens because {beatname_uc} 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 {beatname_uc} is configured to read from more than one file, or the file state will never be removed from the registry.
clean_removed

When this option is enabled, {beatname_uc} 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.

scan_frequency

How often {beatname_uc} 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 scan_frequency. Specify 1s to scan the directory as frequently as possible without causing {beatname_uc} 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 scan_frequency but adjust close_inactive so the file handler stays open and constantly polls your files.

The default setting is 10s.

scan.sort

experimental[]

If you specify a value other than the empty string for this setting you can determine whether to use ascending or descending order using scan.order. Possible values are modtime and filename. To sort by file modification time, use modtime, otherwise use filename. Leave this option empty to disable it.

If you specify a value for this setting, you can use scan.order to configure whether files are scanned in ascending or descending order.

The default setting is disabled.

scan.order

experimental[]

Specifies whether to use ascending or descending order when scan.sort is set to a value other than none. Possible values are asc or desc.

The default setting is asc.

tail_files

If this option is set to true, {beatname_uc} starts reading new files at the end of each file instead of the beginning. When this option is used in combination with log rotation, it’s possible that the first log entries in a new file might be skipped. The default setting is false.

This option applies to files that {beatname_uc} has not already processed. If you ran {beatname_uc} previously and the state of the file was already persisted, tail_files will not apply. Harvesting will continue at the previous offset. To apply tail_files to all files, you must stop {beatname_uc} and remove the registry file. Be aware that doing this removes ALL previous states.

Note
You can use this setting to avoid indexing old log lines when you run {beatname_uc} on a set of log files for the first time. After the first run, we recommend disabling this option, or you risk losing lines during file rotation.

The symlinks option allows {beatname_uc} to harvest symlinks in addition to regular files. When harvesting symlinks, {beatname_uc} 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, {beatname_uc} 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 {beatname_uc} 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.

backoff

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

The backoff option defines how long {beatname_uc} 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.

max_backoff

The maximum time for {beatname_uc} 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 {beatname_uc} 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 {beatname_uc} pick up the file again.

backoff_factor

This option specifies how fast the waiting time is increased. The bigger the backoff factor, the faster the max_backoff value is reached. The backoff factor increments exponentially. The minimum value allowed is 1. If this value is set to 1, the backoff algorithm is disabled, and the backoff value is used for waiting for new lines. The backoff value will be multiplied each time with the backoff_factor until max_backoff is reached. The default is 2.

harvester_limit

The harvester_limit option limits the number of harvesters that are started in parallel for one input. This directly relates to the maximum number of file handlers that are opened. The default for harvester_limit is 0, which means there is no limit. This configuration is useful if the number of files to be harvested exceeds the open file handler limit of the operating system.

Setting a limit on the number of harvesters means that potentially not all files are opened in parallel. Therefore we recommended that you use this option in combination with the close_* options to make sure harvesters are stopped more often so that new files can be picked up.

Currently if a new harvester can be started again, the harvester is picked randomly. This means it’s possible that the harvester for a file that was just closed and then updated again might be started instead of the harvester for a file that hasn’t been harvested for a longer period of time.

This configuration option applies per input. You can use this option to indirectly set higher priorities on certain inputs by assigning a higher limit of harvesters.

file_identity

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

native

The default behaviour of {beatname_uc} 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.

Warning
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.
Warning
This strategy does not support renaming files. If an input file is renamed, {beatname_uc} 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