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Set up prospectors
editSet up prospectors
editFilebeat modules provide the fastest getting started experience for common log formats. See Quick start for common log formats to learn how to get started with modules. Also see Specify which modules to run for information about enabling and configuring modules.
Filebeat uses prospectors to locate and process files. To configure Filebeat,
you specify a list of prospectors in the filebeat.prospectors
section of the
filebeat.yml
config file.
Each item in the list begins with a dash (-) and specifies prospector-specific configuration options, including the list of paths that are crawled to locate the files.
Here is a sample configuration:
filebeat.prospectors: - type: log paths: - /var/log/apache/httpd-*.log - type: log paths: - /var/log/messages - /var/log/*.log
Configuration options
edittype
editOne of the following input types:
- log: Reads every line of the log file (default).
- stdin: Reads the standard in.
- redis: Reads slow log entries from redis (experimental).
-
udp: Reads events over UDP. Also see
max_message_size
.
The value that you specify here is used as the type
for each event published to Logstash and Elasticsearch.
paths
editA list of glob-based paths that should be crawled and fetched. All patterns
supported by Golang 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 (-).
recursive_glob
edit-
enabled
-
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. The feature is disabled by default, and if enabled it expands a single**
into a 8-level deep*
pattern.
encoding
editThe file encoding to use for reading files that contain international characters. See the encoding names recommended by the W3C for use in HTML5.
Here are some sample encodings from W3C recommendation:
- plain, latin1, utf-8, utf-16be-bom, utf-16be, utf-16le, big5, gb18030, gbk, hz-gb-2312,
- euc-kr, euc-jp, iso-2022-jp, shift-jis, and so on
The plain
encoding is special, because it does not validate or transform any input.
exclude_lines
editA 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.
If multiline is also specified, each multiline message is combined into a single line before the lines are filtered by exclude_lines
.
The following example configures Filebeat to drop any lines that start with "DBG".
filebeat.prospectors: - paths: - /var/log/myapp/*.log exclude_lines: ['^DBG']
See Regular expression support for a list of supported regexp patterns.
include_lines
editA 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.
If multiline is also specified, each multiline message is combined into a single line before the lines are filtered by include_lines
.
The following example configures Filebeat to export any lines that start with "ERR" or "WARN":
filebeat.prospectors: - paths: - /var/log/myapp/*.log 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 Apache log lines except the debugging messages (DBGs):
include_lines: ['apache'] exclude_lines: ['^DBG']
See Regular expression support for a list of supported regexp patterns.
exclude_files
editA 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:
exclude_files: ['\.gz$']
See Regular expression support for a list of supported regexp patterns.
tags
editA list of tags that the Beat 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.prospectors: - paths: ["/var/log/app/*.json"] tags: ["json"]
fields
editOptional 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.prospectors: - paths: ["/var/log/app/*.log"] fields: app_id: query_engine_12
fields_under_root
editIf 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.
processors
editA list of processors to apply to the data generated by the prospector.
See Filter and enhance the exported data for information about specifying processors in your config.
ignore_older
editIf 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_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 the prospector, it 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_*
editThe 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, Filebeat will not be able to pick up the file again, and any data that the harvester hasn’t read will be lost.
close_inactive
editWhen 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 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 prospector 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, Filebeat 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
editOnly 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_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 prospector, the file will not be picked up again. Filebeat will not finish reading the file.
WINDOWS: If your Windows log rotation system shows errors because it can’t rotate the files, you should enable this option.
close_removed
editWhen 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_inactive
. However, if a file is removed early and you don’t enable close_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_removed
.
WINDOWS: If your Windows log rotation system shows errors because it can’t rotate files, make sure this option is enabled.
close_eof
editOnly 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_timeout
editOnly 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_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, the prospector 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 Filebeat 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_*
editThe 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
editOnly 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 the prospector. 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.
clean_removed
editWhen 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
.
scan_frequency
editHow often the prospector 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 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 scan_frequency
but adjust close_inactive
so the file handler stays open and constantly polls your files.
The default setting is 10s.
scan.sort
editThis functionality is in technical preview and may be changed or removed in a future release. Elastic will work to fix any issues, but features in technical preview are not subject to the support SLA of official GA features.
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
editThis functionality is in technical preview and may be changed or removed in a future release. Elastic will work to fix any issues, but features in technical preview are not subject to the support SLA of official GA features.
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
.
harvester_buffer_size
editThe size in bytes of the buffer that each harvester uses when fetching a file. The default is 16384.
max_bytes
editThe maximum number of bytes that a single log message can have. All bytes after max_bytes
are discarded and not sent.
This setting is especially useful for multiline log messages, which can get large. The default is 10MB (10485760).
json
editThese options make it possible for Filebeat to decode logs structured as JSON messages. Filebeat processes the logs line by line, so the JSON decoding only works if there is one JSON object per line.
The decoding happens before line filtering and multiline. You can combine JSON decoding with filtering
and multiline if you set the message_key
option. This can be helpful in situations where the application
logs are wrapped in JSON objects, like it happens for example with Docker.
Example configuration:
json.keys_under_root: true json.add_error_key: true json.message_key: log
You must specify at least one of the following settings to enable JSON parsing mode:
-
keys_under_root
- By default, the decoded JSON is placed under a "json" key in the output document. If you enable this setting, the keys are copied top level in the output document. The default is false.
-
overwrite_keys
-
If
keys_under_root
and this setting are enabled, then the values from the decoded JSON object overwrite the fields that Filebeat normally adds (type, source, offset, etc.) in case of conflicts. -
add_error_key
-
If this setting is enabled, Filebeat adds a "error.message" and "error.type: json" key in case of JSON
unmarshalling errors or when a
message_key
is defined in the configuration but cannot be used. -
message_key
- An optional configuration setting that specifies a JSON key on which to apply the line filtering and multiline settings. If specified the key must be at the top level in the JSON object and the value associated with the key must be a string, otherwise no filtering or multiline aggregation will occur.
multiline
editOptions that control how Filebeat deals with log messages that span multiple lines. See Manage multiline messages for more information about configuring multiline options.
tail_files
editIf this option is set to true, Filebeat 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 Filebeat has not already processed. If you ran Filebeat 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 Filebeat and remove the registry file. Be aware that doing this removes ALL previous states.
You can use this setting to avoid indexing old log lines when you run Filebeat 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.
pipeline
editThe Ingest Node pipeline ID to set for the events generated by this prospector.
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 prospector and in the output, the option from the prospector is the one used.
symlinks
editThe 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 prospector is configured to harvest both the symlink and the original file, the prospector will detect the problem and only process the first file it finds. However, if two different prospectors 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 prospectors 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
editThe 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.
max_backoff
editThe 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: max_backoff should always be set to max_backoff <= scan_frequency
. In case max_backoff
should be bigger, it is recommended to close the file handler instead let the prospector pick up the file again.
backoff_factor
editThis 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
editThe harvester_limit
option limits the number of harvesters that are started in parallel for one prospector. 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 prospector. You can use this option to indirectly set higher priorities on certain prospectors by assigning a higher limit of harvesters.
enabled
editThe enabled
option can be used with each prospector to define if a prospector is enabled or not. By default, enabled is set to true.
max_message_size
editWhen used with type: udp
, specifies the maximum size of the message received over UDP. The default is 10240.