This filter will collapse multiline messages from a single source into one Logstash event.
The original goal of this filter was to allow joining of multi-line messages from files into a single event. For example - joining java exception and stacktrace messages into a single event.
The config looks like this:
filter {
multiline {
type => "type"
pattern => "pattern, a regexp"
negate => boolean
what => "previous" or "next"
}
}
The pattern should be a regexp which matches what you believe to be an indicator
that the field is part of an event consisting of multiple lines of log data.
The what must be “previous” or “next” and indicates the relation
to the multi-line event.
The negate can be “true” or “false” (defaults to false). If “true”, a
message not matching the pattern will constitute a match of the multiline
filter and the what will be applied. (vice-versa is also true)
For example, Java stack traces are multiline and usually have the message starting at the far-left, with each subsequent line indented. Do this:
filter {
multiline {
type => "somefiletype"
pattern => "^\s"
what => "previous"
}
}
This says that any line starting with whitespace belongs to the previous line.
Another example is C line continuations (backslash). Here’s how to do that:
filter {
multiline {
type => "somefiletype "
pattern => "\\$"
what => "next"
}
}
This says that any line ending with a backslash should be combined with the following line.
filter {
multiline {
add_field => ... # hash (optional), default: {}
add_tag => ... # array (optional), default: []
enable_flush => ... # boolean (optional), default: false
negate => ... # boolean (optional), default: false
pattern => ... # string (required)
patterns_dir => ... # array (optional), default: []
remove_field => ... # array (optional), default: []
remove_tag => ... # array (optional), default: []
stream_identity => ... # string (optional), default: "%{host}.%{path}.%{type}"
what => ... # string, one of ["previous", "next"] (required)
}
}
If this filter is successful, add any arbitrary fields to this event. Field names can be dynamic and include parts of the event using the %{field} Example:
filter {
multiline {
add_field => { "foo_%{somefield}" => "Hello world, from %{host}" }
}
}
# You can also add multiple fields at once:
filter {
multiline {
add_field => {
"foo_%{somefield}" => "Hello world, from %{host}"
"new_field" => "new_static_value"
}
}
}
If the event has field “somefield” == “hello” this filter, on success, would add field “foo_hello” if it is present, with the value above and the %{host} piece replaced with that value from the event. The second example would also add a hardcoded field.
If this filter is successful, add arbitrary tags to the event. Tags can be dynamic and include parts of the event using the %{field} syntax. Example:
filter {
multiline {
add_tag => [ "foo_%{somefield}" ]
}
}
# You can also add multiple tags at once:
filter {
multiline {
add_tag => [ "foo_%{somefield}", "taggedy_tag"]
}
}
If the event has field “somefield” == “hello” this filter, on success, would add a tag “foo_hello” (and the second example would of course add a “taggedy_tag” tag).
for debugging & testing purposes, do not use in production. allows periodic flushing of pending events
Only handle events without all/any (controlled by exclude_any config option) of these tags. Optional.
Negate the regexp pattern (‘if not matched’)
The regular expression to match.
Logstash ships by default with a bunch of patterns, so you don’t necessarily need to define this yourself unless you are adding additional patterns.
Pattern files are plain text with format:
NAME PATTERN
For example:
NUMBER \d+
If this filter is successful, remove arbitrary fields from this event. Fields names can be dynamic and include parts of the event using the %{field} Example:
filter {
multiline {
remove_field => [ "foo_%{somefield}" ]
}
}
# You can also remove multiple fields at once:
filter {
multiline {
remove_field => [ "foo_%{somefield}" "my_extraneous_field" ]
}
}
If the event has field “somefield” == “hello” this filter, on success, would remove the field with name “foo_hello” if it is present. The second example would remove an additional, non-dynamic field.
If this filter is successful, remove arbitrary tags from the event. Tags can be dynamic and include parts of the event using the %{field} syntax. Example:
filter {
multiline {
remove_tag => [ "foo_%{somefield}" ]
}
}
# You can also remove multiple tags at once:
filter {
multiline {
remove_tag => [ "foo_%{somefield}", "sad_unwanted_tag"]
}
}
If the event has field “somefield” == “hello” this filter, on success, would remove the tag “foo_hello” if it is present. The second example would remove a sad, unwanted tag as well.
The stream identity is how the multiline filter determines which stream an event belongs to. This is generally used for differentiating, say, events coming from multiple files in the same file input, or multiple connections coming from a tcp input.
The default value here is usually what you want, but there are some cases where you want to change it. One such example is if you are using a tcp input with only one client connecting at any time. If that client reconnects (due to error or client restart), then logstash will identify the new connection as a new stream and break any multiline goodness that may have occurred between the old and new connection. To solve this use case, you can use “%{@source_host}.%{@type}” instead.
Only handle events with all/any (controlled by include_any config option) of these tags. Optional.
Note that all of the specified routing options (type,tags.exclude_tags,include_fields,exclude_fields) must be met in order for the event to be handled by the filter. The type to act on. If a type is given, then this filter will only act on messages with the same type. See any input plugin’s “type” attribute for more. Optional.
If the pattern matched, does event belong to the next or previous event?