# regexp

The `regexp` parser plugin parses logs by given regexp pattern. If the parameter value starts and ends with "/", it is considered to be a regexp. The regexp must have at least one named capture (?\PATTERN). If the regexp has a capture named `time`, this is configurable, it is used as the time of the event. You can specify the time format using the time\_format parameter.

```
format /.../ # regexp parser is used
format json  # json parser is used
```

## Parameters

### time\_key

Specify the field for event time. Default is `time`.

### time\_format

Specify time format for `time_key`.

See [Time#strptime](http://ruby-doc.org/stdlib-2.4.1/libdoc/time/rdoc/Time.html#method-c-strptime) for additional format information.

### keep\_time\_key

If you want to keep time field in the record, set `true`. Default is `false`.

### types

Although every parsed field has type `string` by default, you can specify other types. This is useful when filtering particular fields numerically or storing data with sensible type information.

The syntax is

```
types <field_name_1>:<type_name_1>,<field_name_2>:<type_name_2>,...
```

e.g.,

```
types user_id:integer,paid:bool,paid_usd_amount:float
```

As demonstrated above, "," is used to delimit field-type pairs while ":" is used to separate a field name with its intended type.

Unspecified fields are parsed at the default string type.

The list of supported types are shown below:

* string
* bool
* integer ("int" would NOT work!)
* float
* time
* array

For the `time` and `array` types, there is an optional third field after the type name. For the "time" type, you can specify a time format like you would in `time_format`.

For the "array" type, the third field specifies the delimiter (the default is ","). For example, if a field called "item\_ids" contains the value "3,4,5", `types item_ids:array` parses it as \["3", "4", "5"]. Alternatively, if the value is "Adam|Alice|Bob", `types item_ids:array:|` parses it as \["Adam", "Alice", "Bob"].

## Example

```
format /^\[(?<logtime>[^\]]*)\] (?<name>[^ ]*) (?<title>[^ ]*) (?<id>\d*)$/
time_key logtime
time_format %Y-%m-%d %H:%M:%S %z
types id:integer
```

With this config:

```
[2013-02-28 12:00:00 +0900] alice engineer 1
```

This incoming log is parsed as:

```
time:
1362020400 (2013-02-28 12:00:00 +0900)

record:
{
  "name" : "alice",
  "title": "engineer",
  "id"   : 1
}
```

## FAQ

### How to debug my regexp pattern?

[fluentd-ui's in\_tail editor](/0.12/deployment/fluentd-ui.md#intail-setting) helps your regexp testing. Another way, [Fluentular](http://fluentular.herokuapp.com/) is a great website to test your regexp for Fluentd configuration.

NOTE: You may hit Application Error at Fluentular due to [heroku free plan limitation](https://www.heroku.com/pricing). Retry a few hours later or use fluentd-ui instead.

If this article is incorrect or outdated, or omits critical information, please [let us know](https://github.com/fluent/fluentd-docs-gitbook/issues?state=open). [Fluentd](http://www.fluentd.org/) is a open source project under [Cloud Native Computing Foundation (CNCF)](https://cncf.io/). All components are available under the Apache 2 License.


---

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