# Log Reader Binding

This binding reads and analyzes log files. Search patterns are fully configurable, therefore different kind of log files should be possible to monitor by this binding.
When certain log events are recognized, openHAB rules can be used to send notification about the event e.g by email for further analysis.

## Supported Things

This binding supports one ThingType: `reader`.
A reader supports 3 separate channels

  * One for errors
  * one for warnings
  * one custom channel for other purposes.

## Thing Configuration

The `reader` Thing has the following configuration parameters: 

| Parameter                     | Type    | Required | Default if omitted               | Description                                                                             |
| ------------------------------| ------- | -------- | -------------------------------- |-----------------------------------------------------------------------------------------|
| `filePath`                    | String  |   yes    | `${OPENHAB_LOGDIR}/openhab.log`  | Path to log file. ${OPENHAB_LOGDIR} is automatically replaced by the correct directory. |
| `refreshRate`                 | integer |   no     | `1000`                           | Time in milliseconds between individual log reads.                                      |
| `errorPatterns`               | String  |   no     | `ERROR+`                         | Search patterns separated by \| character for error events.                             |
| `errorBlacklistingPatterns`   | String  |   no     |                                  | Search patterns for blacklisting unwanted error events separated by \| character.       |
| `warningPatterns`             | String  |   no     | `WARN+`                          | Search patterns separated by \| character for warning events.                           |
| `warningBlacklistingPatterns` | String  |   no     |                                  | Search patterns for blacklisting unwanted warning events separated by \| character.     |
| `customPatterns`              | String  |   no     |                                  | Search patterns separated by \| character for custom events.                            |
| `customBlacklistingPatterns`  | String  |   no     |                                  | Search patterns for blacklisting unwanted custom events separated by \| character.      |

Search patterns follows [Java regular expression syntax](https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/util/regex/Pattern.html).
Be aware that search patterns are case sensitive.

## Channels

List of channels

| Channel Type ID    | Item Type    | Description                                                 |
| ------------------ | ------------ | ----------------------------------------------------------- |
| `lastErrorEvent`   | `String`     | Displays content of last [ERROR] event                      |
| `lastWarningEvent` | `String`     | Displays content of last [WARN] event                       |
| `lastCustomEvent`  | `String`     | Displays content of last [CUSTOM] event                     |
| `errorEvents`      | `Number`     | Displays number of [ERROR] lines matched to search pattern  |
| `warningEvents`    | `Number`     | Displays number of [WARN] lines matched to search pattern   |
| `customEvents`     | `Number`     | Displays number of [CUSTOM] lines matched to search pattern |
| `logRotated`       | `DateTime`   | Last time when log rotated recognized                       |
| `newErrorEvent`    | -            | Trigger channel for last [ERROR] line                       |
| `newWarningEvent`  | -            | Trigger channel for last [WARN] line                        |
| `newCustomEvent`   | -            | Trigger channel for last [CUSTOM] line                      |

## Examples

### example.things

```xtend

logreader:reader:openhablog[ refreshRate=1000, errorPatterns="ERROR+", errorBlacklistingPatterns="annoying error which should be ignored|Another annoying error which should be ignored" ]

```

### example.items

```xtend

DateTime logreaderLogRotated        "Last Log Rotation [%1$tY.%1$tm.%1$te %1$tR]"   <time>  { channel="logreader:reader:openhablog:logRotated" }
Number   logreaderErrors            "Error events matched [%d]"                     <alarm> { channel="logreader:reader:openhablog:errorEvents" }
String   logreaderLastError         "Last error [%s]"                                       { channel="logreader:reader:openhablog:lastErrorEvent" }
Number   logreaderWarnings          "Warning events matched [%d]"                   <alarm> { channel="logreader:reader:openhablog:warningEvents" }
String   logreaderLastWarning       "Last warning [%s]"                                     { channel="logreader:reader:openhablog:lastWarningEvent" }
Number   logreaderCustoms           "Custom events matched [%d]"                    <alarm> { channel="logreader:reader:openhablog:customEvents" }
String   logreaderLastCustom        "Last Custom [%s]"                                      { channel="logreader:reader:openhablog:lastCustomEvent" }

```

### example.sitemap

```xtend

sitemap logreader_example label="Example" {
	Frame label="openHAB Log Reader" {
		Text item=logreaderErrors
		Text item=logreaderLastError
		Text item=logreaderWarnings
		Text item=logreaderLastWarning
		Text item=logreaderCustoms
		Text item=logreaderLastCustom
		Text item=logreaderLogRotated
	}
}

```

### example.rules

```xtend
rule "LogReader"
    when
        Channel "logreader:reader:openhablog:newErrorEvent" triggered
    then
        // do something
    end
```

Use the rules with your Telegram Bot (need openHAB Telegram Binding installed and configured)

```xtend
rule "LogReader"
    when
        Channel 'logreader:reader:openhablog:newErrorEvent' triggered
    then
        val telegramAction = getActions("telegram","telegram:telegramBot:myBot")
        telegramAction.sendTelegram("*ERROR* LogReader Event!\n%s Errors are in the log! Here is the last row of it:\n`%s`", logreaderErrors.state.toString, logreaderLastError.state.toString)
    end
```

Be careful when sending e.g. email notifications.
You could easily send thousand of *spam* emails in short period if e.g. one binding is in error loop.

### Thing status

Check thing status for errors.

### Verbose logging

Enable DEBUG logging in karaf console to see more precise error messages:

`log:set DEBUG org.openhab.binding.logreader`

See [openHAB2 logging docs](https://www.openhab.org/docs/administration/logging.html#defining-what-to-log) for more help.
