On a closer look, it seems that returning null causes a non-fatal error:
2019-10-27 11:26:36,898 main ERROR No node named null in
org.apache.logging.log4j.core.appender.AppenderSet@71f67a79
2019-10-27 11:26:36,900 main ERROR Null object returned for
ScriptAppenderSelector in Appenders.
2019-10-27 11:26:36,902 main ERROR Unable to locate appender
"SelectSMTP" for logger config "root"
2019-10-27 11:26:37,057 main ERROR No node named null in
org.apache.logging.log4j.core.appender.AppenderSet@48bfb884
2019-10-27 11:26:37,058 main ERROR Null object returned for
ScriptAppenderSelector in Appenders.
2019-10-27 11:26:37,059 main ERROR Unable to locate appender
"SelectSMTP" for logger config "root"
Best regards,
Behrang Saeedzadeh
blog.behrang.org
On Sun, Oct 27, 2019 at 11:02 AM Behrang Saeedzadeh <behran...@gmail.com>
wrote:
> Hi Ralph,
>
> Thanks for the reply. That worked for me, but I have a couple of
> suggestions:
>
> 1.
>
> In the documentation, it is not mentioned that the script can return
> null to signal that none of the appenders in that block’s AppenderSet
> should be selected. It is worthwhile to mention that in the docs.
> 2.
>
> With how ScriptAppenderSelector is working now, the log configuration
> becomes quite verbose:
>
> <?xml version="1.0" encoding="UTF-8"?><Configuration status="debug"
> name="ScriptAppenderSelectorExample">
> <Appenders>
> <ScriptAppenderSelector name="SelectConsole">
> <Script language="groovy"><![CDATA[
> if (System.getProperty("CONSOLE_APPENDER_ENABLED",
> 'true').equalsIgnoreCase('true')) {
> return "Console"
> } else {
> return null
> }
> ]]></Script>
> <AppenderSet>
> <Console name="Console" target="SYSTEM_OUT">
> <PatternLayout pattern="%d{HH:mm:ss.SSS} [%t] %-5level
> %logger{36} - %msg%n"/>
> </Console>
> </AppenderSet>
> </ScriptAppenderSelector>
>
> <ScriptAppenderSelector name="SelectFile">
> <Script language="groovy"><![CDATA[
> if (System.getProperty("FILE_APPENDER_ENABLED",
> 'true').equalsIgnoreCase('true')) {
> return "File"
> } else {
> return null
> }
> ]]></Script>
> <AppenderSet>
> <File name="File" fileName="application.log">
> <PatternLayout pattern="%d{HH:mm:ss.SSS} [%t] %-5level
> %logger{36} - %msg%n" />
> </File>
> </AppenderSet>
> </ScriptAppenderSelector>
>
> <ScriptAppenderSelector name="SelectSMTP">
> <Script language="groovy"><![CDATA[
> if (System.getProperty("SMTP_APPENDER_ENABLED",
> 'true').equalsIgnoreCase('true')) {
> return "SMTP"
> } else {
> return null
> }
> ]]></Script>
> <AppenderSet>
> <SMTP name="SMTP"
> subject="App: Error"
> from="lo...@example.com"
> to="supp...@example.com"
> smtpHost="smtp.example.com"
> smtpPort="25"
> bufferSize="5">
> </SMTP>
> </AppenderSet>
> </ScriptAppenderSelector>
> </Appenders>
> <Loggers>
> <Root level="info">
> <AppenderRef ref="SelectConsole"/>
> </Root>
> </Loggers></Configuration>
>
> If the script could return a list of appenders to be selected instead of
> just one appender, the configuration would become more concise:
>
> <?xml version="1.0" encoding="UTF-8"?>
> <Configuration status="debug" name="ScriptAppenderSelectorExample">
> <Appenders>
> <ScriptAppenderSelector name="SelectMultiple">
> <Script language="groovy"><![CDATA[
> def selected = []
>
> if (System.getProperty("CONSOLE_APPENDER_ENABLED",
> 'true').equalsIgnoreCase('true')) {
> selected.add("Console")
> }
>
> if (System.getProperty("FILE_APPENDER_ENABLED",
> 'true').equalsIgnoreCase('true')) {
> selected.add("File")
> }
>
> if (System.getProperty("SMTP_APPENDER_ENABLED",
> 'true').equalsIgnoreCase('true')) {
> selected.add("SMTP")
> }
>
> return selected
> ]]></Script>
> <AppenderSet>
> <Console name="Console" target="SYSTEM_OUT">
> <PatternLayout pattern="%d{HH:mm:ss.SSS} [%t] %-5level
> %logger{36} - %msg%n"/>
> </Console>
> <File name="File" fileName="application.log">
> <PatternLayout pattern="%d{HH:mm:ss.SSS} [%t] %-5level
> %logger{36} - %msg%n" />
> </File>
> <SMTP name="SMTP"
> subject="App: Error"
> from="lo...@example.com"
> to="supp...@example.com"
> smtpHost="smtp.example.com"
> smtpPort="25"
> bufferSize="5">
> </SMTP>
> </AppenderSet>
> </ScriptAppenderSelector>
> </Appenders>
> <Loggers>
> <Root level="info">
> <AppenderRef ref="SelectMultiple"/>
> </Root>
> </Loggers>
> </Configuration>
>
> If that makes sense, I can work on a PR.
> Best regards,
> Behrang Saeedzadeh
> blog.behrang.org
>
>
> On Sun, Oct 27, 2019 at 3:21 AM Ralph Goers <ralph.go...@dslextreme.com>
> wrote:
>
>> Take a look at the ScriptAppenderSelector -
>> http://logging.apache.org/log4j/2.x/manual/appenders.html#ScriptAppenderSelector
>> <
>> http://logging.apache.org/log4j/2.x/manual/appenders.html#ScriptAppenderSelector>
>> - and see if that does what you want. If not, please let us know.
>>
>> Ralph
>>
>> > On Oct 26, 2019, at 5:26 AM, Behrang Saeedzadeh <behran...@gmail.com>
>> wrote:
>> >
>> > Let’s say I have three appenders:
>> >
>> > <?xml version="1.0" encoding="UTF-8"?><Configuration status="WARN">
>> > <Appenders>
>> > <Console name="Console" target="SYSTEM_OUT">
>> > <PatternLayout pattern="%d{HH:mm:ss.SSS} [%t] %-5level
>> > %logger{36} - %msg%n"/>
>> > </Console>
>> >
>> > <File name="File" fileName="application.log">
>> > <PatternLayout pattern="%d{HH:mm:ss.SSS} [%t] %-5level
>> > %logger{36} - %msg%n" />
>> > </File>
>> >
>> > <SMTP name="SMTP"
>> > subject="App: Error"
>> > from="lo...@example.com"
>> > to="supp...@example.com"
>> > smtpHost="mailserver"
>> > smtpPort="25"
>> > bufferSize="100">
>> > </SMTP>
>> > </Appenders></Configuration>
>> >
>> > I want to enable/disable these appenders using system properties in
>> > different environments.
>> >
>> > One option is to control this using scripts:
>> >
>> > <?xml version="1.0" encoding="UTF-8"?><Configuration status="WARN">
>> > <Scripts>
>> > <Script name="isConsoleAppenderEnabled"
>> language="groovy"><![CDATA[
>> > return System.getProperty("CONSOLE_APPENDER_ENABLED",
>> > 'true').equalsIgnoreCase('true');
>> > ]]></Script>
>> >
>> > <Script name="isFileAppenderEnabled" language="groovy"><![CDATA[
>> > return System.getProperty("FILE_APPENDER_ENABLED",
>> > 'true').equalsIgnoreCase('true');
>> > ]]></Script>
>> >
>> > <Script name="isSmtpAppenderEnabled" language="groovy"><![CDATA[
>> > return System.getProperty("SMTP_APPENDER_ENABLED",
>> > 'true').equalsIgnoreCase('true');
>> > ]]></Script>
>> > </Scripts>
>> >
>> > <Appenders>
>> > <Console name="Console" target="SYSTEM_OUT">
>> > <PatternLayout pattern="%d{HH:mm:ss.SSS} [%t] %-5level
>> > %logger{36} - %msg%n"/>
>> > </Console>
>> >
>> > <File name="File" fileName="application.log">
>> > <PatternLayout pattern="%d{HH:mm:ss.SSS} [%t] %-5level
>> > %logger{36} - %msg%n" />
>> > </File>
>> >
>> > <SMTP name="SMTP"
>> > subject="App: Error"
>> > from="lo...@example.com"
>> > to="supp...@example.com"
>> > smtpHost="smtp.example.com"
>> > smtpPort="25"
>> > bufferSize="5">
>> > </SMTP>
>> > </Appenders>
>> >
>> > <Loggers>
>> > <Root level="info">
>> > <AppenderRef ref="Console">
>> > <ScriptFilter onMatch="ACCEPT" onMisMatch="DENY">
>> > <ScriptRef ref="isConsoleAppenderEnabled"/>
>> > </ScriptFilter>
>> > </AppenderRef>
>> >
>> > <AppenderRef ref="File">
>> > <ScriptFilter onMatch="ACCEPT" onMisMatch="DENY">
>> > <ScriptRef ref="isFileAppenderEnabled"/>
>> > </ScriptFilter>
>> > </AppenderRef>
>> >
>> > <AppenderRef ref="SMTP">
>> > <ScriptFilter onMatch="ACCEPT" onMisMatch="DENY">
>> > <ScriptRef ref="isSmtpAppenderEnabled"/>
>> > </ScriptFilter>
>> > </AppenderRef>
>> > </Root>
>> > </Loggers></Configuration>
>> >
>> > However, this doesn’t really disable the appender, but computes the
>> value
>> > of the script for each log event and based on that suppresses the event
>> > from being sent to the appender.
>> >
>> > Another option is to write a custom appender that implements this logic
>> and
>> > that can decorate other appenders to achieve this behavior.
>> >
>> > But I was wondering if there’s already a built-in feature available that
>> > can enable/disable appenders based on environment variables and/or
>> system
>> > properties?
>> >
>> >
>> > Best regards,
>> > Behrang Saeedzadeh
>> > blog.behrang.org
>>
>>
