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Using GMail with a Log4j SMTP Appender in Grails

Posted by: Burt Beckwith on 2010-02-03 21:55:00.0

I saw a plaintive wail on Twitter about using GMail as the smtp server to send error emails using a Log4j SMTPAppender in Grails. It turned out to be a little tricky (and a bigger solution than 140 characters would allow) so I thought I'd describe the process here.

Most of the properties are configurable as appender attributes (e.g. server name, auth username, etc.) but two important ones aren't. SMTPAppender creates a Properties instance with System.getProperties() as the default values and adds smtp properties to that. But you need to specify the smtp port (it will default to 25 otherwise) and you need to tell it to send a STARTTLS command. Both are configurable via system properties:

System.setProperty 'mail.smtp.port', '587'
System.setProperty 'mail.smtp.starttls.enable', 'true'

and if you add those calls to Config.groovy before the appender is instantiated then it will have the values available when it configures its JavaMail Session:

import org.apache.log4j.Level
import org.apache.log4j.net.SMTPAppender

...

mail.error.server = 'smtp.gmail.com'
mail.error.port = 587
mail.error.username = '[email protected]'
mail.error.password = 'yourpassword'
mail.error.to = '[email protected]'
mail.error.from = '[email protected]'
mail.error.subject = '[Application Error]'
mail.error.starttls = true
mail.error.debug = false

environments {
production {
grails.serverURL = "http://www.changeme.com"
}
development {
grails.serverURL = "http://localhost:8080/${appName}"
}
test {
grails.serverURL = "http://localhost:8080/${appName}"
}
}

log4j = {

System.setProperty 'mail.smtp.port', mail.error.port.toString()
System.setProperty 'mail.smtp.starttls.enable', mail.error.starttls.toString()

appenders {

appender new SMTPAppender(name: 'smtp', to: mail.error.to, from: mail.error.from,
subject: mail.error.subject, threshold: Level.ERROR,
SMTPHost: mail.error.server, SMTPUsername: mail.error.username,
SMTPDebug: mail.error.debug.toString(), SMTPPassword: mail.error.password,
layout: pattern(conversionPattern:
'%d{[ dd.MM.yyyy HH:mm:ss.SSS]} [%t] %n%-5p %n%c %n%C %n %x %n %m%n'))
}

error 'org.codehaus.groovy.grails.web.servlet', // controllers
'org.codehaus.groovy.grails.web.pages', // GSP
'org.codehaus.groovy.grails.web.sitemesh', // layouts
'org.codehaus.groovy.grails.web.mapping.filter', // URL mapping
'org.codehaus.groovy.grails.web.mapping', // URL mapping
'org.codehaus.groovy.grails.commons', // core / classloading
'org.codehaus.groovy.grails.plugins', // plugins
'org.codehaus.groovy.grails.orm.hibernate', // hibernate integration
'org.springframework',
'org.hibernate',
'net.sf.ehcache.hibernate'
warn 'org.mortbay.log'

root {
error 'stdout', 'smtp'
additivity = true
}
}

I've parameterized the properties to make them configurable for each environment or using an external configuration file.

Note that GMail has a limit of 500 emails per day, so if you generate a lot of errors in your app you could hit that limit.

Burt Beckwith's complete blog can be found at: http://burtbeckwith.com/blog/

About Burt Beckwith

Burt Beckwith has been a software developer for 15 years, most of that as a JVM developer, and for the last five years working with Grails and Groovy. He is a core developer on the Grails team at SpringSource, and has created over 40 Grails plugins. Burt is a frequent speaker at conferences and user groups where he shares his passion for Grails and other Groovy-based technologies, in particular those that are related to persistence, security, and performance. He is the author of "Programming Grails" and blogs at http://burtbeckwith.com/blog/

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