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Using GMail with a Log4j SMTP Appender in Grails

Posted by: Burt Beckwith on 02/03/2010

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 = 'your.email@gmail.com'
mail.error.password = 'yourpassword'
mail.error.to = 'to@yourapp.com'
mail.error.from = 'from@yourapp.com'
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 is a Java and Groovy developer with over ten years of experience in a variety of industries including biotech, travel, e-learning, social networking, and financial services. For the past three years he's been working with Grails and Groovy full-time. Along the way he's created over fifteen Grails plugins and made significant contributions to several others. He was the technical editor for Grails in Action.

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