Replies by Tony Marnell for InterSystems Developer Community

Tony Marnell · Sep 22, 2023

I use the NotifyBecomePrimary() hook in the ZMIRROR routine to call some code to send an email.

Here's the ZMIRROR routine from the %SYS namespace:

ZMIRROR    // User-defined code for mirror environment events
    QUIT
    
    //
    // The member has fully become primary so it is now safe to job off processes
    //
    // 20230314 - TM - Initial version
    //
NotifyBecomePrimary()
    
    //
    // Send an alert email to notify support staff that a mirror failover has occurred
    //
    // 20230726 - TM - Initial version
    //
    set Namespace = $znspace
    try {
        znspace "HAPPI"
        do ##class(System.AlertEmail).MirrorFailover()
        znspace Namespace
    }
    catch {
        znspace Namespace
    }
    
    QUIT

The email-sending code from the application namespace references configuration data in a global and constructs a html-formatted message to inform interested parties that a mirror failover has occurred. You should be able to make out what's going on and get it working to your own needs. Here's the class:

/// Description
/// -----------
///
/// Grapevine Solutions - HAPPI
///
/// This class implements the alert email methods for various system events.
///
/// Revision History
/// ----------------
///
/// 20230726 - TM - Initial version
///
Class System.AlertEmail Extends %RegisteredObject
{

/// This method sends an alert email message when a mirror failover occurs.  It is called from
/// the ZMIRROR routine in the %SYS namespace.
///
/// Revision History
/// ----------------
///
/// 20230726 - TM - Initial version
///
ClassMethod MirrorFailover()
{
    // get the current time
    set EmailTimeStampH = $now()
    
    // get the hostname, e.g. HCPGPO11-V, HCDDMC11-V
    set HostName = $zconvert($SYSTEM.INetInfo.LocalHostName(), "U")
    
    // get the environment, e.g. LIVE, TEST, DEV
    set Environment = ^HAPPIConfig("HostName", HostName)
    
    // get a connection to the email server
    set MailServer = ##class(%Net.SMTP).%New()
    set MailServer.smtpserver = ^HAPPIConfig("Environment", Environment, "Email", "SMTPServer")
    set MailServer.port = ^HAPPIConfig("Environment", Environment, "Email", "SMTPPort")
    
    // check for email server authentication details
    set MailServerUserName = $get(^HAPPIConfig("Environment", Environment, "Email", "Authentication", "UserName"))
    set MailServerPassword = $get(^HAPPIConfig("Environment", Environment, "Email", "Authentication", "Password"))
    
    // if there are authentication details then add them to the connection
    if ((MailServerUserName '= "") & (MailServerPassword '= "")) {
        
        set MailAuthentication = ##class(%Net.Authenticator).%New()
        set MailAuthentication.UserName = MailServerUserName
        set MailAuthentication.Password = MailServerPassword
        set MailServer.authenticator = MailAuthentication
        
        }
    
    // create a new HTML-formatted mail message
    set MailMessage = ##class(%Net.MailMessage).%New()
    set MailMessage.IsHTML = 1
    
    // set the recipient list
    set To = $order(^HAPPIConfig("Environment", Environment, "Email", "To", ""))
    while (To '= "") {
        if (^HAPPIConfig("Environment", Environment, "Email", "To", To) = 1) do MailMessage.To.Insert(To)
        set To = $order(^HAPPIConfig("Environment", Environment, "Email", "To", To))
    }
    
    // set the sender
    set MailMessage.From = ^HAPPIConfig("Environment", Environment, "Email", "From")
    
    // set the subject
    set Subject = "Mirror Failover Alert on " _ HostName _ " (" _ Environment _ ")"
    set MailMessage.Subject = Subject
    
    //--------------------------------
    // build the message html document
    //--------------------------------
    
    // start of html document
    do MailMessage.TextData.WriteLine("<!DOCTYPE html>")
    do MailMessage.TextData.WriteLine("<html>")
    
    // start of header
    do MailMessage.TextData.WriteLine("<head>")

    do MailMessage.TextData.WriteLine("<meta charset=""UTF-8"">")
    do MailMessage.TextData.WriteLine("<title>" _ Subject _ "</title>")
    
    // style sheet
    do MailMessage.TextData.WriteLine("<style>")
    do MailMessage.TextData.WriteLine("body {font-family: Arial, Helvetica, sans-serif;}")
    do MailMessage.TextData.WriteLine("h2 {color: blue; font-size: '125%';}")
    do MailMessage.TextData.WriteLine("h3 {color: blue; font-size: '100%';}")
    do MailMessage.TextData.WriteLine("table {border: 1px solid #ddd; border-spacing: 10px; border-collapse: separate;}")
    do MailMessage.TextData.WriteLine(".good {color: green;}")
    do MailMessage.TextData.WriteLine(".bad {color: red;}")
    do MailMessage.TextData.WriteLine("</style>")
    
    // end of header
    do MailMessage.TextData.WriteLine("</head>")
    
    // start of body
    do MailMessage.TextData.WriteLine("<body>")
    
    // write subject as message header
    do MailMessage.TextData.WriteLine("<h2>" _ Subject _ "</h2>")
    
    // write alert details
    do MailMessage.TextData.WriteLine("<h3>Alert Details</h3>")
    do MailMessage.TextData.WriteLine("<table>")
    do MailMessage.TextData.WriteLine("<tr>")
    do MailMessage.TextData.WriteLine("<td>Application</td>")
    do MailMessage.TextData.WriteLine("<td>HAPPI</td>")
    do MailMessage.TextData.WriteLine("</tr>")
    do MailMessage.TextData.WriteLine("<tr class=""bad"">")
    do MailMessage.TextData.WriteLine("<td>Alert Reason</td>")
    do MailMessage.TextData.WriteLine("<td>Mirror Failover")
    do MailMessage.TextData.WriteLine("</tr>")
    do MailMessage.TextData.WriteLine("<tr>")
    do MailMessage.TextData.WriteLine("<td>Host Name</td>")
    do MailMessage.TextData.WriteLine("<td>" _ HostName _ "</td>")
    do MailMessage.TextData.WriteLine("</tr>")
    do MailMessage.TextData.WriteLine("<tr>")
    do MailMessage.TextData.WriteLine("<td>Environment</td>")
    do MailMessage.TextData.WriteLine("<td>" _ Environment _ "</td>")
    do MailMessage.TextData.WriteLine("</tr>")
    do MailMessage.TextData.WriteLine("<tr>")
    do MailMessage.TextData.WriteLine("<td>Alert Time</td>")
    do MailMessage.TextData.WriteLine("<td>" _ $zdatetime($System.Util.UTCtoLocalWithZTIMEZONE(EmailTimeStampH), 3, 1, 3) _ "</td>")
    do MailMessage.TextData.WriteLine("</tr>")
    do MailMessage.TextData.WriteLine("</table>")
    
    // write support instructions
    do MailMessage.TextData.WriteLine("<h3>Support Instructions</h3>")
    do MailMessage.TextData.WriteLine("<p>")
    do MailMessage.TextData.WriteLine("A mirror failover has occurred in the " _ Environment _ " environment and " _ HostName _  " is now the primary failover member.")
    do MailMessage.TextData.WriteLine("</p>")
    do MailMessage.TextData.WriteLine("<p>")
    do MailMessage.TextData.WriteLine("Please ensure that the failover has not disrupted any application processes.")
    do MailMessage.TextData.WriteLine("</p>")
    do MailMessage.TextData.WriteLine("<p>")
    do MailMessage.TextData.WriteLine("Please do not reply to this message as it was automatically generated.")
    do MailMessage.TextData.WriteLine("</p>")
    
    // end of body
    do MailMessage.TextData.WriteLine("</body>")
    
    // end of html document
    do MailMessage.TextData.WriteLine("</html>")
    
    // send the message
    do MailServer.Send(MailMessage)
    
    QUIT
}

}