Alerts

To quickly view any notification alerts, use the Notifications label on the header bar of the Command Center dashboard.

When you open the Notifications window, unread notifications are highlighted in light blue. The alerts are ordered by time and are kept for 7 days. When you close the Notifications window, all alerts are considered read.

To customize the alert notifications, go to the Admin> Alerts page, where an administrator can set up alert rules. The rules help detect and respond to events that occur in the Greenplum Database system and in currently executing database queries. When a rule is matched, Command Center logs a record.

You can set up email alerts by configuring an SMTP server in Greenplum Database or in Command Center. Additionally, you can create a send_alert.sh shell script to forward alerts to other destinations, such as an SMS gateway or a Slack channel. If the script is present, Command Center runs it whenever an alert is raised.

Command Center creates the gpmetrics schema in the gpperfmon database to store both rules and log records. See gpmetrics Schema Reference for information about the gpcc_alert_rule and gpcc_alert_log tables in the gpmetrics schema.

This topic contains the following subtopics:

• Configuring Alert Rules

• Configuring Alert Email

• Creating a Send Alert Script

Configuring Alert Rules

Click EDIT to manage alert event rules. To enable an alert rule, enter any data required in the fields and check the box. Uncheck the box to disable the rule. Click SAVE when you have finished making changes to the alert configuration.

Cluster Level

Master Level

Segment Level

     100 - sum(<available disk space>) / sum(<total disk space>) * 100

Query Level

Configuring Alert Email

Command Center requires an SMTP server to send alert emails.

Command Center first attempts an encrypted TLS connection and then falls back to an unencrypted connection if TLS is not supported. The SMTP server must support one of the following authentication methods: NONE, PLAIN, LOGIN, or CRAM-MD5. Command Center will use the most secure of these methods the SMTP server allows.

Configuring email With Command Center

Click EDIT in the Manage email configuration panel.

The alert email configuration is set with the following Greenplum Database server configuration parameters:

When you click SAVE, Command Center sends a test email to the addresses in the Send emails to field. The email contains a list of the currently configured alert rules. If there is an error in the SMTP server or username/password configuration and the email cannot be sent, Command Center displays an error message.

Configuring email for Greenplum Database

The following server configuration parameters are used to configure SMTP email for Greenplum Database.

Command Center uses the gp_email_smtp_server, gp_email_smtp_userid, and gp_email_smtp_password parameters if they are set. It ignores the remaining parameters.

You can check the current value of a configuration parameter by running the gpconfig -s command on the master host, for example:

$ gpconfig -s gp_email_smtp_server

Use the gpconfig -c option to set the values of server configuration parameters, for example:

$ gpconfig -c gp_email_smtp_server -v "smtp.example.com:465"
$ gpconfig -c gp_email_smtp_userid -v "gpcc-alerts@example.com"
$ gpconfig -c gp_email_smtp_password -v "changeme"
$ gpconfig -c gp_email_from -v "gpcc-alerts@example.com"
$ gpconfig -c gp_email_to -v "gpcc-admin@example.com;gpdb-admin@example.com"

Run gpstop -u to reload the configuration files after changing these configuration parameters.

Creating a Send Alert Script

The send alert script is a shell script that you can use to send Command Center alerts to destinations such as SMS gateways, pagers, team collaboration tools like Slack, chat servers, archive files, alternative email servers, and so on. You can use the send alert script in addition to sending email from Command Center, or as an alternative to sending alert emails from Command Center.

Command Center looks for the script $MASTER_DATA_DIRECTORY/gpmetrics/send_alert.sh on the host where Command Center is running—either the master host or standby host. If the file exists and is executable by the gpadmin user, Command Center executes the script. The following variables are set on the command line when the script runs.

An example script that you can customize is provided at $GPCC_HOME/alert-email/send_alert.sh.sample. The example formats the alert as HTML email text and pipes it through the Linux mail command.

To set up a send alert script:

1. Copy the $GPCC_HOME/alert-email/send_alert.sh.sample file to $MASTER_DATA_DIRECTORY/gpmetrics/send_alert.sh.

2. Customize the script with code to format and deliver the alert to your desired destination.

3. Run gpcc start to restart Command Center and enable the script.

SNMP Alert Script Example

SNMP support is discontinued in Greenplum Database 6, but you can use a Command Center alert script to send alerts to an SNMP manager.

This example alert script sends Command Center alerts as SNMP notifications in a format similar to Greenplum Database 5 SNMP notifications, using the SNMP OIDs for Greenplum Database as arguments.

This is the OID hierarchy structure for Greenplum Database:

iso(1)
identified-organization(3)
dod(6)
internet(1)
private(4)
enterprises(1)
gpdbMIB(31327)
gpdbObjects(1)
gpdbAlertMsg(1)

The following table lists the Greenplum Database OIDs:

Command Center sets environment variables that can be mapped to the gpdbAlertMsg, gpdbAlertSqlStmt, and gpdbAlertSystemName OIDs. For the other OIDs, the script sends an empty string or 0, depending on data type.

Prerequisites

The SNMP service must be configured and enabled on the host where Command Center is running. If the snmpd file is not present in the /usr/sbin directory, then SNMP is not installed on the system.

To install SNMP on Red Hat and CentOS, use yum to install the net-snmp, net-snmp-libs, and net-snmp-utils packages. Configure SNMP following the operating system documentation. This example script specifies the SNMP community public, but you can set a different community string with the rocommunity parameter in the /etc/snmp/snmpd.conf file.

Start the snmpd daemon with the systemctl command:

$ sudo systemctl enable snmpd.service

Verify the system snmpd daemon is running with this command:

$ sudo snmpwalk -v 1 -c public localhost .1.3.6.1.2.1.1.1.0

If the daemon is running, the snmpwalk command output is similar to the following:

SNMPv2-MIB::sysDescr.0 = STRING: Linux gp-mdw 3.10.0-957.12.2.el7.x86_64 #1 SMP Tue May 14 21:24:32 UTC 2019 x86_64

Setting up SNMP Notifications

1. As the gpadmin user, create the file $MASTER_DATA_DIRECTORY/gpmetrics/send_alert.sh with the following contents:

   RUNNINT_TIME=`psql -c 'select extract(epoch from (current_timestamp - pg_postmaster_start_time())) * 100;'|sed -n '3p'|awk '{print $1}'`
   HOST=`hostname`
   snmptrap -v 2c -c public \
       {##trapserver##} \
       "${RUNNINT_TIME}" \
       "enterprises.31327.5.0.1" \
       SNMPv2-SMI::enterprises.31327.1.1 s "${RULEDESCRIPTION}" \
       SNMPv2-SMI::enterprises.31327.1.2 i 0 \
       SNMPv2-SMI::enterprises.31327.1.3 s "" \
       SNMPv2-SMI::enterprises.31327.1.4 s "" \
       SNMPv2-SMI::enterprises.31327.1.5 s "${QUERYTEXT}" \
       SNMPv2-SMI::enterprises.31327.1.6 s "${HOST}"
   

   Replace {##trapserver##} with the name of the host running snmpd.

2. Make the script executable.

   $ chmod +x $MASTER_DATA_DIRECTORY/gpmetrics/send_alert.sh
   

3. Restart Command Center to enable the script.

   $ gpcc start
   

Testing the SNMP Alert Script

To test the script, you can use the snmptrapd trap receiver.

1. As root, edit the /etc/snmp/snmptrap.conf file and add the following line to allow the daemon to receive unauthenticated notifications:

   disableAuthorization yes
   

2. Start the snmptrapd daemon with this command:

   # /usr/sbin/snmptrapd -m ALL -Lf ~/snmptest.log
   

Check the /home/root/snmptest.log file for notifications.