Registering a PEM agent v9

You must register each PEM agent installed on a separate host with the PEM server. (The PEM agent is different from the PEM server host.) The registration process provides the PEM server with the information it needs to communicate with the agent. The PEM agent graphical installer for Windows supports self-registration for the agent. On a Linux host, you must use the pemworker utility to register the agent.

The PEM agent package installer places the PEM agent in the /usr/edb/pem/agent/bin directory. To register an agent, include the --register-agent keywords along with registration details when invoking the pemworker utility. Run the pemworker utility as the root user.

# Running as root
pemworker --register-agent

Append command line options to the command string when invoking the pemworker utility. Follow each option with a corresponding value.

If you want to use any PEM feature for which a database server restart is required by the pemagent (such as Audit Manager, Log Manager, or the Tuning Wizard), then you must set the value for allow_server_restart to true in the agent.cfg file.

Before any changes are made on the PEM database, the connecting agent is authenticated with the PEM database server. When invoking the pemworker utility, you must provide the password associated with the PEM server administrative user role (postgres). You can specify the administrative password in three ways:

• Set the PEM_MONITORED_SERVER_PASSWORD environment variable.
• Provide the password on the command line with the PGPASSWORD keyword.
• Create an entry in the .pgpass file.

If you don't provide the password, a password authentication error occurs. You are prompted for any other missing required information. When the registration is complete, the server confirms that the agent was successfully registered.

Each registered PEM agent must have a unique agent ID. For 9.0 and later:

• The value max(id)+1 is assigned to each agent ID.
• You can override the agent ID manually using the command line.

Examples

This example shows how to register the PEM agent overriding the default configurations in versions 9.0 and later.

Register the PEM agent using the command line. Assign an agent_id value of 8 using the -o option.

# Running as root
/usr/edb/pem/agent/bin/pemworker --register-agent \
--pem-server pemserver \
--pem-user postgres \
--pem-port 5432 \
--display-name agent8 \
-o agent_id=8

Postgres Enterprise Manager Agent registered successfully!

Because the agent_id of 8 is available, the PEM agent registers successfully. If the given ID is already in use by the existing agent, it throws an error.

Register the PEM agent using the command line. Assign the existing SSL certificates and key files to avoid generating new ones for a particular agent ID in versions 9.0 and later. The SSL certificates and key files must be valid for the database user agent<ID> , where <ID> must be the same as provided using the command line. Use the -o option.

# Running as root
# List the location of valid SSL certificates and key files.
ls -l /root/.pem/agent5.*
-rw------- 1 root root 2192 Nov  7 11:27 /root/.pem/agent5.crt
-rw------- 1 root root 3244 Nov  7 11:27 /root/.pem/agent5.key
   
# Register the PEM agent using command line. Assign the 
# SSL ceritificates and key files using the -o option.
/usr/edb/pem/agent/bin/pemworker --register-agent \
--pem-server pemserver \
--pem-user postgres \
--pem-port 5432 \
--config-dir /tmp/pem-config \
--display-name agent5 \
-o agent_id=5 \
-o agent_ssl_crt=/root/.pem/agent5.crt \
-o agent_ssl_key=/root/.pem/agent5.key

Postgres Enterprise Manager Agent registered successfully!

Because the valid SSL certificates and key files are available at the given location with proper permissions, the PEM agent registers successfully. If the certificate or key files are not valid or do not have proper permissions it throws an error.

Unregistering a PEM agent

You can use the pemworker utility to unregister a PEM agent. To unregister an agent, include the --unregister-agent keywords along with the details when invoking the pemworker utility:

# Running as root
pemworker --unregister-agent

Append command line options to the command string when invoking the pemworker utility. Follow each option with a corresponding value:

Setting PEM agent configuration parameters

The PEM agent RPM installer creates a sample configuration file named agent.cfg.sample in the /usr/edb/pem/agent/etc directory. When you register the PEM agent, the pemworker program creates the actual agent configuration file, named agent.cfg. You must modify the agent.cfg file, adding the following configuration parameter:

heartbeat_connection = true

You must also add the location of the ca-bundle.crt certificate authority file. By default, the installer creates a ca-bundle.crt file in the location specified in your agent.cfg.sample file. You can copy the default parameter value from the sample file or, if you use a ca-bundle.crt file that's stored in a different location, specify that value in the ca_file parameter:

ca_file=/usr/libexec/libcurl-pem7/share/certs/ca-bundle.crt

Then, use a platform-specific command to start the PEM agent service. The service is named pemagent.

On a RHEL or CentOS 7.x or 8.x host, use systemctl to start the service:

systemctl start pemagent

The service confirms that it's starting the agent. When the agent is registered and started, it appears on the Global Overview dashboard and in the Object browser tree of the PEM web interface.

For information about using the pemworker utility to register a server, see Registering a database server.

Using a nonroot user account to register a PEM agent

To use a nonroot user account to register a PEM agent, you must first install the PEM agent as a root user. After installation, assume the identity of a nonroot user, such as edb. Then:

1. Log in as edb. Create pem and logs directories and assign read, write, and execute permissions:

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   # Running as nonroot user edb
   mkdir /home/edb/pem
   mkdir /home/edb/pem/logs
   chmod 700 /home/edb/pem
   chmod 700 /home/edb/pem/logs

2. Register the agent with PEM server:

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   export PEM_SERVER_PASSWORD=edb
   
   # Use the following command to create agent certificates and an agent 
   # configuration file (`agent.cfg`) in the `/home/edb/pem` directory. 
   /usr/edb/pem/agent/bin/pemworker --register-agent --pem-server <172.19.11.230> --pem-user postgres --pem-port 5432 --display-name non_root_pem_agent --cert-path /home/edb/pem --config-dir /home/edb/pem
   
   # Use the following command to assign read and write permissions to 
   # these files:
   chmod -R 600 /home/edb/pem/agent*

3. Change the parameters of the agent.cfg file:

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   vi /home/edb/pem/agent.cfg
   agent_ssl_key=/home/edb/pem/agent<id>.key
   agent_ssl_crt=/home/edb/pem/agent<id>.crt
   log_location=/home/edb/pem/worker.log
   agent_log_location=/home/edb/pem/agent.log

   Where <id> is the assigned PEM agent ID.

4. Create a tmp directory, set the environment variable, and start the agent:

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   mkdir /home/edb/pem/tmp
   
   # Create a script file, add the environment variable, give permissions, and execute:
   vi /home/edb/pem/run_pemagent.sh
   #!/bin/bash
   export TEMP=/home/edb/agent/tmp
   /usr/edb/pem/agent/bin/pemagent -c /home/edb/agent/agent.cfg
   chmod a+x /home/edb/pem/run_pemagent.sh
   cd /home/edb/pem
   ./run_pemagent.sh

   Your PEM agent is now registered and started with the edb user. If your machine restarts, then this agent doesn't restart automatically. You need to start it manually using the previous command.

5. Optionally, you can create the service for this PEM agent as the root user to start this agent automatically at machine restart as follows:

   a. Update the values for the configuration file path and the user in the pemagent service file as superuser:

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   # Running as superuser
   sudo vi  /usr/lib/systemd/system/pemagent.service
   [Service]
   Type=forking
   WorkingDirectory=/home/edb/pem
   Environment=LD_LIBRARY_PATH=/usr/edb/pem/agent/lib:/usr/libexec/edb-snmp++/lib 
   Environment=TEMP=/home/edb/pem/tmp
   ExecStart=/usr/edb/pem/agent/bin/pemagent -c /home/edb/pem/agent.cfg

   b. Stop the running agent process, and then restart the agent service:

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   # Find the process id of the running pem agent and pem worker process and kill that process
   ps -ax | grep pemagent
   kill -9 <process_id_of_pemagent>
   ps -ax | grep pemworker
   kill -9 <process_id_of_pemworker>
   # Enable and start pemagent service
   sudo systemctl enable pemagent
   sudo systemctl start pemagent
   sudo systemctl status pemagent

6. Check the agent status on the PEM dashboard.

• On this page
• Unregistering a PEM agent
• Setting PEM agent configuration parameters
• Using a nonroot user account to register a PEM agent