Registering a PEM agent v9

Before a PEM agent can be used, you must register it with a PEM server. PEM agents installed by the PEM server package are registered automatically during server configuration. For all other agents, you must follow these instructions.

How to register PEM agents

On Linux and Windows hosts, the PEM agent package includes a command line utility called pemworker,. You can use it to perform management tasks, including registering the PEM agent.

On Windows, the PEM agent graphical installer allows you to register the agent when installing it. This convenience option doesn't support all the possibilities provided by the pemworker utility. If you don't want the installer to register the agent, clear the Register now checkbox. For more details, see the installation instructions.

Registering a PEM agent using the pemworker utility

The pemworker utility is installed automatically with the PEM agent. It's located in the /usr/edb/pem/agent/bin directory on Linux and C:\Program Files\edb\pem\agent-x64\bin on Windows. To register an agent, set the PEM server password, invoke the utility as shown in the examples, and add the relevant options from the table as needed. Follow each option with a corresponding value.

Linux

export PEM_SERVER_PASSWORD=edb
# Running as root
pemworker --register-agent

Windows

set PEM_SERVER_PASSWORD=edb
# Running as admin
./pemworker.exe REGISTER

Authenticating the pemworker utility

Before any changes are made on the PEM database, the connection 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_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. After authentication succeeds, you're prompted for any other missing required information. When the registration is complete, the server confirms that the agent was successfully registered.

Unregistering a PEM agent

You can use the pemworker utility to unregister a PEM agent. To unregister an agent, invoke the pemworker utility as shown in the examples that follow.

Linux

# Running as root
pemworker --unregister-agent

Windows

./pemworker.exe UNREGISTER-AGENT

When invoking the pemworker utility, append command line options to the command string. Follow each option with a corresponding value.

Advanced usage

The following are some advanced options for PEM agent registration.

Setting the agent ID

Each registered PEM agent must have a unique agent ID. The value max(id)+1 is assigned to each agent ID unless a value is provided using the -o options as shown below.

Overriding default configurations - examples

This example shows how to register the PEM agent overriding the default configurations.

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. 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 certificates 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.

Using a non-root user account to register a PEM agent on Linux

To use a non-root 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 non-root user, such as edb. Then:

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

   → WrapCopy

   # 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:

   → WrapCopy

   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:

   → WrapCopy

   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:

   → WrapCopy

   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:

   → WrapCopy

   # 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:

   → WrapCopy

   # 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.