Retrieving platform state information with SNMP

This task describes how to retrieve IAS hardware and software registries, opened and closed issues, and events using SNMP. snmpget, snmptable, and snmpwalk are used to retrieve IAS state.

1. Verify that snmpd.service is up and running on IAS:

   [apuser@node0101 root]$ service snmpd status
   Redirecting to /bin/systemctl status snmpd.service
   
   ● snmpd.service - Simple Network Management Protocol (SNMP) Daemon.
   
      Loaded: loaded (/usr/lib/systemd/system/snmpd.service; enabled; vendor preset: disabled)
   
      Active: active (running) since Fri 2019-07-12 11:29:22 UTC; 3 weeks 4 days ago
   
   Main PID: 172815 (snmpd)
   
       Tasks: 1
   
      Memory: 11.3M
   
      CGroup: /system.slice/snmpd.service
   
              └─172815 /usr/sbin/snmpd -LS0-6d -f

2. Get the credentials, which will allow to communicate with snmpd.service:
   Note: Superuser access in required for this step.
   1. From the output of the service snmpd status command in the previous step, you can read that snmpd was started with default configuration file snmpd.conf which is located in /etc/snmp/(172815 /usr/sbin/snmpd -LS0-6d -f). If there was -C -c /root/.snmp/snmpd.conf, it would mean that the service reads configuration from the file located in /root/.snmp/, omitting the one located in /etc/snmp/.
   2. Find the file that is used for configuration on your system, and search for the lines beginning with rocommunity. There is a community string defined, which allows to request snmpd.service:

      [root@node0101 ~]# grep -m 1 rocommunity /etc/snmp/snmpd.conf 
      rocommunity ****** <some_ip> default

      Community strings were masked on the above snippet intentionally.

      Attention: If you need to add a directive in the /etc/snmp/snmpd.conf file, which specifies the creation of users who can be used in SNMPv3 requests, consider developing backing-up scripts. The backing-up scripts are needed because appliance upgrade procedures overwrite the /etc/snmp/snmpd.conf file and restore its default content.

      Another recommended way of managing SNMP users is through the snmpusm application. Note that even with the snmpusm application post-upgrade settings restoration is required.

      Tip: For more information, you are suggested to read manual pages snmpusm(1), and the SNMPv3 USM Users section of snmpd.conf(5).
3. Start SNMP sub-agent, which is responsible for responding to requests:

   Inventory retrieving is provided by SNMP sub-agent called magneto-snmp-agent.service, which should be up and running on IAS. The main daemon snmpd.service will delegate SNMP requests aiming the OIDs defined in IIAS-MIB module to the sub-agent. You use the apsnmpagent utility to manage the state of the sub-agent. Note that it allows you to switch on/switch off the sub-agent and the main snmpd.service as well. Use it carefully to avoid stopping snmpd.service by mistake.

   To enable and start snmpd.service after using the command apsnmpagent, run the command with optional argument --snmpd_only or -s as follows:

   'apsnmpagent off && apsnmpagent on --snmpd_only'

   In the above example, the first command stops and disables services magneto-snmp-agent and snmpd, and the second command enables and starts snmpd.

   Called with argument state, apsnmpagent collects information if magneto-snmp-agent is enabled on all nodes of hadomain1. If its state is inconsistent, a proper information is printed. apsnmpagent acts on all active nodes of hadomain1.

4. Use Net-SNMP snmptable application to retrieve tables defined in IIAS-MIB.txt. IIAS-MIB.txt is located in /usr/share/snmp/mibs. You can use snmptranslate -Tp -IR IIAS-MIB::iias to see its structure as a tree. A node called applianceTables contains defined tables which could be used to retrieve system state provided by the ap command with different arguments. The following table shows the mapping:

   Option	Description
   hwInventoryTable	ap hw -d
   softwareTable	ap sw -d
   openIssuesTable	ap issues
   closedIssuesTable	ap issues -c
   eventsTable	ap issues -e
   nodesTable	ap node -d
   dfSharedTable	ap df
   dfLocalTable	ap df
   gpfsFilesystemTable	ap fs
   fsMountTable	ap fs

   Tip: It might be convenient to use -Cl optional argument in snmptable command to set 'left justify' to the output.

   Using snmpget with hwInventoryTable, you can get the 'details' column, where useful information is gathered in a in comma-separated format. For example, you can find node average power consumption:

   [root@node0101 ~]# snmpwalk -v2c -c $(grep rocommunity -m 1 /etc/snmp/snmpd.conf | cut -d' ' -f2) 
   localhost IIAS-MIB::hwUnitDetails.\"hadomain1\".\"node1\".\"\"
   
   IIAS-MIB::hwUnitDetails."hadomain1"."node1"."" = STRING: 
   cpu_clock_exp:3325.0MHz,inlet_temp_celsius:21,power:on,unrecoverable_events:0,cpu_clock_avg:3325.0MHz,
   led:on,base_temp1_celsius:28,cpu_clock_tuned:active,cpu_smt_config:SMT=4,memsize:512GB,cpu_cores_enab:24,
   position:P1,avgpwr:650 Watts,base_temp3_celsius:33,base_temp2_celsius:35