[ClusterLabs] FW: Fence agent definition under Centos7.6

[Michael Powell]

I'm basically re-posting this request again, since I've gotten no response over the last two weeks.  If someone can take pity on a newbie, I'd sure appreciate it.

In the interim, I've done some experiments, trying to use fence-ipmilan in lieu of the mgpstonith fence agent described in the previous e-mail.  Without going into a lot of details, the results have been unsatisfactory, so I've renewed my efforts to get the in-house mgpstonith fence agent to work.

I'm still not sure about the specific question of where the mgpstonith executable needs to reside.  By moving it from /usr/lib64/stonith/plugins/external to /usr/lib64/stonith/plugins, and /usr/sbin,  I was able to eliminate the "Unknown fence agent" error.   That said, the following commands produce the subsequent log error messages:

        crm configure primitive mgraid-stonith stonith:mgpstonith \
            params hostlist="mgraid-canister" \
            meta requires="quorum" \
            op monitor interval="0" timeout="20s"

This produces the following messages to stderr:

ERROR: stonith:mgpstonith: got no meta-data, does this RA exist?
ERROR: stonith:mgpstonith: got no meta-data, does this RA exist?
ERROR: stonith:mgpstonith: no such resource agent


What would be most helpful at this point is a full description of the Fence Agent API.

Regards,
  Michael Powell

From: Michael Powell
Sent: Friday, May 31, 2019 3:33 PM
To: users at clusterlabs.org
Subject: Fence agent definition under Centos7.6

Although I am personally a novice wrt cluster operation, several years ago my company developed a product that used Pacemaker.  I've been charged with porting that product to a platform running Centos 7.6.  The old product ran Pacemaker 1.1.13 and heartbeat.  For the most part, the transition to Pacemaker 1.1.19 and Corosync has gone pretty well, but there's one aspect that I'm struggling with: fence-agents.

The old product used a fence agent developed in house to implement STONITH.  While it was no trouble to compile and install the code, named mgpstonith, I see lots of messages like the following in the system log -

stonith-ng[31120]:    error: Unknown fence agent: external/mgpstonith
stonith-ng[31120]:    error: Agent external/mgpstonith not found or does not support meta-data: Invalid argument (22)
stonith-ng[31120]:    error: Could not retrieve metadata for fencing agent external/mgpstonith

I've put debug messages in mgpstonith, and as they do not appear in the system log, I've inferred that it is in fact never executed.

Initially, I installed mgpstonith on /lib64/stonith/plugins/external, which is where it was located on the old product.  I've copied it to other locations, e.g. /usr/sbin, with no better luck.  I've searched the web and while I've found lots of information about using the available fence agents, I've not turned up any information on how to create one "from scratch".

Specifically, I need to know where to put mgpstonith on the target system(s).  Generally, I'd appreciate a pointer to any documentation/specification relevant to writing code for a fence agent.

Thanks,
  Michael
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