PID Cache Error on SiteMinder Web Agent When Performing an Apache Graceful Restart

Products

• CA Single Sign On Secure Proxy Server (SiteMinder)
• CA Single Sign-On
• CA Single Sign On Agents (SiteMinder)
• SITEMINDER

Issue/Introduction

When running a Web Agent on Apache and restarting the Apache server with the following command:

# service reload myinstance

the Web Agent reports the following errors in error.log:

May 23 14:19:36 <host> [23/May/2017:14:19:36] [Info] [CA WebAgent IPC] [31025] [CSmSem::getSem] Attempted to attach to non-existent semaphore with key <key>
May 23 14:19:36 <host> [23/May/2017:14:19:36] [Info] [CA WebAgent IPC] [31025] [CSmSem::getSem] Created semaphore 30081042 using key <key>
May 23 14:19:36 <host> [23/May/2017:14:19:36] [Error] [CA WebAgent IPC] [31025] [CSmSharedSegment::smalloc] Error allocating shared memory segment using key <key> - File exists (17)
May 23 14:19:36 <host> [23/May/2017:14:19:36] [Info] [CA WebAgent IPC] [31025] [CSmSem::SemRm] Removed semaphore <key>
May 23 14:19:36 <host> [23/May/2017:14:19:36] [Error] SiteMinder Agent
May 23 14:19:36 <host> PID Cache error.
May 23 14:19:36 <host> Failed to initialize PID Cache
May 23 14:19:40 <host> nm: '/{webserver_home}/bin/httpd': No such file
May 23 14:19:40 <host> [Tue May 23 14:19:40 2017] [warn] Siteminder Web Agent: restart not supported.

Environment

• Web Agent 12.52SP1CR10 build 2813
• Apache 2.4.43 64-bit
• Red Hat 7.8

Cause

Running nm -A against /usr/sbin/httpd and /usr/sbin/httpd.worker on the Red Hat Apache binaries returns the following message:

"no symbols"

For example:

# nm -A /{webserver_home}/bin/httpd
nm: /{webserver_home}/bin/httpd: no symbols

# nm -A /{webserver_home}/bin/httpd.worker
nm: /{webserver_home}/bin/httpd.worker: no symbols

For the Web Agent to support a graceful restart, symbols must be available in the httpd binary (1). If no symbols are available, the following message appears:

nm: '/{webserver_home}/bin/httpd': No such file

If symbols are available in the httpd binary but the restart_pending symbol is not found, the following warning appears:

Siteminder Web Agent: restart not supported

Out of the box, the Web Agent performs this check for the start, stop, restart, and graceful options of the apachectl command.

Resolution

Compile Apache, or obtain an Apache build whose binaries expose symbols — including the restart_pending symbol — so that the LLAWP process does not shut down when a restart or graceful option is sent to the apachectl command. If the restart_pending symbol is not present, the LLAWP process will shut down and start over.

The following commands should return symbols, including the restart_pending symbol:

# nm -A /{webserver_home}/bin/httpd
# nm -A /{webserver_home}/bin/httpd.worker

Note: This applies up to Apache version 2.4.27 (1).

Additional Information

1. WebAgent does not support restart with Apache 2.4