pmdaroot is a special Performance Metrics Domain Agent (PMDA) which cooperates closely with pmcd(1) and
other PMDAs to provide limited privileged services to these unprivileged processes.
In this role it is used to discover operating system containers running on the local host. It also
enables access to performance data from within those containers by other PMDAs running on the bare-metal
host, using the pmdaRootConnect(3) and the associated namespace interfaces.
Like all other PMDAs, it also exports performance metrics from the domain it controls. Currently, this
is limited to information about the containers on the local system; currently Docker and LXC containers
can be detected.
If a non-default Docker parent-cgroup name is being used, this value can be indicated to pmdaroot through
addition of a $PCP_SYSTEMD_CGROUP variable in /etc/pcp.conf.
-d It is absolutely crucial that the performance metrics domain number specified here is unique and
consistent. That is, domain should be different for every PMDA on the one host, and the same domain
number should be used for the same PMDA on all hosts.
-l Location of the log file. By default, a log file named root.log is written in the current directory
of pmcd(1) when pmdaroot is started, i.e. $PCP_LOG_DIR/pmcd. If the log file cannot be created or
is not writable, output is written to the standard error instead.
-s Location of the unix(7) domain socket for communication with clients seeking privileged operations.
By default, a socket file named $PCP_TMP_DIR/pmcd/root.socket is used.