# pmdaroot

## NAME



           **pmdaroot** - a privileged PMCD helper performance metrics domain
           agent
    


## SYNOPSIS



           **$PCP_PMDAS_DIR/root/pmdaroot**[**-D** _debug_] [**-d** _domain_] [**-l** _logfile_]
           [**-s** _sockname_]
    


## DESCRIPTION



           **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.
    


## INSTALLATION



           Access to the names, help text and values for the kernel
           performance metrics is available by default - unlike most other
           agents, no action is required to enable them and they should not
           be removed.
    


## FILES



           **$PCP_PMDAS_DIR/root/help**
                  default help text file for metrics exported by the root
                  PMDA.
           **$PCP_LOG_DIR/pmcd/root.log**
                  default log file for error messages and other information
                  from the root PMDA.
           **$PCP_VAR_DIR/pmcd/root.socket**
                  default socket file for communication with root PMDA
                  clients.
    


## PCP ENVIRONMENT



           Environment variables with the prefix **PCP_** are used to
           parameterize the file and directory names used by PCP.  On each
           installation, the file _/etc/pcp.conf_ contains the local values for
           these variables.  The **$PCP_CONF** variable may be used to specify an
           alternative configuration file, as described in pcp.conf(5).
    


## DEBUGGING OPTIONS



           The **-D** or **--debug** option enables the output of additional
           diagnostics on _stderr_ to help triage problems, although the
           information is sometimes cryptic and primarily intended to provide
           guidance for developers rather end-users.  _debug_ is a comma
           separated list of debugging options; use pmdbg(1) with the **-l**
           option to obtain a list of the available debugging options and
           their meaning.
    
           Debugging options specific to **pmdaroot** are as follows:
           ┌────────┬───────────────────────────┐
           │ **Option** │ **Description** │
           ├────────┼───────────────────────────┤
           │ **appl0** │ interactions with pmcd(1) │
           ├────────┼───────────────────────────┤
           │ **appl1** │ PMDA startup processing   │
           └────────┴───────────────────────────┘
    


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