NAME

       pmdaRootConnect,       pmdaRootShutdown,      pmdaRootContainerHostName,      pmdaRootContainerProcessID,
       pmdaRootContainerCGroupName - privileged PCP collector services

C SYNOPSIS

       #include <pcp/pmapi.h>
       #include <pcp/pmda.h>

       int pmdaRootConnect(void);
       void pmdaRootShutdown(int fd);
       int pmdaRootContainerHostName(int fd, char *name, int namelen, char *buffer, int buflen);
       int pmdaRootContainerProcessID(int fd, char *name, int namelen);
       int pmdaRootContainerCGroupName(int fd, char *name, int namelen, char *buffer, int buflen);

       cc ... -lpcp_pmda -lpcp

DESCRIPTION

       pmdaRootConnect initializes an IPC channel between a PCP collector process - either a PMDA(3) or  pmcd(1)
       itself - and the pmdaroot(1) server.

       On  success,  the return value from pmdaRootConnect is a unix(7) domain socket file descriptor, which can
       be subsequently passed to each of the other APIs described here.  This channel can  be  used  to  perform
       limited privilege escalation for specific scenarios needed by PCP collector services.  The channel can be
       deactivated using the pmdaRootShutdown interface.

       Currently,  these  services  provide access to the container facilities of modern Linux distributions, as
       needed by various agents accessing kernel features related to containers.

       pmdaRootContainerHostName allows lookup of the current hostname for a named container on behalf of an un‐
       privileged process, via the setns(3) system call on Linux.  On success, the hostname is returned  in  the
       supplied buffer, of size buflen and the return value indicates the length of the hostname.

       pmdaRootContainerProcessID  performs  a  name  to process identifier translation - on success, the return
       value is the identifier of the first process started (process 1) in the named container.

       pmdaRootContainerCGroupName fills the supplied buffer with the engine-specific names  of  kernel  control
       groups  that have been used to build the container identified by name.  When successful, the return value
       indicates the length of the cgroup name resolved for the container.

       The name of the container is interpreted by pmdaroot(1), which attempts to match up  the  specified  name
       with  one  of  the implementations of containers that it is aware of.  Hence, the name argument is poten‐
       tially interpreted differently, depending on the installed container engine, as determined internally  by
       pmdaroot(1)).

       In  the  case  of the Docker container engine, for example, a valid container name can be the unique hash
       identifier, the human-readable name, or any unique identifier substring. This is the  algorithm  used  by
       the Docker client tools themselves.

DIAGNOSTICS

       All pmdaRoot interfaces will return negative status codes suitable for passing to pmErrStr_r(3).

SEE ALSO

       pmcd(1), pmdaroot(1), pmErrStr_r(3), PMDA(3), setns(3) and unix(7).

Performance Co-Pilot                                   PCP                                    PMDAROOTCONNECT(3)