'\"macro stdmacro
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.TH PMDAPIPE 1 "PCP" "Performance Co-Pilot"
.SH NAME
\f3pmdapipe\f1 \- command output capture performance metrics domain agent (PMDA)
.SH SYNOPSIS
\f3$PCP_PMDAS_DIR/pipe/pmdapipe\f1
[\f3\-c\f1 \f2configfile\f1]
[\f3\-d\f1 \f2domain\f1]
[\f3\-l\f1 \f2logfile\f1]
[\f3\-m\f1 \f2memory\f1]
.SH DESCRIPTION
.B pmdapipe
is a configurable command output monitoring Performance Metrics Domain
Agent (PMDA).
It can be seen as analogous to a restricted shell, where options can be
passed to preset commands, and each line of their output is converted
into a performance event.
These events can be consumed by client tools like
.BR pmval (1).
.PP
The
.B pipe
PMDA exports both event-style metrics reflecting timestamped event records
for text-oriented command output,
as well as the more orthodox sample-style metrics such as event counts
and throughput size values.
.PP
The PMDA is configured via a
.I configfile
which contains one line for each process from which output can be
captured, as described in the ``CONFIGURATION'' section below.
.PP
A brief description of the
.B pmdapipe
command line options follows:
.TP 5
.B \-c
specifies an alternate configuration file for the PMDA.
By default, a file named
.I $PCP_PMDAS_DIR/pipe/pipe.conf
and any files below the
.I $PCP_SYSCONF_DIR/pipe.conf.d/
directory are used.
.TP
.B \-d
It is absolutely crucial that the performance metrics
.I domain
number specified here is unique and consistent.
That is,
.I domain
should be different for every PMDA on the one host, and the same
.I domain
number should be used for the same PMDA on all hosts.
.TP
.B \-l
Location of the log file.  By default, a log file named
.I pipe.log
is written in the current directory of
.BR pmcd (1)
when
.B pmdapipe
is started, i.e.
.BR $PCP_LOG_DIR/pmcd .
If the log file cannot
be created or is not writable, output is written to the standard error instead.
.TP
.B \-m
Limit the physical memory used by the PMDA to buffer event records to
.I maxsize
bytes.
As log events arrive at the PMDA, they must be buffered until individual
client tools request the next batch since their previous batch of events.
The default maximum is 2 megabytes.
.SH CONFIGURATION
The set of allowed pipe commands is configured by simple text file(s).
The format is a single line for each command followed by an optional
access control section.
.PP
Blank lines and comments are permitted (even encouraged) in the
configuration file.
A comment begins with a ``#''
character and finishes at the end of the line.
.PP
Each command configuration line is of the form:
.TP
\&
\f2instance\f1 \f2username\f1 \f2command\f1 \f2options\f1
.PP
Where,
.TP 14
.PD 0
.I instance
is a string identifying the pipe command, also exported as the metric
instance identifier.
.TP 14
.I username
is the name of the user account under which the command should run
(e.g. "root")
.TP 14
.I command
is the path to the binary which will be run to generate piped output
.TP 14
.I options
is an optional space-separated list of parameters to pass to the \f2command\f1
.PD
.IP "" 14
This
.I options
list may contain numeric parameters prefixed by the dollar-sign,
and these will be substituted with user-supplied values at the time
the \f2command\f1 is run (similar to shell parameter substitution).
.PP
Parameters are passed as a single space-separated or comma-separated
string to the
.I pipe.firehose
metric, using the
.B pmStore (3)
interface.
The
.B pmval
command provides store access via its \f3\-x\f1 option.
User-supplied parameters are restricted to containing alphanumeric
characters.
.PP
The access control section of the file must start with a line of the form:
.TP
.B [access]
.PP
Leading and trailing whitespace may appear around and within the brackets and
the case of the
.B access
keyword is ignored.
No other text may appear on the line except a trailing comment.
.PP
Following this line, the remainder of the configuration file should contain
lines that allow or disallow use of \f2commands\f1 from particular users or
groups.
.PP
User names and group names will be verified using the local
.B /etc/passwd
and
.B /etc/groups
files (or an alternative directory service), using the
.BR getpwent (3)
and
.BR getgrent (3)
routines.
.PP
Access for users or groups are allowed or disallowed by specifying
statements of the form:
.TP
\&
\f3allow user\f1 \f2username\f1 \f3:\f1 \f2instance\f1
.br
\f3disallow user\f1 \f2username\f1 \f3:\f1 \f2instance\f1
.br
\f3allow group\f1 \f2groupname\f1 \f3:\f1 \f2instance\f1
.br
\f3disallow group\f1 \f2groupname\f1 \f3:\f1 \f2instance\f1
.PP
The
.IR username
and
.I groupname
names will be verified using the local
.B /etc/passwd
and
.B /etc/groups
files (or an alternative directory service), using the
.BR getpwent (3)
and
.BR getgrent (3)
routines.
.PP
The wildcard ``*'' can be used to refer to all \f2instance\f1 names.
.SH INSTALLATION
If you want access to the names, help text and values for the pipe
performance metrics, do the following as root:
.PP
.ft CR
.nf
.in +0.5i
# cd $PCP_PMDAS_DIR/pipe
# ./Install
.in
.fi
.ft 1
.PP
This is an interactive installation process which prompts for each
log file path to be monitored (or command to be run), a metric
instance name to identify it, and whether access should be restricted
(refer to the
.B \-x
option to
.BR pmval (1)
for further details).
.PP
If you want to undo the installation, do the following as root:
.PP
.ft CR
.nf
.in +0.5i
# cd $PCP_PMDAS_DIR/pipe
# ./Remove
.in
.fi
.ft 1
.PP
.B pmdapipe
is launched by
.B pmcd
and should never be executed directly.
The Install and Remove scripts notify
.B pmcd
when the agent is installed or removed.
.SH EXAMPLES
Following is a simple example of
.B pmdapipe
configuration and use of the pipe metrics to run the
.B btrace
command, by user \f3bob\f1:
.de CS
.in +0.5i
.ft CR
.nf
..
.de CE
.fi
.ft 1
.in
..
.PP
.CS
bob> cat $PCP_PMDAS_DIR/pipe/pipe.conf
# instance      user      command
rw_syscalls     root      perf script rw-by-file $1
bdev_trace      root      btrace -w $1 /dev/$2

[access]
allow user bob : *;
allow user jane : bdev_trace;
allow group perf : rw_syscalls;

bob> pmval -i bdev_trace -x '5 sda' pipe.firehose
 8,2  5  1  0.000000000 25227  A  WS 734332384 + 24 <- (253,2) 734330336
 8,0  5  2  0.000000414 25227  A  WS 735358432 + 24 <- (8,2) 734332384
 8,0  5  3  0.000000756 25227  Q  WS 735358432 + 24 [qemu-kvm]
 [...5 seconds worth]
bob>
.CE
.SH FILES
.PD 0
.TP 10
.B $PCP_PMCDCONF_PATH
command line options used to launch
.B pmdapipe
.TP 10
.B $PCP_PMDAS_DIR/pipe/pipe.conf
default configuration file for the pipe metrics
.TP 10
.B $PCP_PMDAS_DIR/pipe/help
default help text file for the pipe metrics
.TP 10
.B $PCP_PMDAS_DIR/pipe/Install
installation script for the
.B pmdapipe
agent
.TP 10
.B $PCP_PMDAS_DIR/pipe/Remove
undo installation script for the
.B pmdapipe
agent
.TP 10
.B $PCP_LOG_DIR/pmcd/pipe.log
default log file for error messages and other information from
.B pmdapipe
.TP 10
.B $PCP_SYSCONF_DIR/pipe.conf.d
directory containing additional configuration files for the pipe metrics
.PD
.SH "PCP ENVIRONMENT"
Environment variables with the prefix
.B PCP_
are used to parameterize the file and directory names
used by PCP.
On each installation, the file
.I /etc/pcp.conf
contains the local values for these variables.
The
.B $PCP_CONF
variable may be used to specify an alternative
configuration file,
as described in
.BR pcp.conf (5).
.SH SEE ALSO
.BR PCPIntro (1),
.BR pmval (1),
.BR pmcd (1),
.BR getpwent (3),
.BR getgrent (3),
.BR pmStore (3),
.BR pcp.conf (5)
and
.BR pcp.env (5).