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NAME | SYNOPSIS | DESCRIPTION | INSTALLATION | CONFIGURATION | CAVEATS | FILES | PCP ENVIRONMENT | SEE ALSO | COLOPHON |
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PMDAWEBLOG(1) General Commands Manual PMDAWEBLOG(1)
pmdaweblog - performance metrics domain agent (PMDA) for Web server
logs
$PCP_PMDAS_DIR/weblog/pmdaweblog [-Cp] [-d domain] [-h helpfile] [-i
port] [-l logfile] [-n idlesec] [-S num] [-t delay] [-u socket] [-U
username] configfile
pmdaweblog is a Performance Metrics Domain Agent (PMDA(3)) that scans
Web server logs to extract metrics characterizing Web server
activity. These performance metrics are then made available through
the infrastructure of the Performance Co-Pilot (PCP).
The configfile specifies which Web servers are to be monitored, their
associated access logs and error logs, and a regular-expression based
scheme for extracting detailed information about each Web access.
This file is maintained as part of the PMDA installation and/or de-
installation by the scripts Install and Remove in the directory
$PCP_PMDAS_DIR/weblog. For more details, refer to the section below
covering installation.
Once started, pmdaweblog monitors a set of log files and in response
to a request for information, will process any new information that
has been appended to the log files, similar to a tail(1). There is
also periodic "catch up" to process new information from all log
files, and a scheme to detect the rotation of log files.
Like all other PMDAs, pmdaweblog is launched by pmcd(1) using command
line options specified in $PCP_PMCDCONF_PATH - the Install script
will prompt for appropriate values for the command line options, and
update $PCP_PMCDCONF_PATH.
A brief description of the pmdaweblog command line options follows:
-C Check the configuration and exit.
-d domain
Specify the domain number. 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 pmdaweblog PMDA on all hosts.
For most installations, the default domain as encapsulated in
the file $PCP_PMDAS_DIR/weblog/domain.h will suffice. For
alternate values, check $PCP_PMCDCONF_PATH for the domain
values already in use on this host, and the file
$PCP_VAR_DIR/pmns/stdpmid contains a repository of ``well
known'' domain assignments that probably should be avoided.
-h helpfile
Get the help text from the supplied helpfile rather than from
the default location.
-i port
Communicate with pmcd(1) on the specified Internet port (which
may be a number or a name).
-l logfile
Location of the log file. By default, a log file named
weblog.log is written in the current directory of pmcd(1) when
pmdaweblog 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.
-n idlesec
If a Web server log file has not been modified for idlesec
seconds, then the file will be closed and re-opened. This is
the only way pmdaweblog can detect any asynchronous rotation
of the logs by Web server administrative scripts. The default
period is 20 seconds. This value may be changed dynamically
using pmstore(1) to modify the value of the performance metric
web.config.check.
-p Communicate with pmcd(1) via a pipe.
-S num Specify the maximum number of Web servers per sproc. It may
be desirable (from a latency and load balancing perspective)
or necessary (due to file descriptor limits) to delegate
responsibility for scanning the Web server log files to
several sprocs. pmdaweblog will ensure that each sproc
handles the log files for at most num Web servers. The
default value is 80 Web servers per sproc.
-t delay
To avoid the need to scan a lot of information from the Web
server logs in response to a single request for performance
metrics, all log files will be checked at least once every
delay seconds. The default is 15 seconds. This value may by
changed dynamically using pmstore(1) to modify the value of
the performance metric web.config.catchup.
-u socket
Communicate with pmcd(1) via the given Unix domain socket.
-U User account under which to run the agent. The default is the
unprivileged "pcp" account in current versions of PCP, but in
older versions the superuser account ("root") was used by
default.
The PCP framework allows metrics to be collected on one host and
monitored from another. These hosts are referred to as collector and
monitor hosts, respectively. A host may be both a collector and a
monitor.
Collector hosts require the installation of the agent, while
monitoring hosts require no agent installation at all.
For collector hosts do the following as root:
# cd $PCP_PMDAS_DIR/weblog
# ./Install
The installation procedure prompts for a default or non-default
installation. A default installation will search for known server
configurations and automatically configure the PMDA for any server
log files that are found. A non-default installation will step
through each server, prompting the user for other server
configurations and arguments to pmdaweblog. The end result of a
collector installation is to build a configuration file that is
passed to pmdaweblog via the configfile argument.
If you want to undo the installation, do the following as root:
# cd $PCP_PMDAS_DIR/weblog
# ./Remove
pmdaweblog is launched by pmcd(1) and should never be executed
directly. The Install and Remove scripts notify pmcd(1) when the
agent is installed or removed.
The configuration file for the weblog PMDA is an ASCII file that can
be easily modified. Empty lines and lines beginning with '#' are
ignored. All other lines must be either a regular expression or
server specification.
Regular expressions, which are used on both the access and error log
files, must be of the form:
regex regexName regexp
or
regex_posix regexName ordering regexp_posix
The regexName is a word which uniquely identifies the regular
expression. This is the reference used in the server specification.
The regexp for access logs is in the format described for regcmp(3).
The regexp_posix for access logs is in the format described for
regcomp(3). The argument ordering is explained below. The Posix form
should be available on all platforms.
The regular expression requires the specification of up to four
arguments to be extracted from each line of a Web server access log,
depending on the type of server. In the most common case there are
two arguments representing the method and the size.
For the non- Posix version, argument $0 should contain the method:
GET, HEAD , POST or PUT. The method PUT is treated as a synonym for
POST, and anything else is categorized as OTHER.
The second argument, $1, should contain the size of the request. A
size of ``-'' or `` '' is treated as unknown.
Argument $3 should contain the status code returned to the client
browser and argument $4 should contain the status code returned to
the server from a remote host. These latter two arguments are used
for caching servers and must be specified as a pair (or $3 will be
ignored). For further information on status codes, refer to the web
site http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html
Some legal non- Posix regex expression specifications for monitoring
an access log are:
# pattern for CERN, NCSA, Netscape etc Access Logs
regex CERN ] "([A-Za-z][-A-Za-z]+)$0 .*" [-0-9]+ ([-0-9]+)$1
# pattern for FTP Server access logs (normally in SYSLOG)
regex SYSLOG_FTP ftpd[.*]: ([gp][-A-Za-z]+)$0( )$1
There is 1 special types of access logs with the RegexName SQUID.
This formats extract 4 parameters but since the Squid log file uses
text-based status codes, it is handled as a special case.
In the examples below, NS_PROXY parses the Netscape/W3C Common
Extended Log Format and SQUID parses the default Squid Object Cache
format log file.
# pattern for Netscape Proxy Server Extended Logs
regex NS_PROXY ] "([A-Za-z][-A-Za-z]+)$0 .*" ([-0-9]+)$2 \
([-0-9]+)$1 ([-0-9]+)$3
# pattern for Squid Cache logs
regex SQUID [0-9]+.[0-9]+[ ]+[0-9]+ [a-zA-Z0-9.]+ \
([_A-Z]+)$3([0-9]+)$2 ([0-9]+)$1 ([A-Z]+)$0
The regexp for the error logs does not require any arguments, only a
match. Some legal expressions are:
# pattern for CERN, NCSA, Netscape etc Error Logs
regex CERN_err .
# pattern for FTP Server error logs (normally in SYSLOG)
regex SYSLOG_FTP_err FTP LOGIN FAILED
If POSIX compliant regular expressions are used, additional
information is required since the order of parameters cannot be
specified in the regular expression. For backwards compatibility,
the common case of two parameters the order may be specified as
method,size or size,method In the general case, the ordering is
specified by one of the following methods:
n1,n2,n3,n4
where nX is a digit between 1 and 4. Each comma-seperated field
represents (in order) the argument number for
method,size,client_status,server_status
- Used for cases like the error logs where the content is ignored.
As for the non- Posix format, the SQUID RegexName is treated as a
special case to match the non-numerical status codes.
Some legal Posix regex expression specifications for monitoring an
access log are:
# pattern for CERN, NCSA, Netscape, Apache etc Access Logs
regex_posix CERN method,size ][ \]+"([A-Za-z][-A-Za-z]+) \
[^"]*" [-0-9]+ ([-0-9]+)
# pattern for CERN, NCSA, Netscape, Apache etc Access Logs
regex_posix CERN 1,2 ][ \]+"([A-Za-z][-A-Za-z]+) \
[^"]*" [-0-9]+ ([-0-9]+)
# pattern for FTP Server access logs (normally in SYSLOG)
regex_posix SYSLOG_FTP method,size ftpd[.*]: \
([gp][-A-Za-z]+)( )
# pattern for Netscape Proxy Server Extended Logs
regex_posix NS_PROXY 1,3,2,4 ][ ]+"([A-Za-z][-A-Za-z]+) \
[^"]*" ([-0-9]+) ([-0-9]+) ([-0-9]+)
# pattern for Squid Cache logs
regex_posix SQUID 4,3,2,1 [0-9]+.[0-9]+[ ]+[0-9]+ \
[a-zA-Z0-9.]+ ([_A-Z]+)([0-9]+) ([0-9]+) ([A-Z]+)
# pattern for CERN, NCSA, Netscape etc Error Logs
regex_posix CERN_err - .
# pattern for FTP Server error logs (normally in SYSLOG)
regex_posix SYSLOG_FTP_err - FTP LOGIN FAILED
A Web server can be specified using this syntax:
server serverName on|off accessRegex accessFile errorRegex errorFile
The serverName must be unique for each server, and is the name given
to the instance for the associated performance metrics. See PMAPI(3)
for a discussion of PCP instance domains. The on or off flag
indicates whether the server is to be monitored when the PMDA is
installed. This can altered dynamically using pmstore(1) for the
metric web.perserver.watched, which has one instance for each Web
server named in configfile.
Two files are monitored for each Web server, the access and the error
log. Each file requires the name of a previously declared regular
expression, and a file name. The log files specified for each server
do not have to exist when the weblog PMDA is installed. The PMDA
will continue to check for non-existent log files and open them when
possible. Some legal server specifications are:
# Netscape Server on Port 80 at IP address 127.55.555.555
server 127.55.555.555:80 on CERN /logs/access CERN_err /logs/errors
# FTP Server.
server ftpd on SYSLOG_FTP /var/log/messages SYSLOG_FTP_err /var/log/messages
Specifying regular expressions with an incorrect number of arguments,
anything other than 2 for access logs, and none for error logs, may
cause the PMDA to behave incorrectly and even crash. This is due to
limitations in the interface of regex(3).
$PCP_PMDAS_DIR/weblog
installation directory for the weblog PMDA
$PCP_PMDAS_DIR/weblog/Install
installation script for the weblog PMDA
$PCP_PMDAS_DIR/weblog/Remove
de-installation script for the weblog PMDA
$PCP_LOG_DIR/pmcd/weblog.log
default log file for error reporting
$PCP_PMCDCONF_PATH
pmcd configuration file that specifies the command line
options to be used when pmdaweblog is launched
$PCP_LOG_DIR/NOTICES
log of PMDA installations and removals
$PCP_VAR_DIR/config/web/weblog.conf
likely location of the weblog PMDA configuration file
$PCP_DOC_DIR/pcpweb/index.html
the online HTML documentation for PCPWEB
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).
pmcd(1), pmchart(1), pmdawebping(1), pminfo(1), pmstore(1),
pmview(1), tail(1), weblogvis(1), webvis(1), PMAPI(3), PMDA(3) and
regcmp(3).
This page is part of the PCP (Performance Co-Pilot) project.
Information about the project can be found at ⟨http://www.pcp.io/⟩.
If you have a bug report for this manual page, send it to
pcp@groups.io. This page was obtained from the project's upstream
Git repository ⟨https://github.com/performancecopilot/pcp.git⟩ on
2018-02-02. (At that time, the date of the most recent commit that
was found in the repository was 2018-02-02.) If you discover any
rendering problems in this HTML version of the page, or you believe
there is a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
man-pages@man7.org
Performance Co-Pilot PCP PMDAWEBLOG(1)
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