pmmgr

A pmmgr configuration identifies which hosts should be monitored, which daemons should be maintained for them, and what options those daemons should be run with. pmmgr uses a small number of files in a configuration directory, instead of lines in a single text file. The individual files carry zero or more lines of 100% pure configuration text, and no comments.  (If desired, a configuration may be commented upon within other files, such as a free-form README.)

Some of the configuration files are forked into pairs: per-hostid and common.  This permits numerous almost-identical-configuration targets to be managed from the same configuration directory.  For these files, marked with * below, pmmgr will concatenate a per-hostid file (if it exists) and a common file (if it exists) in order to form the complete configuration item.

For example, for pmie configuration for target hostid foo, pmmgr will search files named pmie.foo then pmie.  For single-line configuration items, the first file & line found will "win"; for multi-line configuration items, they all "win".

This set of configuration files identifies where pmmgr should search for pmcd instances, how to uniquely identify them, and where state such as log files should be kept for each.  Ideally, a persistent and unique hostid string is computed for each potential target pmcd from specified metric values.  This hostid is also used as a subdirectory name for locating daemon data.  The rare empty hostid is mapped to "-".

hostid-static

This file contains one or more lines specifying the static string that should be used as multiple distinct hostids for the same target pmcd.  Treatment of the distinct hostids may be customized using per-hostid configuration files. Specifying values in this file overrides the hostid-metrics file specified below.  It should be noted that using this option will cause all target pmcds to be assigned the same set of hostids.  Thus, this is useful in monitoring single hosts or if each monitored host has its own configuration directory.

hostid-metrics

This file contains one or more lines of metric specifications in the format accepted by pmParseMetricSpec. Metrics without instance specifiers mean all instances of that metric. These are used to generate the unique hostid string for each pmcd server that pmmgr discovers. Upon discovery, all the metrics/instances named are queried, string values fetched, and normalized/concatenated into a single hyphenated printable string. The default is the single metric pmcd.hostname, which is sufficient if all the hosts discovered have unique hostname(2).  If they don't, you should add other pcp metric specifications to set them apart at your site.  The more you add, the longer the hostid string, but the more likely that accidental duplication is prevented.

However, it may be desirable for a hostid to also be persistent, so that if the target host goes offline and later returns, the new hostid matches the previous one, because then old and new histories can be joined. This argues against using metrics whose values vary from boot to boot.

Some candidate metrics to consider: network.interface.hw_addr, network.interface.inet_addr["eth0"], network.interface.ipv6_addr, kernel.uname.nodename

log-directory

This file contains the path of a directory beneath which the per-hostid subdirectories are to be created by pmmgr. If it is not a full path, it is implicitly relative to the configuration directory itself.  The default is $PCP_LOG_DIR/pmmgr/.

target-host

This file contains one or more lines containing pmcd host specifications, as described on the PCPintro(1) manual page. The default is to target pmcd at local:.

target-discovery

This file contains one or more lines containing specifications for the pmDiscoverServices PMAPI call, each of which may map onto a fluctuating set of local or remote pmcd servers.  Each poll interval, pmmgr will attempt to rerun discovery with all of the given specifications.  Again, it is not a problem if more than one specification matches the same actual pmcd: one confirmed access path is arbitrarily selected.  The default is to do no discovery. Consider including avahi,timeout=5 to rely in pmcd self-announcements on the local network (searching for up to five seconds each time).  Consider including probe=192.168.1.0/24 to quickly scan the given IP address range.

subtarget-containers

If this file exists, pmmgr will scan each host that is found for running containers.  For each running container, it will create independent subtargets for running requested daemons. The hostid string for these subtargets is the host's hostid string, followed by a double-hyphen, then the full unique container instance-name string.

target-threads

This file contains a limit on the number of concurrent threads that analyze potential target pmcds for their hostids and/or containers.  The default is a few dozen threads per CPU core, if known.  Set this to zero if remote pmcds should be analyzed sequentially.  A small number of threads is not a good idea if any potential target pmcds are unreachable, since $PMCD_CONNECT_TIMEOUT may be several seconds long each.

log-subdirectory-gc

This file may contain a time interval specification as per the PCPintro(1) manual page. All subdirectories of the log-directory are presumed to contain data for pmmgr-monitored servers. Those that have not been modified in at least that long, and not associated with a currently monitored target, are deleted entirely. This value should be longer than the longest interval that pmmgr normally recreates archives (such as due to pmmgr restarts, and pmlogmerge intervals). The default value is 90days.

This group of configuration options controls a pmlogger daemon for each host.  This may include generating its configuration, and managing its archives.

pmlogger*

If and only if this file exists, pmmgr will maintain a pmlogger daemon for each targeted host. This file contains one line of additional space-separated options for the pmlogger daemon.  (pmmgr already adds -h, -H, -f, -r, -l, and perhaps -c.) The default is to maintain no pmlogger (and no other configuration in this section is processed).

pmlogger-timefmt*

Specify a time format to use in the archive-* name for pmlogger generated archives. The default is "%Y%m%d.%H%M%S". Expected to be in strftime(3) format.

pmlogconf*

If and only if this file exists, pmmgr will run pmlogconf to generate a configuration file for each target pmcd. The file contains one line of space-separated additional options for the pmlogconf program. pmlogconf's generated output file will be stored under the log-directory/hostid subdirectory.  (pmmgr already adds -c, -r, and -h.) The default is no pmlogconf, so instead, the pmlogger file above should probably contain a -c option, to specify a fixed pmlogger configuration.

Default pmlogger configurations can collect tens of megabytes of data per day (possibly split into multiple archives), per target host. If your disk space is less than infinite, or archive-splitting unwieldy, this should be managed.  In the default, unmanaged case, the system administrator is responsible for managing the individual archive-* files from the per-host logging subdirectories. pmmgr offers several other options, each representing different performance and usability tradeoffs.

This style of archive log management regularly creates a single merged archive from prior archives for each target host, in effect lopping off old data and appending the new.  A single merged archive can be relatively large (defaults to approximately 100-400 MB per host), and puts a corresponding I/O load on storage, but is most convenient for a detailed long-timeframe analysis. Once pmlogger is restarted, it always creates a new archive, so in the steady state, there will be one merged archive of recent history, and one current archive being written-to by pmlogger.

pmlogmerge*

If this file exists, pmmgr will run pmlogextract to periodically merge together preexisting log archives for each target pmcd into a single large one.  Then, the preexisting log archives are deleted (including any prior merged ones). This configuration file may contain a time interval specification as per the PCPintro(1) manual page, representing the period after which pmlogger should be temporarily stopped, and archives merged. It represents the maximum amount of time that the merged archive lags the present time. The default is 24hours.

pmlogmerge-granular*

If this file also exists, pmmgr will merge only a subset of preexisting log archives into the new one, instead of all of them, so as to approximate a granular, aligned set of merged archives. The subset chosen corresponds to the previous time interval specified by the pmlogmerge control file. The default is no granularity.

pmlogcheck-corrupt-gc*

Before archives are considered for merging, they are processed through pmlogcheck to check for corruption. In the unlikely case of a problem, such archives are renamed out of the way (named "corrupt-*"), and retained up to a limited time. This file specifies how long. If this file exists, it the time interval it contains is the maximum age. The default is 90days. To store corrupt archives indefinitely, set this to a large quantity like "99999weeks".

pmlogmerge-rewrite*

If this file exists, pmmgr will run pmlogrewrite -i (plus any other options listed in this file) on each input archive before merging it.  This will naturally require more disk I/O.  The default is no rewriting.

pmlogmerge-retain*

pmmgr reduces/deletes any original-resolution archives after a time period specified by this file, as measured by the file mtime. The period will also be passed to pmlogextract as a negative parameter to -S. The default is 14days. To store archives indefinitely, set this to a large quantity like "99999weeks".

pmlogreduce*

If this file exists, then prior to removing archives that expire past the pmlogmerge-retain period, they are processed with pmlogreduce to create reduced archives (named reduced-*).  If the file contains space-separated options, they are passed onto pmlogreduce.  (By default, pmlogreduce down-samples to a 600-second interval.)

pmlogreduce-retain*

If this file exists, then reduced archives (identified by the reduced-* pattern) are deleted after a time period specified by this file, as measured from the file mtime. Since this time is likely that of the pmlogreduce run, the total retention time will be approximately the pmlogmerge-retain time plus the pmlogreduce-retain time. The default is 90days. To store reduced archives indefinitely, set this to a large quantity like "99999weeks".

disk-full-threshold

If this file exists, then pmmgr will track the disk space available where pmlogger archives are kept.  If that partition fills up past the configured percentage, pmmgr will linearly reduce the duration logs are kept via the disk-full-retention variable.

Values must be greater than zero, and expressed either a value between 0 and 1, or decimal value between 1 and 100.

disk-full-retention

If expressed, this variable scales the rate at which logs are culled when disk-full-threshold has been surpassed.  A lower percentage will cull logs more quickly (in favour of preserving disk space), while a higher percentage will opt to retain more pcp archives.

Normalized Full Threshold	Full Retention	Final Retention Factor
1	0.0	0.0
0.75	0.0	0.25
0.5	0.0	0.5
0.0	0.0	1.0
1	0.5	0.5
0.75	0.5	0.625
0.5	0.5	0.75
0.0	0.5	1.0
1	1.0	1.0
0.75	1.0	1.0
0.5	1.0	1.0
0.0	1.0	1.0

This group of configuration options controls a pmie daemon for each host. This may include generating a custom configuration.

pmie*

If and only if this file exists, pmmgr will maintain a pmie daemon for each targeted pmcd. This file contains one line of additional space-separated options for the pmie daemon.  (pmmgr already adds -h, -f, -l, and perhaps -c.) The default is to maintain no pmie (and no other configuration in this section is processed).

pmieconf*

If and only if this file exists, pmmgr will run pmieconf to generate a configuration file for each target pmcd. The file contains one line of space-separated additional options for the pmieconf program. pmieconf- generated output file will be stored under the log-directory/hostid subdirectory.  (pmmgr already adds -F, -c, and -f.) The default is no pmieconf, so instead, the pmie file above should probably contain a -c option, to specify a fixed pmie configuration.

pmmgr may be used to invoke arbitrary PCP client programs for each target pmcd. This can enable automated invocation of reporting or relaying tools, such as pmrep, pcp2graphite or pcp2influxdb without needing a specialized system service.

monitor*

If this file exists, then for each line in this file, a new background process will be invoked.  (It is restarted if it exits.)  The line specifies the beginning of the command line (including the program name); pmmgr appends a -h HOSTSPEC, and arranges to collect the standard output and standard error into separate monitor-NN.out and monitor-NN.err files under the log directory.  Errors messages in the latter are transcribed to pmmgr's own logs.