1PMDAPROMETHEUS(1) General Commands Manual PMDAPROMETHEUS(1)
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6 pmdaprometheus - Prometheus PMDA
7
9 $PCP_PMDAS_DIR/prometheus/pmdaprometheus [-D] [-n] [-c config] [-d
10 domain] [-l logfile] [-t timeout] [-u user]
11
13 pmdaprometheus is a Performance Metrics Domain Agent (PMDA) which cre‐
14 ates PCP metrics from Prometheus endpoints, which provide HTTP based
15 access to application metrics. The default config directory is
16 $PCP_PMDAS_DIR/prometheus/config.d/, see ``CONFIGURATION SOURCES''
17 below. The default URL fetch timeout is 2 seconds. The default user,
18 if not specified with the -u option, is the current user. If the -n
19 option is given, the list of configuration files will not be sorted
20 prior to processing. This list is sorted by default but that can be
21 expensive if there are a large number of configuration files (URLs
22 and/or scripts).
23 If the -D option is given, additional diagnostic messages will be writ‐
25 ten to the PMDA log file, which is $PCP_LOG_DIR/pmcd/prometheus.log by
26 default (see also -lbelow). In addition, the metric prometheus.con‐
27 trol.debug controls the same debug flag and can be set with the follow‐
28 ing command:
29 pmstore prometheus.control.debug value
30 where value is either 1 (to enable verbose log messages) or 0 (to dis‐
31 able verbose log messages). This is particularly useful for examining
32 the http headers passed to each fetch request, filter settings and
33 other processing details that are logged when the debugging flag is
34 enabled.
35 The -d option may be used to override the default performance metrics
37 domain number, which defaults to 144. It is strongly recommended not
38 to change this. The domain number should be different for every PMDA
39 on the one host, and the same domain number should be used for
40 pmdaprometheus PMDA on all hosts.
41 The -l option may be used to specify logfile as the destination for
43 PMDA messages instead of the default, $PCP_LOG_DIR/pmcd/prometheus.log.
44 As a special case, logfile may be "-" to send messages to the stderr
45 stream instead, e.g. -l-. This would normally be the stderr stream
46 for the parent process, pmcd(1), which may itself have redirected
47 stderr. This redirection is normally most useful in a containerized
48 environment, or when using dbpmda(1).
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51 As it runs, pmdaprometheus periodically recursively scans the
52 $PCP_PMDAS_DIR/prometheus/config.d directory (or the directory speci‐
53 fied with the -c option), looking for source URL files (*.url) and exe‐
54 cutable scripts or binaries. Any files that do not have the .url suf‐
55 fix or are not executable, are ignored - this allows documentation
56 files such as "README" and non-executable "common" script function def‐
57 initions to be present without being considered as config files.
58 A remote server does not have to be up or stay running - the PMDA tol‐
60 erates remote URLs that may come and go over time. The PMDA will relay
61 data and metadata when/if they are available, and will return errors
62 when/if they are down. PCP metric IDs, internal and external instance
63 domain identifiers are persisted and will be restored when individual
64 metric sources become available and/or when the PMDA is restarted. In
65 addition, the PMDA checks directory modification times and will rescan
66 for new or changed configuration files dynamically. It is not neces‐
67 sary to restart the PMDA when adding, removing or changing configura‐
68 tion files.
69
71 Each file with the .url suffix found in the config directory or sub-
72 directory contains one complete HTTP or HTTPS URL at which
73 pmdaprometheus can reach a Prometheus endpoint. Local file access is
74 also supported with a conventional file://somepath/somefile URL, in
75 which case somepath/somefile should contain prometheus formatted metric
76 data.
77 The first line of a .url config file should be the URL, as described
79 above. Subsequent lines, if any, are prefixed with a keyword that can
80 be used to alter the http GET request. A keyword must end with ':'
81 (colon) and the text extends to the end of the line. Comment lines
82 that start with # and blank lines are ignored. The only currently sup‐
83 ported keywords are HEADER: and FILTER:.
84 HEADER: headername: value ... to end of line
86 Adds headername and its value to the headers passed in the http GET
87 request for the configured URL. An example configuration file that
88 provides 3 commonly used headers and an authentication token might be :
89 http://somehost/path/endpoint.html
91 # this is a comment
92 HEADER: Accept: text/html
93 HEADER: Keep-Alive: 300
94 HEADER: Connection: keep-alive
95 HEADER: Authorization: token ABCDEF1234567890
96 As mentioned above, header values extend to the end of the line. They
98 may contain any valid characters, including colons. Multiple spaces
99 will be collapsed to a single space, and leading and trailing spaces
100 are trimmed. A common use for headers is to configure a proxy agent
101 and the assorted parameters it may require.
102 FILTER: INCLUDE METRIC regex
104 or
105 FILTER: EXCLUDE METRIC regex
106 Dynamically created metric names that match regex will be either
107 included or excluded in the name space, as specified. The simple rule
108 is that the first matching filter regex for a particular metric name is
109 the rule that prevails. If no filter regex matches (or there are no
110 filters), then the metric is included by default, i.e. the default fil‐
111 ter if none are specified is FILTER: INCLUDE METRIC .* This is back‐
112 ward compatible with older versions of the configuration file that did
113 not support filters. Multiple FILTER: lines would normally be used,
114 e.g. to include some metrics but exclude all others, use FILTER:
115 EXCLUDE METRIC .* as the last of several filters that include the
116 desired metrics. Conversely, to exclude some metrics but include all
117 others, use FILTER: EXCLUDE METRIC regex. In this case it's not neces‐
118 sary (though doesn't hurt) to specify the final FILTER: INCLUDE METRIC
119 .* because, as stated above, any metric that does not match any filter
120 regex will be included by default.
121 Label filtering uses similar FILTER: syntax and semantics. FILTER:
123 EXCLUDE LABEL regex will delete all labels matching regex from all met‐
124 rics defined in the configuration file. The same rules as for metrics
125 apply for labels too - an implicit rule: FILTER: INCLUDE LABEL .*
126 applies to all labels that do not match any earlier filter rule.
127 Caution is needed with label filtering because by default, all labels
129 are used to construct the PCP instance name. By excluding some labels,
130 the instance names will change. Excluding all labels for a particular
131 metric changes that metric to be singular, i.e. have no instance
132 domain. In addition, by excluding some labels, different instances of
133 the same metric may become duplicates. When such duplicates occur, the
134 last duplicate instance returned by the end-point URL prevails over any
135 earlier instances. For these reasons, it is recommended that label
136 filtering rules be configured when the configuration file is first
137 defined, and not changed thereafter. If a label filtering change is
138 required, the configuration file should be renamed, which effectively
139 defines a new metric, with the new (or changed) instance naming.
140 Unrecognized keywords in configuration files are reported in the PMDA
142 log file but otherwise ignored.
143
145 Executable scripts present in the $PCP_PMDAS_DIR/prometheus/config.d
146 directory or sub-directories will be executed and the stdout stream
147 containing prometheus formatted metric data will be parsed as though it
148 had come from a URL or file. The stderr stream from a script will be
149 sent to the PMDA log file, which by default can be found in
150 $(PCP_LOG_DIR)/pmcd/prometheus.log.
151 Note that scripted sources do not support label or metric filtering (as
153 described above for URL sources) - they can simply do their own filter‐
154 ing in the script itself with sed(1), awk(1), or whatever tool is
155 desired.
156 A simple example of a scripted config entry follows:
158 #! /bin/sh
160 awk '{
161 print("# HELP loadavg local load average")
162 print("# Type loadavg gauge")
163 printf("loadavg {interval=\"1-minute\"} %.2f\n", $1)
164 printf("loadavg {interval=\"5-minute\"} %.2f\n", $2)
165 printf("loadavg {interval=\"15-minute\"} %.2f\n", $3)
166 }' /proc/loadavg
167 This script produces the following Prometheus-formatted metric data
169 when run:
170 # HELP loadavg local load average
172 # Type loadavg gauge
173 loadavg {interval="1-minute"} 0.12
174 loadavg {interval="5-minute"} 0.27
175 loadavg {interval="15-minute"} 0.54
176 If the above script was saved and made executable in a file named
178 $PCP_PMDAS_DIR/prometheus/config.d/local/system.sh then this would
179 result in a new PCP metric named prometheus.local.system.loadavg which
180 would have three instances for the current load average values:
181 1-minute, 5-minute and 15-minute.
182 Scripted config entries may produce more than one PCP leaf metric name.
184 For example, the above "system.sh" script could also export other met‐
185 rics such as CPU statistics, by reading /proc/stat on the local system.
186 Such additional metrics would appear as peer metrics in the same PCP
187 metric subtree. In the case of CPU counters, the metric type defini‐
188 tion should be counter, not gauge. For full details of the prometheus
189 exposition formats, see https://prometheus.io/docs/instrumenting/expo‐
190 sition_formats.
191
193 All metrics from a file named JOB.* will be exported as PCP metrics
194 with the prometheus.JOB metric name prefix. Therefore, the JOB name
195 must be a valid non-leaf name for PCP PMNS metric names. If the JOB
196 name has multiple dot-separated components, the resulting PMNS names
197 will include those components and care is needed to ensure there are no
198 overlapping definitions, e.g. metrics returned by JOB.response may
199 overlap or conflict with metrics returned by JOB.response.time.
200 Config file entries (URLs or scripts) found in subdirectories of the
202 config directory will also result in hierarchical metric names. For
203 example, a config file named $PCP_PMDAS_DIR/prometheus/con‐
204 fig.d/mysource/latency/get.url will result in metrics being created (by
205 fetching that source URL) below prometheus.mysource.latency.get in the
206 PCP namespace. Scripts found in subdirectories of the config directory
207 similarly result in hierarchical PCP metric names.
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210 As described above, changes and new additions can be made to files in
211 the configuration directory without having to restart the PMDA. These
212 changes are detected automatically and the PCP metric names below
213 prometheus in the PMNS will be updated accordingly, i.e. new metrics
214 will be dynamically added and/or existing metrics removed. In addi‐
215 tion, pmdaprometheus honors the PMCD_NAMES_CHANGE pmFetch(3) protocol
216 that was introduced in PCP version 4.0. In particular, if prometheus
217 metrics are being logged by a PCP version 4.0 or later pmlogger(1), new
218 metrics that appear as a result of changes in the PMDA configuration
219 directory will automatically start to be logged, provided the root of
220 the prometheus PMDA namespace is configured for logging in the pmlogger
221 configuration file. See pmlogger(1) for details. An example of such a
222 pmlogger configuration file is :
223 log mandatory on 2 second {
225 # log all metrics below the root of the prometheus namespace
226 prometheus
227 }
228
230 The PMDA maintains special control metrics, as described below. Apart
231 from prometheus.control.debug, each of these metrics is a counter and
232 has one instance for each configured metric source. The instance
233 domain is adjusted dynamically as new sources are discovered. If there
234 are no sources configured, the metric names are still defined but the
235 instance domain will be empty and a fetch will return no values.
236 prometheus.control.calls
238 total number of times each configured metric source has been
239 fetched (if it's a URL) or executed (if it's a script), since
240 the PMDA started.
241 prometheus.control.fetch_time
243 Total time in milliseconds that each configured metric source
244 has taken to return a document, excluding the time to parse the
245 document.
246 prometheus.control.parse_time
248 Total time in milliseconds that each configured metric source
249 has taken to parse each document, excluding the time to fetch
250 the document.
251 When converted to a rate, the calls metric represents the average fetch
253 rate of each source over the sampling interval (time delta between sam‐
254 ples). The fetch_time and parse_time counters, when converted to a
255 rate, represent the average fetch and parsing latency (respectfully),
256 during the sampling interval.
257 The prometheus.control.debug metric has a singular value, defaulting to
259 0. If a non-zero value is stored into this metric using pmstore(1),
260 additional debug messages will be written to the PMDA log file.
261
263 pmdaprometheus and libpcp internals impose some numerical constraints
264 about the number of sources (4095), metrics (1024) within each source,
265 and instances for each metric (4194304).
266
268 Install the Prometheus PMDA by using the Install script as root:
269 # cd $PCP_PMDAS_DIR/prometheus
271 # ./Install
272 To uninstall, do the following as root:
274 # cd $PCP_PMDAS_DIR/prometheus
276 # ./Remove
277 pmdaprometheus is launched by pmcd(1) and should never be executed
279 directly. The Install and Remove scripts notify pmcd when the agent is
280 installed or removed.
281 When scripts and .url files are added, removed or changed in the con‐
283 figuration directory, it is usually not necessary to restart the PMDA -
284 the changes will be detected and managed on subsequent requests to the
285 PMDA.
286
288 $PCP_PMDAS_DIR/prometheus/Install
289 installation script for the pmdaprometheus agent
290 $PCP_PMDAS_DIR/prometheus/Remove
292 undo installation script for the pmdaprometheus agent
293 $PCP_PMDAS_DIR/prometheus/config.d/
295 contains URLs and scripts used by the pmdaprometheus agent as
296 sources of prometheus metric data.
297 $PCP_LOG_DIR/pmcd/prometheus.log
299 default log file for error messages from pmdaprometheus
300 $PCP_VAR_DIR/config/144.*
302 files containing internal tables for metric and instance ID number
303 persistence (domain 144).
304
306 Environment variables with the prefix PCP_ are used to parameterize the
307 file and directory names used by PCP. On each installation, the file
308 /etc/pcp.conf contains the local values for these variables. The
309 $PCP_CONF variable may be used to specify an alternative configuration
310 file, as described in pcp.conf(5).
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313 pmcd(1), pminfo(1), pmlogger(1), pmstore(1), PMWEBAPI(3), pmFetch(3)
314 and https://prometheus.io/docs/instrumenting/exposition_formats.
315Performance Co-Pilot PCP PMDAPROMETHEUS(1)