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NAME | HTTP SYNOPSIS | C SYNOPSIS | DESCRIPTION | OPEN METRICS AND OPEN TELEMETRY | SCALABLE TIME SERIES | FULL TEXT SEARCH | PMAPI HOST SERVICES | NOTES | SEE ALSO | COLOPHON |
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PMWEBAPI(3) Library Functions Manual PMWEBAPI(3)
PMWEBAPI - introduction to the Performance Metrics Web Application
Programming Interface
GET /metrics
GET /series/...
GET /search/...
GET /pmapi/...
POST /logger/...
#include <pcp/pmwebapi.h>
... assorted routines ...
cc ... -lpcp_web -lpcp
The PMWEBAPI is a collection of interfaces providing Performance
Co-Pilot services for web applications. It consists of APIs for
web applications querying and analysing both live and historical
performance data, as well as APIs used by web servers.
The usual HTTP URL-encoded optional parameter rules apply and
PMWEBAPI REST requests always follow the convention:
/api/endpoint?parameter1=value1¶meter2=value2
Examples in all following sections use the curl(1) command line
utility with a local pmproxy(1) server listening on port 44322
(default port). The pmjson(1) utility is used to neatly format
any JSON output, as opposed to the compact (minimal whitespace)
form provided by default. The examples in the scalable time se‐
ries section use historical data recorded by the pmlogger(1) ser‐
vice, in conjunction with a local key-value server.
Exporting of live performance metrics in either Open Metrics
(https://openmetrics.io ) or Open Telemetry
(https://opentelemetry.io ) formats is available.
All requests are performed on the web server host by default, un‐
less a hostspec parameter is provided.
GET /metrics
┌────────────┬─────────┬──────────────────────────┐
│ Parameters │ Type │ Explanation │
├────────────┼─────────┼──────────────────────────┤
│ names │ string │ Comma-separated list of │
│ │ │ metric names │
│ filter │ string │ Comma-separated list of │
│ │ │ excluded metric names │
│ match │ string │ Pattern matching style │
│ │ │ (exact, glob or regex) │
│ times │ boolean │ Append sample times │
│ │ │ (milliseconds since │
│ │ │ epoch) │
├────────────┼─────────┼──────────────────────────┤
│ hostspec │ string │ Host specification as │
│ │ │ described in PCPIntro(1) │
└────────────┴─────────┴──────────────────────────┘
Fetches current values and metadata for all metrics, or only met‐
rics indicated by a comma-separated list of names.
For all numeric metrics with the given NAME prefixes, create an
open text export format giving their current value and related
metadata.
Choice of output format is selected using the HTTP Accept header.
With no header, the default response format is Open Metrics text.
Using the header with value application/json switches the response
to the Open Telemetry JSON format.
In Open Telemetry response mode, sample timestamps are always in‐
cluded and are reported using nanosecond precision.
$ curl -H Accept:application/json -s http://localhost:44322/metrics?names=disk.dev,filesys | pmjson
{
"resourceMetrics": [
{
"resource": {
"attributes": [ ... ]
},
"scopeMetrics": [
{
"scope": { ... },
"metrics": [
{
"name": "disk.dev.total.bytes",
"description": "per-disk count of total bytes read and written",
"unit": "KiBy",
"sum": {
"aggregationTemporality": "CUMULATIVE",
"isMonotonic": true,
"dataPoints": [
{
"attributes": [ ... ]
"timeUnixNano": "1753934255798173",
"asInt": "68927569"
}
]
}
},
...
In Open Metrics response mode, the native PCP metric metadata
(metric name, type, indom, semantics and units) is first output
for each metric with # PCP prefix. The metadata reported is of
the form described on pmTypeStr(3), pmInDomStr(3), pmSemStr(3) and
pmUnitsStr(3) respectively. If the pmUnitsStr(3) units string is
empty, then none is output. The units metadata string may contain
spaces and extends to the end of the line.
PCP metric names are mapped so that the . separators are exchanged
with _ (':' in back-compatibility mode, where "# PCP" is the iden‐
tifying line suffix). Both metric labels and instances are repre‐
sented as Open Metrics labels, with external instance names being
quoted and the flattened PCP label hierarchy being presented with
each value.
When metric names pattern matching is performed using the filter
option, the default mode is glob-based matching. The match option
can be used to instead request regex-based or exact-match metric
filtering.
$ curl -s http://localhost:44322/metrics?names=proc.nprocs,kernel.pernode.cpu.intr,filesys.blocksize
# PCP5 proc.nprocs 3.8.99 u32 PM_INDOM_NULL instant none
# HELP proc_nprocs instantaneous number of processes
# TYPE proc_nprocs gauge
proc_nprocs {hostname="app1"} 7
# PCP5 kernel.pernode.cpu.intr 60.0.66 u64 60.19 counter millisec
# HELP kernel_pernode_cpu_intr total interrupt CPU [...]
# TYPE kernel_pernode_cpu_intr counter
kernel_pernode_cpu_intr{hostname="app1",instname="node0"} 25603
# PCP5 filesys.blocksize 60.5.9 u32 60.5 instant byte
# HELP filesys_blocksize Size of each block on mounted file[...]
# TYPE filesys_blocksize gauge
filesys_blocksize{hostname="app1",instname="/dev/sda1"} 4096
filesys_blocksize{hostname="app1",instname="/dev/sda2"} 4096
The fast, scalable time series query capabilities provided by the
pmseries(1) command are also available through a REST API. These
queries provide access to performance data (metric metadata and
values) from multiple hosts simultaneously, and in a fashion suit‐
ed to efficient retrieval by any number of web applications.
All requests in this group can be accompanied by an optional
client parameter. The value passed in the request will be sent
back in the response - all responses will be in JSON object form
in this case, with top level "client" and "result" fields.
REST API clients can optionally submit an URL-encoded query string
in the body of the HTTP request unless otherwise noted. In this
case the POST method must be used instead of the GET method.
[1mGET /series/ping
Simple liveness test for clients to check whether the server is up
and supports the /series API.
GET /series/query - pmSeriesQuery(3)
┌────────────┬────────┬────────────────────────────────────────────┐
│ Parameters │ Type │ Explanation │
├────────────┼────────┼────────────────────────────────────────────┤
│ expr │ string │ Query string in pmseries(1) format │
│ client │ string │ Request identifier sent back with response │
└────────────┴────────┴────────────────────────────────────────────┘
Performs a time series query for either matching identifiers, or
matching identifiers with series of time-stamped values.
The query is in the format described in pmseries(1) and is passed
to the server via either the expr parameter (HTTP GET) or via the
message body (HTTP POST).
When querying for time series matches only, no time window options
are specified and matching series identifiers are returned in a
JSON array.
$ curl -s 'http://localhost:44322/series/query?expr=disk.dev.read*' | pmjson
[
"9d8c7fb51ce160eb82e3669aac74ba675dfa8900",
"ddff1bfe286a3b18cebcbadc1678a68a964fbe9d",
"605fc77742cd0317597291329561ac4e50c0dd12"
]
When querying for time series values as well, a time window must
be specified as part of the query string. The simplest form is to
just request the most recent sample.
$ curl -s 'http://localhost:44322/series/query?expr=disk.dev.read*[samples:1]' | pmjson
[
{
"series": "9d8c7fb51ce160eb82e3669aac74ba675dfa8900",
"instance": "c3795d8b757506a2901c6b08b489ba56cae7f0d4",
"timestamp": 1547483646.2147431,
"value": "12499"
}, {
"series": "ddff1bfe286a3b18cebcbadc1678a68a964fbe9d",
"instance": "6b08b489ba56cae7f0d4c3795d8b757506a2901c",
"timestamp": 1547485701.7431218,
"value": "1118623"
}, {
"series": "605fc77742cd0317597291329561ac4e50c0dd12",
"instance": "c3795d8b757506a2901c6b08b489ba56cae7f0d4",
"timestamp": 1547483646.2147431,
"value": "71661"
}
]
GET /series/values - pmSeriesValues(3)
┌────────────┬────────┬────────────────────────────────────────────┐
│ Parameters │ Type │ Explanation │
├────────────┼────────┼────────────────────────────────────────────┤
│ series │ string │ Comma-separated list of series identifiers │
│ client │ string │ Request identifier sent back with response │
├────────────┼────────┼────────────────────────────────────────────┤
│ samples │ number │ Count of samples to return │
│ interval │ string │ Time between successive samples │
│ start │ string │ Sample window start time │
│ finish │ string │ Sample window end time │
│ offset │ string │ Sample window offset │
│ align │ string │ Sample time alignment │
│ zone │ string │ Time window timezone │
└────────────┴────────┴────────────────────────────────────────────┘
Performs values retrievals for one or more time series identi‐
fiers. The JSON response contains the same information as the pm‐
series -q/--query option using any of the time window parameters
described on pmseries(1). If no time window parameters are speci‐
fied, the single most recent value observed is retrieved.
$ curl -s http://localhost:44322/series/values?series=605fc77742cd0317597291329561ac4e50c0dd12 | pmjson
[
{
"series": "605fc77742cd0317597291329561ac4e50c0dd12",
"timestamp": 1317633022959.959241041,
"value": "71660"
}
]
GET /series/descs - pmSeriesDescs(3)
┌────────────┬────────┬────────────────────────────────────────────┐
│ Parameters │ Type │ Explanation │
├────────────┼────────┼────────────────────────────────────────────┤
│ series │ string │ Comma-separated list of series identifiers │
│ client │ string │ Request identifier sent back with response │
└────────────┴────────┴────────────────────────────────────────────┘
Performs a descriptor lookup for one or more time series identi‐
fiers. The JSON response contains the same information as the pm‐
series -d/--desc option.
$ curl -s http://localhost:44322/series/descs?series=605fc77742cd0317597291329561ac4e50c0dd12 | pmjson
[
{
"series": "605fc77742cd0317597291329561ac4e50c0dd12",
"source": "f5ca7481da8c038325d15612bb1c6473ce1ef16f",
"pmid": "60.0.4",
"indom": "60.1",
"semantics": "counter",
"type": "u32",
"units": "count",
}
]
GET /series/labels - pmSeriesLabels(3), pmSeriesLabelValues(3)
┌────────────┬────────┬────────────────────────────────────────────┐
│ Parameters │ Type │ Explanation │
├────────────┼────────┼────────────────────────────────────────────┤
│ series │ string │ Comma-separated list of series identifiers │
│ match │ string │ Glob pattern string to match on all labels │
│ name │ string │ Find all known label values for given name │
│ names │ string │ Comma-separated list of label names │
│ client │ string │ Request identifier sent back with response │
└────────────┴────────┴────────────────────────────────────────────┘
This command operates in one of three modes. It can perform a
label set lookup for one or more time series identifiers, when
given the series parameter). It can produce a list of all known
label names, in the absence of name, names or series parameters.
The JSON responses for these modes contains the same information
as the pmseries -l/--labels option.
Alternatively, it can produce a list of all known label values for
a given label name or names. The JSON response for this mode
contains the same information as the pmseries -v/--values option.
$ curl -s http://localhost:44322/series/labels?series=605fc77742cd0317597291329561ac4e50c0dd12 | pmjson
[
{
"series": "605fc77742cd0317597291329561ac4e50c0dd12",
"labels": {
"agent": "linux",
"domainname": "acme.com",
"groupid": 1000,
"hostname": "www.acme.com",
"latitude": -25.28496,
"longitude": 152.87886,
"machineid": "295b16e3b6074cc8bdbda8bf96f6930a",
"platform": "dev",
"userid": 1000
}
}
]
Alternatively, with no name, names or series parameters, return
the list of all known label names.
$ curl -s http://localhost:44322/series/labels | pmjson
[
"agent",
"appversion",
"domainname",
"groupid",
"hostname",
"jobid",
"latitude",
"longitude",
"machineid",
"platform",
"userid"
]
Use the name or names parameters to find all possible label values
for the given name(s).
$ curl -s http://localhost:44322/series/labels?names=hostname,domainname | pmjson
{
"hostname": [ "app", "nas" ],
"domainname": [ "acme.com" ]
}
GET /series/metrics - pmSeriesMetrics(3)
┌────────────┬────────┬────────────────────────────────────────────┐
│ Parameters │ Type │ Explanation │
├────────────┼────────┼────────────────────────────────────────────┤
│ series │ string │ Comma-separated list of series identifiers │
│ match │ string │ Glob pattern string to match on all names │
│ client │ string │ Request identifier sent back with response │
└────────────┴────────┴────────────────────────────────────────────┘
Performs a metric name lookup for one or more time series identi‐
fiers. The JSON response contains the same information as the pm‐
series -m/--metrics option.
$ curl -s http://localhost:44322/series/metrics?series=605fc77742cd0317597291329561ac4e50c0dd12 | pmjson
[
{
"series": "605fc77742cd0317597291329561ac4e50c0dd12",
"name": "disk.dev.read_bytes"
}
]
Alternatively, with no series argument, this request will return
the list of all known metric names.
$ curl -s http://localhost:44322/series/metrics | pmjson
[
"disk.dev.read",
"disk.dev.read_bytes",
"disk.dev.read_merge",
"kernel.all.load",
"kernel.all.pswitch",
...
]
GET /series/sources - pmSeriesSources(3)
┌────────────┬────────┬─────────────────────────────────────────────┐
│ Parameters │ Type │ Explanation │
├────────────┼────────┼─────────────────────────────────────────────┤
│ series │ string │ Comma-separated list of source identifiers │
│ match │ string │ Glob pattern string to match on all sources │
│ client │ string │ Request identifier sent back with response │
└────────────┴────────┴─────────────────────────────────────────────┘
Performs a lookup for one or more time series sources, returning
an array of all PMAPI context names used to access the time series
from that source. The JSON response contains the same information
as the pmseries -S/--source option.
$ curl -s http://localhost:44322/series/sources?source=2cd6a38f9339f2dd1f0b4775bda89a9e7244def6 | pmjson
[
{
"source": "2cd6a38f9339f2dd1f0b4775bda89a9e7244def6",
"context": [
"/var/log/pcp/pmlogger/acme",
"www.acme.com"
]
}
]
GET /series/instances - pmSeriesInstances(3)
┌────────────┬────────┬──────────────────────────────────────────┐
│ Parameters │ Type │ Explanation │
├────────────┼────────┼──────────────────────────────────────────┤
│ series │ string │ Comma-separated list of series │
│ │ │ identifiers │
│ match │ string │ Glob pattern string to match on all │
│ │ │ instances │
│ client │ string │ Request identifier sent back with │
│ │ │ response │
└────────────┴────────┴──────────────────────────────────────────┘
Provide instance identifiers and names for one or more time series
identifiers. The JSON response contains the same information as
the pmseries -i/--instance option.
$ curl -s http://localhost:44322/series/instances?series=605fc77742cd0317597291329561ac4e50c0dd12 | pmjson
[
{
"series": "605fc77742cd0317597291329561ac4e50c0dd12",
"source": "97261ac7742cd4e50c0d03175913295d12605fc7",
"instance": "c3795d8b757506a2901c6b08b489ba56cae7f0d4"
"id": 1,
"name": "sda",
}, {
"series": "605fc77742cd0317597291329561ac4e50c0dd12",
"source": "97261ac7742cd4e50c0d03175913295d12605fc7",
"instance": "57506a2901c6b08b489ba56cae7f0d4c3795d8b7"
"id": 2,
"name": "sdb",
}
]
Alternatively, with no series argument, this request will return
the list of all known instance names.
$ curl -s http://localhost:44322/series/instances | pmjson
[
"1 minute",
"5 minute",
"15 minute",
"cpu0",
"cpu1",
"cpu2",
"cpu3",
"node0",
"node1",
"sda",
"sdb",
...
]
GET /series/load - pmSeriesLoad(3)
┌────────────┬────────┬────────────────────────────────────────────┐
│ Parameters │ Type │ Explanation │
├────────────┼────────┼────────────────────────────────────────────┤
│ expr │ string │ Source load string in pmseries(1) format │
│ client │ string │ Request identifier sent back with response │
└────────────┴────────┴────────────────────────────────────────────┘
Load time series performance data from the specified source into
the key-value server cache. This request is equivalent to the pm‐
series -l/--load option.
$ curl -s http://localhost:44322/series/load?expr={source.name:"/var/log/pcp/pmlogger/acme"}
{
"success": true
}
The full text search capabilities provided by the pmsearch(1) com‐
mand are also available through a REST API. These queries provide
access to an index over performance metric names, instances, in‐
stance domains and help text, suitable for a metric search engine,
and in a fashion suited to efficient querying by any number of web
applications.
In order to use this functionality, the optional ValkeySearch mod‐
ule must be loaded in the key-value server at the time pmproxy is
started, such that metrics, instances and help text it discovers
can be automatically indexed.
GET /search/text - pmSearchTextQuery(3)
┌────────────┬────────┬─────────────────────────────────────────────┐
│ Parameters │ Type │ Explanation │
├────────────┼────────┼─────────────────────────────────────────────┤
│ query │ string │ Query string in pmsearch(1) format │
│ highlight │ fields │ Include matching markup in response fields │
│ offset │ number │ Result offset cursor for pagination │
│ limit │ number │ Maximum results to include in response │
│ field │ fields │ Queried fields (defaults to all) │
│ return │ fields │ Fields to actually return (defaults to all) │
│ type │ types │ Entity types to filter (defaults to all) │
└────────────┴────────┴─────────────────────────────────────────────┘
Performs a text search query across metrics and instance domains -
all forms of names and help texts.
The mandatory search string is further described in pmsearch(1)
and is passed to the server via the query parameter (HTTP GET).
$ curl -s http://localhost:44322/search/text?query=halt | pmjson
{
"total": 2,
"offset": 0,
"limit": 10,
"elapsed": 0.000504,
"results": [
{
"name": "kvm.halt_exits",
"type": "metric",
"indom": "95.0.4",
"oneline": "Number of guest exits due to halt calls.",
"helptext": "This type of exit is usually seen when a guest is idle."
},
{
"name": "kvm.halt_wakeup",
"type": "metric",
"indom": "95.0.6",
"oneline": "Number of wakeups from a halt.",
}
]
}
The available search entity types are metric, indom and instance.
Query parameters highlight and field take name, oneline and help‐
text.
Query parameter return takes name, type, oneline, helptext, indom.
There is typically both a name and help text associated with met‐
rics. Contents of these are then matched against query. An in‐
stance domain has help text and a numeric identifier, while in‐
stances have a name only (which can be searched).
GET /search/suggest - pmSearchTextSuggest(3)
┌────────────┬────────┬────────────────────────────────────┐
│ Parameters │ Type │ Explanation │
├────────────┼────────┼────────────────────────────────────┤
│ query │ string │ Search query for search engine │
│ limit │ number │ Max results to include in response │
└────────────┴────────┴────────────────────────────────────┘
Provides search query suggestions, that is, metric and instance
names.
The mandatory search string is further described in pmsearch(1)
and is passed to the server via the query parameter (HTTP GET).
$ curl -s http://localhost:44322/search/suggest?query=disk&limit=4 | pmjson
[
"disk.all.avactive",
"disk.all.aveq",
"disk.all.blkread",
"disk.all.blktotal"
]
GET /search/indom - pmSearchTextInDom(3)
┌────────────┬────────┬─────────────────────────────────────┐
│ Parameters │ Type │ Explanation │
├────────────┼────────┼─────────────────────────────────────┤
│ query │ string │ Target indom for search engine │
│ offset │ number │ Result offset cursor for pagination │
│ limit │ number │ M results to include in response │
└────────────┴────────┴─────────────────────────────────────┘
Provides all entities (instances, metrics) related to indom, in‐
cluding itself, that is passed to the server via the query parame‐
ter.
GET /search/info - pmSearchInfo(3)
Provides metrics relating to operation of the search engine, in
particular showing document and text record counts.
$ curl -s http://localhost:44322/search/info | pmjson
{
"docs": 1589,
"terms": 3855,
"records": 116831,
"records_per_doc_avg": 73.52,
"bytes_per_record_avg": 6.36,
"inverted_sz_mb": 0.71,
"inverted_cap_mb": 0.00,
"inverted_cap_ovh": 0.00,
"skip_index_size_mb": 0.00,
"score_index_size_mb": 0.00,
"offsets_per_term_avg": 9.41,
"offset_bits_per_record_avg": 8.00
}
The live performance collection facilities available from pmcd(1)
can also be accessed through a REST API.
All requests are performed on the web server host by default, un‐
less either a hostspec or context parameter is provided. hostname
can be used in place of hostspec.
Context identifiers are used as a persistent way to refer to PMAPI
contexts across related web requests. These contexts expire after
a configurable period of disuse, and are either explicitly allo‐
cated using the /pmapi/context interface, or implicitly allocated
using other interfaces.
The timeout interval is configurable at context creation time, and
as such the polltimeout parameter can be used anywhere the host‐
spec is specified. It sets the context timeout in terms of length
of inactive time. The unit for the timeout value is seconds and
the default is 5.
To specify a specific existing context in any PMAPI web request,
the endpoints can be accessed with either the context parameter or
embedded in the endpoint URL itself, such as /pmapi/[num‐
ber]/fetch.
GET /pmapi/context - pmNewContext(3)
┌─────────────┬────────┬──────────────────────────┐
│ Parameters │ Type │ Explanation │
├─────────────┼────────┼──────────────────────────┤
│ hostspec │ string │ Host specification as │
│ │ │ described in PCPIntro(1) │
│ polltimeout │ number │ Seconds of inactivity │
│ │ │ before closing context │
│ client │ string │ Request identifier sent │
│ │ │ back with response │
└─────────────┴────────┴──────────────────────────┘
To create a context for live sampling, a web client can access any
/pmapi URL (optionally using the hostspec or context parameter).
If no context exists, a new one will be created for that web
client, and its identifier returned for future accesses.
However, /pmapi/context is provided as a dedicated URL for appli‐
cations wishing to explicitly create the contexts they use.
If successful, the server responds with a HTTP 200 (OK) code and
JSON message body of the form:
$ curl -s http://localhost:44322/pmapi/context?hostspec=www.acme.com&polltimeout=0.5 | pmjson
{
"context": 348734,
"source": "05af7f3eb840277fd3cfa91f90ef0067199743c",
"hostspec": "www.acme.com",
"labels": {
"domainname": "acme.com",
"groupid": 1000,
"hostname": "www.acme.com",
"machineid": "295b7623b6074cc8bdbda8bf96f6930a"
"platform": "dev",
"userid": 1000
}
}
The context (a 32-bit unsigned decimal number) can then be used
with all later requests.
In the case of a hostspec containing authentication information,
such as a username, the server will follow the HTTP Basic Authen‐
tication protocol to ascertain necessary authentication details
from the user, providing the client web application an opportunity
to request these from the user.
GET /pmapi/metric - pmLookupDesc(3), pmLookupLabels(3),
pmLookupName(3), pmLookupText(3)
┌─────────────┬────────┬──────────────────────────┐
│ Parameters │ Type │ Explanation │
├─────────────┼────────┼──────────────────────────┤
│ name │ string │ An individual metric │
│ │ │ name │
│ names │ string │ Comma-separated list of │
│ │ │ metric names │
│ pmid │ pmID │ Numeric or pmIDStr(3) │
│ │ │ metric identifier │
│ pmids │ string │ Comma-separated numeric │
│ │ │ or pmIDStr(3) pmIDs │
│ prefix │ string │ Metric namespace compo‐ │
│ │ │ nent as in PMNS(5) │
├─────────────┼────────┼──────────────────────────┤
│ hostspec │ string │ Host specification as │
│ │ │ described in PCPIntro(1) │
│ context │ number │ Web context number (op‐ │
│ │ │ tional like hostspec) │
│ polltimeout │ number │ Seconds of inactivity │
│ │ │ before context closed │
│ client │ string │ Request identifier sent │
│ │ │ back with response │
└─────────────┴────────┴──────────────────────────┘
The metric endpoint provides detailed PMAPI metric metadata for
one or more metrics. If no parameters are supplied, the response
will be for all metrics found when traversing the entire Perfor‐
mance Metrics Name Space (PMNS).
The prefix parameter can be used to specify a subtree of the PMNS
for traversal. Alternatively, a specific metric or comma-separat‐
ed list of metrics can be specified using either name or names
The server response is a JSON document that provides metric meta‐
data as an array.
$ curl -s http://localhost:44322/pmapi/metric?names=kernel.all.load,disk.all.read | pmjson
{
"context": 348734,
"metrics": [
{
"name": "kernel.all.load",
"pmid": "60.2.0",
"indom": "60.2",
"type": "FLOAT",
"sem": "instant",
"units": "none",
"series": "d2b28c7f6dc0d69ffd21dba7ba955e78c37719b",
"source": "05af7f3eb840277fd3cfa91f90ef0067199743c",
"labels": {
"agent": "linux",
"domainname": "acme.com",
"groupid": 1000,
"hostname": "www.acme.com",
"platform": "dev",
"userid": 1000
},
"text-oneline": "1, 5 and 15 minute load average"
},
{
"name": "disk.all.read",
"pmid": "60.0.24",
"type": "U64",
"sem": "counter",
"units": "count",
"series": "d2b28c7f6dc0d69ffd21dba7ba955e78c37719b",
"source": "05af7f3eb840277fd3cfa91f90ef0067199743c",
"labels": {
"agent": "linux",
"domainname": "acme.com",
"groupid": 1000,
"hostname": "www.acme.com",
"platform": "dev",
"userid": 1000
},
"text-oneline": "total read operations, summed for all disks",
"text-help": "Cumulative number of disk read operations [...]"
}
]
}
Most of the fields are directly transcribed from the PMAPI calls
for metric descriptors, labels and help text mentioned above and
are exactly as would be observed using the pminfo(1) command with
the -dlmstT options.
The semantics, type and units fields are as returned by
pmTypeStr(3), pmUnitsStr(3) and pmSemStr(3).
GET /pmapi/fetch - pmFetch(3)
┌─────────────┬────────┬──────────────────────────┐
│ Parameters │ Type │ Explanation │
├─────────────┼────────┼──────────────────────────┤
│ delta │ string │ Sampling interval in pm‐ │
│ │ │ ParseInterval(3) form │
│ name │ string │ An individual metric │
│ │ │ name │
│ names │ string │ Comma-separated list of │
│ │ │ metric names │
│ pmid │ pmID │ Numeric or pmIDStr(3) │
│ │ │ metric identifier │
│ pmids │ string │ Comma-separated numeric │
│ │ │ or pmIDStr(3) pmIDs │
├─────────────┼────────┼──────────────────────────┤
│ hostspec │ string │ Host specification as │
│ │ │ described in PCPIntro(1) │
│ context │ number │ Web context number (op‐ │
│ │ │ tional like hostspec) │
│ polltimeout │ number │ Seconds of inactivity │
│ │ │ before context closed │
│ client │ string │ Request identifier sent │
│ │ │ back with response │
└─────────────┴────────┴──────────────────────────┘
This request fetches (samples) current values for given metrics.
If any of the names or pmids provided are valid, the response is a
JSON document that provides the values for all instances of the
metrics, unless a instance profile has been set for the web con‐
text (see section on InDom profiles below).
$ curl -s http://localhost:44322/pmapi/fetch?names=kernel.all.load,disk.all.read | pmjson
{
"context": 348734,
"timestamp": 1547483646.2147431,
"values": [
{
"pmid": "60.2.0",
"name": "kernel.all.load",
"instances:" [
{ "instance": 1, "value": 0.1 },
{ "instance": 5, "value": 0.17 },
{ "instance": 15, "value": 0.22 }
]
},
{
"pmid":"60.0.24",
"name":"disk.all.read",
"instances:" [
{ "instance": null, "value": 639231 }
]
}
]
}
The response fields map directly to fields from the underlying
pmFetch(3) sampling interface.
Numeric metric types are represented as JSON integer or floating-
point values. Strings are passed verbatim, except that non-ASCII
values are replaced with a Unicode 0xFFFD replacement character
code.
In backward compatibility mode the timestamp is presented as a
JSON map with second (sec) and microsecond (us) fields, instead of
using the more compact floating point representation shown above.
GET /pmapi/children - pmGetChildren(3), pmGetChildrenStatus(3)
┌─────────────┬────────┬──────────────────────────┐
│ Parameters │ Type │ Explanation │
├─────────────┼────────┼──────────────────────────┤
│ prefix │ string │ Metric namespace compo‐ │
│ │ │ nent as in PMNS(5) │
├─────────────┼────────┼──────────────────────────┤
│ hostspec │ string │ Host specification as │
│ │ │ described in PCPIntro(1) │
│ context │ number │ Web context number (op‐ │
│ │ │ tional like hostspec) │
│ polltimeout │ number │ Seconds of inactivity │
│ │ │ before context closed │
│ client │ string │ Request identifier sent │
│ │ │ back with response │
└─────────────┴────────┴──────────────────────────┘
The children endpoint provides iterative namespace traversal for a
context. If no parameters are supplied, the response will de‐
scribe the direct descendants of the Performance Metrics Name
Space (PMNS) root.
The prefix parameter can be used to specify a subtree of the PMNS
for traversal.
The server response is a JSON document that provides the set of
leaf and non-leaf nodes below the given namespace node or root.
$ curl -s http://localhost:44322/pmapi/children?prefix=mem | pmjson
{
"context": 348734,
"name": "mem",
"leaf": [
"physmem",
"freemem"
],
"nonleaf": [
"util",
"numa",
"vmstat",
"buddyinfo",
"slabinfo",
"zoneinfo",
"ksm"
]
}
GET /pmapi/indom - pmGetInDom(3), pmNameInDom(3), pmLookupInDom(3)
┌─────────────┬─────────┬──────────────────────────┐
│ Parameters │ Type │ Explanation │
├─────────────┼─────────┼──────────────────────────┤
│ iname │ string │ Comma-separated list of │
│ │ │ instance names │
│ indom │ pmInDom │ Numeric or pmInDomStr(3) │
│ │ │ instance domain │
│ instance │ number │ Comma-separated list of │
│ │ │ instance numbers │
│ match │ string │ Pattern matching style │
│ │ │ (exact, glob or regex) │
│ name │ string │ An individual metric │
│ │ │ name │
├─────────────┼─────────┼──────────────────────────┤
│ hostspec │ string │ Host specification as │
│ │ │ described in PCPIntro(1) │
│ context │ number │ Web context number (op‐ │
│ │ │ tional like hostspec) │
│ polltimeout │ number │ Seconds of inactivity │
│ │ │ before context closed │
│ client │ string │ Request identifier sent │
│ │ │ back with response │
└─────────────┴─────────┴──────────────────────────┘
This request lists the current instances of an instance domain.
The instance domain is either specified directly (in numeric or
string form) or indirectly, by association with the specified met‐
ric.
The request can be further qualified with a comma-separated list
of the instances to report on, either by name or number, using the
instance and iname parameters.
In the case of instance name qualifiers, these will be matched by
exact string comparison by default. Alternatively, the match pa‐
rameter can be used to specify that regular expression or glob
pattern matching should be used instead.
The response is a JSON document that provides the instance domain
metadata as an array.
$ curl -s http://localhost:44322/pmapi/indom?name=kernel.all.load | pmjson
{
"context": 348734,
"indom": "60.2",
"labels": {
"domainname": "acme.com",
"groupid": 1000,
"hostname": "www.acme.com",
"machineid": "295b7623b6074cc8bdbda8bf96f6930a"
"platform": "dev",
"userid": 1000
},
"instances": [
{
"instance": 1,
"name": "1 minute"
"labels": { ... },
},
{
"instance": 5,
"name": "5 minute"
"labels": { ... },
},
{
"instance": 15,
"name": "15 minute"
"labels": { ... },
}
]
}
GET /pmapi/profile - pmAddProfile(3), pmDelProfile(3)
┌─────────────┬─────────┬──────────────────────────┐
│ Parameters │ Type │ Explanation │
├─────────────┼─────────┼──────────────────────────┤
│ iname │ string │ Comma-separated list of │
│ │ │ instance names │
│ indom │ pmInDom │ Numeric or pmInDomStr(3) │
│ │ │ instance domain │
│ instance │ number │ Comma-separated list of │
│ │ │ instance numbers │
│ expr │ string │ One of "add" or "del" │
│ │ │ (mandatory). │
│ match │ string │ Pattern matching style │
│ │ │ (exact, glob or regex) │
├─────────────┼─────────┼──────────────────────────┤
│ hostspec │ string │ Host specification as │
│ │ │ described in PCPIntro(1) │
│ context │ number │ Web context number (op‐ │
│ │ │ tional like hostspec) │
│ polltimeout │ number │ Seconds of inactivity │
│ │ │ before context closed │
│ client │ string │ Request identifier sent │
│ │ │ back with response │
└─────────────┴─────────┴──────────────────────────┘
Some PMAPI operations can be performed with an active instance do‐
main profile which restricts (filters) the set of resulting in‐
stances returned, as described on pmAddProfile(3).
$ curl -s http://localhost:44322/pmapi/profile?expr=add,indom=60.2,iname=1%20minute
{ "context": 348734, "success": true }
GET /pmapi/store - pmStore(3)
┌─────────────┬────────┬────────────────────────────────────────────┐
│ Parameters │ Type │ Explanation │
├─────────────┼────────┼────────────────────────────────────────────┤
│ iname │ string │ Comma-separated list of instance names │
│ instance │ number │ Comma-separated list of instance numbers │
│ name │ string │ An individual metric name │
│ value │ (any) │ New value for the given metric instance(s) │
├─────────────┼────────┼────────────────────────────────────────────┤
│ hostspec │ string │ Host specification as described in PCPIn‐ │
│ │ │ tro(1) │
│ context │ number │ Web context number (optional like host‐ │
│ │ │ spec) │
│ polltimeout │ number │ Seconds of inactivity before context │
│ │ │ closed │
│ client │ string │ Request identifier sent back with response │
└─────────────┴────────┴────────────────────────────────────────────┘
Some performance metrics allow their value to be modified, for ex‐
ample to re-initialize counters or to modify control variables.
This operation takes a single metric name to modify, and optional‐
ly specific instances. The mandatory value will be interpreted
according to the type of the metric being modified.
If successful, the response from these requests is a JSON document
of the form:
$ curl -s http://localhost:44322/pmapi/store?name=pmcd.control.timeout&value=10
{
"context": 348734,
"success": true
}
GET /pmapi/derive: pmAddDerived(3)
┌─────────────┬────────┬───────────────────────────┐
│ Parameters │ Type │ Explanation │
├─────────────┼────────┼───────────────────────────┤
│ expr │ string │ Derived metric expression │
│ name │ string │ New derived metric name │
├─────────────┼────────┼───────────────────────────┤
│ hostspec │ string │ Host specification as de‐ │
│ │ │ scribed in PCPIntro(1) │
│ context │ number │ Web context number (op‐ │
│ │ │ tional like hostspec) │
│ polltimeout │ number │ Seconds of inactivity be‐ │
│ │ │ fore context closed │
│ client │ string │ Request identifier sent │
│ │ │ back with response │
└─────────────┴────────┴───────────────────────────┘
Create a new derived metric, as defined by the pmAddDerived(3)
metric interface. Derived metrics are associated with the named
context, or a new context is created and returned in the result.
This interface is one of the few that allows a POST to be used in
place of a GET. In this case the HTTP POST request body may be
used to provide one or more derived metrics specifications (all at
once, across multiple lines, as a convenience).
$ curl -s http://localhost:44322/pmapi/derive?name=blkio.avgsz&expr=disk.all.blktotal/disk.all.total | pmjson
{
"context": 348734,
"success": true
}
$ curl -s http://localhost:44322/pmapi/fetch?name=blkio.avgsz&samples=2 | pmjson
{
"context": 348734,
"timestamp": 1547483648.2147428,
"values": [
{
"pmid": "511.0.27",
"name": "blkio.avgsz",
"instances:" [
{
"instance": null,
"value": 9231
}
]
}
]
}
GET /pmapi/metrics: pmLookupDesc(3),pmLookupLabels(3), pmFetch(3)
┌─────────────┬─────────┬──────────────────────────┐
│ Parameters │ Type │ Explanation │
├─────────────┼─────────┼──────────────────────────┤
│ names │ string │ Comma-separated list of │
│ │ │ metric names │
│ times │ boolean │ Append sample times │
│ │ │ (milliseconds since │
│ │ │ epoch) │
├─────────────┼─────────┼──────────────────────────┤
│ context │ number │ Web context number (op‐ │
│ │ │ tional like hostspec) │
│ hostspec │ string │ Host specification as │
│ │ │ described in PCPIntro(1) │
│ polltimeout │ number │ Seconds of inactivity │
│ │ │ before context closed │
│ client │ string │ Request identifier sent │
│ │ │ back with response │
└─────────────┴─────────┴──────────────────────────┘
This request is a subset of the style described in the ``OPEN MET‐
RICS AND OPEN TELEMETRY'' section, allowing a web context identi‐
fier to be passed as a parameter. It is otherwise very similar in
terms of parameters and response handling, please refer to the
earlier section for details.
ARCHIVE WEBHOOK - LOGARCHIVE(5) %%%SH%%%
Remote archive push functionality is available via the pmlogger(1)
and pmlogpush(1) utilities. This is achieved through a series of
HTTP POST operations to the API endpoints described here.
All requests in this group can be accompanied by an optional
client parameter. The value passed in the request will be sent
back in the response - all responses are in JSON object form and
will include an additional top level "client" field.
[1mGET /logger/ping
Basic liveness test for clients to check whether the server is up
and supports the /logger API.
[1mPOST /logger/label
The body of this API is the machine-agnostic binary (on-disk) rep‐
resentation of a PCP archive label as described in LOGARCHIVE(5).
Either version 2 and 3 are accepted, and the volume field of this
stucture will be ignored - one API call suffices for all of the
volumes of an archive, pmproxy ensures correct content is written
for each.
This API returns a numeric token (LOGID) that must be used in all
subsequent API interactions for this archive as described below.
[1mPOST /logger/meta/LOGID
The request body contains metadata file records as described in
LOGARCHIVE.
[1mPOST /logger/index/LOGID
The request body contains temporal index records as described in
LOGARCHIVE.
[1mPOST /logger/volume/VOLID/LOGID
The request body contains timestamped metric value samples, as de‐
scribed in LOGARCHIVE. The numeric volume (VOLID) to which these
records is to be written is a mandatory part of the API endpoint.
For the REST APIs, errors generally result in HTTP-level error re‐
sponses. Wherever possible, any PMAPI error string will also be
provided in a message along with the response.
All responses will be returned using HTTP 1.1 protocol and with
chunked encoding being used to stream responses that are larger
than a configured maximum size. Compression will be used on re‐
sponses whenever the client indicates appropriate support.
An Access-Control-Allow-Origin: * header is added to all REST API
responses.
PCPIntro(1), curl(1), pmcd(1), pmdaopenmetrics(1), pminfo(1),
pmjson(1), pmlogger(1), pmlogpush(1), pmproxy(1), pmseries(1),
PCPIntro(3), PMAPI(3) and LOGARCHIVE(5)
This page is part of the PCP (Performance Co-Pilot) project. In‐
formation 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
2026-01-16. (At that time, the date of the most recent commit
that was found in the repository was 2026-01-16.) 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 PMWEBAPI(3)
Pages that refer to this page: pcpcompat(1), pmdaopenmetrics(1), pmdaopentelemetry(1), pmfind(1), pmjson(1), pmlogpush(1), pmproxy(1), pmseries(1), pmapi(3), pmda(3), pmdiscoversetup(3), pmhttpnewclient(3), pmsearchinfo(3), pmsearchsetup(3), pmsearchtextindom(3), pmsearchtextquery(3), pmsearchtextsuggest(3), pmseriesdescs(3), pmseriesquery(3), pmseriessetup(3), pmwebtimerregister(3)
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