Provided by: libpcp3-dev_5.3.7-1_amd64 
NAME
PMWEBAPI - introduction to the Performance Metrics Web Application Programming Interface
HTTP SYNOPSIS
GET /metrics
GET /series/...
GET /search/...
GET /pmapi/...
C SYNOPSIS
#include <pcp/pmwebapi.h>
... assorted routines ...
cc ... -lpcp_web -lpcp
DESCRIPTION
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 series section use historical data
recorded by the pmlogger(1) service, in conjunction with a local redis-server(1).
OPEN METRICS
Exporting of live performance metrics in an Open Metrics compatible format (as described
at https://openmetrics.io and popularized by the https://prometheus.io project) is
available.
All requests are performed on the web server host by default, unless a hostspec parameter
is provided.
GET /metrics
┌───────────┬─────────┬────────────────────────────────────────────────┐
│Parameters │ Type │ Explanation │
├───────────┼─────────┼────────────────────────────────────────────────┤
│names │ string │ Comma-separated list of metric names │
│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 metrics indicated by a comma-
separated list of names.
For all numeric metrics with the given NAME prefixes, create an Open Metrics (Prometheus)
text export format giving their current value and related metadata.
The response has plain text type rather than JSON commonly used elsewhere in the REST API.
This format can be injested by many open source monitoring tools, including Prometheus and
pmdaopenmetrics(1).
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 identifying line suffix). Both metric labels and
instances are represented as Prometheus labels, with external instance names being quoted
and the flattened PCP metric hierarchy being presented with each value.
$ 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
SCALABLE TIME SERIES
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 suited
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.
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 identifiers. The JSON response
contains the same information as the pmseries -q/--query option using any of the time
window parameters described on pmseries(1). If no time window parameters are specified,
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 identifiers. The JSON response
contains the same information as the pmseries -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 identifiers. The JSON response
contains the same information as the pmseries -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 redis-server cache.
This request is equivalent to the pmseries -l/--load option.
$ curl -s http://localhost:44322/series/load?expr={source.name:"/var/log/pcp/pmlogger/acme"}
{
"success": true
}
FULL TEXT SEARCH
The full text search capabilities provided by the pmsearch(1) command are also available
through a REST API. These queries provide access to an index over performance metric
names, instances, instance 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 RediSearch module must be loaded in the
redis-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 helptext.
Query parameter return takes name, type, oneline, helptext, indom. There is typically
both a name and help text associated with metrics. Contents of these are then matched
against query. An instance domain has help text and a numeric identifier, while instances
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, including itself, that is
passed to the server via the query parameter.
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
}
PMAPI HOST SERVICES
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, unless 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 allocated using the /pmapi/context interface, or implicitly allocated using
other interfaces.
The timeout interval is configurable at context creation time, and as such the polltime
parameter can be used anywhere the hostspec 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/[number]/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 applications 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&polltime=500 | 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 Authentication 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 component as in PMNS(5) │
├────────────┼────────┼────────────────────────────────────────────────┤
│hostspec │ string │ Host specification as described in PCPIntro(1) │
│context │ number │ Web context number (optional 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 Performance 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-separated list of metrics can be specified using
either name or names
The server response is a JSON document that provides metric metadata 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 pmParseInterval(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 (optional 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 context (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 component as in PMNS(5) │
├────────────┼────────┼────────────────────────────────────────────────┤
│hostspec │ string │ Host specification as described in PCPIntro(1) │
│context │ number │ Web context number (optional 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 describe 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 (optional 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 metric.
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 parameter 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 (optional 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 domain profile which
restricts (filters) the set of resulting instances 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 PCPIntro(1) │
│context │ number │ Web context number (optional like hostspec) │
│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 example to re-initialize
counters or to modify control variables.
This operation takes a single metric name to modify, and optionally 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 described in PCPIntro(1) │
│context │ number │ Web context number (optional like hostspec) │
│polltimeout │ number │ Seconds of inactivity before 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 (optional 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 METRICS'' section, allowing
a web context identifier 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.
NOTES
For the REST APIs, errors generally result in HTTP-level error responses. 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 responses whenever the client indicates appropriate support.
An Access-Control-Allow-Origin: * header is added to all REST API responses.
SEE ALSO
PCPIntro(1), curl(1), pmcd(1), pmdaopenmetrics(1), pminfo(1), pmjson(1), pmlogger(1),
pmproxy(1), pmseries(1), redis-server(1), PCPIntro(3) and PMAPI(3)