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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | OPERATION | EXAMPLE | SAFETY AND SECURITY | SEE ALSO | BUGS | COLOPHON |
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STAP-EXPORTER(8) System Manager's Manual STAP-EXPORTER(8)
stap-exporter - systemtap-prometheus interoperation mechanism
stap-exporter [ OPTIONS ]
stap-exporter runs a set of systemtap scripts and relays their
procfs outputs to remote HTTP clients on demand. This makes
systemtap scripts directly usable as individual prometheus
exporters. This is assisted by a set of macros provided in the
prometheus.stpm tapset file.
The stap-exporter program supports the following options.
-p --port PORT
Listen to the specified TCP port for HTTP requests. Port
9900 is used by default.
-k --keepalive KEEPALIVE
Scripts that run longer than KEEPALIVE seconds beyond the
last request are shut down. There is no timeout by
default, so once started, scripts are kept running.
-s --scripts SCRIPTS
Search the directory SCRIPTS for *.stp files to be
exposed. The default is given in the stappaths.7 man
page.
-h --help
Print help message.
Upon startup, stap-exporter searches the directory specified by
the -s directory for files named *.stp. The name of each file
becomes available as a URL component for subsequent GET HTTP
requests. For example, when an HTTP client asks for /foo.stp,
and the foo.stp script (executable / shell-script) was known,
then it is spawned with additional stap options to set a module
name. This predictable module name makes it possible for stap-
exporter to transcribe a procfs file from that running script to
HTTP clients.
After a configurable period of disuse (-k or --keepalive option),
a systemtap script is terminated. It will be restarted again if
a client requests.
All files whose name includes the substring autostart are started
immediately (and restarted if they stop), rather than on-demand.
These are excluded from keepalive considerations. Scripts that
may be too slow to start or wish to report long-term statistics
are candidates for this treatment.
Suppose that example.stp contains the following script. It
counts read syscalls on a per-thread & per-cpu basis.
global arr%
probe syscall.read {
arr[tid(), cpu()]++
}
probe prometheus {
@prometheus_dump_array2(arr, "count", "tid", "cpu")
}
The prometheus_dump_array macros are used to produce metrics from
an array. Systemtap provides a prometheus_dump_arrayN macro for
all N from 1 to 8. The first argument of the macros represents
an array with N-element keys. The second argument represents the
name of the metric. The remaining N arguments represent the names
of the metric's labels.
One may launch stap-exporter as root, or equivalent stapdev priv‐
ileges, then after a brief delay, use any web client to fetch da‐
ta:
# stap-exporter -p 9999 -k 60 -c . &
$ curl http://localhost:9999/example.stp
Refresh page to access metrics. [...]
$ curl http://localhost:9999/example.stp
count{tid="12614",cpu="0"} 9
count{tid="12170",cpu="3"} 107
count{tid="1802",cpu="0"} 33687
count{tid="12617",cpu="1"} 99
[...]
The same URL may be added to a Prometheus server's scrape_config
section, or a Performance Co-Pilot pmdaprometheus config.d direc‐
tory, to collect this data into a monitoring system.
The stap-exporter server does not enforce any particular security
mechanisms. Therefore, deployment in an untrusted environment
needs to consider:
script selection
Since systemtap scripts are run under the privileges of
the stap-exporter process (probably root), the system ad‐
ministrator must select only safe & robust scripts. Check
the scripts installed by default before activating the
service. Scripts cannot take input from the web clients.
TCP/IP firewalling
Since stap-exporter exposes the selected TCP/HTTP port to
all interfaces on the host, it may be necessary to add a
firewall. It is unlikely to be appropriate to expose such
a service to an untrusted network.
HTTP filtering
Since stap-exporter exposes the configured systemtap
scripts to all HTTP clients without authentication, it may
be necessary to protect it from abuse even on mostly
trusted networks. An HTTP proxy may be used to impose
URL- or client- or usage- or authentication-dependent fil‐
ters.
HTTPS Since stap-exporter speaks only plain HTTP, an HTTP proxy
may be used to support HTTPS secure protocols.
stap(1), stapprobes(3stap), stappaths(7) tapset::prometheus(7)
Use the Bugzilla link of the project web page or our mailing
list. http://sourceware.org/systemtap/ ,
<[email protected]>.
error::reporting(7stap),
https://sourceware.org/systemtap/wiki/HowToReportBugs
This page is part of the systemtap (a tracing and live-system
analysis tool) project. Information about the project can be
found at ⟨https://sourceware.org/systemtap/⟩. If you have a bug
report for this manual page, send it to [email protected].
This page was obtained from the project's upstream Git repository
⟨git://sourceware.org/git/systemtap.git⟩ on 2024-06-14. (At that
time, the date of the most recent commit that was found in the
repository was 2024-06-13.) 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
[email protected]
STAP-EXPORTER(8)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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