stap-exporter(8) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | OPERATION | EXAMPLE | SAFETY AND SECURITY | SEE ALSO | BUGS | COLOPHON

STAP-EXPORTER(8)         System Manager's Manual        STAP-EXPORTER(8)

NAME         top

       stap-exporter - systemtap-prometheus interoperation mechanism

SYNOPSIS         top

       stap-exporter [ OPTIONS ]

DESCRIPTION         top

       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.

OPTIONS         top

       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.

OPERATION         top

       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.

EXAMPLE         top

       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
       privileges, then after a brief delay, use any web client to fetch
       data:

              # 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
       directory, to collect this data into a monitoring system.

SAFETY AND SECURITY         top

       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
              administrator 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
              filters.

       HTTPS  Since stap-exporter speaks only plain HTTP, an HTTP proxy
              may be used to support HTTPS secure protocols.

SEE ALSO         top

       stap(1), stapprobes(3stap), stappaths(7) tapset::prometheus(7)

BUGS         top

       Use the Bugzilla link of the project web page or our mailing
       list.  http://sourceware.org/systemtap/ ,
       <systemtap@sourceware.org>.

       error::reporting(7stap),
       https://sourceware.org/systemtap/wiki/HowToReportBugs 

COLOPHON         top

       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 systemtap@sourceware.org.
       This page was obtained from the project's upstream Git repository
       ⟨git://sourceware.org/git/systemtap.git⟩ on 2021-08-27.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2021-08-26.)  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

                                                        STAP-EXPORTER(8)