stap-server(8) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | ARGUMENTS | OPTIONS | CONFIGURATION | Global Configuration | Individual Server Configuration | SERVER AUTHENTICATION | EXAMPLES | SAFETY AND SECURITY | FILES | SEE ALSO | BUGS | COLOPHON

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

NAME         top

       stap-server - systemtap compile server management

SYNOPSIS         top

       [ service ] stap-server { start | stop | restart | condrestart |
       try-restart | force-reload | status } [ options ]

DESCRIPTION         top

       A systemtap compile server listens for connections from stap
       clients on a secure SSL network port and accepts requests to run
       the stap front end. Each server advertises its presence and
       configuration on the local network using mDNS (avahi) allowing
       for automatic detection by clients.

       The stap-server script aims to provide:

       •   management of systemtap compile servers as a service.

       •   convenient control over configured servers and individual
           (ad-hoc) servers.

ARGUMENTS         top

       One of the actions below must be specified:

       start  Start servers. The specified servers are started.  If no
              server is specified, the configured servers are started.
              If no servers are configured, a server for the kernel
              release and architecture of the host is started.  If a
              specified server is already started, this action will be
              ignored for that server. If a server fails to start, this
              action fails.

       stop   Stop server(s). The specified servers are stopped.  If no
              server is specified, all currently running servers are
              stopped.  If a specified server is not running, this
              action will be successful for that server. If a server
              fails to stop, this action fails.

       restart
              Stop and restart servers. The specified servers are
              stopped and restarted.  If no server is specified, all
              currently running servers are stopped and restarted. If no
              servers are running, this action behaves like start.

       condrestart
              Stop and restart servers. The specified servers are
              stopped and restarted.  If a specified server is not
              running, it is not started. If no server is specified, all
              currently running servers are stopped and restarted.  If
              no servers are running, none will be started.

       try-restart
              This action is identical to condrestart.

       force-reload
              Stop all running servers, reload config files and restart
              the service as if start was specified.

       status Print information about running servers. Information about
              the specified server(s) will be printed. If no server is
              specified, information about all running servers will be
              printed.

OPTIONS         top

       The following options are used to provide additional
       configuration and to specify servers to be managed:

       -c configfile
              This option specifies a global configuration file in
              addition to the default global configuration file
              described below. This file will be processed after the
              default global configuration file. If the -c option is
              specified more than once, the last configuration file
              specified will be used.

       -a architecture
              This option specifies the target architecture of the
              server and is analogous to the -a option of stap. See the
              stap(1) manual page for more details.  The default
              architecture is the architecture of the host.

       -r kernel-release
              This option specifies a target kernel release of the
              server and is analogous to the -r option of stap.  See the
              stap(1) manual page for more details.  The default release
              is that of the currently running kernel.  A server can
              handle multiple releases by specifying multiple -r flags.

       -I path
              This option specifies an additional path to be searched by
              the server(s) for tapsets and is analogous to the -I
              option of stap.  See the stap(1) manual page for more
              details.

       -R path
              This option specifies the location of the systemtap
              runtime to be used by the server(s) and is analogous to
              the -R option of stap.  See the stap(1) manual page for
              more details.

       -B options
              This option specifies options to be passed to make when
              building systemtap modules and is analogous to the -B
              option of stap.  See the stap(1) manual page for more
              details.

       -i     This option is a shortcut which specifies a server that
              handles every release installed in /lib/modules/.

       -n nickname
              This option allows the specification of a server
              configuration by nickname.  When -n is specified, a
              currently running server with the given nickname will be
              searched for. If no currently running server with the
              given nickname is found, a server configuration with the
              given nickname will be searched for in the configuration
              files for default servers, or the path configured in the
              global configuration file or the configuration file
              specified by the -c option. If a server configuration for
              the given nickname is found, the -a, -r, -I, -R, -B and -u
              options for that server will be used as if they were
              specified on the command line. If no configuration with
              the given nickname is found, and the action is start (or
              an action behaving like start (see ARGUMENTS), the server
              will be started with the given nickname.  If no
              configuration with the given nickname is found, and the
              action is not start (or an action behaving like start), it
              is an error. If a nickname is not specified for a server
              which is being started, its nickname will be its process
              id.

       -p pid This option allows the specification of a server
              configuration by process id.  When -p is specified, a
              currently running server with the given process id will be
              searched for. If no such server is found, it is an error.
              If a server with the given process id is found, the -a,
              -r, -I, -R, -B and -u options for that server will be used
              as if they were specified on the command line.

       -u user-name
              Each systemtap compile server is normally run by the user
              name stap-server (for the initscript) or as the user
              invoking stap-server, unless otherwise configured (see
              FILES). This option specifies the user name used to run
              the server(s). The user name specified must be a member of
              the group stap-server.

       --log logfile
              This option allows the specification of a separate log
              file for each server.  Each --log option is added to a
              list which will be applied, in turn, to each server
              specified. If more servers are specified than --log
              options, the default log file (see FILES) will be used for
              subsequent servers.

       --port port-number
              This option allows the specification of a specific network
              port for each server. Each --port option is added to a
              list which will be applied, in turn, to each server
              specified. If more servers are specified than --port
              options, a randomly selected port is used for subsequent
              servers.

       --ssl certificate-db-path
              This option allows the specification of a separate NSS
              certificate database for each server. Each --ssl option is
              added to a list which will be applied, in turn, to each
              server specified. If more servers are specified than --ssl
              options, the default certificate database (see FILES) for
              subsequent servers.

       --max-threads threads
              This option allows the specification of the maximum number
              of worker threads to handle concurrent requests. If
              threads == 0, each request will be handled on the main
              thread, serially.  The default is the number of available
              processor cores.

       --max-request-size size
              This options allows the specification of the maximum size
              of an uncompressed client request. The arguement size is
              specified in bytes. The default is the 50000 bytes.

       --max-compressed-request size
              This options allows the specification of the maximum size
              of a compressed client request. The arguement size is
              specified in bytes. The default is the 5000 bytes.

CONFIGURATION         top

       Configuration files allow us to:

       •   specify global configuration of logging, server configuration
           files, status files and other global parameters.

       •   specify which servers are to be started by default.

Global Configuration         top

       The Global Configuration file contains variable assignments used
       to configure the overall operation of the service.  Each line
       beginning with a '#' character is ignored. All other lines must
       be of the form VARIABLE=VALUE. This is not a shell script. The
       entire contents of the line after the = will be assigned as-is to
       the variable.

       The following variables may be assigned:

       CONFIG_PATH
              Specifies the absolute path of the directory containing
              the default server configurations.

       STAT_PATH
              Specifies the absolute path of the running server status
              directory.

       LOG_FILE
              Specifies the absolute path of the log file.

       STAP_USER
              Specifies the userid which will be used to run the
              server(s) (default: for the initscript stap-server,
              otherwise the user running stap-server).

       Here is an example of a Global Configuration file:

              CONFIG_PATH=~<user>/my-stap-server-configs
              LOG_FILE=/tmp/stap-server/log

Individual Server Configuration         top

       Each server configuration file configures a server to be started
       when no server is specified for the start action, or an action
       behaving like the start action (see ARGUMENTS). Each
       configuration file contains variable assignments used to
       configure an individual server.

       Each line beginning with a '#' character is ignored. All other
       lines must be of the form VARIABLE=VALUE. This is not a shell
       script. The entire contents of the line after the = will be
       assigned as-is to the variable.

       Each configuration file must have a filename suffix of .conf. See
       stappaths(7) for the default location of these files.  This
       default location can be overridden in the global configuration
       file using the -c option (see OPTIONS).

       The following variables may be assigned:

       ARCH   Specifies the target architecture for this server and
              corresponds to the -a option (see OPTIONS). If ARCH is not
              set, the architecture of the host will be used.

       RELEASE
              Specifies a kernel release for this server and corresponds
              to the -r option (see OPTIONS). If RELEASE is not set, the
              release of the kernel running on the host will be used.

       BUILD  Specifies options to be passed to the make process used by
              systemtap to build kernel modules.  This an array variable
              with each element corresponding to a -B option (see
              OPTIONS). Using the form BUILD=STRING clears the array and
              sets the first element to STRING. Using the form
              BUILD+=STRING adds STRING as an additional element to the
              array.

       INCLUDE
              Specifies a list of directories to be searched by the
              server for tapsets.  This is an array variable with each
              element corresponding to a -I option (see OPTIONS). Using
              the form INCLUDE=PATH clears the array and sets the first
              element to PATH. Using the form INCLUDE+=PATH adds PATH as
              an additional element to the array.

       RUNTIME
              Specifies the directory which contains the systemtap
              runtime code to be used by this server and corresponds to
              the -R option (see OPTIONS).

       USER   Specifies the user name to be used to run this server and
              corresponds to the -u option (see OPTIONS).

       NICKNAME
              Specifies the nickname to be used to refer to this server
              and corresponds to the -n option (see OPTIONS).

       LOG    Specifies the location of the log file to be used by this
              server and corresponds to the --log option (see OPTIONS).

       PORT   Specifies the network port to be used by this server and
              corresponds to the --port option (see OPTIONS).

       SSL    Specifies the location of the NSS certificate database to
              be used by this server and corresponds to the --ssl option
              (see OPTIONS).

       MAXTHREADS
              Specifies the maximum number of worker threads to handle
              concurrent requests to be used by this server and
              corresponds to the --max-threads option (see OPTIONS).

       MAXREQSIZE
              Specifies the maximum size of an uncompressed client
              request, to be used by this server and correspnds to the
              --max-request-size option (see OPTIONS).

       MAXCOMPRESSEDREQ
              Specifies the maximum size of an compressed client
              request, to be used by this server and correspnds to the
              --max-compressed-request option (see OPTIONS).

       Here is an example of a server configuration file:

              ARCH=
              USER=
              RELEASE=
              NICKNAME=native

       By keeping the ARCH, USER, and RELEASE fields blank, they will
       default to the current arch and release and use the default user.

       A more specific example:

              ARCH=i386
              RELEASE=2.6.18-128.el5
              PORT=5001
              LOG=/path/to/log/file

       And here is a more complicated example:

              USER=serveruser
              RELEASE=/kernels/2.6.18-92.1.18.el5/build
              INCLUDE=/mytapsets
              INCLUDE+=/yourtapsets
              BUILD='VARIABLE1=VALUE1 VARIABLE2=VALUE2'
              DEFINE=STP_MAXMEMORY=1024
              DEFINE+=DEBUG_TRANS
              RUNTIME=/myruntime
              NICKNAME=my-server
              SSL=/path/to/NSS/certificate/database

SERVER AUTHENTICATION         top

       The security of the SSL network connection between the client and
       server depends on the proper management of server certificates.

       The trustworthiness of a given systemtap compile server can not
       be determined automatically without a trusted certificate
       authority issuing systemtap compile server certificates. This is
       not practical in everyday use and so, clients must authenticate
       servers against their own database of trusted server
       certificates. In this context, establishing a given server as
       trusted by a given client means adding that server's certificate
       to the client's database of trusted servers.

       For the stap-server initscript, on the local host, this is
       handled automatically.  When the systemtap-server package is
       installed, the server's certificate for the default user
       (stap-server) is automatically generated and installed. This
       means that servers started by the stap-server initscript, with
       the default user, are automatically trusted by clients on the
       local host, both as an SSL peer and as a systemtap module signer.

       Furthermore, when stap is invoked by an unprivileged user (not
       root, not a member of the group stapdev, but a member of the
       group stapusr and possibly the group stapsys), the options
       --use-server and --privilege are automatically added to the
       specified options.  This means that unprivileged users on the
       local host can use a server on the local host in unprivileged
       mode with no further setup or options required. Normal users
       (those in none of the SystemTap groups) can also use compile-
       servers through the --use-server and --privilege options. But
       they will of course be unable to load the module (the -p4 option
       can be used to stop short of loading).

       In order to use a server running on another host, that server's
       certificate must be installed on the client's host.  See the
       --trust-servers option in the stap(1) manual page for more
       details and README.unprivileged in the systemtap sources for more
       details.

EXAMPLES         top

       See the stapex(3stap) manual page for a collection of sample
       systemtap scripts.

       To start the configured servers, or the default server, if none
       are configured:

        $ [ service ] stap-server start

       To start a server that handles all kernel versions installed in
       /lib/modules:

        $ [ service ] stap-server start -i

       To obtain information about the running server(s):

        $ [ service ] stap-server status

       To start a server like another one, except targeting a different
       architecture, by referencing the first server's nickname:

        $ [ service ] stap-server start -n NICKNAME -a ARCH

       To start a server for a kernel release not installed (cross-
       compiling)

        $ [ service ] stap-server start -a ARCH -r /BUILDDIR

       To stop one of the servers by referencing its process id
       (obtained by running stap-server status):

        $ [ service ] stap-server stop -p PID

       To run a script using a compile server:

        $ stap SCRIPT --use-server

       To run a script as an unprivileged user using a compile server:

        $ stap SCRIPT

       To stop all running servers:

        $ [ service ] stap-server stop

       To restart servers after a global configuration change and/or
       when default servers have been added, changed, or removed:

        $ [ service ] stap-server force-reload

SAFETY AND SECURITY         top

       Systemtap is an administrative tool.  It exposes kernel internal
       data structures and potentially private user information.  See
       the stap(1) manual page for additional information on safety and
       security.

       As a network server, stap-server should be activated with care in
       order to limit the potential effects of bugs or mischevious
       users.  Consider the following prophylactic measures.

       1      Run stap-server as an unprivileged user, never as root.

              When invoked as a service (i.e. service stap-server ...),
              each server is run, by default, as the user stap-server.
              When invoked directly (i.e. stap-server ...), each server
              is run, by default, as the invoking user. In each case,
              another user may be selected by using the -u option on
              invocation, by specifying STAP_USER=username in the global
              configuration file or by specifying USER=username in an
              individual server configuration file. The invoking user
              must have authority to run processes as another user.  See
              CONFIGURATION.

              The selected user must have write access to the server log
              file.  The location of the server log file may be changed
              by setting LOG_FILE=path in the global configuration file.
              See CONFIGURATION.

              The selected user must have read/write access to the
              directory containing the server status files.  The
              location of the server status files may be changed by
              setting STAT_PATH=path in the global configuration file.
              See CONFIGURATION.

              The selected user must have read/write access to the
              uprobes.ko build directory and its files.

              Neither form of stap-server will run if the selected user
              is root.

       2      Run stap-server requests with resource limits that impose
              maximum cpu time, file size, memory consumption, in order
              to bound the effects of processing excessively large or
              bogus inputs.

              When the user running the server is stap-server, each
              server request is run with limits specified in ~stap-
              server/.systemtap/rc otherwise, no limits are imposed.

       3      Run stap-server with a TMPDIR environment variable that
              points to a separate and/or quota-enforced directory, in
              order to prevent filling up of important filesystems.

              The default TMPDIR is /tmp/.

       4      Activate network firewalls to limit stap client
              connections to relatively trustworthy networks.

              For automatic selection of servers by clients, avahi must
              be installed on both the server and client hosts and mDNS
              messages must be allowed through the firewall.

       The systemtap compile server and its related utilities use the
       Secure Socket Layer (SSL) as implemented by Network Security
       Services (NSS) for network security. NSS is also used for the
       generation and management of certificates. The related
       certificate databases must be protected in order to maintain the
       security of the system.  Use of the utilities provided will help
       to ensure that the proper protection is maintained. The systemtap
       client will check for proper access permissions before making use
       of any certificate database.

FILES         top

       Important files and their corresponding paths can be located in
       the
              stappaths (7) manual page.

SEE ALSO         top

       stap(1),
       staprun(8),
       stapprobes(3stap),
       stappaths(7),
       stapex(3stap),
       avahi,
       ulimit(1),
       NSS

BUGS         top

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

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 2021-06-20.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2021-06-18.)  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-SERVER(8)

Pages that refer to this page: stap(1)stap-merge(1)stappaths(7)warning::debuginfo(7stap)stapdyn(8)staprun(8)