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 de‐
       fault 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 2017-05-03.  If you dis‐
       cover 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)

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