STAP-SERVER(8) System Manager's Manual STAP-SERVER(8)
stap-server - systemtap compile server management
[ service ] stap-server { start | stop | restart | condrestart |
try-restart | force-reload | status } [ options ]
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.
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.
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 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.
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
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
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.
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
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.
Important files and their corresponding paths can be located in
the
stappaths (7) manual page.
stap(1),
staprun(8),
stapprobes(3stap),
stappaths(7),
stapex(3stap),
avahi,
ulimit(1),
NSS
Use the Bugzilla link of the project web page or our mailing
list. http://sourceware.org/systemtap/ ,
<systemtap@sourceware.org>.
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 2022-12-17. (At that
time, the date of the most recent commit that was found in the
repository was 2022-12-16.) 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)
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