NAME

clsync - live sync tool, written in GNU C

SYNOPSIS

clsync [ ... ]

DESCRIPTION

clsync executes sync-handler with appropriate arguments on FS events in directory watch-dir using the inotify(7) Linux kernel subsystem.

Extended regex-rules to filter what files and directories to sync may be placed in rules-file

OPTIONS

This options can be passed as arguments or to be used in the configuration file.

To disable numeric option set to zero:

To disable string option (for example path to file) set to empty string:

Also you can use previously set values while setting new options. Substring %option_name% will be substituted with previously set value of option option_name. (see CONFIGURATION FILE)

-W, --watch-dir watch-dir

Root directory to be monitored by clsync.

Required.

-S, --sync-handler sync-handler

Path to sync-handler to be used for syncing by clsync. (see --mode)

Required.

-R, --rules-file rules-file

Path to file with filter rules of objects to be monitored. (see RULES)

Is not set by default.

-D, --destination-dir destination-directory

Defines directory to sync to for modes "rsyncdirect", "rsyncso" and "so". (see --mode)

Is not set by default.

-M, --mode mode

Sets syncing mode. Possible values:

simple

calls sync-handler for every event

shell

calls sync-handler for every sync

rsyncdirect

calls rsync by path sync-handler directly (inflexible and unreliable, should be used only as a proof of concept)"

rsyncshell

calls sync-handler that supposed to run rsync for every sync (recommended mode)"

rsyncso

loads shared object by path sync-handler with dlopen(3) and calls function clsyncapi_rsync function for every sync

loads shared object by path sync-handler with dlopen(3) and calls function clsyncapi_sync function for every sync

See SYNC HANDLER MODES

Required.

-b, --background

Daemonize, forcing clsync to fork() on start.

Is not set by default.

-H, --config-file config-file-path

Use configuration from file config-file-path (see CONFIGURATION FILE).

Set to "/NULL/" if no config files should be read.

Is not set by default.

-K, --config-block config-block-name

Use configuration block with name config-block-name (see CONFIGURATION FILE).

Default value is "default".

--config-block-inherits config-parent-block-name

Use configuration block with name config-parent-block-name as parent for config-block-name (see CONFIGURATION FILE). Options from config-parent-block-name will be inherited to config-block-name.

Default value is "default".

-z, --pid-file path-to-pidfile

Writes pid to file by path path-to-pidfile.

Is not set by default.

--status-file status-file-path

Write status description into file with path status-file-path.

Possible statuses:

starting

initializing subsystems and marking file tree with FS monitor subsystem

initsync

processing initial syncing

running

waiting for events or syncing

rehashing

reloading configuration files

thread gc

running threads' garbage collector

terminating

received signal to die, preparing to die

exiting

cleaning up [for valgrind(1)]

Is not set by default.

-u, --uid uid

Drop user privileges to uid uid with setuid(2)

Is not set by default.

-g, --gid gid

Drop group privileges to gid gid with setgid(2)

Is not set by default.

-r, --retries number-of-tries

Tries limit to sync with sync-handler.

clsync will die after number-of-tries tries.

To try infinite set "0".

Delay between tries is equal to --delay-sync value.

Default value is "1".

--ignore-failures

Don't die on sync failures.

Is not set by default.

-p, --threading threading-mode

Use pthreads(7) to parallelize syncing processes. For example if clsync (with --threading=off) is already syncing a huge file then all other syncs will be suspended until the huge file syncing finish. To prevent this suspends you can use "safe" or "full" threading mode.

Possbile values:

off

disable threading for syncing processes.

safe

parallelize syncs but suspend syncings of object that are already syncing in another process (until the process finish).

full

parallelize syncs without suspendings.

Characteristics:

off

New modifications won't be synced until old ones finish.

safe

Theoretically is the best way. But may utilize of lot of CPU if there's a lot of simultaneous parallel syncs. (also this way is not well tested)

full

May cause multiple simultaneous syncing of the same file, which in turn can cause bug inside sync-handler (see below).

If you're running clsync with option --threading=full in conjunction with rsync with option --backup, you may catch a bug due to nonatomicity of rsync's file replace operation. (see DIAGNOSTICS)

Default value is "off".

-Y, --output log-destination

Sets destination for log writing (errors, warnings, infos and debugging).

Possible values:

stderr
stdout
syslog

Default value is "stderr".

--one-file-system

Don't follow to different devices' mount points. This option just adds option "FTS_XDEV" for fts_open(3) function.

Warning! If you're using this option (but no --exclude-mount-points) clsync will write neither includes nor excludes of content of mount points.
This may cause problems e.g. you're using rsync for sync-handler without similar option "--one-file-system".

Is not set by default.

-X, --exclude-mount-points

Forces --one-file-system but also add excludes to do not sync mount points.

This requires to do stat(2) syscalls on every dir and can reduce performance.

Is not set by default.

-c, --cluster-iface interface-ip

Not implemented, yet.

DANGEROUS OPTION. This functionality wasn't tested well. You can lost your data.

Enables inter-node notifing subsystem to prevent sync looping between nodes. This's very useful features that provides ability of birectional sync of the same directory between two or more nodes. interface-ip is an IP-address already assigned to the interface that will be used for multicast notifing.

Not enabled by default.

To find out the IP-address on interface "eth0", you can use for example next command:

ip a s eth0 | awk '{if($1=="inet") {gsub("/.*", "", $2); print $2}}'

Is not set by default.

-m, --cluster-ip multicast-ip

Not implemented yet.

Sets IP-address for multicast group.

This option can be used only in conjunction with --cluster-interface.

Use IP-addresses from 224.0.0.0/4 for this option.

Default value is "227.108.115.121". [(128+"c")."l"."s"."y"]

-P, --cluster-port multicast-port

Not implemented yet.

Sets UDP-port number for multicast messages.

This option can be used only in conjunction with --cluster-interface.

multicast-port should be greater than 0 and less than 65535.

Default value is "40079". [("n" << 8) + "c"]

-W, --cluster-timeout cluster-timeout

Not implemented yet.

Sets timeout (in milliseconds) of waiting answer from another nodes of the cluster. If there's no answer from some node, it will be excluded.

Default value is "1000". [1 second]

-n, --cluster-node-name cluster-node-name

Not implemented yet.

Sets the name of current node in the cluster. It will be used in action scripts of another nodes (see SYNC HANDLER MODES).

Default value is $(uname -n).

-o, --cluster-hash-dl-min hash-dirlevel-min

Sets minimal directory level for ctime hashing (see CLUSTERING).

Default value is "1".

-O, --cluster-hash-dl-max hash-dirlevel-max

Not implemented yet.

Sets maximal directory level for ctime hashing (see CLUSTERING).

Default value is "16".

--cluster-scan-dl-max scan-dirlevel-max

Not implemented yet.

Sets maximal directory level for ctime scanning (see CLUSTERING).

Default value is "32".

--standby-file standby-file-path

Sets file to path that should be checked before every sync. If file exists the sync will be suspended until the file is deleted. It may be useful if you need freeze destination directory while running some scripts.

Is not set by default.

--max-iterations iterations-count

Sets synchronization iterations limit. One iteration means one sync-handler execution.

iterations-count

set to 0 means no limit (infinite loop).

set to 1 means that only initial sync will be done

set to n means that only initial sync and (n-1) sync-ups after that will be done

Hint: This option may be useful in conjunction with --exit-on-no-events to prevent infinite sync-up processes.

Default value is "0".

-k, --timeout-sync sync-timeout

Sets timeout for syncing processes. clsync will die if syncing process alive more than sync-timeout seconds.

Set "0" to disable the timeout.

Default value is "86400" ["24 hours"].

-w, --delay-sync additional-delay

Sets the minimal delay (in seconds) between syncs.

Default value is "30".

-t, --delay-collect ordinary-delay

Sets the delay (in seconds) to collect events about ordinary files and directories.

Default value is "30".

-T, --delay-collect-bigfile bigfiles-delay

Sets the delay (in seconds) to collect events about "big files" (see --threshold-bigfile).

Default value is "1800".

-B, --threshold-bigfile filesize-threshold

Sets file size threshold (in bytes) that separates ordinary files from "big files". Events about "big files" are processed in another queue with a separate collecting delay. This is supposed to be used as a means of unloading IO resources.

Default value is "134217728" ["128 MiB"].

-L, --lists-dir tmpdir-path

Sets directory path to output temporary events-lists files.

If this option is enabled, clsync will execute sync-handler once for each aggregated event list, passing the path to a file containing this list (actions "synclist" and "rsynclist"). Otherwise, clsync will execute sync-handler for every file in the aggregated event list (action "sync").

Cannot be used in mode "so".

See SYNC HANDLER MODES.

Is not set by default.

--have-recursive-sync

Use action "recursivesync" instead of "synclist" for directories that were just marked (see SYNC HANDLER MODES case shell).

Is not set by default.

--synclist-simplify

Removes the first 3 parameters in list files of action "synclist" (see SYNC HANDLER MODES case shell).

Is not set by default.

-A, --auto-add-rules-w

Forces clsync to create a "w-rule" for every non-"w-rule" (see RULES).

Not recommended to use in modes "rsyncdirect", "rsyncshell" and "rsyncso"

Is not set by default.

--rsync-inclimit rsync-includes-line-limit

Sets soft limit for lines count in files by path rsync-listpath. Unfortunately, rsync works very slowly with huge "--include-from" files. So, clsync splits that list with approximately rsync-includes-line-limit lines per list if it's too big, and executes by one rsync instance per list part. Use value "0" to disable the limit.

Default value is "20000".

--rsync-prefer-include

Forces clsync to prefer a "lot of includes" method instead of a "excludes+includes" for rsync on recursive syncing.

See cases rsyncshell, rsyncdirect and rsyncso of SYNC HANDLER MODES.

This option is not recommended.

Is not set by default.

-x, --ignore-exitcode exitcode

Forces clsync to do not process exitcode exitcode of sync-handler as an error. You can set multiple ignores by passing this option multiple times.

Recommended values for rsync case is "24". You can set multiple values with listing a lot of "-x" options (e.g. "-x 23 -x 24") or via commas (e.g. "-x 23,24"). To drop the list use zero exitcode (e.g. "-x 0"). For example you can use "-x 0,23" to drop the list and set "23"-th exitcode to be ignored.

Is not set by default (or equally is set to "0").

-U, --dont-unlink-lists

Do not delete list-files after sync-handler has finished.

This may be used for debugging purposes.

Is not set by default.

-F, --full-initialsync

Ignore filter rules from rules-file on initial sync.

This may be useful for quick start or e.g. if it's required to sync "/var/log/" tree but not sync every change from there.

Is not set by default.

--only-initialsync

Exit after initial syncing on clsync start.

Is not set by default.

--exit-on-no-events

Exit if there's no events. Works like --only-initialsync, but also syncs events collected while the initial syncing.

Unlike --only-initialsync this option uses FS monitor subsystem to monitor for new events while the initial syncing. This may reduce performance. On the other hand this way may be used to be sure, that everything is synced at the moment before clsync will exit.

Is not set by default.

--skip-initialsync

Skip initial syncing on clsync start.

Is not set by default.

--exit-hook path-of-exit-hook-program

Sets path of program to be executed on clsync exit.

If this parameter is set, clsync will exec on exit:

path-of-exit-hook-program label

The execution will be skipped if syncing process wasn't started.

Is not set by default.

-v, --verbose

This option is supposed to increase verbosity. But at the moment there's no "verbose output" in the code, so the option does nothing. :)

Is not set by default.

-d, --debug

Increases debugging output. This may be supplied multiple times for more debugging information, up to a maximum of five "d" flags (more will do nothing), for example "-d -d -d -d -d" or "-d5" (equivalent cases)

Is not set by default.

--dump-dir

Directory to write clsync's instance information by signal 29 (see SIGNALS). The directory shouldn't exists before dumping.

Is set to "/tmp/clsync-dump-%label%" by default.

-q, --quiet

Suppresses error messages.

Is not set by default.

--monitor monitor-subsystem

Switches FS monitor subsystem.

Possible values:

inotify

inotify(7) [Linux]

Native, fast, reliable and well tested Linux FS monitor subsystem.

There's no performance profit to use "inotify" instead of "kevent" on FreeBSD using "libinotify". It backends to "kevent" anyway. However inotify support is well tested and may be useful even via "libinotify".

kqueue

kqueue(2) [FreeBSD]

A *BSD kernel event notification mechanism (inc. timer, sockets, files etc).

This monitor subsystem that cannot determine file creation event, but it can determine a directory where something happened. So clsync is have to rescan whole dir every time on any content change.

Also this API requires to open every monitored file and directory. So it may produce a huge amount of file descriptors. Be sure that kern.maxfiles is big enough (in FreeBSD).

CPU/HDD expensive way.

Not well tested. Use with caution!

FreeBSD users: notify me about found bugs or performance issues, please. And before the bugfix you can switch to "inotify" through libinotify or to "bsm".

bsm

bsm(3) [FreeBSD]

Basic Security Module (BSM) Audit API.

This is not a FS monitor subsystem, actually. It's just an API to access to audit information (inc. logs). clsync can setup audit to watch FS events and report it into log. After that clsync will just parse the log via auditpipe(4) [FreeBSD].

Reliable, but hacky way. It requires global audit reconfiguration that may hopple audit analysis.

Not well tested. Use with caution! Also file /etc/security/audit_control will be overwritten with:

#clsync

dir:/var/audit
flags:fc,fd,fw,fm,cl
minfree:0
naflags:fc,fd,fw,fm,cl
policy:cnt
filesz:1M

dtracepipe

dtrace(1) [FreeBSD]

clsync will run dtrace with special script (on "d") using popen(3) and parse it's output.

IMHO, this way is the best for FreeBSD.

The default value on Linux is "inotify".
The default value on FreeBSD is "kqueue".

-l, --label label

Sets a label for this instance of clsync. The label will be passed to sync-handler every execution.

Default value is "nolabel".

-h, --help

Outputs options list and exits with exitcode "0".

Is not set by default.

-V, --version

Outputs clsync version and exits with exitcode "0".

Is not set by default.

SYNC HANDLER MODES

clsync executes sync-handler that supposed to take care of the actual syncing process. Therefore clsync is only a convenient way to run a syncing script.

clsync can run sync-handler in six ways. Which way will be used depends on specified mode (see --mode)

case simple

Executes for every syncing file/dir:
sync-handler sync label evmask path [nodes]

In this case, sync-handler is supposed to non-recursively sync file or directory by path. With evmask it's passed bitmask of events with the file or directory (see "/usr/include/linux/inotify.h").

Not recommended. Not well tested.

case shell

Executes for every sync (if recursivesync is not used instead):
sync-handler synclist label listpath [nodes]

Executes for initial syncs if option --have-recursive-sync is set:
sync-handler recursivesync label dirpath [nodes]

In this case, sync-handler is supposed to non-recursively sync files and directories from list in a file by path listpath (see below). With evmask it's passed bitmask of events with the file or directory (see "/usr/include/linux/inotify.h").

Also sync-handler is supposed to recursively sync data from directory by path dirpath with manual excluding extra files.

Not recommended. Not well tested.

case rsyncdirect

Executes for every sync:
sync-handler --inplace -aH --delete-before [--exclude-from rsync-exclude-listpath ] --include-from rsync-listpath --exclude '*' watch-dir/ dest-dir/

In this case, sync-handler is supposed to be a path to rsync binary.

Error code "24" from sync-handler will be ignored in this case.

This case is supposed to be used only as a proof of concept.

case rsyncshell

Executes for every sync:
sync-handler rsynclist label rsync-listpath [nodes] [rsync-exclude-listpath]

In this case, sync-handler is supposed to run "rsync" application with parameters:

-aH --delete-before --include-from rsync-listpath --exclude '*'

if option --rsync-prefer-include is enabled.

And with parameters:

-aH --delete-before --exclude-from rsync-exclude-listpath --include-from rsync-listpath --exclude '*'

if option --rsync-prefer-include is disabled.

Recommended case.

case rsyncso

In this case there's no direct exec*() calling. In this case clsync loads sync-handler as a shared library with dlopen(3) and calls function "int clsyncapi_rsync(const char *inclist, const char *exclist)" from it for every sync.
inclist is a path to file with rules for "--include-from" option of rsync. This argument is always not NULL.
exclist is a path to file with rules for "--exclude-from" option of rsync. This argument is NULL if --rsync-prefer-include is set.
Excludes takes precedence over includes.

Also may be defined functions "int clsyncapi_init(ctx_t *, indexes_t *)" and "int clsyncapi_deinit()" to initialize and deinitialize the syncing process by this shared object.

To fork the process should be used function "pid_t clsyncapi_fork(ctx_t *)" instead of "pid_t fork()" to make clsync be able to kill the child.

See example file "clsync-synchandler-rsyncso.c".

Recommended case. IMHO, this way is the best.

case so

In this case there's no direct exec*() calling. In this case clsync loads sync-handler as a shared library with dlopen(3) and calls function "int clsyncapi_sync(int n, api_eventinfo_t *ei)" from it for every sync. n is number of elements of ei. ei is an array of structures with information about what and how to sync (see below).

api_eventinfo_t is a structure:

struct api_eventinfo { uint32_t evmask; // event bitmask for file/dir by path path. uint32_t flags; // flags of "how to sync" the file/dir size_t path_len; // strlen(path) const char *path; // the path to file/dir need to be synced eventobjtype_t objtype_old; // type of object by path path before the event. eventobjtype_t objtype_new; // type of object by path path after the event.
};
typedef struct api_eventinfo api_eventinfo_t;

The event bitmask (evmask) values can be learned from "/usr/include/linux/inotify.h".

There may be next flags' values (flags):

enum eventinfo_flags { EVIF_NONE = 0x00000000, // No modifier EVIF_RECURSIVELY = 0x00000001 // sync the file/dir recursively
};

Flag "EVIF_RECURSIVELY" may be used if option --have-recursive-sync is set.

Is that a file or directory by path path can be determined with objtype_old and objtype_new.
objtype_old reports about which type was the object by the path before the event.
objtype_new reports about which type became the object by the path after the event.

objtype_old and objtype_new have type eventobjtype_t.

enum eventobjtype { EOT_UNKNOWN = 0, // Unknown EOT_DOESNTEXIST = 1, // Doesn't exist (not created yet or already deleted) EOT_FILE = 2, // File EOT_DIR = 3, // Directory
} typedef enum eventobjtype eventobjtype_t;

Also may be defined functions "int clsyncapi_init(options_t *, indexes_t *)" and "int clsyncapi_deinit()" to initialize and deinitialize the syncing process by this shared object.

To fork the process should be used function "pid_t clsyncapi_fork(options_t *)" instead of "pid_t fork()" to make clsync be able to kill the child.

See example file "clsync-synchandler-so.c".

Recommended case.

About the label see --label.
nodes is comma-separated list of cluster nodes names where to sync to (see --cluster-node-name)

The listfile by path listpath contains lines separated by NL (without CR) of next format:

sync label evmask path

if option --synclist-simplify is not set

path

if option --synclist-simplify is set

Every lines is supposed to be proceed by external syncer to sync file or directory by path path. With evmask it's passed bitmask of events with the file or directory (see "/usr/include/linux/inotify.h").

ENVIRONMENT VARIABLES

Output variables - variables that are set by clsync before calling sync-handler.

Output variables

CLSYNC_STATUS - clsync's status (see possible statuses in description of --status-file)

CLSYNC_ITERATION - count of done synchronizaton iterations after initial sync see --max-iterations option

RULES

Filter riles can be placed into rules-file with one rule per line.

Rule format: [+-][fdw*]regexp

+ - means include; - - means exclude; f - means file; d - means directory; w - means walking to directory; * - means all.

For example: -*^/[Tt]est

It's not recommended to use w rules in modes "rsyncdirect", "rsyncshell" and "rsyncso". rsync(1) allows one to set syncing and walking only together in "--include" rules ("--files-from" is not appropriate due to problem with syncing files deletions). So there may be problems with clsync's w rules in this cases.

More examples:

Syncing pwdb files and sshd_config (non-rsync case):

+f^/passwd$
+f^/group$
+f^/shadow$
+f^/ssh/sshd_config$
+w^$
+w^/ssh$
-*

Syncing pwdb files and sshd_config (non-rsync case with option --auto-add-rules-w):

+f^/passwd$
+f^/group$
+f^/shadow$
+f^/ssh/sshd_config$
-*

Syncing pwdb files and sshd_config (rsync case):

+f^/passwd$
+f^/group$
+f^/shadow$
+f^/ssh/sshd_config$
+d^$
+d^/ssh$
-*

Syncing /srv/lxc tree (rsync case):

-d/sess(ion)?s?$
-f/tmp/
+*

SIGNALS

1 - to reread filter rules

10 - runs threads' GC function

12 - runs full resync

16 - interrupts sleep()/select() and wait() [for debugging and internal uses]

29 - dump information to dump-dir [for debugging]

DIAGNOSTICS

Initial rsync process works very slow on clsync start

Probably there's too huge exclude list is passed to rsync. This can happened if you're excluding with regex in clsync's rules a lot of thousands files. They will be passed to rsync's exclude list one by one.

To diagnose it, you can use "-U" option and look into rsync-exclude-listpath file (see SYNC HANDLER case d)

To prevent this, it's recommended to write such rules for rsync directly (not via clsync).

For example, often problem is with PHP's session files. You shouldn't exclude them in clsync's rules with "-f/sess_.*", but you should exclude it in rsync directly (e.g with «--exclude "sess_*"»).

The following diagnostics may be issued on stderr:

Error: Cannot inotify_add_watch() on [...]: No space left on device (errno: 28)

Not enough inotify watching descriptors is allowed. It can be fixed by increasing value of "sysctl fs.inotify.max_user_watches"

Error: Got non-zero exitcode exitcode [...]

sync-handler returned non-zero exitcode. Probably, you should process exitcodes in it or your syncer process didn't worked well. I case of using rsync, you can find the exitcodes meanings in man 1 rsync.

If exitcode equals to 23 and you're using clsync in conjunction with rsync, this may happend, for example in next cases:

- Not enough space on destination.

- You're running clsync with --threading and rsync with --backup. See bugreport by URL: https://bugzilla.samba.org/show_bug.cgi?id=10081.

To confirm the problem, you can try to add "return 0" or "exit 0" into your sync-handler.

To get support see SUPPORT.

CONFIGURATION FILE

clsync supports configuration file.

By default clsync tries to read next files (in specified order):

~/.clsync.conf
/etc/clsync/clsync.conf

This may be overrided with option --config-file.

clsync reads only one configuration file. In other words, if option --config-file is not set and file ~/.clsync.conf is accessible and parsable, clsync will not try to open /etc/clsync/clsync.conf. Command line options have precedence over config file options.

Configuration file is parsed with glib's g_key_file_* API. That means, that config should consits from groups (blocks) of key-value lines as in the example:

[default]
background = 1
mode = rsyncshell
debug = 0
output = syslog
label = default
pid-file = /var/run/clsync-%label%.pid

[debug]
config-block-inherits = default
debug = 5
background = 0
output = stderr

[test]
mode=rsyncdirect
debug=3

Also glib's gkf API doesn't support multiple assignments. If you need to list some values (e.g. exitcodes) just list them with commas in single assignment (e.g. "ignore-exitcode=23,24").

In this example there're 3 blocks are set - "default", "debug" and "test". And block "debug" inherited setup of block "default" except options "debug", "background" and "output".

By default clsync uses block with name "default". Block name can be set by option --config-block.

CLUSTERING

Not implemented yet. Don't try to use cluster functionality.

Not described yet.

EXAMPLES

Working examples you can try out in "/usr/share/doc/clsync/examples/" directory. Copy this directory somewhere (e.g. into "/tmp"). And try to run "clsync-start-rsync.sh" in there. Any files/directories modifications in "testdir/from" will be synced to "testdir/to" with few seconds delay.

AUTHOR

Dmitry Yu Okunev <dyokunev@ut.mephi.ru> 0x8E30679C

SUPPORT

You can get support on official IRC-channel in Freenode "#clsync" or on github's issue tracking system of repository "https://github.com/xaionaro/clsync".

Don't be afraid to ask about clsync configuration, ;).