Config Layer 4: Default Config

You can simply choose from a set of three default implementations which are: rsync, rsyncssh and direct.

To sync a local directory using the default rsync behavior, just add this to a config file:

sync {
   default.rsync,
   source = "DIRNAME",
   target = "DIRNAME"
}

The order of the arguments is of no importance. If target is a local directory, take care that it is an absolute pathname. You can add multiple syncs that way. The source directories may be identical or differ without problems. source is an universal parameter that must be given for every sync. All other sync parameters can differ depending on the behavior selected. Optionally you can override the default or settings values maxDelays or maxProcesses per Sync.

One can also skip the initial rsync process by setting the default init function to false:

sync {
    default.rsync,
    source = "DIRNAME",
    target = "DIRNAME",
    init   = false
}

This is an optimization which can be dangerous; so, please use it only if you are sure that source and target are synchronized when Lsyncd is started.

The default behaviors you can select from are following:

Shared Settings

Following settings are shared between all defaults:

default.rsync

The default rsync configuration will aggregate events up to delay seconds or 1000 separate uncollapsible events, which ever happens first. Then it will spawn one Rsync with a filter of all files that changed. The filter list is transmitted to Rsync trough a pipe. A call from Lsyncd to Rsync will thus look like this:

/usr/bin/rsync -ltsd --delete --include-from=- --exclude=* SOURCE TARGET

You can change the options Rsync is called and the Rsync binary that is call with the rsync parameter.

Example:

sync {
    default.rsync,
    source    = "/home/user/src/",
    target    = "foohost.com:~/trg/",
    delay     = 15,
    rsync     = {
        binary   = "/usr/local/bin/rsync",
        archive  = true,
        compress = true
    }
}

Additional settings: | Name | Description | |—————–|————-| | batchSizeLimit | Files larger then this limit should not be batched into on transfer. Only makes sense with processes > 1 which prevents rsyncssh |

Below is a table of options for the rsync parameter. Please have a look at the Rsync documentation for an in depth explanation.

default.rsyncssh

This configuration differs from the standard rsync configuration in that it uses ssh commands to move files or directories locally at the target host instead of deleting and transferring again. This configuration does spawn Rsync processes like default.rsync but additionally will spawn /usr/bin/ssh HOST mv ORIGIN DESTINATION commands.

Different to default.rsync it does not take an uniform target parameter, but needs host and targetdir separated.

Rsync’s options can be changed with the rsync parameter like in default.rsync described above.

Additional to that ssh can be configured via the ssh parameter.

Example:

settings {
    logfile = "/var/log/lsyncd.log",
    statusFile = "/var/log/lsyncd-status.log",
    statusInterval = 20
}

sync {
   default.rsyncssh,
   source="/srcdir",
   host="remotehost",
   excludeFrom="/etc/lsyncd.exclude",
   targetdir="/dstdir",
   rsync = {
     archive = true,
     compress = false,
     whole_file = false
   },
   ssh = {
     port = 1234
   }
}

Please note the comma between the rsync parameter set and the ssh parameter set.

Caution If you are upgrading from 2.0.x, please notice that settings became a function from a variable, so you MUST delete the equal sign ‘=’ between settings and the {.

Lsyncd will call xargs on the remote host to handle multiple tasks in a single connection. Xargs options can be specified by the xargs parameter.

Example:

sync {
    default.rsyncssh,
    source    = "/home/user/src/",
    host      = "foohost.com",
    targetdir = "~/trg/",
}

default.direct

Default.direct can be used to keep two local directories in sync with better performance than using default.rsync. Default.direct uses (just like default.rsync) rsync on startup to initially synchronize the target directory with the source directory. However, during normal operation default.direct uses /bin/cp, /bin/rm and /bin/mv to keep the synchronization. All parameters are just like default.rsync.

Example:

sync {
    default.direct,
    source  = "/home/user/src/",
    target  = "/home/user/trg/"
}

Exclusions

Two additional parameters can be specified to sync{}:

Exclusion rules are modeled after rsync’s exclusion patterns but are a bit simpler. Lsyncd supports these features:

• Generally if any segment of the pathname (see below Layer 3) of an event matches the text, it is excluded. E.g. the file “/bin/foo/bar” matches the rule “foo”.
• If the rule starts with a slash, it will only be matched at the beginning of the pathname
• If the rule ends with a slash, it will only be matched at the end of a pathname
• ? matches any character that is not a slash.
• * matches zero or more characters that are not a slash
• ** matches zero or more characters, this can be slashes.

Example:

sync {
    default.rsync,
    source    = "/home/user/src/",
    targetdir = "/home/user/dst/",
    exclude = { '_.bak' , '_.tmp' }
}

Deletions

By default Lsyncd will delete files on the target that are not present at the source since this is a fundamental part of the idea of keeping the target in sync with the source. However, many users requested exceptions for this, for various reasons, so all default implementations take delete as an additional parameter.

Valid values for delete are:

Tunnels

New in: 2.3.0

Lsyncd is able to start and manage external programs to provide a tunnel for data transfer. Additionally it can spawn multiple connections and load-balance connections among them. A tunnel is created through the tunnel function.

<figure class="highlight"><pre><code class="language-lua" data-lang="lua"><span class="n">sync</span> <span class="p">{</span>
    <span class="n">default</span><span class="p">.</span><span class="n">rsync</span><span class="p">,</span>
    <span class="n">tunnel</span>    <span class="o">=</span> <span class="n">tunnel</span> <span class="p">{</span>
        <span class="n">command</span> <span class="o">=</span> <span class="p">{</span><span class="s2">"ssh"</span><span class="p">,</span> <span class="s2">"-N"</span><span class="p">,</span> <span class="s2">"-L"</span><span class="p">,</span> <span class="s2">"localhost:5432:localhost:873"</span><span class="p">,</span> <span class="s2">"tunnel@testmachine"</span><span class="p">},</span>
    <span class="p">}</span>
    <span class="n">target</span>    <span class="o">=</span> <span class="s2">"rsync://localhost:5432/projects"</span><span class="p">,</span>
    <span class="n">source</span>    <span class="o">=</span> <span class="s2">"/home/user/src/"</span><span class="p">,</span>
<span class="p">}</span></code></pre></figure>

You can then set the shell for the tunnel user to /bin/false and configure the rsyncd server side appropriately.

Valid arguments for tunnel are:

Pool Mode

In pool mode, lsyncd allocates a new local port which is then passed as variable to the host command. All variables can be substituded by ^variable syntax. See ../../../../examples/lrsyncssh-tunnel.lua for a extended configuration.

List of variables

Example

Run 2 tunnel ssh processes and 4 rsync processes at the same time. Use extra transfers for all files larger 30 MB.

sync {
    default.rsync,
    tunnel = tunnel {
        command = {"ssh", "-N", "-L", "localhost:^localport:localhost:873", "user@testmachine"},
        mode = "pool",
        parallel = 2,
    },
    source = "/data/projects",
    target    = "rsync://localhost:^localport/projects",
    delay = 5,
    batchSizeLimit = 1024 * 1024 * 30,
    maxProcesses = 4
}

This example will open 2 ssh connections for port forwarding and load balance 4 parallel rsync processes in a round roubin fashion.

Workflow in Poolmodel

When a sync with a tunnel parameter is started, all events are queued until the tunnel reaches the UP state, which is when one successful tunnel process exists for at least readyDelay seconds. Dead tunnel processes are automatically restarted. When the tunnel process count drops to 0, tunnel falls back to the CONNECTING state. There is a retryDelay seconds delay between each attempt to restart the tunnel.

Once the tunnel is UP, a full transfer is initiated. Subsequent transfers are then load balanced over multiple connections.

Notes on Poolmode

• Pool mode only works with rsync backend, since there is no way to prevent multiple transfers to the same file in a relieable way, the rsync backend only supports maxProcesses = 1 which renders pool mode useless. Since the remote side rsync daemon can prevent file trashing, the rsync backend is safe.

Periodic Full-Sync

New in: 2.3.0

It is possible to trigger a full sync command from within lsync with the crontab feature. This requires that lua-crontab is installed on the system. The crontab configuration accepts a list of crontab patterns to which a full sync will be triggered.

sync {
    ...
    crontab = {
            -- does a full sync once a day at 3:00:01
            "1 0 3 * * *",
    },
    ...
}

Field destination

Each field is seperated by " " and can contain multiple values seperated by ,.