Ubuntu Manpage: ldirectord - Linux Director Daemon

Provided by: ldirectord_4.13.0-1ubuntu4_all

NAME

       ldirectord - Linux Director Daemon

       Daemon to monitor remote services and control Linux Virtual Server

SYNOPSIS

       ldirectord [-d|--debug] [--] [configfile] start | stop | restart | try-restart | reload |
       force-reload | status

       ldirectord [-h|-?|--help|-v|--version]

DESCRIPTION

       ldirectord is a daemon to monitor and administer real servers in a cluster of load
       balanced virtual servers. ldirectord typically is started from heartbeat but can also be
       run from the command line. On startup ldirectord reads the file
       /etc/ha.d/conf/configuration.  After parsing the file, entries for virtual servers are
       created on the LVS.  Now at regular intervals the specified real servers are monitored and
       if they are considered alive, added to a list for each virtual server. If a real server
       fails, it is removed from that list. Only one instance of ldirectord can be started for
       each configuration, but more instances of ldirectord may be started for different
       configurations. This helps to group clusters of services.  Normally one would put an entry
       inside /etc/ha.d/haresources

       nodename virtual-ip-address ldirectord::configuration

       to start ldirectord from heartbeat.

OPTIONS

       configuration: This is the name for the configuration as specified in the file
       /etc/ha.d/conf/configuration

       -d|--debug Don't start as daemon and log verbosely.

       -h|--help Print user manual and exit.

       -v|--version Print version and exit.

       start the daemon for the specified configuration.

       stop the daemon for the specified configuration. This is the same as sending a TERM signal
       to the running daemon.

       restart the daemon for the specified configuration. The same as stopping and starting.

       reload the configuration file. This is only useful for modifications inside a virtual
       server entry. It will have no effect on adding or removing a virtual server block. This is
       the same as sending a HUP signal to the running daemon.

       status of the running daemon for the specified configuration.

SYNTAX

Description of how to write configuration files
virtual = (ip_address|hostname:portnumber|servicename)|firewall-mark

Defines a virtual service by IP-address (or hostname) and port (or servicename) or
firewall-mark. A firewall-mark is an integer greater than zero. The configuration of
marking packets is controlled using the "-m" option to ipchains(8). All real services and
flags for a virtual service must follow this line immediately and be indented.

checktimeout = n

Timeout in seconds for connect, external, external-perl and ping checks. If the timeout is
exceeded then the real server is declared dead.

If defined in a virtual server section then the global value is overridden.

If undefined then the value of negotiatetimeout is used. negotiatetimeout is also a
global value that may be overridden by a per-virtual setting.

If both checktimeout and negotiatetimeout are unset, the default is used.

Default: 5 seconds

negotiatetimeout = n

Timeout in seconds for negotiate checks.

If defined in a virtual server section then the global value is overridden.

If undefined then the value of checktimeout is used. checktimeout is also a global value
that may be overridden by a per-virtual setting.

If both negotiatetimeout and checktimeout are unset, the default is used.

Default: 30 seconds

checkinterval = n

Defines the number of second between server checks.

When fork=no this option defines the amount of time ldirectord sleeps between running all
of the realserver checks in all virtual service pools.

When fork=yes this option defines the amount of time each forked child sleeps per virtual
service pool after running all realserver checks for that pool.

If set in the virtual server section then the global value is overridden, but ONLY if
using forking mode (fork = yes).

Default: 10 seconds

checkcount = n

This option is deprecated and slated for removal in a future version. Please see the
'failurecount' option.

The number of times a check will be attempted before it is considered to have failed. Only
works with ping checks. Note that the checktimeout/negotiatetimeout is additive, so if a
connect check is used, checkcount is 3 and checktimeout is 2 seconds, then a total of 6
seconds worth of timeout will occur before the check fails.

If defined in a virtual server section then the global value is overridden.

Default: 1

failurecount = n

The number of consecutive times a failure will have to be reported by a check before the
realserver is considered to have failed. A value of 1 will have the realserver considered
failed on the first failure. A successful check will reset the failure counter to 0.

If defined in a virtual server section then the global value is overridden.

Default: 1

autoreload = yes | no

Defines if <ldirectord> should continuously check the configuration file for modification.
If this is set to 'yes' and the configuration file changed on disk and its modification
time (mtime) is newer than the previous version, the configuration is automatically
reloaded.

Default: no

callback = "/path/to/callback"

If this directive is defined, ldirectord automatically calls the executable
/path/to/callback after the configuration file has changed on disk. This is useful to
update the configuration file through scp on the other heartbeated host. The first
argument to the callback is the name of the configuration.

This directive might also be used to restart ldirectord automatically after the
configuration file changed on disk. However, if autoreload is set to yes, the
configuration is reloaded anyway.

fallback = ip_address|hostname[:portnumber|sercvicename] [gate | masq | ipip]

the server onto which a webservice is redirected if all real servers are down. Typically
this would be 127.0.0.1 with an emergency page.

If defined in a virtual server section then the global value is overridden.

fallbackcommand = "path to script"

If this directive is defined, the supplied script is executed whenever all real servers
for a virtual service are down or when the first real server comes up again. In the first
case, it is called with "start" as its first argument, in the latter with "stop".
Additional parameters are vserver with vport (vserver:vport) as second param and protocol
(tcp/udp) as third param to identify the virtual service within the fallback script.

If defined in a virtual server section then the global value is overridden.

logfile = "/path/to/logfile"|syslog_facility

An alternative logfile might be specified with this directive. If the logfile does not
have a leading '/', it is assumed to be a syslog(3) facility name.

Default: log directly to the file /var/log/ldirectord.log.

emailalert = "emailaddress[, emailaddress]..."

A valid email address for sending alerts about the changed connection status to any real
server defined in the virtual service. This option requires perl module MailTools to be
installed. Automatically tries to send email using any of the built-in methods. See
perldoc Mail::Mailer for more info on methods.

Multiple addresses may be supplied, comma delimited.

If defined in a virtual server section then the global value is overridden.

emailalertfrom = emailaddress

A valid email address to use as the from address of the email alerts. You can use a plain
email address or any RFC-compliant string for the From header in the body of an email
message (such as: "ldirectord Alerts" <alerts@example.com>) Do not quote this string
unless you want the quotes passed in as part of the From header.

Default: unset, take system generated default (probably root@hostname)

emailalertfreq = n

Delay in seconds between repeating email alerts while any given real server in the virtual
service remains inaccessible. A setting of zero seconds will inhibit the repeating
alerts. The email timing accuracy of this setting is dependent on the number of seconds
defined in the checkinterval configuration option.

If defined in a virtual server section then the global value is overridden.

Default: 0

Comma delimited list of server states in which email alerts should be sent. all is a
short-hand for "starting,running,stopping,reloading". If none is specified, no other
option may be specified, otherwise options are ored with each other.

If defined in a virtual server section then the global value is overridden.

Default: all

smtp = ip_address|hostname"

A valid SMTP server address to use for sending email via SMTP.

If defined in a virtual server section then the global value is overridden.

execute = "configuration"

Use this directive to start an instance of ldirectord for the named configuration.

supervised = yes | no

If yes, then ldirectord does not go into background mode. All log-messages are redirected
to stdout instead of a logfile. This is useful to run ldirectord supervised from
daemontools. See http://untroubled.org/rpms/daemontools/ or
http://cr.yp.to/daemontools.html for details.

Default: no

fork = yes | no

If yes, then ldirectord will spawn a child process for every virtual server, and run
checks against the real servers from them. This will increase response times to changes
in real server status in configurations with many virtual servers. This may also use less
memory then running many separate instances of ldirectord. Child processes will be
automatically restarted if they die.

Default: no

quiescent = yes | no

If yes, then when real or failback servers are determined to be down, they are not
actually removed from the kernel's LVS table. Rather, their weight is set to zero which
means that no new connections will be accepted.

This has the side effect, that if the real server has persistent connections, new
connections from any existing clients will continue to be routed to the real server, until
the persistent timeout can expire. See ipvsadm for more information on persistent
connections.

This side-effect can be avoided by running the following:

echo 1 > /proc/sys/net/ipv4/vs/expire_quiescent_template

If the proc file isn't present this probably means that the kernel doesn't have LVS
support, LVS support isn't loaded, or the kernel is too old to have the proc file. Running
ipvsadm as root should load LVS into the kernel if it is possible.

If no, then the real or failback servers will be removed from the kernel's LVS table. The
default is yes.

If defined in a virtual server section then the global value is overridden.

Default: yes

readdquiescent = yes | no

If yes, then when real or failback servers are determined to be down, they are readded to
the kernel's LVS table with weight 0 if they do not exist in the table. Setting the value
to no, allows manually removing the realserver to manually disable all persistent
connections.

cleanstop = yes | no

If yes, then when ldirectord exits it will remove all of the virtual server pools that it
is managing from the kernel's LVS table.

If no, then the virtual server pools it is managing and any real or failback servers
listed in them at the time ldirectord exits will be left as-is. If you want to be able to
stop ldirectord without having traffic to your realservers interrupted you will want to
set this to no.

If defined in a virtual server section then the global value is overridden.

Default: yes

maintenancedir = directoryname

If this option is set ldirectord will look for a special file in the specified directory
and, if found, force the status of the real server identified by the file to down,
skipping the normal health check. This would be useful if you wish to force servers down
for maintenance without having to modify the actual ldirectord configuration file.

For example, given a realserver with IP 172.16.1.2, service on port 4444, and a resolvable
reverse DNS entry pointing to "realserver2.example.com" ldirectord will check for the
existence of the following files:

172.16.1.2:4444
172.16.1.2
realserver2.example.com:4444
realserver2.example.com
realserver2:4444
realserver2

If any one of those files is found then ldirectord will immediately force the status of
the server to down as if the check had failed.

Note: Since it checks for the IP/hostname without the port this means you can decide to
place an entire realserver into maintenance across a large number of virtual service pools
with a single file (if you were going to reboot the server, for instance) or include the
port number and put just a particular service into maintenance.

This option is not valid in a virtual server section.

Default: disabled

Section virtual
The following commands must follow a virtual entry and must be indented with a minimum of
4 spaces or one tab.

Defines a real service by IP-address (or hostname) and port (or servicename). If the port
is omitted then a 0 will be used, this is intended primarily for fwmark services where the
port for real servers is ignored. Optionally a range of IPv4 addresses (or two hostnames)
may be given, in which case each IPv4 address in the range will be treated as a real
server using the given port. The second argument defines the forwarding method, must be
gate, ipip or masq. The third argument is optional and defines the weight for that real
server. If omitted then a weight of 1 will be used. The next two arguments are also
optional. They define a request-receive pair to be used to check if a server is alive.
They override the request-receive pair in the virtual server section. These two strings
must be quoted. If the request string starts with http://... the IP-address and port of
the real server is overridden, otherwise the IP-address and port of the real server is
used. The last two optionals arguments set lower and upper connection thresholds for real
servers using -y and -x ipvsadm argument.

For TCP and UDP (non fwmark) virtual services, unless the forwarding method is masq and the
IP address of a real server is non-local (not present on a interface on the host running
ldirectord) then the port of the real server will be set to that of its virtual service.
That is, port-mapping is only available to if the real server is another machine and the
forwarding method is masq. This is due to the way that the underlying LVS code in the
kernel functions.
More than one of these entries may be inside a virtual section. The checktimeout,
negotiatetimeout, checkcount, fallback, emailalert, emailalertfreq and quiescent options
listed above may also appear inside a virtual section, in which case the global setting is
overridden.
checktype = connect | external | external-perl | negotiate | off | on | ping |
checktimeoutN

Type of check to perform. Negotiate sends a request and matches a receive string. Connect
only attempts to make a TCP/IP connection, thus the request and receive strings may be
omitted. If checktype is a number then negotiate and connect is combined so that after
each N connect attempts one negotiate attempt is performed. This is useful to check often
if a service answers and in much longer intervals a negotiating check is done. Ping means
that ICMP ping will be used to test the availability of real servers. Ping is also used
as the connect check for UDP services. Off means no checking will take place and no real
or fallback servers will be activated. On means no checking will take place and real
servers will always be activated. Default is negotiate.

The type of service to monitor when using checktype=negotiate. None denotes a service that
will not be monitored.

simpletcp sends the request string to the server and tests it against the receive regexp.
The other types of checks connect to the server using the specified protocol. Please see
the request and receive sections for protocol specific information.

Default:

• Virtual server port is 21: ftp

• Virtual server port is 25: smtp

• Virtual server port is 53: dns

• Virtual server port is 80: http

• Virtual server port is 110: pop

• Virtual server port is 119: nntp

• Virtual server port is 143: imap

• Virtual server port is 389: ldap

• Virtual server port is 443: https

• Virtual server port is 587: submission

• Virtual server port is 636 ldaps

• Virtual server port is 993: imaps

• Virtual server port is 995: pops

• Virtual server port is 1521: oracle

• Virtual server port is 1812: radius

• Virtual server port is 3128: http_proxy

• Virtual server port is 3306: mysql

• Virtual server port is 5432: pgsql

• Virtual server port is 5060: sip

• Otherwise: none

checkcommand = "path to script"

This setting is used if checktype is external or external-perl and is the command to be
run to check the status of a real server. It should exit with status 0 if everything is
ok, or non-zero otherwise.

Four parameters are passed to the script:

• virtual server ip/firewall mark

• virtual server port

• real server ip

• real server port

If the checktype is external-perl then the command is assumed to be a Perl script and it
is evaluated into an anonymous subroutine which is called at check time, avoiding a fork-
exec. The argument signature and exit code conventions are identical to checktype
external. That is, an external-perl checktype should also work as an external checktype.

Default: /bin/true

checkport = n

Number of port to monitor. Sometimes check port differs from service port.

Default: port specified for each real server

request = "uri to requested object"

This object will be requested each checkinterval seconds on each real server. The string
must be inside quotes. Note that this string may be overridden by an optional per real-
server based request-string.

For an HTTP/HTTPS check, this should be a relative URI, while it has to be absolute for
the 'http_proxy' check type. In the latter case, this URI will be requested through the
proxy backend that is being checked.

For a DNS check this should the name of an A record, or the address of a PTR record to
look up.

For a MySQL, Oracle or PostgeSQL check, this should be an SQL SELECT query. The data
returned is not checked, only that the answer is one or more rows. This is a required
setting.

For a simpletcp check, this string is sent verbatim except any occurrences of \n are
replaced with a new line character.

receive = "regexp to compare"

If the requested result contains this regexp to compare, the real server is declared
alive. The regexp must be inside quotes. Keep in mind that regexps are not plain strings
and that you need to escape the special characters if they should as literals. Note that
this regexp may be overridden by an optional per real-server based receive regexp.

For a DNS check this should be any one the A record's addresses or any one of the PTR
record's names. In case of dynamic DNS answers (different answers on the same question) a
regex to match multiple addresses or PTR record names could also defined.

For a MySQL check, the receive setting is not used.

httpmethod = GET | HEAD

Sets the HTTP method which should be used to fetch the URI specified in the request-
string. GET is the method used by default if the parameter is not set. If HEAD is used,
the receive-string should be unset.

Default: GET

virtualhost = "hostname"

Used when using a negotiate check with HTTP or HTTPS. Sets the host header used in the
HTTP request. In the case of HTTPS this generally needs to match the common name of the
SSL certificate. If not set then the host header will be derived from the request url for
the real server if present. As a last resort the IP address of the real server will be
used.

For FTP, IMAP, LDAP, MySQL, Oracle, POP and PostgreSQL, the username used to log in.

For RADIUS the username is used for the attribute User-Name.

For SIP, the username is used as both the to and from address for an OPTIONS query.

Default:

• FTP: Anonymous

• MySQL Oracle, and PostgreSQL: Must be specified in the configuration

• SIP: ldirectord\@<hostname>, hostname is derived as per the passwd option below.

• Otherwise: empty string, which denotes that case authentication will not be
attempted.

passwd = "password"

Password to use to login to FTP, IMAP, LDAP, MySQL, Oracle, POP, PostgreSQL and SIP
servers.

For RADIUS the passwd is used for the attribute User-Password.

Default:

• FTP: ldirectord\@<hostname>, where hostname is the environment variable HOSTNAME
evaluated at run time, or sourced from uname if unset.

• Otherwise: empty string. In the case of LDAP, MySQL, Oracle, and PostgreSQL this
means that authentication will not be performed.

database = "databasename"

Database to use for MySQL, Oracle and PostgreSQL servers, this is the database that the
query (set by receive above) will be performed against. This is a required setting.

secret = "radiussecret"

Secret to use for RADIUS servers, this is the secret used to perform an Access-Request
with the username (set by login above) and passwd (set by passwd above).

Default: empty string

scheduler = scheduler_name

Scheduler to be used by LVS for loadbalancing. For an information on the available
sehedulers please see the ipvsadm(8) man page.

Default: "wrr"

persistent = n

Number of seconds for persistent client connections.

netmask = w.x.y.z | prefixlen

Netmask to be used for granularity of persistent client connections. IPv4 netmask should
be specified in dotted quad notation. IPv6 netmask should be specified as a prefix length
between 1 and 128.

protocol = tcp | udp | fwm

Protocol to be used. If the virtual is specified as an IP address and port then it must be
one of tcp or udp. If a firewall mark then the protocol must be fwm.

Default:

• Virtual is an IP address and port, and the port is not 53: tcp

• Virtual is an IP address and port, and the port is 53: udp

• Virtual is a firewall mark: fwm

monitorfile = "/path/to/monitorfile"

File to continuously log the real service checks to for this virtual service. This is
useful for monitoring when and why real services were down or for statistics.

The log format is: [timestamp|pid|real_service_id|status|message]

Default: no separate logging of service checks.

ops = yes | no

Specify that a virtual service uses one-packet scheduling. This option can be used only
for UDP services. If this option is specified, all connections are created only to
schedule one packet. Option is useful to schedule UDP packets from same client port to
different real servers.

servicename = short name

A name for this service. This is for the sole purpose of making it easier to know which
service is affected when e-mail notifications are sent out. It will be included in the
e-mail subject and body.

comment = comment

Notes about this service to be included in e-mail notifications (for example, purpose of
the service or relevant administrator to contact).

IPv6

       Directives for IPv6 are virtual6, real6, fallback6.  IPv6 addresses specified for
       virtual6, real6, fallback6 and a file of maintenance directory should be enclosed by
       brackets ([2001:db8::abcd]:80).

       Following checktype and service are supported.

       checktype: connect | external | external-perl | negotiate | off | on | checktimeoutN

       service: dns | http | https | nntp | none | simpletcp | sip

       Note: When using a service type with http or https, you need to install perl module
       perl-Net-INET6Glue.

FILES

       /etc/ha.d/ldirectord.cf

       /var/log/ldirectord.log

       /var/run/ldirectord.configuration.pid

       /etc/services

AUTHORS

       Horms <horms@verge.net.au>

       Jacob Rief <jacob.rief@tiscover.com>

NAME

SYNOPSIS

DESCRIPTION

OPTIONS

SYNTAX

IPv6

FILES

SEE ALSO

AUTHORS