INNWATCH.CTL(5)INNWATCH.CTL(5)NAMEinnwatch.ctl - control Usenet supervision by innwatch
DESCRIPTION
The file <pathetc in inn.conf>/innwatch.ctl is used to
determine what actions are taken during the periodic
supervisions by innwatch.
The file consists of a series of lines; blank lines and
lines beginning with a number sign (``#'') are ignored.
All other lines consist of seven fields, each preceded by
a delimiting character:
:label:state:condition:test:limit:command:reason
The delimiter can be any one of several non-alphanumeric
characters that does not appear elsewhere in the line;
there is no way to quote it to include it in any of the
fields. Any of ``!'', ``,'', ``:'', ``@'', ``;'', or
``?'' is a good choice. Each line can have a different
delimiter; the first character on each line is the delim-
iter for that line. White space surrounding delimiters,
except before the first, is ignored, and does not form
part of the fields, white space within fields is permit-
ted. All delimiters must be present.
The first field is a label for the control line. It is
used as an internal state indicator and in ctlinnd mes-
sages to control the server. If omitted, the line number
is used.
The second field specifies when this control line should
be used. It consists of a list of labels, and special
indicators, separated by whitespace. If the current state
matches against any of the labels in this field, this line
will be used as described below. The values that may be
used are:
- This line matches if the current state is the same
as the label on this line, or if the current state
is ``run,'' the initial state. This is also the
default state if this field is empty.
+ This line matches if the current state is ``run.''
* This line always matches.
label This line matches if the current state is the spec-
ified ``label.''
-label This line matches if the current state is not the
specified ``label.''
The third field specifies a shell command that is invoked
if this line matches. Do not use any shell filename
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INNWATCH.CTL(5)INNWATCH.CTL(5)
expansion characters such as ``*'', ``?'', or ``['' (even
quoted, they're not likely to work as intended). If the
command succeeds, as indicated by its exit status, it is
expected to have printed a single integer to standard out-
put. This gives the value of this control line, to be
used below. If the command fails, the line is ignored.
The command is executed with its current directory set to
the news spool directory, <patharticles in inn.conf>.
The fourth field specifies the operator to use to test the
value returned above. It should be one of the two letter
numeric test operators defined in test(1) such as ``eq'',
``lt'' and the like. The leading dash (``-'') should not
be included.
The fifth field specifies a constant with which to compare
the value using the operator just defined. This is done
by invoking the command:
test value -operator constant
The line is said to ``succeed'' if it returns true.
The sixth field specifies what should be done if the line
succeeds, and in some cases if it fails. Any of the fol-
lowing words may be used:
throttle
Causes innwatch to throttle the server if this line
succeeds. It also sets the state to the value of
the line's label. If the line fails, and the state
was previously equal to the label on this line
(that is, this line had previously succeeded), then
a go command will be sent to the server, and
innwatch will return to the ``run'' state. The
``throttle'' is only performed if the current state
is ``run'' or a state other than the label of this
line, regardless of whether the command succeeds.
pause Is identical to ``throttle'' except that the server
is paused.
shutdown
Sends a ``shutdown'' command to the server. It is
for emergency use only.
flush Sends a ``flush'' command to the server.
go Causes innwatch to send a ``go'' command to the
server and to set the state to ``run.''
exit Causes innwatch to exit.
skip The result of the control file is skipped for the
current pass.
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INNWATCH.CTL(5)INNWATCH.CTL(5)
The last field specifies the reason that is used in those
ctlinnd commands that require one. More strictly, it is
part of the reason -- innwatch appends some information to
it. In order to enable other sites to recognize the state
of the local innd server, this field should usually be set
to one of several standard values. Use ``No space'' if
the server is rejecting articles because of a lack of
filesystem resources. Use ``loadav'' if the server is
rejecting articles because of a lack of CPU resources.
Once innwatch has taken some action as a consequence of
its control line, it skips the rest of the control file
for this pass. If the action was to restart the server
(that is, issue a ``go'' command), then the next pass will
commence almost immediately, so that innwatch can discover
any other condition that may mean that the server should
be suspended again.
EXAMPLES
@@@inndf .@lt@10000@throttle@No space
@@@inndf -i .@lt@1000@throttle@No space (inodes)
The first line causes the server to be throttled if the
free space drops below 10000 units (using whatever units
inndf(8) uses), and restarted again when free space
increases above the threshold.
The second line does the same for inodes.
The next three lines act as a group and should appear in
the following order. It is easier to explain them, how-
ever, if they are described from the last up.
!load!load hiload!loadavg!lt!5!go!
:hiload:+ load:loadavg:gt:8:throttle:loadav
/load/+/loadavg/ge/6/pause/loadav
The final line causes the server to be paused if innwatch
is in the ``run'' state and the load average rises to, or
above, six. The state is set to ``load'' when this hap-
pens. The previous line causes the server to be throttled
when innwatch is in the ``run'' or ``load'' state, and the
load average rises above eight. The state is set to
``hiload'' when this happens. Note that innwatch can
switch the server from ``paused'' to ``throttled'' if the
load average rises from below six to between six and
seven, and then to above eight. The first line causes the
server to be sent a ``go'' command if innwatch is in the
``load'' or ``hiload'' state, and the load average drops
below five.
Note that all three lines assume a mythical command load-
avg that is assumed to print the current load average as
an integer. In more practical circumstances, a pipe of
uptime into awk is more likely to be useful.
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INNWATCH.CTL(5)INNWATCH.CTL(5)BUGS
This file must be tailored for each individual site, the
sample supplied is truly no more than a sample. The file
should be ordered so that the more common problems are
tested first.
The ``run'' state is not actually identified by the label
with that three letter name, and using it will not work as
expected.
Using an ``unusual'' character for the delimiter such as
``('', ``*'', ``&'', ```'', ``''', and the like, is likely
to lead to obscure and hard to locate bugs.
HISTORY
Written by <kre@munnari.oz.au> for InterNetNews. This is
revision 1.1.2.1, dated 1999/06/12.
SEE ALSOinn.conf(5), innd(8), ctlinnd(8), news.daily(8).
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