1INNWATCH.CTL(5) InterNetNews Documentation INNWATCH.CTL(5)
2
6 innwatch.ctl - List of supervisory actions taken by innwatch
7
9 The file pathetc/innwatch.ctl is used to determine what actions are
10 taken during the periodic supervisions by innwatch.
11 The file consists of a series of lines; blank lines and lines beginning
13 with a number sign ("#") are ignored. All other lines consist of seven
14 fields, each preceded by a delimiting character, for example:
15 !state!when!condition!test!limit!command!reason
17 or:
19 @state@when@condition@test@limit@command@reason
21 The delimiter can be any one of several non-alphanumeric characters
23 that does not appear elsewhere in the line; there is no way to quote it
24 to include it in any of the fields. Any of "!", ",", ":", "@", ";", or
25 "?" is a good choice. Each line can have a different delimiter; the
26 first character on each line is the delimiter for that line. White
27 space surrounding delimiters, except before the first, is ignored, and
28 does not form part of the fields; white space within fields is
29 permitted. All delimiters must be present.
30 The first field is the state to enter if the condition for this control
32 line is true. It is used as an internal state indicator and in ctlinnd
33 messages to control the server. If this field is empty, the line
34 number is used.
35 The second field specifies when this control line should be used. It
37 consists of a list of states and special indicators, separated by
38 whitespace. If the current state matches against any of the states in
39 this field, this line will be used as described below. The values that
40 may be used are:
41 "-" This line matches if the current state is the same as the label on
43 this line, or if the current state is "run", the initial state.
44 This is also the default state if this field is empty.
45 "+" This line matches if the current state is "run".
47 "*" This line always matches.
49 "label"
51 This line matches if the current state is the specified "label".
52 "-label"
54 This line matches if the current state is not the specified
55 "label".
56 The third field specifies a shell command that is invoked if this line
58 matches. Do not use any shell filename expansion characters such as
59 "*", "?", or "[" (even quoted, they're not likely to work as intended).
60 The command is executed with its current directory set to the news
61 spool articles directory (patharticles).
62 If the command succeeds, as indicated by its exit status, it is
64 expected to have printed a single integer to standard output. This
65 gives the value of this control line, to be used below. If the command
66 fails, the line is ignored.
67 The fourth field specifies the operator to use to test the value
69 returned above. It should be one of the two letter numeric test
70 operators defined in test(1) such as "eq", "lt" and the like. The
71 leading dash ("-") should not be included.
72 The fifth field specifies a constant with which to compare the value
74 using the operator just defined. This is done by invoking the command:
75 test value -operator constant
77 The line is said to succeed if it returns true.
79 The sixth field specifies what should be done if the line succeeds, and
81 in some cases if it fails. Any of the following words may be used:
82 "throttle"
84 Causes innwatch to throttle the server if this line succeeds. It
85 also sets the state to the value of the line's label. If the line
86 fails, and the state was previously equal to the label on this line
87 (that is, this line had previously succeeded), then a "ctlinnd go"
88 command will be sent to the server, and innwatch will return to the
89 "run" state. The "ctlinnd throttle" command is only performed if
90 the current state is "run" or a state other than the label of this
91 line, regardless of whether the command succeeds.
92 "pause"
94 Is identical to "throttle" except that the server is paused via the
95 "ctlinnd pause" command.
96 "shutdown"
98 Sends a "ctlinnd shutdown" command to the server. It is for
99 emergency use only.
100 "flush"
102 Sends a "ctlinnd flush" command to the server.
103 "go"
105 Causes innwatch to send a "ctlinnd go" command to the server and to
106 set the state to "run".
107 "exit"
109 Causes innwatch to exit.
110 "skip"
112 The remainder of the control file is skipped for the current pass.
113 The last field specifies the reason that is used in those "ctlinnd"
115 commands that require one. More strictly, it is part of the reason, as
116 innwatch appends some information to it.
117 In order to enable other sites to recognize the state of the local innd
119 server, this field should usually be set to one of several standard
120 values. Use for instance "No space" if the server is rejecting
121 articles because of a lack of filesystem resources, or "loadav" if the
122 server is rejecting articles because of a lack of CPU resources.
123 Once innwatch has taken some action as a consequence of its control
125 line, it skips the rest of the control file for this pass. If the
126 action was to restart the server (that is, issue a "ctlinnd go"
127 command), then the next pass will commence almost immediately, so that
128 innwatch can discover any other condition that may mean that the server
129 should be suspended again.
130
132 !!! inndf . ! lt ! 10000 ! throttle ! No space (spool)
133 !!! inndf -i . ! lt ! 1000 ! throttle ! No space (inodes)
134 The first line causes the server to be throttled if the free space
136 drops below 10000 units (using whatever units inndf uses), and
137 restarted again when free space increases above the threshold.
138 The second line does the same for inodes.
140 The next three lines act as a group and should appear in the following
142 order. It is easier to explain them, however, if they are described
143 from the last up.
144 ! load ! load hiload ! loadavg ! lt ! 5 ! go ! loadav
146 : hiload : + load : loadavg : gt : 8 : throttle : loadav
147 / load / + / loadavg / gt / 6 / pause / loadav
148 The final line causes the server to be paused if innwatch is in the
150 "run" state and the load average rises to, or above, six. The state is
151 set to "load" when this happens. The previous line causes the server
152 to be throttled when innwatch is in the "run" or "load" state, and the
153 load average rises above eight. The state is set to "hiload" when this
154 happens. Note that innwatch can switch the server from "pause" to
155 "throttle" if the load average rises from below six to between six and
156 seven, and then to above eight. The first line causes the server to be
157 sent a "ctlinnd go" command if innwatch is in the "load" or "hiload"
158 state, and the load average drops below five.
159 Note that all three lines assume a mythical command "loadavg" that is
161 assumed to print the current load average as an integer. In more
162 practical circumstances, a pipe of uptime into AWK is more likely to be
163 useful.
164
166 The "run" state is not actually identified by the label with that three
167 letter name, and using it will not work as expected ("go" is the wanted
168 state in that case).
169 Using an unusual character for the delimiter such as "(", "*", "&",
171 "`", "'", and the like, is likely to lead to obscure and hard to locate
172 bugs.
173
175 Written by <kre@munnari.oz.au> for InterNetNews. Rewritten into POD by
176 Julien Elie.
177
179 ctlinnd(8), inndf(8), news.daily(8), rc.news(8).
180INN 2.6.5 2022-01-23 INNWATCH.CTL(5)