1: #!/usr/bin/perl
2:
3: =pod
4:
5: =head1 SYNOPSIS
6:
7: clusteradmin command [args]
8:
9: =head1 DESCRIPTION
10:
11: Performs an adminstrative action on DNS hosts in the current hosts.tab
12: file. For this to work, the current host must be the cluster administrator
13: on the target systems. That is this must be a host in managers.tab
14: Furthermore, lonc must be running on this system.
15:
16: The action is specified by the 'command' parameter which may have additional arguments.
17:
18: All communications with remote clients are made critical so that
19: they will eventually happen even if the host we want to talk with
20: is dead.
21:
22:
23: =head1 ACTIONS
24:
25: =over 3
26:
27: =item help
28:
29: Outputs a brief description of the actions supported and what they do.
30:
31: =item update file
32:
33: Update the contents of an administrative file with the contents of that file
34: on this system. 'file' is the name of that file, not the path for example:
35:
36: clusteradmin update dns_hosts.tab
37:
38: =back
39:
40: =head1 ASSUMPTIONS
41:
42: Assume that loncapa is installedin /home/httpd/lib/perl so that we can use
43: it's modules. If this is not the case, you mus modify the
44: use lib line in the program before you can use it.
45:
46:
47: =cut
48:
49: use strict;
50:
51: # I'm not sure if there's a better way to establish the location of the libs:
52:
53: use lib ('/home/httpd/lib/perl');
54:
55: use LONCAPA::Configuration;
56: use File::Basename;
57: use Apache::lonnet;
58:
59: #----------------------------------------------------------------------------------
60: #
61: # Command dispatch handling:
62:
63: #
64: # Dispatch hash for the subcommands.
65: # indexed by the subcommand name, each item is
66: # a reference to the sub that handles the command:
67: #
68:
69: my %Dispatch;
70:
71: #
72: # Define a subcommand:
73: #
74: # Parameters:
75: # command - subcommand name string
76: # handler - reference to the handler sub.
77: # Notes:
78: # The handler is dispatched to with the tail of the command
79: # as an array reference parameter. Suppose the command is
80: #
81: # clusteradmin update dns_hosts.tab,
82: #
83: # the array will have a single element: 'dns_hosts.tab'.
84: #
85: sub define_command {
86: my ($command, $handler) = @_;
87:
88: $Dispatch{$command} = $handler;
89: }
90:
91: #
92: # Dispatch to a command:
93: # Parameters:
94: # command - Name of the command.
95: # tail - Reference to the command tail array.
96: # Returns:
97: # 1 - Success.
98: # 0 - Failure
99: # Notes:
100: # 1. The command handler is assumed to have output any error messages
101: # to stderr by now.
102: # 2. This function will indicate to stderr if the command isn't in the
103: # dispatch hash.
104: #
105: sub dispatch_command {
106: my ($command, $tail) = @_;
107: my $sub;
108:
109: if (exists($Dispatch{$command})) {
110: $sub = $Dispatch{$command};
111: return $sub->($tail);
112: } else {
113: print STDERR "Unrecognized subcommand keyword $command\n";
114: &usage();
115: return 0;
116: }
117: }
118: #-----------------------------------------------------------------------------------
119:
120: #
121: # Provide usage/help string:
122: #
123:
124: sub usage {
125: print STDERR "Usage:\n";
126: print STDERR " clusteradmin subcommand [args]\n";
127: print STDERR "Where:\n";
128: print STDERR " subcommand describes what to actually do:\n";
129: print STDERR " help - Prints this message (args ignored)\n";
130: print STDERR " update - Updates an administrative file\n";
131: print STDERR " args is one of dns_hosts.tab or dns_domain.tab\n";
132:
133: }
134:
135: &define_command("help", \&usage);
136:
137:
138: #--------------------------------------------------------------------------------
139: #
140: # File update subsystem:
141:
142:
143: # Given the basename of an administrative file, return the
144: # full path to that file.
145: # Pre-requisistes:
146: # Requires that LONCAPA::Configuration is in the use lib path.
147: # Parameters:
148: # $basename - Base name of the file to locate.
149: # Returns:
150: # Full path to that file.
151: #
152:
153: my $config_vars = LONCAPA::Configuration::read_conf('loncapa.conf');
154: my %config = %{$config_vars};
155:
156:
157: sub construct_table_path {
158: my ($basename) = @_;
159: my $directory = $config{'lonTabDir'};
160:
161: return $directory . '/' . $basename;
162: }
163:
164: # Returns the set of hosts that are specified as DNS hosts in the hosts.tab file.
165: # Those are the ones with a ^ in column one.
166: #
167: # Returns:
168: # The list of host that are DNS hosts.
169: #
170: sub get_dns_hosts()
171: {
172: my @result;
173: my $hosts_tab = &construct_table_path('hosts.tab');
174: open(HOSTS, "<$hosts_tab");
175: while (my $line = <HOSTS>) {
176: chomp($line);
177: if ($line =~ /^\^/) {
178: $line =~ s/^\^//; # Get rid of leading ^
179: $line =~ s/\s*$//; # and any trailing whitespace.
180: push(@result, $line);
181: }
182: }
183: return (@result);
184: }
185:
186: # Actually push the new files to the systems to update. This is done as a critical
187: # transaction so that the files eventually get pushed, even if the target hosts
188: # are down about now.
189: #
190: # Parameters:
191: # specifier - The specifier to hand in the push transaction. This
192: # identifies the target file in the remote lond process.
193: # pushfile - Full path to the file to push.
194: # hosts - Reference to an array of hosts into which the file should be pushed.
195: #
196: # Returns:
197: # 1 - Success.
198: # 0 - Failure with appropriate output to stderr.
199: #
200: sub push_file {
201: my ($specifier, $pushfile, $hosts) = @_;
202:
203: # Read in the entire file:
204:
205: my $contents;
206: my $line;
207: open(FILE, "<$pushfile");
208: while ($line = <FILE>) {
209: $contents .= $line;
210: }
211:
212:
213: # Construct the transaction for safety we encrypt the transaction
214: #
215: my $cmd = "encrypt:pushfile:$specifier:$contents";
216:
217: # Iterate over the hosts and run cmd as a critical
218: # operation:
219:
220: foreach my $host (@$hosts) {
221: my $loncapa_name = &Apache::lonnet::host_from_dns($host);
222: next if ($loncapa_name eq $config{'lonHostID'});
223: my $reply = &Apache::lonnet::critical($cmd, $loncapa_name);
224: if ($reply ne 'ok') {
225: print STDERR "Reply from $host ($loncapa_name) not 'ok' was: $reply\n";
226: }
227: }
228:
229: }
230:
231: #
232: # Controls the push of a file to the servers that deserve to get it.
233: # Parameters:
234: # args - Tail of the command line (array reference).
235: # Returns:
236: # 1 - Success.
237: # 0 - Failure (printing messages to stderr.
238: #
239: sub update_file {
240: my ($args) = @_;
241:
242: if (scalar(@$args) != 1) {
243: print STDERR "Incorrect number of command arguments\n";
244: &usage();
245: return 0;
246: } else {
247: my $filename = shift(@$args);
248:
249: # Validate the filename:
250:
251: if ($filename eq 'dns_hosts.tab' || $filename eq 'dns_domain.tab') {
252: my $pushfile = &construct_table_path($filename);
253: my $specifier = basename($filename, ('.tab'));
254: my @hosts = (&get_dns_hosts());
255: return &push_file($specifier, $pushfile, \@hosts);
256: } else {
257: print STDERR "Only dns_hosts.tab or dns_domain.tab can be updated\n";
258: &usage();
259: return 0;
260: }
261: }
262: }
263: &define_command("update", \&update_file);
264:
265: #
266: # Checks if current lonHostID is in managers.tab for the cluster, and is in the cluster.
267: # Parameters:
268: # args - none
269: # Returns:
270: # 1 - lonHostID is is managers.tab
271: # '' - Failure (printing messages to STDERR).
272: #
273: sub is_manager {
274: my $currhost = $config{'lonHostID'};
275: my $canmanage;
276: if ($currhost eq '') {
277: print STDERR "Could not determine LON-CAPA host ID\n";
278: return;
279: } elsif (!defined &Apache::lonnet::get_host_ip($currhost)) {
280: print STDERR "This LON-CAPA host is not part of the cluster.\n";
281: }
282: my $tablename = &construct_table_path('managers.tab');
283: if (!open (MANAGERS, $tablename)) {
284: print STDERR "No managers.tab table. Could not verify host is a manager\n";
285: return;
286: }
287: while(my $host = <MANAGERS>) {
288: chomp($host);
289: next if ($host =~ /^\#/);
290: if ($host eq $currhost) {
291: $canmanage = 1;
292: last;
293: }
294: }
295: close(MANAGERS);
296: return $canmanage;
297: }
298: #---------------------------------------------------------------------------------
299: #
300: # Program entry point. Decode the subcommand from the args array and
301: # dispatch to the appropriate command processor.
302: #
303:
304: my $argc = scalar(@ARGV);
305: if ($argc == 0) {
306: print STDERR "Missing subcommand\n";
307: &usage();
308: exit(-1);
309: }
310:
311: if (!&is_manager()) {
312: print STDERR 'Script needs to be run from a server designated as a "Manager" in the LON-CAPA cluster'."\n";
313: exit(-1);
314: }
315:
316: my $subcommand = shift(@ARGV); # argv now the tail.
317:
318: if (!&dispatch_command($subcommand, \@ARGV)) {
319: exit(0);
320: } else {
321: exit(-1);
322: }
323:
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