1: #!/usr/bin/perl
2: # The LearningOnline Network with CAPA
3: # Push admin files from cluster manager to cluster's "name servers".
4: #
5: # $Id: clusteradmin,v 1.6 2018/08/20 22:27:16 raeburn Exp $
6: #
7: # Copyright Michigan State University Board of Trustees
8: #
9: # This file is part of the LearningOnline Network with CAPA (LON-CAPA).
10: # LON-CAPA is free software; you can redistribute it and/or modify
11: # it under the terms of the GNU General Public License as published by
12: # the Free Software Foundation; either version 2 of the License, or
13: # (at your option) any later version.
14: #
15: # LON-CAPA is distributed in the hope that it will be useful,
16: # but WITHOUT ANY WARRANTY; without even the implied warranty of
17: # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18: # GNU General Public License for more details.
19: #
20: # You should have received a copy of the GNU General Public License
21: # along with LON-CAPA; if not, write to the Free Software
22: # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
23: #
24: # /home/httpd/html/adm/gpl.txt
25: #
26: # http://www.lon-capa.org/
27:
28: =pod
29:
30: =head1 SYNOPSIS
31:
32: clusteradmin command [args]
33:
34: =head1 DESCRIPTION
35:
36: Performs an adminstrative action on DNS hosts in the current hosts.tab
37: file. For this to work, the current host must be the cluster administrator
38: on the target systems. That is this must be a host in managers.tab
39: Furthermore, lonc must be running on this system.
40:
41: The action is specified by the 'command' parameter which may have additional arguments.
42:
43: All communications with remote clients are made critical so that
44: they will eventually happen even if the host we want to talk with
45: is dead.
46:
47:
48: =head1 ACTIONS
49:
50: =over 3
51:
52: =item help
53:
54: Outputs a brief description of the actions supported and what they do.
55:
56: =item update file
57:
58: Update the contents of an administrative file with the contents of that file
59: on this system. 'file' is the name of that file, not the path for example:
60:
61: clusteradmin update dns_hosts.tab
62:
63: =back
64:
65: =head1 ASSUMPTIONS
66:
67: Assume that loncapa is installedin /home/httpd/lib/perl so that we can use
68: it's modules. If this is not the case, you mus modify the
69: use lib line in the program before you can use it.
70:
71:
72: =cut
73:
74: use strict;
75:
76: # I'm not sure if there's a better way to establish the location of the libs:
77:
78: use lib ('/home/httpd/lib/perl');
79:
80: use LONCAPA::Configuration;
81: use File::Basename;
82: use Apache::lonnet;
83:
84: #----------------------------------------------------------------------------------
85: #
86: # Command dispatch handling:
87:
88: #
89: # Dispatch hash for the subcommands.
90: # indexed by the subcommand name, each item is
91: # a reference to the sub that handles the command:
92: #
93:
94: my %Dispatch;
95:
96: #
97: # Define a subcommand:
98: #
99: # Parameters:
100: # command - subcommand name string
101: # handler - reference to the handler sub.
102: # Notes:
103: # The handler is dispatched to with the tail of the command
104: # as an array reference parameter. Suppose the command is
105: #
106: # clusteradmin update dns_hosts.tab,
107: #
108: # the array will have a single element: 'dns_hosts.tab'.
109: #
110: sub define_command {
111: my ($command, $handler) = @_;
112:
113: $Dispatch{$command} = $handler;
114: }
115:
116: #
117: # Dispatch to a command:
118: # Parameters:
119: # command - Name of the command.
120: # tail - Reference to the command tail array.
121: # Returns:
122: # 1 - Success.
123: # 0 - Failure
124: # Notes:
125: # 1. The command handler is assumed to have output any error messages
126: # to stderr by now.
127: # 2. This function will indicate to stderr if the command isn't in the
128: # dispatch hash.
129: #
130: sub dispatch_command {
131: my ($command, $tail) = @_;
132: my $sub;
133:
134: if (exists($Dispatch{$command})) {
135: $sub = $Dispatch{$command};
136: return $sub->($tail);
137: } else {
138: print STDERR "Unrecognized subcommand keyword $command\n";
139: &usage();
140: return 0;
141: }
142: }
143: #-----------------------------------------------------------------------------------
144:
145: #
146: # Provide usage/help string:
147: #
148:
149: sub usage {
150: print STDERR "Usage:\n";
151: print STDERR " clusteradmin subcommand [args]\n";
152: print STDERR "Where:\n";
153: print STDERR " subcommand describes what to actually do:\n";
154: print STDERR " help - Prints this message (args ignored)\n";
155: print STDERR " update - Updates an administrative file\n";
156: print STDERR " args is one of dns_hosts.tab or dns_domain.tab\n";
157:
158: }
159:
160: &define_command("help", \&usage);
161:
162:
163: #--------------------------------------------------------------------------------
164: #
165: # File update subsystem:
166:
167:
168: # Given the basename of an administrative file, return the
169: # full path to that file.
170: # Pre-requisistes:
171: # Requires that LONCAPA::Configuration is in the use lib path.
172: # Parameters:
173: # $basename - Base name of the file to locate.
174: # Returns:
175: # Full path to that file.
176: #
177:
178: my $config_vars = LONCAPA::Configuration::read_conf('loncapa.conf');
179: my %config = %{$config_vars};
180: my $logfile = $config{'lonDaemons'}.'/logs/dns_updates.log';
181:
182:
183: sub construct_table_path {
184: my ($basename) = @_;
185: my $directory = $config{'lonTabDir'};
186:
187: return $directory . '/' . $basename;
188: }
189:
190: # Returns the set of hosts that are specified as DNS hosts in the hosts.tab file.
191: # Those are the ones with a ^ in column one.
192: #
193: # Returns:
194: # The list of host that are DNS hosts.
195: #
196: sub get_dns_hosts()
197: {
198: my @result;
199: my $hosts_tab = &construct_table_path('hosts.tab');
200: open(HOSTS, "<$hosts_tab");
201: while (my $line = <HOSTS>) {
202: chomp($line);
203: if ($line =~ /^\^/) {
204: if ($line =~ /^\^([\w.\-]+)/) {
205: push(@result,$1);
206: }
207: }
208: }
209: return (@result);
210: }
211:
212: # Actually push the new files to the systems to update. This is done as a critical
213: # transaction so that the files eventually get pushed, even if the target hosts
214: # are down about now.
215: #
216: # Parameters:
217: # specifier - The specifier to hand in the push transaction. This
218: # identifies the target file in the remote lond process.
219: # pushfile - Full path to the file to push.
220: # hosts - Reference to an array of hosts into which the file should be pushed.
221: #
222: # Returns:
223: # 1 - Success.
224: # 0 - Failure with appropriate output to stderr.
225: #
226: sub push_file {
227: my ($specifier, $pushfile, $hosts, $fh) = @_;
228:
229: # Read in the entire file:
230:
231: my $contents;
232: my $line;
233: open(FILE, "<$pushfile");
234: while ($line = <FILE>) {
235: $contents .= $line;
236: }
237:
238:
239: # Construct the transaction for safety we encrypt the transaction
240: #
241: my $cmd = "encrypt:pushfile:$specifier:$contents";
242:
243: # Iterate over the hosts and run cmd as a critical
244: # operation:
245:
246: my @ids=&Apache::lonnet::current_machine_ids();
247: foreach my $host (@$hosts) {
248: my $loncapa_name = &Apache::lonnet::host_from_dns($host);
249: next if (grep(/^\Q$loncapa_name\E$/,@ids));
250: my $reply = &Apache::lonnet::critical($cmd, $loncapa_name);
251: my $msg;
252: if ($reply eq 'ok') {
253: $msg = "$pushfile pushed to $host ($loncapa_name): $reply\n";
254: } else {
255: $msg = "Reply from $host ($loncapa_name) not 'ok' was: $reply\n";
256: }
257: print $fh $msg;
258: print STDERR $msg;
259: }
260: return;
261: }
262:
263: #
264: # Controls the push of a file to the servers that deserve to get it.
265: # Parameters:
266: # args - Tail of the command line (array reference).
267: # Returns:
268: # 1 - Success.
269: # 0 - Failure (printing messages to stderr.
270: #
271: sub update_file {
272: my ($args) = @_;
273:
274: if (scalar(@$args) != 1) {
275: print STDERR "Incorrect number of command arguments\n";
276: &usage();
277: return 0;
278: } else {
279: my $filename = shift(@$args);
280:
281: # Validate the filename:
282:
283: if (($filename eq 'dns_hosts.tab') || ($filename eq 'dns_domain.tab') ||
284: ($filename eq 'hosts.tab') || ($filename eq 'domain.tab')) {
285: my ($result,$fh);
286: if (!-e $logfile) {
287: system("touch $logfile");
288: system("chown www:www $logfile");
289: }
290: if (open ($fh,">>$logfile")) {
291: print $fh "clusteradmin update started: ".localtime(time)."\n";
292: my $pushfile = &construct_table_path($filename);
293: my $specifier = basename($filename, ('.tab'));
294: my @hosts = (&get_dns_hosts());
295: $result = &push_file($specifier, $pushfile, \@hosts, $fh);
296: print $fh "ended: ".localtime(time)."\n";
297: close($fh);
298: } else {
299: print STDERR "Could not open $logfile to append. Exiting.\n";
300: }
301: return $result;
302: } else {
303: print STDERR "Only dns_hosts.tab or dns_domain.tab can be updated\n";
304: &usage();
305: return 0;
306: }
307: }
308: }
309: &define_command("update", \&update_file);
310:
311: #
312: # Checks if current lonHostID is in managers.tab for the cluster, and is in the cluster.
313: # Parameters:
314: # args - none
315: # Returns:
316: # 1 - lonHostID is is managers.tab
317: # '' - Failure (printing messages to STDERR).
318: #
319: sub is_manager {
320: my $currhost = $config{'lonHostID'};
321: my $canmanage;
322: if ($currhost eq '') {
323: print STDERR "Could not determine LON-CAPA host ID\n";
324: return;
325: } elsif (!defined &Apache::lonnet::get_host_ip($currhost)) {
326: print STDERR "This LON-CAPA host is not part of the cluster.\n";
327: }
328: my $tablename = &construct_table_path('managers.tab');
329: if (!open (MANAGERS, $tablename)) {
330: print STDERR "No managers.tab table. Could not verify host is a manager\n";
331: return;
332: }
333: while(my $host = <MANAGERS>) {
334: chomp($host);
335: next if ($host =~ /^\#/);
336: if ($host eq $currhost) {
337: $canmanage = 1;
338: last;
339: }
340: }
341: close(MANAGERS);
342: return $canmanage;
343: }
344: #---------------------------------------------------------------------------------
345: #
346: # Program entry point. Decode the subcommand from the args array and
347: # dispatch to the appropriate command processor.
348: #
349:
350: if ($< != 0) { # Am I root?
351: print('You must be root in order to run clusteradmin.'.
352: "\n");
353: exit(-1);
354: }
355:
356: my $argc = scalar(@ARGV);
357: if ($argc == 0) {
358: print STDERR "Missing subcommand\n";
359: &usage();
360: exit(-1);
361: }
362:
363: if (!&is_manager()) {
364: print STDERR 'Script needs to be run from a server designated as a "Manager" in the LON-CAPA cluster'."\n";
365: exit(-1);
366: }
367:
368: my $subcommand = shift(@ARGV); # argv now the tail.
369:
370: if (!&dispatch_command($subcommand, \@ARGV)) {
371: exit(0);
372: } else {
373: exit(-1);
374: }
375:
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