Use slaveOk read in mongodump to allow dumping of secondaries. SERVER-3854.

jstests/tool/dumpsecondary.js

@@ -0,0 +1,31 @@
+var replTest = new ReplSetTest( {name: 'testSet', nodes: 2} );
+
+var nodes = replTest.startSet();
+replTest.initiate();
+
+var master = replTest.getMaster();
+db = master.getDB("foo")
+db.foo.save({a: 1000});
+replTest.awaitReplication();
+
+assert.eq( 1 , db.foo.count() , "setup" );
+
+var slaves = replTest.liveNodes.slaves;
+assert( slaves.length == 1, "Expected 1 slave but length was " + slaves.length );
+slave = slaves[0];
+
+runMongoProgram.apply(null, ['mongodump', '-h', slave.host, '--out', '/data/db/jstests_tool_dumpsecondary_external/'])
+
+db.foo.drop()
+
+assert.eq( 0 , db.foo.count() , "after drop" );
+
+runMongoProgram.apply(null, ['mongorestore', '-h', master.host, '/data/db/jstests_tool_dumpsecondary_external/'])
+
+assert.soon( "db.foo.findOne()" , "no data after sleep" );
+assert.eq( 1 , db.foo.count() , "after restore" );
+assert.eq( 1000 , db.foo.findOne().a , "after restore 2" );
+
+resetDbpath('/data/db/jstests_tool_dumpsecondary_external')
+
+replTest.stopSet(15)

tools/tool.cpp

@@ -402,7 +402,7 @@ namespace mongo {
             // findOne throws an AssertionException if it's not authenticated.
             if (_coll.size() > 0) {
                 // BSONTools don't have a collection
-                conn().findOne(getNS(), Query("{}"));
+                conn().findOne(getNS(), Query("{}"), 0, QueryOption_SlaveOk);
             }
             return;
         }