# I assume the 2 shard is running from Shard.txt
  # and Shard.txt is finished. 

  # We take liberties knowing no data is being written
  # and the shards are not in replicaa sets. 
  # This deals with the hardest part of 
  # retoring the shards. With replica sets for
  # shards it gets more complicated but this deal with
  # the theory if you get in a mess. 

  # You can take note of the shard setup if you wish and need to turn off balancer
mongo --quiet --eval 'sh.setBalancerState(false)'
mongo --quiet --eval 'sh.status()' | egrep '\-\->>|state|host' > /tmp/shard_setup.log1

  # Take backups
map="
s1:4001 to z1:5001
s2:4002 to z2:5002

replica name of c to d on config server. It may not be needed. 

"

rm -rf /tmp/mogno_temp_backups
mkdir -p /tmp/mongo_temp_backups/config
mkdir -p /tmp/mogno_temp_backups/s1
mkdir -p /tmp/mogno_temp_backups/s2

for i in chunks collections databases settings;
    do
      mongo --quiet --port 4003 --eval "db.$i.find()" config > /tmp/mongo_temp_backups/config_$i
    done

mongo --port 4001 --quiet --eval "db.system.version.find()" admin  > /tmp/mongo_temp_backups/s1_system
mongo --port 4002 --quiet --eval "db.system.version.find()" admin  > /tmp/mongo_temp_backups/s2_system
mongo --quiet --port 4003 --eval 'db.getCollection("version").find()' config > /tmp/mongo_temp_backups/config_version

mongodump --port 4003 -o /tmp/mongo_temp_backups/config -d config
mongodump --port 4001 -o /tmp/mongo_temp_backups/s1a -d admin
mongodump --port 4002  -o /tmp/mongo_temp_backups/s2a -d admin
mongodump --port 4001 -o /tmp/mongo_temp_backups/s1d -d shard_test
mongodump --port 4002  -o /tmp/mongo_temp_backups/s2d -d shard_test

killall mongod
killall mongos
killall mongo
sleep 2

  # You shouldn't have any mongo stuff running
ps auxw | grep mongo
jobs

  # Make the new data servers and mongo config server. 
  # We blow away the original databases, so we pray the backups are good. 
rm -rf mongo
mkdir -p mongo/e1 mongo/e2 mongo/e3 mongo/logs

  # Lets make the data servers and config servers start
mongod --shardsvr --dbpath mongo/e1 --smallfiles --oplogSize 10 --bind_ip 127.0.0.1 --port 5001 > mongo/logs/e1.log 2>&1  &
   #Now add a 2nd shard. 
mongod --shardsvr --dbpath mongo/e2 --smallfiles --oplogSize 10 --bind_ip 127.0.0.1 --port 5002 > mongo/logs/e2.log 2>&1  &
  # Start a mongo config server --- in the Sharding2 document, we will
  # have 3 in a replica set. 
mongod --configsvr --replSet z --dbpath mongo/e3 --smallfiles --oplogSize 10  --bind_ip 127.0.0.1 --port 5003 > mongo/logs/e3.log 2>&1  &
  # Stupid but single config server still has to be in a replica set. 
sleep 2
mongo --port 5003 --eval "rs.initiate({ _id: 'z', version: 1, members: [ {_id :0, host: 'localhost:5003' } ] })"
sleep 3

  # Start a mongos -- this connects to the mongod, since the default for a config server is 5003
mongos --configdb "z/127.0.0.1:5003" --bind_ip 127.0.0.1 > mongo/logs/ms_2.log 2>&1  &
sleep 5

  # Turn off the balaner.
mongo --quiet --eval 'sh.setBalancerState(false)'

steps="
1. add the shards
2. restore config server
3. change values in config server. 
   a. db.shards
   b. db.databases
   c. db.chunks -- partitions
   d. db.chunks -- cluster Id
   e. db.collections -- ObjectId
4. Kill config and mongos
5. Restore data servers -- without system.version
6. Start config and mongos
7. Check, insert, check again.  
"
  # 1
mongo --eval 'db.runCommand({addShard: "localhost:5001", name: "t1"})' admin
mongo --eval 'db.runCommand({addShard: "localhost:5002", name: "t2"})' admin

  #2 Do not drop the collections, we have ids that 
   # we have to delete, that can't be changed. easily. 
mongorestore  --port 5003 /tmp/mongo_temp_backups/config        -d config

  # 3a
#mongo --port 5003 --quiet --eval 'db.shards.insert({"_id" : "t1", "host" : "localhost:5001", "state" : 1})' config
#mongo --port 5003 --quiet --eval 'db.shards.insert({"_id" : "t2", "host" : "localhost:5002", "state" : 1})' config

mongo --port 5003 --quiet --eval 'db.shards.remove({_id: "s1"})' config
mongo --port 5003 --quiet --eval 'db.shards.remove({_id: "s2"})' config
  #3b
mongo --port 5003 --quiet --eval 'db.databases.update({"primary": "s1"}, {"primary": "t1", "partitioned" : true })' config
  #3c
mongo --port 5003 --quiet --eval 'db.chunks.update({"shard" : "s1"}, {$set: {"shard" : "t1"}})' config
mongo --port 5003 --quiet --eval 'db.chunks.update({"shard" : "s1"}, {$set: {"shard" : "t1"}})' config
mongo --port 5003 --quiet --eval 'db.chunks.update({"shard" : "s1"}, {$set: {"shard" : "t1"}})' config
mongo --port 5003 --quiet --eval 'db.chunks.update({"shard" : "s1"}, {$set: {"shard" : "t1"}})' config
mongo --port 5003 --quiet --eval 'db.chunks.update({"shard" : "s1"}, {$set: {"shard" : "t1"}})' config
mongo --port 5003 --quiet --eval 'db.chunks.update({"shard" : "s1"}, {$set: {"shard" : "t1"}})' config
mongo --port 5003 --quiet --eval 'db.chunks.update({"shard" : "s1"}, {$set: {"shard" : "t1"}})' config

mongo --port 5003 --quiet --eval 'db.chunks.update({"shard" : "s2"}, {$set: {"shard" : "t2"}})' config
mongo --port 5003 --quiet --eval 'db.chunks.update({"shard" : "s2"}, {$set: {"shard" : "t2"}})' config
mongo --port 5003 --quiet --eval 'db.chunks.update({"shard" : "s2"}, {$set: {"shard" : "t2"}})' config
mongo --port 5003 --quiet --eval 'db.chunks.update({"shard" : "s2"}, {$set: {"shard" : "t2"}})' config
mongo --port 5003 --quiet --eval 'db.chunks.update({"shard" : "s2"}, {$set: {"shard" : "t2"}})' config
mongo --port 5003 --quiet --eval 'db.chunks.update({"shard" : "s2"}, {$set: {"shard" : "t2"}})' config
mongo --port 5003 --quiet --eval 'db.chunks.update({"shard" : "s2"}, {$set: {"shard" : "t2"}})' config

  # 3d - this is complicated
myId=`mongo --quiet --port 5003 --eval 'var x = db.getCollection("version").findOne(); print (x.clusterId)' config`
echo "clusterId", $myId
echo "
db = db.getSiblingDB('config')
db.chunks.find().forEach(function(doc){
    doc.lastmodEpoch = $myId;
    db.chunks_new.insert(doc);
});
db.chunks.renameCollection('chunks_old');
db.chunks_new.renameCollection('chunks');
" > mongo/replace_chunks.js
mongo --port 5003 mongo/replace_chunks.js 

  # 3e
echo "
db = db.getSiblingDB('config')
db.collections.find().forEach(function(doc){
    doc.lastmodEpoch = $myId;
    db.collections_new.insert(doc);
});
db.collections.renameCollection('collections_old');
db.collections_new.renameCollection('collections');
" > mongo/replace_collections.js
mongo --port 5003 mongo/replace_collections.js
 
  #4
killall mongod
killall mongos
killall mongo
sleep 2

mongod --shardsvr --dbpath mongo/e1 --smallfiles --oplogSize 10 --bind_ip 127.0.0.1 --port 5001 > mongo/logs/e1.log 2>&1  &
mongod --shardsvr --dbpath mongo/e2 --smallfiles --oplogSize 10 --bind_ip 127.0.0.1 --port 5002 > mongo/logs/e2.log 2>&1  &
mongod --configsvr --replSet z --dbpath mongo/e3 --smallfiles --oplogSize 10  --bind_ip 127.0.0.1 --port 5003 > mongo/logs/e3.log 2>&1  &
sleep 10

  #5 
mongorestore --drop --port 5001 /tmp/mongo_temp_backups/s1 --nsExclude system.version
mongorestore --drop --port 5002 /tmp/mongo_temp_backups/s2 --nsExclude system.version

  #6
mongos --configdb "z/127.0.0.1:5003" --bind_ip 127.0.0.1 > mongo/logs/ms_2.log 2>&1  &
sleep 2


  # These databases that are sharded should exist on the target servers. 
  # You can ignore the local databases. 
mongo --quiet --eval 'db.databases.find()' config
mongo --quiet --eval "db.getMongo().getDBNames()" --port 5001
mongo --quiet --eval "db.getMongo().getDBNames()" --port 5002
  
  # save the config
mongo --quiet --eval 'sh.status()' | egrep '\-\->>|state|host' > /tmp/shard_setup.log2

  # compare the differences
diff  /tmp/shard_setup.log1  /tmp/shard_setup.log2
  # count the no of documents

mongo --port 5001 --quiet --eval 'db.no.count()' shard_test
mongo --port 5002 --quiet --eval 'db.no.count()' shard_test
mongo --quiet --eval 'db.no.count()' shard_test

mongo --quiet --eval 'db.no.insert({value:1.1})' shard_test
mongo --quiet --eval 'db.no.insert({value:900.1})' shard_test
mongo --quiet --eval 'db.no.insert({value:900.2})' shard_test

echo "Should detect some increases for all 3 below."
mongo --port 5001 --quiet --eval 'db.no.count()' shard_test
mongo --port 5002 --quiet --eval 'db.no.count()' shard_test
mongo --quiet --eval 'db.no.count()' shard_test


notes="
Notice I restored, the data mongod servers. You don't have to. 
If you can get the admin database settings, which I couldn't change
to be correct on another server, just back that up and restore on
your target server --- after everything. Its a little more
complicated. This demo is just to show it can be done. 
To make it efficient and other stuff, will take more steps. 
"