Code For Food

Author: admin

  • MongoDB restore DB from MMS backup on shard clusters with different IPs than original shard

    When restore shards using MongoDB MMS backup files, if the new shard IP addresses are not the same as the IPs from where you do backup, MongoDB will raise the error “11002 exception: socket exception [CONNECT_ERROR] for <shard id/ip:port>” since the old IPs is stored in config server DB.

    Solution: Open a shell to MongoDB config server(s) and update the shard cluster IP in config DB:

    use config;
    db.shards.find()
    db.shards.update({_id: “shard_id”}, {$set: {“host”: “shard_id/new_ip:port”}} })

  • MongoDB error can’t add shard because a local database ‘test’ exists in another shard

    Error: When add shard with sh.addShard(), if new shard contains a DB with the same name as in previously added shards, MongoDB can’t automatically merge them:

    errmsg” : “can’t add shard server2:27017 because a local database ‘test’ exists in another shard000:server1:27017

    Solutions: mongodump the data on new shard, then drop that database and addShard. After that you can import the dump data using mongorestore

  • PHP cURL error code 60 SSL certificate problem self signed certificate in certificate chain

    Error: When using PHP curl_exec() to a site with https and self signed certificate (which should be likely a staging site, not a production site)

    Error code 60 SSL certificate problem: self signed certificate in certificate chain

    Solution:

    Since it is staging environment, we can completely ignore the certificate verification:

    curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);

  • PHP cURL error code 7 failed to connect

    Error code 7 (CURLE_COULDNT_CONNECT) when calling curl_exec()

    $ch = curl_init("http://www.google.com");    
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);
$data = curl_exec($ch);
print($data); // false
print(curl_error($ch)); // Failed to connect to www.google.com 80
print(curl_errno($ch)); // 7

    Solution:

    1. Check your internet connection

    2. Check your firewall

    3. Add your proxy if you are connecting through proxy:

    $proxy = “192.168.1.1:8080”;
    curl_setopt($ch, CURLOPT_PROXY, $proxy);

  • Extract tar gz without the parent folder

    Use –strip 1

    tar -xvf ZendFramework-1.7.2.tar.gz --strip 1

  • MongoDB Replica Set STARTUP2 error initial sync need a member to be primary or secondary to do our initial sync

    Error: MongoDB replica set stuck in STARTUP2 status with no replica becoming PRIMARY

     error initial sync need a member to be primary or secondary to do our initial sync

    Cause: You accidentally delete the local.* files in MongoDB DB path on one or multiple but not all replicas

    Solution: Stop all replicas, delete local.* on all replicas, and then start them and redo the rs.initiate() and rs.add() command from any replica member.

  • Centos Linux limit a shell download bandwidth

    Use trickle

    sudo yum install trickle
    trickle -d <kB/s for download> -u <kB/s for upload> bash

  • Install telnet client on Windows

    • Open a command prompt window. Click Start, type cmd in the Start Search box, and then press ENTER.
    • Type the following command: 
      pkgmgr /iu:"TelnetClient"

  • AuthenticationFailed MONGODB-CR credentials missing in the user document

    Error Description: When you are using MongoDB 3.0 and decide to use MONGODB-CR as password authentification mechanism instead of the default SCRAM-SHA-1 (or maybe MONGODB-CR is not your choice but is your legacy PHP/Java/Ruby driver support), the new user you create don’t have MONGODB-CR credentials as expected:

    use admin
    db.system.users.findOne({user: “”admin”,”})
    {
    “_id” : “admin.admin”,
    “user” : “admin”,
    “db” : “admin”,
    “credentials” : {
    “SCRAM-SHA-1” : {
    “iterationCount” : 10000,
    “salt” : “FPnmqmCI04KHJVZunfaI2Q==”,
    “storedKey” : “i+jvORcFsnx6CXt0Bd924e2f804=”,
    “serverKey” : “PQHG8nYYcJTjFEClqjFRZ8PTLTA=”
    },
    “MONGODB-CR” : “8aab8902fd862afad8064b73bd149d00”
    },
    “roles” : [
    {
    “role” : “userAdminAnyDatabase”,
    “db” : “admin”
    }
    ]
    }

    Cause: authSchemaVersion is set  to “5” and only SCRAM credentials will be generated in MongoDB 3.0:

    use admin
    db.system.version.find()
    { “_id” : “authSchema”, “currentVersion” : 5 }

    Solution: Restart mongod/mongos while disable –auth, then change authSchemaVersion to “3” to support MONGODB-CR. See https://jira.mongodb.org/browse/SERVER-17459

    use admin
    db.system.version.update({ “_id” : “authSchema”},{$set: {“currentVersion” : 3} })

  • MongoDB PHP Exception: Can’t connect over SSL, is mongod running with SSL?

    Error:Connect to MongoClient using SSL = true

    $mc = new MongoClient("mongodb://server1", array("ssl" => true));

    Cause: Your mongod instance is running but not properly configured with ssl.