{"id":561,"date":"2018-02-10T19:20:17","date_gmt":"2018-02-10T11:20:17","guid":{"rendered":"https:\/\/www.techcoil.com\/blog\/?p=561"},"modified":"2018-02-19T16:49:20","modified_gmt":"2018-02-19T08:49:20","slug":"how-to-migrate-your-mongodb-database-instance-with-mongodump-mongorestore-tar-and-scp","status":"publish","type":"post","link":"https:\/\/www.techcoil.com\/blog\/how-to-migrate-your-mongodb-database-instance-with-mongodump-mongorestore-tar-and-scp\/","title":{"rendered":"How to migrate your MongoDB database instance with mongodump, mongorestore, tar and scp"},"content":{"rendered":"

Migration of MongoDB<\/a> database is part and parcel of DevOps<\/a>, especially when you are running your own projects. <\/p>\n

MongoDB provides us with two utilities for performing database migration - mongodump<\/code><\/a> and mongorestore<\/code><\/a>. <\/p>\n

A simple MongoDB database migration can be performed in 5 steps:<\/p>\n

    \n
  1. \nUse the mongodump<\/code> command to export the data of a MongoDB database instance as files in the source server's filesystem.<\/li>\n
  2. Use the tar<\/code> command to compress the exported files as a single .tar.gz<\/code> file in the source server's filesystem.<\/li>\n
  3. Use the scp<\/code> command to send the .tar.gz<\/code> file from the source server to the destination server.<\/li>\n
  4. Use the tar<\/code> command to decompress the .tar.gz<\/code> file at the destination server.<\/li>\n
  5. Use the mongorestore<\/code> to import the extracted files into the destination MongoDB database.<\/li>\n<\/ol>\n

    This post discusses how you can perform MongoDB database migration with utilities provided by MongoDB and most Linux servers.<\/p>\n

    Exporting data from MongoDB server with mongodump<\/h2>\n

    The way you run mongodump<\/code> depends on whether access control is turned on for your MongoDB server.<\/p>\n

    Exporting data from MongoDB server without access control<\/h3>\n

    When you have a MongoDB server listening at the default port of localhost, you run the following command to export the data from the MongoDB database instance, a_database<\/code><\/strong>, onto the server's file system.<\/p>\n

    \r\nmongodump --db a_database\r\n<\/pre>\n
    After the command completes, you will find a directory named as dump<\/code><\/strong> in the current working directory. Inside the dump<\/code><\/strong> directory, you will find the a_database<\/code><\/strong> directory. And inside the a_database<\/code> directory, you will find .bson<\/code> and .json<\/code> files that describe the contents of the MongoDB database instance that you are exporting data from.<\/p>\n
    Exporting data from MongoDB server with access control<\/h3>\n
    Suppose you have a MongoDB user account with the username auser<\/code><\/strong> and password apassword<\/code><\/strong> created inside the database admin<\/code><\/strong>, you run the following command to extract the data from the database instance a_database<\/code><\/strong> from the MongoDB server listening at the default port of localhost: <\/p>\n
    \r\nmongodump --username auser --password apassword \\\r\n--authenticationDatabase admin --db a_database\r\n<\/pre>\n
    As with the case of exporting data from a MongoDB server without access control, you will find similar output in the current working directory when the mongodump<\/code> command completes.<\/p>\n
    Make sure that the user that is able to read from the database, if not you will encounter the following error: <\/p>\n
    \r\nFailed: error connecting to db server: server returned error on SASL authentication step: Authentication failed.\r\n<\/pre>\n
    Using the tar command to compress the exported files as a single .tar.gz file in the source server's filesystem<\/h2>\n
    When we compress all the contents inside the dump directory into a single .tar.gz file, we can transfer the exported data over to the destination server's file system easily. You can use the tar<\/code> command to compress all the contents inside the dump<\/code> directory into a single .tar.gz<\/code> file:<\/p>\n
    \r\ntar -czvf dump.tar.gz dump\r\n<\/pre>\n
    When the command completes, you will be able to see the dump.tar.gz<\/code> file in your current working directory. The dump.tar.gz<\/code> file will contain the dump<\/code> directory along with its subdirectories and files.<\/p>\n
    Using the scp command to send the .tar.gz into the destination server<\/h2>\n
    If there is a SSH server running at your destination server, you can use the scp<\/code> command to send the dump.tar.gz<\/code><\/strong> file from your current working directory to the destination server. Suppose your destination server is reachable by the domain example.com<\/code><\/strong>, has a user account with username root<\/code><\/strong> and has a \/var\/receiving directory<\/code><\/strong>, you can run the following command to send your dump.tar.gz<\/code><\/strong> file to the destination server:<\/p>\n
    \r\nscp dump.tar.gz root@example.com:\/var\/receiving\/dump.tar.gz\r\n<\/pre>\n
    Using the tar command to decompress the single .tar.gz file back into output files generated by mongodump<\/h2>\n
    Once the file transfer is done, you can use the ssh<\/code> command to get into your destination server to extract the contents of dump.tar.gz:<\/p>\n
    \r\nssh root@example.com\r\n<\/pre>\n
    Once you had logged into the destination server, you can run the following commands to extract the dump<\/code><\/strong> directory from dump.tar.gz<\/code><\/strong>:<\/p>\n
    \r\ncd \/var\/receiving\r\ntar -zxvf dump.tar.gz\r\n<\/pre>\n
    After the command completes, you will find the output files generated by mongodump<\/code> at the \/var\/receiving<\/code><\/strong> folder.<\/p>\n
    Importing data into MongoDB server with mongorestore<\/h2>\n
    As with the case of exporting data from MongoDB server, the way you run mongorestore<\/code> depends on whether access control is turned on for your MongoDB.<\/p>\n
    Importing data into MongoDB server with no access control<\/h3>\n
    When you have a MongoDB server listening at the default port of localhost, you run the following command to import the data from the dump<\/code><\/strong> directory into the MongoDB database instance, a_database<\/code><\/strong>:<\/p>\n
    \r\nmongorestore --drop --db a_database dump\/a_database\r\n<\/pre>\n
    This command will drop all existing collections inside the MongoDB database instance a_database<\/code><\/strong> before populating the contents from dump\/a_database<\/code>. When the command completes, the MongoDB database instance at the destination server will contain the migrated data from the source server.<\/p>\n
    Importing data into MongoDB server with access control<\/h3>\n
    Suppose you have a MongoDB user account with the username auser<\/code><\/strong> and password apassword<\/code><\/strong> created inside the database admin<\/code><\/strong>, you run the following command to import the data from dump\/a_database<\/code><\/strong> into the MongoDB server listening at the default port of localhost: <\/p>\n
    \r\nmongorestore --drop --db a_database --username auser \r\n\\ --password apassword --authenticationDatabase admin dump\/a_database\r\n<\/pre>\n
    Similar to the case of importing data into the MongoDB server without access control, the command will drop all existing collections inside the MongoDB database instance a_database<\/code> before populating the contents from dump\/a_database<\/code>. After the command completes, the MongoDB database instance at the destination server will contain the migrated data from the source server.<\/p>\n
    Make sure that the user that is able to write to the database, if not you will encounter the following error: <\/p>\n
    \r\nFailed: error connecting to db server: server returned error on SASL authentication step: Authentication failed.\r\n<\/pre>\n\n