PowerShell Scripting to Replicate Elasticsearch Data to MySQL

The CData Cmdlets for Elasticsearch offer live access to Elasticsearch data from within PowerShell. Using PowerShell scripts, you can easily automate regular tasks like data replication. This article will walk through using the CData Cmdlets for Elasticsearch and the CData Cmdlets for MySQL in PowerShell to replicate Elasticsearch data to a MySQL database.

After obtaining the needed connection properties, accessing Elasticsearch data in PowerShell and preparing for replication consists of four basic steps.

Set the Server and Port connection properties to connect. To authenticate, set the User and Password properties, PKI (public key infrastructure) properties, or both. To use PKI, set the SSLClientCert, SSLClientCertType, SSLClientCertSubject, and SSLClientCertPassword properties.

The data provider uses X-Pack Security for TLS/SSL and authentication. To connect over TLS/SSL, prefix the Server value with 'https://'. Note: TLS/SSL and client authentication must be enabled on X-Pack to use PKI.

Once the data provider is connected, X-Pack will then perform user authentication and grant role permissions based on the realms you have configured.

Collecting Elasticsearch Data

1. Install the module:

   Install-Module ElasticsearchCmdlets

2. Connect to Elasticsearch:

   $elasticsearch = Connect-Elasticsearch -Server $Server -Port $Port -User $User -Password $Password

3. Retrieve the data from a specific resource:

   $data = Select-Elasticsearch -Connection $elasticsearch -Table "Orders"

   You can also use the Invoke-Elasticsearch cmdlet to execute pure SQL-92 statements:

   $data = Invoke-Elasticsearch -Connection $elasticsearch -Query 'SELECT * FROM Orders WHERE ShipCity = @ShipCity' -Params @{'@ShipCity'='New York'}

4. Save a list of the column names from the returned data.

   $columns = ($data | Get-Member -MemberType NoteProperty | Select-Object -Property Name).Name

Inserting Elasticsearch Data into the MySQL Database

With the data and column names collected, you are ready to replicate the data into a MySQL database.

1. Install the module:

   Install-Module MySQLCmdlets

2. Connect to MySQL, using the server address and port of the MySQL server, valid user credentials, and a specific database with the table in which the data will be replicated:

   $mysql = Connect-MySQL -User $User -Password $Password -Database $Database -Server $Server -Port $Port

3. Loop through the Elasticsearch data, store the values, and use the Add-MySQL cmdlet to insert the data into the MySQL database, one row at a time. In this example, the table will need to have the same name as the Elasticsearch resource (Orders) and to exist in the database.

   $data | % { $row = $_ $values = @() $columns | % { $col = $_ $values += $row.$($col) } Add-MySQL -Connection $mysql -Table "Orders" -Columns $columns -Values $values }

You have now replicated your Elasticsearch data to a MySQL database. This gives you freedom to work with Elasticsearch data in the same way that you work with other MySQL tables, whether that is performing analytics, building reports, or other business functions.

Notes

• Once you have connected to Elasticsearch and MySQL in PowerShell, you can pipe command results to perform the replication in a single line:

  Select-Elasticsearch -Connection $elasticsearch -Table "Orders" | % { $row = $_ $values = @() $columns | % { $col = $_ $values += $row.$($col) } Add-MySQL -Connection $mysql -Table "Orders" -Columns $columns -Values $values }

• If you wish to replicate the Elasticsearch data to another database using another PowerShell module, you will want to exclude the Columns, Connection, and Table columns from the data returned by the Select-Elasticsearch cmdlet since those columns are used to help pipe data from one CData cmdlet to another:

  $columns = ($data | Get-Member -MemberType NoteProperty | Select-Object -Property Name).Name | ? {$_ -NotIn @('Columns','Connection','Table')}