Configuring SQL for High Availability in Terraform

Hello All, a short post this week, but as we talk about availability, chaos engineering, etc. One of the most common data elements I see out there is SQL, and Azure SQL. SQL is a prevelant and common data store, it’s everywhere you look.

Given that, many shops are implementing infrastructure-as-code to manage configuration drift and provide increased resiliency for their applications. Which is definitely a great way to do that. The one thing that I’ve had a couple of people talk to me about that isn’t clear…how can I configure geo-replication in TerraForm.

This actually built into the TerraForm azure rm provider, and can be done with the following code:

provider "azurerm" {
    subscription_id = ""
    features {
    key_vault {
      purge_soft_delete_on_destroy = true
    }
  }
}

data "azurerm_client_config" "current" {}

resource "azurerm_resource_group" "rg" {
  name     = "sqlpoc"
  location = "{region}"
}

resource "azurerm_sql_server" "primary" {
  name                         = "kmack-sql-primary"
  resource_group_name          = azurerm_resource_group.rg.name
  location                     = azurerm_resource_group.rg.location
  version                      = "12.0"
  administrator_login          = "sqladmin"
  administrator_login_password = "{password}"
}

resource "azurerm_sql_server" "secondary" {
  name                         = "kmack-sql-secondary"
  resource_group_name          = azurerm_resource_group.rg.name
  location                     = "usgovarizona"
  version                      = "12.0"
  administrator_login          = "sqladmin"
  administrator_login_password = "{password}"
}

resource "azurerm_sql_database" "db1" {
  name                = "kmackdb1"
  resource_group_name = azurerm_sql_server.primary.resource_group_name
  location            = azurerm_sql_server.primary.location
  server_name         = azurerm_sql_server.primary.name
}

resource "azurerm_sql_failover_group" "example" {
  name                = "sqlpoc-failover-group"
  resource_group_name = azurerm_sql_server.primary.resource_group_name
  server_name         = azurerm_sql_server.primary.name
  databases           = [azurerm_sql_database.db1.id]
  partner_servers {
    id = azurerm_sql_server.secondary.id
  }

  read_write_endpoint_failover_policy {
    mode          = "Automatic"
    grace_minutes = 60
  }
}

Now above TF, will deploy two database servers with geo-replication configured. The key part is the following:

resource "azurerm_sql_failover_group" "example" {
  name                = "sqlpoc-failover-group"
  resource_group_name = azurerm_sql_server.primary.resource_group_name
  server_name         = azurerm_sql_server.primary.name
  databases           = [azurerm_sql_database.db1.id]
  partner_servers {
    id = azurerm_sql_server.secondary.id
  }

  read_write_endpoint_failover_policy {
    mode          = "Automatic"
    grace_minutes = 60
  }
}

The important elements are “server_name” and “partner_servers”, this makes the connection to where the data is being replicated. And then the “read_write_endpoint_failover_policy” setups up the failover policy.