‍Step 1: Copy the curl Command from the UI
‍On the Create a new replicaset (Master) screen, click { REST API }. The following example is copied:

curl -v \
  -H "Authorization: Bearer <YOUR_JWT_TOKEN>" \
  -H "Content-Type: application/json" \
  -H "Accept: application/json" \
  -d '{
    "host": {
      "name":         "<MONGO_HOST_IP>",
      "ssh_port":     <SSH_PORT>,
      "username":     "<SSH_USERNAME>",
      "password":     "<SSH_PASSWORD>",
      "private_key":  "<OPTIONAL_PRIVATE_KEY_CONTENT>"
    },
    "cluster": {
      "name":         "<CLUSTER_NAME>"
    },
    "ex_params": {
      "replicaset_name": "<REPLICASET_NAME>",
      "repository":      "<BACKUP_REPOSITORY>",
      "ssl":             false
    },
    "name":              "<NODE_NAME>",
    "auto_delete":       false,
    "version":           "<MONGODB_VERSION>",
    "auto_delete_days":  1,
    "port":              <MONGO_PORT>,
    "sizing":            "SMALL",
    "dir_123Cluster":    "<DATA_DIRECTORY>",
    "drop_inventories":  false,
    "database_user":     "<DB_ADMIN_USER>",
    "database_pwd":      "<DB_ADMIN_PASSWORD>",
    "rest_api":          true
  }' \
  <API_BASE_URL>/create_mongo_master/

Step 2: Parse the curl Command

• Authorization header
  Extract your JWT token from Bearer <YOUR_JWT_TOKEN>.
• Content-Type & Accept
  Preserve both application/json headers.
• Payload fields
  • host.name / host.ssh_port / host.username / host.password / host.private_key
  • cluster.name
  • ex_params.replicaset_name / ex_params.repository / ex_params.ssl
  • name (node identifier)
  • auto_delete / auto_delete_days
  • version / port / sizing / dir_123Cluster / drop_inventories
  • database_user / database_pwd
  • rest_api
• Endpoint
  • Base URI: <API_BASE_URL>
  • Resource path: /create_mongo_master/

Step 3: Translate into Terraform

• Create directory & file

integration/
└── terraform/
    └── create_replicaset_master/
        └── main.tf

• Provider block

// Terraform configuration for provisioning a MongoDB replicaset master node in 123cluster
terraform {
  required_providers {
    restapi = {
      source  = "Mastercard/restapi"
      version = "1.19.1" // Pin provider version for consistency and reproducibility
    }
  }
}

/*
  REST API provider configuration:
  - uri: Base endpoint for 123cluster API requests.
  - headers: Authentication and content negotiation for REST API.
  - write_returns_object: Ensures outputs are object-typed for further usage.
  - debug: Enables detailed logging for troubleshooting.
  - HTTP methods: POST for create/update/destroy as required by the API.
*/
provider "restapi" {
  uri                  = "<API_BASE_URL>"
  write_returns_object = true
  debug                = true
  headers = {
    Authorization = "Bearer <YOUR_JWT_TOKEN>" // Use a valid JWT token for API authentication
    Content-Type  = "application/json"
    Accept        = "application/json"
  }
  create_method  = "POST"
  update_method  = "POST"
  destroy_method = "POST"
}

• Variable declarations

/*
  Input variables for all relevant parameters.
  - Facilitates reuse across environments and automation in CI/CD pipelines.
*/

variable "mongo_host_ip" {
  description = "IP address of the MongoDB host"
  type        = string
  default     = "<MONGO_HOST_IP>"
}

variable "ssh_port" {
  description = "SSH port for initial host setup"
  type        = number
  default     = <SSH_PORT>
}

variable "ssh_user" {
  description = "SSH username"
  type        = string
  default     = "<SSH_USERNAME>"
}

variable "ssh_password" {
  description = "SSH password"
  type        = string
  default     = "<SSH_PASSWORD>"
}

variable "cluster_name" {
  description = "Name of the new MongoDB replicaset cluster"
  type        = string
  default     = "<CLUSTER_NAME>"
}

variable "replicaset_name" {
  description = "Internal replicaset identifier"
  type        = string
  default     = "<REPLICASET_NAME>"
}

variable "repository" {
  description = "Backup repository location"
  type        = string
  default     = "<BACKUP_REPOSITORY>"
}

variable "mongodb_version" {
  description = "Desired MongoDB version"
  type        = string
  default     = "<MONGODB_VERSION>"
}

variable "mongo_port" {
  description = "MongoDB service port"
  type        = number
  default     = <MONGO_PORT>
}

variable "data_directory" {
  description = "Data directory for MongoDB files"
  type        = string
  default     = "<DATA_DIRECTORY>"
}

variable "database_user" {
  description = "Database administrator username"
  type        = string
  default     = "<DB_ADMIN_USER>"
}

variable "database_pwd" {
  description = "Database administrator password"
  type        = string
  default     = "<DB_ADMIN_PASSWORD>"
}

• Resource definition

/*
  This resource maps all required parameters from variables into the API payload.
  - Uses jsonencode() for correct JSON formatting.
  - All fields from the reference curl command are represented and can be parameterized.
  - Handle sensitive values securely in real environments.
*/
resource "restapi_object" "create_master" {
  path = "/create_mongo_master/"
  data = jsonencode({
    host = {
      name        = var.mongo_host_ip
      ssh_port    = var.ssh_port
      username    = var.ssh_user
      password    = var.ssh_password
      private_key = "" // Optionally set var.private_key if required
    }
    cluster = {
      name = var.cluster_name
    }
    ex_params = {
      replicaset_name = var.replicaset_name
      repository      = var.repository
      ssl             = false // SSL can be parameterized if needed
    }
    name              = var.cluster_name // Node identifier; matches cluster name for master
    auto_delete       = false            // Prevents auto-deletion
    version           = var.mongodb_version
    auto_delete_days  = 1                // Retention period before auto-delete (if enabled)
    port              = var.mongo_port
    sizing            = "SMALL"          // Resource size; adjust as needed
    dir_123Cluster    = var.data_directory
    drop_inventories  = false            // Retain inventories after setup
    database_user     = var.database_user
    database_pwd      = var.database_pwd
    rest_api          = true             // Enables management via REST API
  })
}

• Output block‍

/*
  Output the full JSON response from the create_mongo_master API call.
  - Useful for logging, audit, or passing to downstream workflows.
*/
output "master_response" {
  description = "Raw JSON response from create_mongo_master"
  value       = restapi_object.create_master.data
}

Step 4: Initialize & Apply

cd integration/terraform/create_replicaset_master
# Initialize the Terraform working directory and download necessary providers
terraform init

# Apply the configuration, review the planned actions, and confirm execution
terraform apply

# Output the API response for logging or integration with other tools
terraform output master_response

‍

Additional Guidance & Best Practices

• Parameterization: By exposing all user-specific and environment-specific values as Terraform variables, the configuration is portable and reusable across multiple clusters and environments.
• Security: Store sensitive values (passwords, private keys, tokens) securely using environment variables, secrets management, or Terraform's sensitive variable types.
• CI/CD Integration: Integrate these steps into a CI/CD workflow for fully automated and consistent cluster provisioning.
• API Versioning: Always verify endpoint and payload requirements with the latest 123cluster API documentation to ensure compatibility.

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