Sample ARM template to deploy a custom FreeBSD image generated from the Marketplace image

parameters.json

{
    "$schema": "https://schema.management.azure.com/schemas/2015-01-01/deploymentParameters.json#",
    "contentVersion": "1.0.0.0",
    "parameters": {
        "subnetName": {
            "value": null
        },
        "virtualNetworkName": {
            "value": null
        },
        "virtualMachineName": {
            "value": null
        },
        "virtualMachineSize": {
            "value": "Standard_B2s"
        },
        "adminUsername": {
            "value": "azure-user"
        },
        "adminPublicKey": {
            "value": null
        },
        "imageId": {
            "value": null
        }
    }
}

template.json

{
    "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
    "contentVersion": "1.0.0.0",
    "parameters": {
        "location": {
            "type": "String",
            "defaultValue": "[resourceGroup().location]"
        },
        "networkInterfaceName": {
            "type": "String",
            "defaultValue": "[concat(parameters('virtualMachineName'), uniqueString(resourceGroup().id))]"
        },
        "subnetName": {
            "type": "String"
        },
        "virtualNetworkName": {
            "type": "String"
        },
        "virtualMachineName": {
            "type": "String"
        },
        "osDiskType": {
            "type": "String",
            "defaultValue": "Premium_LRS"
        },
        "virtualMachineSize": {
            "type": "String"
        },
        "adminUsername": {
            "type": "String"
        },
        "adminPublicKey": {
            "type": "SecureString"
        },
        "diagnosticsStorageAccountName": {
            "type": "String",
            "defaultValue": "[concat('bootdiag', uniqueString(resourceGroup().id))]"
        },
        "imageId": {
            "type": "string"
        }
    },
    "variables": {
        "vnetId": "[resourceId('Microsoft.Compute/virtualNetworks', parameters('virtualNetworkName'))]",
        "subnetRef": "[concat(variables('vnetId'), '/subnets/', parameters('subnetName'))]"
    },
    "resources": [
        {
            "type": "Microsoft.Network/networkInterfaces",
            "apiVersion": "2019-07-01",
            "name": "[parameters('networkInterfaceName')]",
            "location": "[parameters('location')]",
            "dependsOn": [],
            "properties": {
                "ipConfigurations": [
                    {
                        "name": "ipconfig1",
                        "properties": {
                            "subnet": {
                                "id": "[variables('subnetRef')]"
                            },
                            "privateIPAllocationMethod": "Dynamic"
                        }
                    }
                ]
            }
        },
        {
            "name": "[parameters('diagnosticsStorageAccountName')]",
            "type": "Microsoft.Storage/storageAccounts",
            "apiVersion": "2019-06-01",
            "location": "[resourceGroup().location]",
            "kind": "StorageV2",
            "sku": {
                "name": "Standard_LRS",
                "tier": "Standard"
            }
        },
        {
            "type": "Microsoft.Compute/virtualMachines",
            "apiVersion": "2019-07-01",
            "name": "[parameters('virtualMachineName')]",
            "location": "[parameters('location')]",
            "dependsOn": [
                "[concat('Microsoft.Network/networkInterfaces/', parameters('networkInterfaceName'))]",
                "[parameters('diagnosticsStorageAccountName')]"
            ],
            "identity": {
                "type": "systemAssigned"
            },
            "plan": {
                "name": "12_1-release",
                "publisher": "thefreebsdfoundation",
                "product": "freebsd-12_1"
            },
            "properties": {
                "hardwareProfile": {
                    "vmSize": "[parameters('virtualMachineSize')]"
                },
                "storageProfile": {
                    "osDisk": {
                        "createOption": "fromImage",
                        "managedDisk": {
                            "storageAccountType": "[parameters('osDiskType')]"
                        }
                    },
                    "imageReference": {
                        "id": "[parameters('imageId')]"
                    }
                },
                "networkProfile": {
                    "networkInterfaces": [
                        {
                            "id": "[resourceId('Microsoft.Network/networkInterfaces', parameters('networkInterfaceName'))]"
                        }
                    ]
                },
                "osProfile": {
                    "computerName": "[parameters('virtualMachineName')]",
                    "adminUsername": "[parameters('adminUsername')]",
                    "linuxConfiguration": {
                        "disablePasswordAuthentication": true,
                        "ssh": {
                            "publicKeys": [
                                {
                                    "path": "[concat('/home/', parameters('adminUsername'), '/.ssh/authorized_keys')]",
                                    "keyData": "[parameters('adminPublicKey')]"
                                }
                            ]
                        }
                    }
                },
                "diagnosticsProfile": {
                    "bootDiagnostics": {
                        "enabled": true,
                        "storageUri": "[concat('https://', parameters('diagnosticsStorageAccountName'), '.blob.core.windows.net/')]"
                    }
                }
            }
        }
    ],
    "outputs": {
        "adminUsername": {
            "type": "String",
            "value": "[parameters('adminUsername')]"
        }
    }
}