Configuring the rollback_hosts_win.ps1 Script

Modify the configuration in the example script to meet you specific requirements.

Prerequisites

You have completed all preparations.

Procedure

Create a file named rollback_hosts_win.ps1 on the server where the script is executed, and copy the following script content to the file.

# Configuration
# Path to the CSV file with server information. Must exist before running the script.
$csvFile = "C:\Users\Public\target_servers.csv"  # Manually configure
 
# Directory for storing log files. Will be created if it doesn't exist.
$logDir = "C:\Users\Public\Hosts_Script_Logs"  # Automatically created
 
# Log file for general run information.
$runLog = Join-Path $logDir "run.log"  # Automatically created
 
# Log file for error messages.
$errorLog = Join-Path $logDir "error.log"  # Automatically created
 
# Log file for summary information.
$summaryLog = Join-Path $logDir "summary.log"  # Automatically created
 
 
# Initialize log directory and files
function Initialize-Logs {
    if (-not (Test-Path $logDir)) {
        New-Item -Path $logDir -ItemType Directory
    }
    Add-Content -Path $runLog -Value "========================================"
    Add-Content -Path $runLog -Value "[INFO] $(Get-Date -Format 'yyyy-MM-dd HH:mm:ss') - Starting new restore execution"
    Add-Content -Path $runLog -Value "========================================"
 
    Add-Content -Path $errorLog -Value "========================================"
    Add-Content -Path $errorLog -Value "[INFO] $(Get-Date -Format 'yyyy-MM-dd HH:mm:ss') - Starting new restore execution"
    Add-Content -Path $errorLog -Value "========================================"
 
    Add-Content -Path $summaryLog -Value "========================================"
    Add-Content -Path $summaryLog -Value "[INFO] $(Get-Date -Format 'yyyy-MM-dd HH:mm:ss') - Starting new restore execution"
    Add-Content -Path $summaryLog -Value "========================================"
}
 
# Log info function
function Log-Info {
    param (
        [string]$message
    )
    $logMessage = "[INFO] $(Get-Date -Format 'yyyy-MM-dd HH:mm:ss') - $message"
    Add-Content -Path $runLog -Value $logMessage
    Write-Output $logMessage
}
 
# Log error function
function Log-Error {
    param (
        [string]$message
    )
    $logMessage = "[ERROR] $(Get-Date -Format 'yyyy-MM-dd HH:mm:ss') - $message"
    Add-Content -Path $runLog -Value $logMessage
    Add-Content -Path $errorLog -Value $logMessage
    Write-Output $logMessage
}
 
# Read server information from CSV file
function Read-ServersFromCSV {
    param (
        [string]$csvFile
    )
    if (-not (Test-Path $csvFile)) {
        Log-Error "CSV file '$csvFile' not found."
        exit 1
    }
    return Import-Csv -Path $csvFile
}
 
# Add to TrustedHosts
function Add-ToTrustedHosts {
    param (
        [string]$ip
    )
    # Check current TrustedHosts list
    $trustedHostsPath = "WSMan:\localhost\Client\TrustedHosts"
    $trustedHosts = (Get-Item $trustedHostsPath).Value
 
    if ($trustedHosts -eq $null -or $trustedHosts -eq "") {
        # Set the initial trusted host
        Set-Item $trustedHostsPath -Value $ip -Force
        Log-Info "Set initial TrustedHosts value to $ip"
    } elseif ($trustedHosts -notlike "*$ip*") {
        # Add new IP to TrustedHosts if not already present
        $updatedTrustedHosts = if ($trustedHosts -eq "*") { $ip } else { "$trustedHosts,$ip" }
        try {
            Set-Item $trustedHostsPath -Value $updatedTrustedHosts -Force
            Log-Info "Added $ip to TrustedHosts"
        } catch {
            Log-Error "Failed to add $ip to TrustedHosts: $_"
        }
    } else {
        Write-Host "TrustedHosts list already contains IP $ip."
    }
}
 
# Initialize log files
Initialize-Logs
 
# Verify CSV file
if (-not (Test-Path $csvFile)) {
    Log-Error "CSV file '$csvFile' not found."
    exit 1
}
 
# Read server information from CSV file
$servers = Read-ServersFromCSV -csvFile $csvFile
 
# Counters for success and failure
$successCount = 0
$failureCount = 0
$failedServers = @()
 
# Remote script block
$remoteScriptBlock = {
    param ()
 
    $hostsFilePath = 'C:\Windows\System32\drivers\etc\hosts'
 
    # Read the file content
    $content = Get-Content -Path $hostsFilePath
 
    # Initialize flag
    $inBlock = $false
    $newContent = @()
 
    # Traverse file content
    foreach ($line in $content) {
        if ($line -match '#Migration-proxy-start') {
            $inBlock = $true
        }
        if (-not $inBlock) {
            $newContent += $line
        }
        if ($line -match '#Migration-proxy-end') {
            $inBlock = $false
            continue
        }
    }
 
    # Remove trailing empty lines
    while ($newContent[-1] -eq '') {
        $newContent = $newContent[0..($newContent.Count - 2)]
    }
 
    # Write the new content back to the file
    $newContent | Set-Content -Path $hostsFilePath
 
    Write-Output 'Successfully restored hosts file on remote server.'
}
 
# Main script logic
Log-Info "Script execution started."
 
foreach ($server in $servers) {
    $username = $server.username
    $ip = $server.ip
    $password = $server.password
 
    if (-not $username -or -not ${ip} -or -not $password) {
        Log-Error "Invalid server entry: $username, ${ip}, $password. Skipping."
        continue
    }
 
    Log-Info "Starting restore for $username@${ip}"
 
    $securePassword = ConvertTo-SecureString $password -AsPlainText -Force
    $credential = New-Object System.Management.Automation.PSCredential ($username, $securePassword)
 
    Add-ToTrustedHosts -ip $ip
 
    try {
        $session = New-PSSession -ComputerName ${ip} -Credential $credential -ErrorAction Stop
 
        Invoke-Command -Session $session -ScriptBlock $remoteScriptBlock
 
        Remove-PSSession -Session $session
        Log-Info "Restored hosts on ${ip} successfully"
        $successCount++
    }
    catch {
        Log-Error "Failed to restore hosts on ${ip}: $_"
        $failedServers += "$username@${ip}"
        $failureCount++
    }
}
 
# Calculate failure and success percentages
$totalCount = $servers.Count
if ($totalCount -gt 0) {
    $failurePercentage = [math]::Round(($failureCount / $totalCount) * 100, 2)
    $successPercentage = [math]::Round(($successCount / $totalCount) * 100, 2)
} else {
    $failurePercentage = 0
    $successPercentage = 100
}
 
# Output summary result and log to file
$summaryContent = @"
========================================
[SUMMARY] $(Get-Date -Format 'yyyy-MM-dd HH:mm:ss') - Execution Rollback Summary
========================================
Total number of servers: $totalCount
Number of successful restores: $successCount
Number of failed restores: $failureCount
Failure rate: $failurePercentage%
Success rate: $successPercentage%
----------------------------------------
"@
 
if ($failedServers.Count -gt 0) {
    $summaryContent += "Failed servers:`n"
    foreach ($server in $failedServers) {
        $summaryContent += "  - $server`n"
    }
}
$summaryContent += "========================================"
 
# Output summary result to log file and terminal
$summaryContent | Add-Content -Path $summaryLog
Write-Output $summaryContent
Log-Info "Script execution completed. Check $summaryLog for summary."

Modify the following parameters in the script to meet your needs:
- $logDir = "C:\Users\Public\Hosts_Script_Logs"
  - Description: log directory, which is used to store run, error, and summary logs.
  - Default value: C:\Users\Public\Hosts_Script_Logs
  - Suggestion: Change the value to a directory for which the current user has the write permission.
  - Example: $logDir ="C:\Users\username\Documents\Hosts_Script_Logs"
- $csvFile = "C:\Users\Public\target_servers.csv"
  - Description: CSV file path. The file contains the source server information.
  - Default value: C:\Users\Public\target_servers.csv
  - Suggestion: Use an absolute path or a correct relative path. If the CSV file path changes, you need to update the path here.
  - Example: $csvFile = "C:\Users\username\Documents\servers.csv"
After the configuration items are modified and saved, open the PowerShell window as the administrator and run the following command to execute the script:
```
.\rollback_hosts_win.ps1
```
The script will output log information in the terminal window and generate a result report upon completion. You can view this report in the summary.log file in the directory specified by $logDir.