fix(core): windows cloudwatch agent install script (#296)

Fixes #295

This fixes a bug that is preventing the deployment of any worker
instance that is using an AMI with a Windows OS.

packages/aws-rfdk/lib/core/scripts/powershell/configureCloudWatchAgent.ps1

@@ -16,62 +16,105 @@ param (
 
 $ErrorActionPreference = "Stop"
 
-$file = "$env:temp\amazon-cloudwatch-agent.msi"
+Write-Output "Starting CloudWatch installation and configuration script."
 
-# We hardcode the version number here since the verification below is tightly coupled with this specific version
+$is_cloudwatch_installed = $False
 try {
-  Read-S3Object -BucketName amazoncloudwatch-agent -Key windows/amd64/1.242486.0/amazon-cloudwatch-agent.msi -File $file -Region us-east-1
+  # If this command doesn't throw an error, we have the CloudWatch agent installed already
+  $status = & $Env:ProgramFiles\Amazon\AmazonCloudWatchAgent\amazon-cloudwatch-agent-ctl.ps1 -m ec2 -a status
+  $is_cloudwatch_installed = $True
+  Write-Output "Found CloudWatch agent already installed, skipping installation."
 } catch {
-  # Fallback to the latest version (this is the case when the above version is currently "latest")
-  Write-Output "Initial attempt to download Amazon CloudWatch agent failed. Falling back to the latest version."
+  Write-Output "CloudWatch agent is not already installed, proceeding with installation."
+}
+
+if (-Not $is_cloudwatch_installed) {
+  $cwa_installer = "$env:temp\amazon-cloudwatch-agent.msi"
   try {
-    Read-S3Object -BucketName amazoncloudwatch-agent -Key windows/amd64/latest/amazon-cloudwatch-agent.msi -File $file -Region us-east-1
+    Read-S3Object -BucketName amazoncloudwatch-agent -Key windows/amd64/latest/amazon-cloudwatch-agent.msi -File $cwa_installer -Region us-east-1
   } catch {
-    Write-Output "Failed to download CloudWatchAgent installer."
+    Write-Output "Failed to download CloudWatch agent installer."
     Exit 1
   }
-}
 
-# The below verification is tied to the version of the msi installer
-# If the installer version changes, the below verification could break and should be updated accordingly.
-# See https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/verify-CloudWatch-Agent-Package-Signature.html
-if (-Not $s) {
-  $sig = Get-AuthenticodeSignature $file
-  $status = $sig | Select-Object -ExpandProperty 'Status'
-  if ( $status -ne 'Valid' ) {
-    Write-Output "CloudWatchAgent installer does not have a valid signature."
+  $cwa_installer_sig = "$env:temp\amazon-cloudwatch-agent.msi.sig"
+  try {
+    Read-S3Object -BucketName amazoncloudwatch-agent -Key windows/amd64/latest/amazon-cloudwatch-agent.msi.sig -File $cwa_installer_sig -Region us-east-1
+  } catch {
+    Write-Output "Failed to download CloudWatch agent installer signature file."
     Exit 1
   }
 
-  # CA Certificate is:
-  #  - Subject: CN=DigiCert Timestamp Responder, O=DigiCert, C=US
-  #  - Valid: [Not After] 10/21/2024 7:00:00 PM
-  #  - Thumbprint: 614D271D9102E30169822487FDE5DE00A352B01D
-  $ca = $sig | Select-Object -ExpandProperty 'TimeStamperCertificate'
-  $ca_thumbprint = $ca | Select-Object -ExpandProperty 'Thumbprint'
-  if ( $ca_thumbprint -ne '614D271D9102E30169822487FDE5DE00A352B01D' ) {
-    Write-Output "CA Thumbprint failed verification. Has the CA certificate been changed? If so, then please submit a PR to fix this."
-    Write-Output $( $ca | Format-List )
-    Exit 1
-  }
+  if (-Not $s) {
+    $gpg_keyring = "$env:temp\keyring.gpg"
 
-  # Amazon.com certificate is:
-  #  - Subject: 'CN=Amazon.com Services LLC, OU=Software Services, O=Amazon.com Services LLC, L=Seattle, S=Washington, C=US'
-  #  We do not check the Thumbprint because it will change when the certificate is rotated. This seems to be yearly.
-  $cert = $sig | Select-Object -ExpandProperty 'SignerCertificate'
-  $cert_subject = $cert | Select-Object -ExpandProperty 'Subject'
-  if ( $cert_subject -ne 'CN=Amazon.com Services LLC, OU=Software Services, O=Amazon.com Services LLC, L=Seattle, S=Washington, C=US' ) {
-    Write-Output "Amazon.com is not the issuer of this installer. If this is the correct then please submit a PR to fix this."
-    Write-Output $( $cert | Format-List )
-    Exit 1
+    # Download GPG
+    $gpg_installer = "$env:temp\gnupg-w32-2.2.27_20210111.exe"
+    wget https://gnupg.org/ftp/gcrypt/binary/gnupg-w32-2.2.27_20210111.exe -OutFile $gpg_installer
+
+    # Verify GPG
+    $gpg_sig = Get-AuthenticodeSignature $gpg_installer
+    $status = $gpg_sig | Select-Object -ExpandProperty 'Status'
+    if ( $status -ne 'Valid' ) {
+      Write-Output "GPG installer does not have a valid signature."
+      Exit 1
+    }
+    $sha256_expected = '5D89E239790822711EAE2899467A764879D21440AB68E9413452FA96CEDEBA50'
+    $sha256 = Get-FileHash $gpg_installer -Algorithm SHA256
+    if ( $sha256 -inotmatch $sha256_expected) {
+      Write-Output "GPG failed checksum verification. Expected sha256 to equal $sha256_expected but got:"
+      Write-Output $sha256
+      Exit 1
+    }
+
+    # Install GPG
+    Start-Process -Wait -FilePath $gpg_installer -ArgumentList "/S /v/qn" -PassThru
+
+    # Refresh the PATH so gpg is available
+    $env:Path = [System.Environment]::GetEnvironmentVariable("Path","Machine")
+
+    # Download Amazon's public key and import it to GPG's keyring
+    $cloudwatch_pub_key = "$env:temp\amazon-cloudwatch-agent.gpg"
+    Read-S3Object -BucketName amazoncloudwatch-agent -Key assets/amazon-cloudwatch-agent.gpg -File $cloudwatch_pub_key -Region us-east-1
+    gpg --no-default-keyring --keyring $gpg_keyring --import $cloudwatch_pub_key
+
+    # Verify that the imported key has the correct fingerprint
+    $fingerprint = '937616F3450B7D806CBD9725D58167303B789C72'
+    $keys = gpg --no-default-keyring --keyring $gpg_keyring -k
+    $keys = ($keys | Out-String).Trim() -replace "\r", "" -replace "\n", "" -replace "\[", "" -replace "\]", ""
+
+    if ($keys -inotlike "*$fingerprint*") {
+      Write-Output "Expected CloudWatch agent's public key to equal $fingerprint but got:"
+      Get-Content $keys
+      Exit 1
+    }
+
+    # Now that we have the public key on the keyring, we can use gpg to perform the verification of the installer with the signature file.
+    # We will write the output to file and then perform a text search to make sure there's a good signature present in it
+    $gpg_output = "$env:temp\gpg_out.txt"
+    Start-Process gpg -ArgumentList " --no-default-keyring --keyring $gpg_keyring --verify $cwa_installer_sig $cwa_installer" `
+    -wait -NoNewWindow -PassThru -RedirectStandardError $gpg_output
+
+    $verification = Select-String -Path $gpg_output -Pattern 'Good signature from "Amazon CloudWatch Agent"' | Select-Object -ExpandProperty Matches -First 1
+    if (-Not $verification) {
+      Write-Output "Could not verify CloudWatch agent's signature file with GPG."
+      Get-Content $gpg_output
+      Exit 1
+    }
   }
-}
 
-# Install the agent
-Start-Process "msiexec.exe" -ArgumentList "/i $env:temp\amazon-cloudwatch-agent.msi /qn /norestart" -Wait -Passthru -NoNewWindow
+  # Install the agent
+  Start-Process "msiexec.exe" -ArgumentList "/i $cwa_installer /qn /norestart" -Wait -Passthru -NoNewWindow
+
+  Remove-Item -Path $cloudwatch_pub_key -Force
+  Remove-Item -Path $cwa_installer -Force
+  Remove-Item -Path $cwa_installer_sig -Force
+  Remove-Item -Path $gpg_installer -Force
+  Remove-Item -Path $gpg_output -Force
+  Remove-Item -Path $gpg_keyring -Force
+}
 
 # Configure the agent from an ssm parameter-store parameter.
 & 'C:/Program Files/Amazon/AmazonCloudWatchAgent/amazon-cloudwatch-agent-ctl.ps1' -a append-config -m ec2 -c ssm:$ssmParameterName -s
 
-Remove-Item -Path $file -Force
-Write-Output "CloudWatchAgent has been successfully installed and configured"
+Write-Output "CloudWatch agent has been successfully installed and configured"

packages/aws-rfdk/lib/core/test/asset-constants.ts

@@ -13,8 +13,8 @@ export const CWA_ASSET_LINUX = {
 
 // ConfigureCloudWatchAgent.ps1
 export const CWA_ASSET_WINDOWS = {
-  Bucket: 'AssetParameters05415690a7593cdde72555787eaac1d784dd3173e6083f23f83dc795bfe1741fS3Bucket0E53698F',
-  Key: 'AssetParameters05415690a7593cdde72555787eaac1d784dd3173e6083f23f83dc795bfe1741fS3VersionKeyE92C9DEB',
+  Bucket: 'AssetParameters07782992a7a530f8752341d912c95ba2fe3f0a212d413b5d097959c51ea8e2ecS3Bucket95C4512E',
+  Key: 'AssetParameters07782992a7a530f8752341d912c95ba2fe3f0a212d413b5d097959c51ea8e2ecS3VersionKey3DB883AC',
 };
 
 // mountEbsBlockVolume.sh + metadataUtilities.sh + ec2-certificates.crt