Set locale to C.UTF-8 in Docker containers for consistent behavior

Adds LANG and LC_ALL environment variables in the Dockerfile prolog
to prevent container behavior from depending on the host's locale.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: gfraiteur

Dockerfile

@@ -14,6 +14,10 @@ ENV TEMP=C:\Temp
 ENV TMP=C:\Temp
 ENV RUNNING_IN_DOCKER=TRUE
 
+# Set locale for consistent behavior regardless of host locale
+ENV LANG=C.UTF-8
+ENV LC_ALL=C.UTF-8
+
 # Add Windows PowerShell to PATH (pwsh added later by PowershellComponent)
 ENV PATH="C:\Windows\System32\WindowsPowerShell\v1.0;${PATH}"
 

Dockerfile.claude

@@ -14,6 +14,10 @@ ENV TEMP=C:\Temp
 ENV TMP=C:\Temp
 ENV RUNNING_IN_DOCKER=TRUE
 
+# Set locale for consistent behavior regardless of host locale
+ENV LANG=C.UTF-8
+ENV LC_ALL=C.UTF-8
+
 # Add Windows PowerShell to PATH (pwsh added later by PowershellComponent)
 ENV PATH="C:\Windows\System32\WindowsPowerShell\v1.0;${PATH}"
 

src/PostSharp.Engineering.BuildTools/Docker/PrologComponent.cs

@@ -1,41 +1,45 @@
-// Copyright (c) SharpCrafters s.r.o. See the LICENSE.md file in the root directory of this repository root for details.
-
-using System.IO;
-
-namespace PostSharp.Engineering.BuildTools.Docker;
-
-internal class PrologComponent : ContainerComponent
-{
-    public override string Name => "Prolog";
-
-    public override ContainerComponentKind Kind => ContainerComponentKind.Prolog;
-
-    public override void WriteDockerfile( TextWriter writer )
-    {
-        writer.WriteLine(
-            """
-            # escape=`
-
-            # This file is auto-generated by PostSharp.Engineering.
-
-            FROM mcr.microsoft.com/windows/servercore:ltsc2025
-
-            # The initial shell is Windows PowerShell (use full path to avoid HCS issues)
-            SHELL ["C:\\Windows\\System32\\WindowsPowerShell\\v1.0\\powershell.exe", "-Command"]
-
-            # Prepare environment
-            ENV PSExecutionPolicyPreference=Bypass
-            ENV POWERSHELL_UPDATECHECK=Off
-            ENV TEMP=C:\Temp
-            ENV TMP=C:\Temp
-            ENV RUNNING_IN_DOCKER=TRUE
-
-            # Add Windows PowerShell to PATH (pwsh added later by PowershellComponent)
-            ENV PATH="C:\Windows\System32\WindowsPowerShell\v1.0;${PATH}"
-
-            # Enable long path support
-            RUN Set-ItemProperty -Path 'HKLM:\SYSTEM\CurrentControlSet\Control\FileSystem' -Name 'LongPathsEnabled' -Value 1
-
-            """ );
-    }
+// Copyright (c) SharpCrafters s.r.o. See the LICENSE.md file in the root directory of this repository root for details.
+
+using System.IO;
+
+namespace PostSharp.Engineering.BuildTools.Docker;
+
+internal class PrologComponent : ContainerComponent
+{
+    public override string Name => "Prolog";
+
+    public override ContainerComponentKind Kind => ContainerComponentKind.Prolog;
+
+    public override void WriteDockerfile( TextWriter writer )
+    {
+        writer.WriteLine(
+            """
+            # escape=`
+
+            # This file is auto-generated by PostSharp.Engineering.
+
+            FROM mcr.microsoft.com/windows/servercore:ltsc2025
+
+            # The initial shell is Windows PowerShell (use full path to avoid HCS issues)
+            SHELL ["C:\\Windows\\System32\\WindowsPowerShell\\v1.0\\powershell.exe", "-Command"]
+
+            # Prepare environment
+            ENV PSExecutionPolicyPreference=Bypass
+            ENV POWERSHELL_UPDATECHECK=Off
+            ENV TEMP=C:\Temp
+            ENV TMP=C:\Temp
+            ENV RUNNING_IN_DOCKER=TRUE
+
+            # Set locale for consistent behavior regardless of host locale
+            ENV LANG=C.UTF-8
+            ENV LC_ALL=C.UTF-8
+
+            # Add Windows PowerShell to PATH (pwsh added later by PowershellComponent)
+            ENV PATH="C:\Windows\System32\WindowsPowerShell\v1.0;${PATH}"
+
+            # Enable long path support
+            RUN Set-ItemProperty -Path 'HKLM:\SYSTEM\CurrentControlSet\Control\FileSystem' -Name 'LongPathsEnabled' -Value 1
+
+            """ );
+    }
 }