Alpine docker image does not obey local timezone anymore

[nalla]

Description

The release 6.0.0-rc.1 does not obey the local timezone information. This is a regression, see the following steps to reproduce

Steps to reproduce

private static void Main(string[] args)
{
	Console.WriteLine(TimeZoneInfo.Local.DisplayName);
}

Working

FROM mcr.microsoft.com/dotnet/sdk:5.0 AS build
    WORKDIR /build
    COPY src/Foo.sln .
    COPY src/Foo/*.csproj ./Foo/
    RUN dotnet restore ./Foo.sln
    COPY src/Foo/ ./Foo/
FROM build as publish
    WORKDIR /build/Foo
    RUN dotnet publish -c Release -o out
FROM mcr.microsoft.com/dotnet/aspnet:5.0-alpine AS runtime
    RUN apk update --no-cache && apk upgrade --no-cache
    RUN apk add --no-cache tzdata
    ENV TZ=Europe/Berlin
    ENV LANG=de_DE.UTF-8
    ENV LANGUAGE=${LANG}
    ENV LC_ALL=${LANG}
    RUN ln -snf /usr/share/zoneinfo/$TZ /etc/localtime && echo $TZ > /etc/timezone
    WORKDIR /app
    COPY --from=publish /build/Foo/out ./
    ENTRYPOINT [ "dotnet", "Foo.dll" ]

This will produce the following output

(UTC+01:00) CET

Bug

When you now take the same code, change target framework from net5.0 to net6.0 and use the same Dockerfile as a base and use mcr.microsoft.com/dotnet/sdk:6.0 and mcr.microsoft.com/dotnet/aspnet:6.0-alpine, you will get the following output

(UTC+00:00) Coordinated Universal Time

I couldn't figure out the best area label to add to this issue. If you have write-permissions please help me learn by adding exactly one area label.

[am11]

Seems like TZ was working as expected on .NET 5 with DOTNET_SYSTEM_GLOBALIZATION_INVARIANT=true (preset environment variable in alpine runtime container), but not on .NET 6.

- FROM mcr.microsoft.com/dotnet/aspnet:5.0-alpine AS runtime
+ FROM mcr.microsoft.com/dotnet/aspnet:6.0-alpine AS runtime
    RUN apk update --no-cache && apk upgrade --no-cache
-   RUN apk add --no-cache tzdata
+   RUN apk add --no-cache tzdata icu-libs
    ENV TZ=Europe/Berlin
    ENV LANG=de_DE.UTF-8
    ENV LANGUAGE=${LANG}
    ENV LC_ALL=${LANG}
+   ENV DOTNET_SYSTEM_GLOBALIZATION_INVARIANT=false
    RUN ln -snf /usr/share/zoneinfo/$TZ /etc/localtime && echo $TZ > /etc/timezone
    WORKDIR /app
    COPY --from=publish /build/Foo/out ./
    ENTRYPOINT [ "dotnet", "Foo.dll" ]

results in:

Console.WriteLine(TimeZoneInfo.Local.DisplayName)
// (UTC+01:00) Mitteleuropäische Zeit (Berlin)

Console.WriteLine(TimeZoneInfo.Local.Id)
// (Berlin) Europe/Berlin

on both, 5.0 and 6.0.

not sure if it is an intentional change or accidental breakage.

[nalla]

Thanks, this works. So current behavior is correct, net5.0 behavior was somewhat faulty?

[am11]

Perhaps @GrabYourPitchforks and @tarekgh can answer more accurately whether or not if it is a regression. To me the behavior of net5.0 seems correct; recognize correct TZ even in the invariant mode.

Tagging subscribers to this area: @dotnet/area-system-runtime
See info in area-owners.md if you want to be subscribed.

Issue Details

---

Description

The release 6.0.0-rc.1 does not obey the local timezone information. This is a regression, see the following steps to reproduce

Steps to reproduce

private static void Main(string[] args)
{
	Console.WriteLine(TimeZoneInfo.Local.DisplayName);
}

Working

FROM mcr.microsoft.com/dotnet/sdk:5.0 AS build
    WORKDIR /build
    COPY src/Foo.sln .
    COPY src/Foo/*.csproj ./Foo/
    RUN dotnet restore ./Foo.sln
    COPY src/Foo/ ./Foo/
FROM build as publish
    WORKDIR /build/Foo
    RUN dotnet publish -c Release -o out
FROM mcr.microsoft.com/dotnet/aspnet:5.0-alpine AS runtime
    RUN apk update --no-cache && apk upgrade --no-cache
    RUN apk add --no-cache tzdata
    ENV TZ=Europe/Berlin
    ENV LANG=de_DE.UTF-8
    ENV LANGUAGE=${LANG}
    ENV LC_ALL=${LANG}
    RUN ln -snf /usr/share/zoneinfo/$TZ /etc/localtime && echo $TZ > /etc/timezone
    WORKDIR /app
    COPY --from=publish /build/Foo/out ./
    ENTRYPOINT [ "dotnet", "Foo.dll" ]

This will produce the following output

(UTC+01:00) CET

Bug

When you now take the same code, change target framework from net5.0 to net6.0 and use the same Dockerfile as a base and use mcr.microsoft.com/dotnet/sdk:6.0 and mcr.microsoft.com/dotnet/aspnet:6.0-alpine, you will get the following output

(UTC+00:00) Coordinated Universal Time

Author:	nalla
Assignees:	-
Labels:	area-System.Runtime
Milestone:	-

[tarekgh]

Thanks @nalla for reporting this issue. It is a regression and I am looking at it.