Asp.Net Core 2.1發布后，正式支持System.Drawing.Common繪圖了，可以用來做一些圖片驗證碼之類的功能。但是把網站部署到docker容器里運行會遇到很多問題，也是非常鬧心的，本文記錄這些問題，希望幫到有需要的人。
創建網站
前提條件：安裝最新版VS2017和Net Core SDK 2.1。
首先新建網站，選擇Asp.Net Core 2.1 Web應用程序（模型視圖控制器），不勾選docker，我習慣自行編寫Dockerfile。
指定網站訪問端口5000。
public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
WebHost.CreateDefaultBuilder(args)
//必須指定端口，否則在Win10命令行運行端口是5000，在CentOS docker運行端口是80
.UseUrls("http://*:5000")
.UseStartup<Startup>();
為了調試方便，把隱私要求和https要求先屏蔽。
public void ConfigureServices(IServiceCollection services)
{
services.Configure<CookiePolicyOptions>(options =>
{
// This lambda determines whether user consent for non-essential cookies is needed for a given request.
//options.CheckConsentNeeded = context => true;
options.MinimumSameSitePolicy = SameSiteMode.None;
});
services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);
}
public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
if (env.IsDevelopment())
{
app.UseDeveloperExceptionPage();
}
else
{
app.UseExceptionHandler("/Home/Error");
//app.UseHsts();
}
//app.UseHttpsRedirection();
app.UseStaticFiles();
app.UseCookiePolicy();
app.UseMvc(routes =>
{
routes.MapRoute(
name: "default",
template: "{controller=Home}/{action=Index}/{id?}");
});
}
修改appsettings.json輸出全部調試信息，便於查找錯誤。
{
"Logging": {
"LogLevel": {
"Default": "Debug"
}
},
"AllowedHosts": "*"
}
調試運行一下，確認網站沒問題。
把Home控制器的Index頁面改一下，簡單粗暴一點，就顯示一個圖片好了。
@{
ViewData["Title"] = "Home Page";
}
<h4>System.Drawing.Common繪圖</h4>
<img src="Home/GetImg" alt="pic" class="img-thumbnail" width="400" height="200" />
NuGet安裝System.Drawing.Common。
給Home控制器增加一個繪圖函數GetImg。
public IActionResult GetImg()
{
_logger.LogInformation($"{DateTime.Now:yyyy-MM-dd HH:mm:ss:fff}, start create image");
string msg = $"{DateTime.Now:HH:mm:ss}, 您好 drawing from .NET Core";
Image image = new Bitmap(400, 200);
Graphics graph = Graphics.FromImage(image);
graph.Clear(Color.Azure);
Pen pen = new Pen(Brushes.Black);
graph.DrawLines(pen, new Point[] { new Point(10, 10), new Point(380, 180) });
graph.DrawString(msg, new Font(new FontFamily("微軟雅黑"), 12, FontStyle.Bold), Brushes.Blue, new PointF(10, 90));
//把圖片保存到內存文件流
MemoryStream ms = new MemoryStream();
image.Save(ms, ImageFormat.Png); ;
byte[] buf = ms.GetBuffer();
_logger.LogInformation($"{DateTime.Now:yyyy-MM-dd HH:mm:ss:fff}, finish create image");
return File(buf, "image/png");
}
調試運行一下，是沒問題的。
部署網站到docker
編寫Dockerfile，注意把文件屬性“復制到輸出目錄”設置為“如果較新則復制”。
FROM microsoft/dotnet:2.1-aspnetcore-runtime WORKDIR /app COPY . /app EXPOSE 5000 ENTRYPOINT ["dotnet", "NetCoreDraw.dll"]
重新編譯網站，以文件夾方式發布到默認的bin\Release\PublishOutput。在Windows控制台進入發布目錄，輸入dotnet NetCoreDraw.dll運行網站，瀏覽器訪問http://localhost:5000/，確認沒問題。
編寫docker-compose.yml
version: '3'
services:
myweb:
container_name: myweb
image: mywebimage
build:
context: ./PublishOutput
dockerfile: Dockerfile
ports:
- "5000:5000"
environment:
- ASPNETCORE_ENVIRONMENT=Production
- TZ=Asia/Shanghai
restart: always
我用CentOS 7.3虛擬機做試驗，安裝好docker環境，用Xshell訪問虛擬機，用Xftp把PublishOutput文件夾、docker-compose.yml拖到Home下面。
進入Home目錄，把容器跑起來。
[root@localhost home]# docker-compose up
Creating network "home_default" with the default driver
Building myweb
Step 1/5 : FROM microsoft/dotnet:2.1-aspnetcore-runtime
2.1-aspnetcore-runtime: Pulling from microsoft/dotnet
be8881be8156: Pull complete
f854db899319: Pull complete
4591fd524b8e: Pull complete
65f224da8749: Pull complete
Digest: sha256:a43b729b84f918615d4cdce92a8bf59e3e4fb2773b8491a7cf4a0d728886eeba
Status: Downloaded newer image for microsoft/dotnet:2.1-aspnetcore-runtime
---> fcc3887985bb
Step 2/5 : WORKDIR /app
Removing intermediate container aba36715acfc
---> 25bc5bb6871f
Step 3/5 : COPY . /app
---> 9baaa790a82f
Step 4/5 : EXPOSE 5000
---> Running in 269408c67989
Removing intermediate container 269408c67989
---> fbd444c44d20
Step 5/5 : ENTRYPOINT ["dotnet", "NetCoreDraw.dll"]
---> Running in 2a9ba559b137
Removing intermediate container 2a9ba559b137
---> b1bb1dccd49a
Successfully built b1bb1dccd49a
Successfully tagged mywebimage:latest
WARNING: Image for service myweb was built because it did not already exist. To rebuild this image you must use `docker-compose build` or `docker-compose up --build`.
Creating myweb ... done
Attaching to myweb
myweb | warn: Microsoft.AspNetCore.DataProtection.KeyManagement.XmlKeyManager[35]
myweb | No XML encryptor configured. Key {1f87d27e-c6b1-435f-bab6-aebacd6d6817} may be persisted to storage in unencrypted form.
myweb | Hosting environment: Production
myweb | Content root path: /app
myweb | Now listening on: http://[::]:5000
myweb | Application started. Press Ctrl+C to shut down.
在瀏覽器訪問我的虛擬機里的網站http://192.168.41.129:5000/，圖片顯示不出來。
在Xshell可以看到容器調試信息，發生了錯誤。
myweb | 2018-07-29 09:50:04:753, start create image myweb | info: Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker[2] myweb | Executed action NetCoreDraw.Controllers.HomeController.GetImg (NetCoreDraw) in 18.5988ms myweb | fail: Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware[1] myweb | An unhandled exception has occurred while executing the request. myweb | System.TypeInitializationException: The type initializer for 'Gdip' threw an exception. ---> System.DllNotFoundException: Unable to load shared library 'libdl' or one of its dependencies. In order to help diagnose loading problems, consider setting the LD_DEBUG environment variable: liblibdl: cannot open shared object file: No such file or directory myweb | at Interop.Libdl.dlopen(String fileName, Int32 flag) myweb | at System.Drawing.SafeNativeMethods.Gdip.LoadNativeLibrary() myweb | at System.Drawing.SafeNativeMethods.Gdip..cctor() myweb | --- End of inner exception stack trace ---
找不到庫文件libdl，網上有類似的問題和解決方案，就是建立一個文件連接。
https://q.cnblogs.com/q/107946/
但是aspnetcore容器中的庫文件位置，跟正式發行版本的CentOS和Ubuntu不太一樣，得進入容器去找。在容器運行的時候，通過Xshell的復制功能，再開一個終端窗口，進入容器。
docker exec -it myweb /bin/bash
aspnetcore容器不支持locate命令，我對Linux系統文件位置不熟，只好硬着頭皮挨個看了一遍，還好目錄不多，最后確定在這里。
root@544f7be29f68:/# ls lib/x86_64-linux-gnu/libdl*
lib/x86_64-linux-gnu/libdl-2.24.so lib/x86_64-linux-gnu/libdl.so.2
所以修改Dockerfile為
FROM microsoft/dotnet:2.1-aspnetcore-runtime RUN ln -s /lib/x86_64-linux-gnu/libdl-2.24.so /lib/x86_64-linux-gnu/libdl.so WORKDIR /app COPY . /app EXPOSE 5000 ENTRYPOINT ["dotnet", "NetCoreDraw.dll"]
重新編譯、發布網站到虛擬機，重新運行編譯運行容器。
[root@localhost home]# docker-compose up --build
瀏覽網站，仍然無法顯示圖片，但是錯誤內容變了。
myweb | fail: Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware[1] myweb | An unhandled exception has occurred while executing the request. myweb | System.TypeInitializationException: The type initializer for 'Gdip' threw an exception. ---> System.DllNotFoundException: Unable to load DLL 'libgdiplus': The specified module could not be found. myweb | at System.Runtime.InteropServices.FunctionWrapper`1.get_Delegate() myweb | at System.Drawing.SafeNativeMethods.Gdip.GdiplusStartup(IntPtr& token, StartupInput& input, StartupOutput& output) myweb | at System.Drawing.SafeNativeMethods.Gdip..cctor() myweb | --- End of inner exception stack trace ---
這次是找不到libgdiplus，網上也有關於這個問題的解決方案。
https://q.cnblogs.com/q/103863/
因為需要在容器跑起來的時候安裝一些東西，所以要更換為國內的源，提高速度。參考
https://www.cnblogs.com/OMango/p/8519980.html
把Dockerfile改為這樣了，注意更新源之后要apt-get update一下，否則會報錯Unable to locate package libgdiplus。
FROM microsoft/dotnet:2.1-aspnetcore-runtime RUN ln -s /lib/x86_64-linux-gnu/libdl-2.24.so /lib/x86_64-linux-gnu/libdl.so RUN echo "deb http://mirrors.aliyun.com/debian wheezy main contrib non-free \ deb-src http://mirrors.aliyun.com/debian wheezy main contrib non-free \ deb http://mirrors.aliyun.com/debian wheezy-updates main contrib non-free \ deb-src http://mirrors.aliyun.com/debian wheezy-updates main contrib non-free \ deb http://mirrors.aliyun.com/debian-security wheezy/updates main contrib non-free \ deb-src http://mirrors.aliyun.com/debian-security wheezy/updates main contrib non-free" > /etc/apt/sources.list RUN apt-get update RUN apt-get install libgdiplus -y && ln -s libgdiplus.so gdiplus.dll WORKDIR /app COPY . /app EXPOSE 5000 ENTRYPOINT ["dotnet", "NetCoreDraw.dll"]
再次運行，終於看到圖片了，但是漢字沒有顯示出來。
參考上面的文章，把字體文件復制到容器中，再安裝字體相關的功能即可。最終Dockerfile長這樣。
FROM microsoft/dotnet:2.1-aspnetcore-runtime RUN ln -s /lib/x86_64-linux-gnu/libdl-2.24.so /lib/x86_64-linux-gnu/libdl.so RUN echo "deb http://mirrors.aliyun.com/debian wheezy main contrib non-free \ deb-src http://mirrors.aliyun.com/debian wheezy main contrib non-free \ deb http://mirrors.aliyun.com/debian wheezy-updates main contrib non-free \ deb-src http://mirrors.aliyun.com/debian wheezy-updates main contrib non-free \ deb http://mirrors.aliyun.com/debian-security wheezy/updates main contrib non-free \ deb-src http://mirrors.aliyun.com/debian-security wheezy/updates main contrib non-free" > /etc/apt/sources.list RUN apt-get update RUN apt-get install libfontconfig1 -y RUN apt-get install libgdiplus -y && ln -s libgdiplus.so gdiplus.dll COPY ./fonts/msyh.ttc /usr/share/fonts/dejavu WORKDIR /app COPY . /app EXPOSE 5000 ENTRYPOINT ["dotnet", "NetCoreDraw.dll"]
把Win10的微軟雅黑字體文件msyh.ttc放到項目的fonts目錄下，設置文件屬性“復制到輸出目錄”設置為“如果較新則復制”。
再次運行容器，搞定了。
Asp.Net Core網站跨平台部署到Linux容器運行是一個飛躍性的技術進步，但是時不時會碰到一些跟Linux系統相關的問題，總感覺是又愛又恨，心太累。
源代碼
https://github.com/woodsun2018/NetCoreDraw