swift - swift “print”未出现在STDOut中，但是在ECS上的docker中运行时，第三方c库日志会显示

Question

因此，在本地通过xcode在开发人员中或使用SPM进行编译时，控制台日志会按预期显示。

即在本地使用SPM一切都很好

swift build --configuration release 
.build/release/Myapp # prints to console

但是当我通过在ECS(我想是Linux)上运行的docker容器运行可执行文件时，我看不到我的Swift代码生成的日志，但是我确实看到stderr被第三方库打印(即libssl正在打印错误)以及启动应用程序时的Shell日志

例如:

Docker文件

FROM swift
WORKDIR /app

COPY Package.swift ./
COPY Sources ./Sources
COPY Tests ./Tests
RUN swift package clean
RUN swift build --configuration release
RUN chmod +x start.sh
CMD ["start.sh"] # just a wrapper to see if "echo" works

在start.sh中

# prints as expected
echo "hi this will print"
# nothing in the executable will print though
.build/release/MyApp

Answer 1

有同样的问题，我提起了雷达，苹果回答了:

When piped to another process print is buffered, so no characters appear until the buffer is filled up. (When piped to the terminal we only buffer until we hit a newline.)

You can get the behavior you want by calling setbuf(stdout, nil) once at startup:

 import Darwin
 setbuf(stdout, nil)