go – stdout被缓冲在docker容器中

我不完全确定这里发生了什么,但是当我在容器中运行代码时,似乎缓冲了stdout,但是如果我在主机或OSX上运行它,则不会.

https://github.com/myles-mcdonnell/procwrap/blob/master/procwrap.go

相关部分(为简洁起见而修改)：

    cmd := exec.Command("ping","127.0.0.1")

    logger := &lumberjack.Logger{
        Filename:   conf.LogFile,MaxSize:    conf.MaxLogSizeMb,MaxBackups: conf.MaxLogBackups,MaxAge:     conf.MaxLogAgeDays,}

    cmd.Stdout = io.MultiWriter(os.Stdout,logger)  

    err := cmd.Run()

在容器中运行子进程运行正常,但我只是间隔地看到输出(到stdout和日志文件),就像刷新缓冲区一样.在容器外部运行它,并在生成时输出.我正在使用1.6.3.我看到以交互方式和后台运行容器的相同行为.

Docker版本：

Client:
 Version:      1.10.3
 API version:  1.22
 Go version:   go1.5.3
 Git commit:   20f81dd
 Built:        Thu Mar 10 21:49:11 2016
 OS/Arch:      darwin/amd64

Server:
 Version:      1.12.0
 API version:  1.24
 Go version:   go1.6.3
 Git commit:   8eab29e
 Built:        Thu Jul 28 23:54:00 2016
 OS/Arch:      linux/amd64

=======更新======

我看到基于基本图像的不同行为.在debian上运行procwrap：wheezy base我得到缓冲输出.在ubuntu上做同样的事情：相信它是同步的.下面的Dockerfiles,只需在每个上执行’docker run {image_name}’即可观察.在wheezy VM上运行procwrap(不涉及docker)不会缓冲输出.

可靠：

FROM ubuntu:trusty
RUN apt-get update
RUN apt-get install -y curl
RUN apt-get install -y git
RUN curl -O https://storage.googleapis.com/golang/go1.6.3.linux-amd64.tar.gz
RUN tar -xvf go1.6.3.linux-amd64.tar.gz
RUN mv go /usr/local
ENV GOROOT=/usr/local/go
RUN mkdir -p /go/src/github.com/myles-mcdonnell
ENV GOPATH=/go
ENV PATH=$PATH:$GOPATH/bin:$GOROOT/bin
RUN go get github.com/myles-mcdonnell/procwrap
WORKDIR /go/src/github.com/myles-mcdonnell/procwrap
CMD procwrap -v

喘息：

FROM debian:wheezy
RUN apt-get update
RUN apt-get install -y curl
RUN apt-get install -y git
RUN curl -O https://storage.googleapis.com/golang/go1.6.3.linux-amd64.tar.gz
RUN tar -xvf go1.6.3.linux-amd64.tar.gz
RUN mv go /usr/local
ENV GOROOT=/usr/local/go
RUN mkdir -p /go/src/github.com/myles-mcdonnell
ENV GOPATH=/go
ENV PATH=$PATH:$GOPATH/bin:$GOROOT/bin
RUN go get github.com/myles-mcdonnell/procwrap
WORKDIR /go/src/github.com/myles-mcdonnell/procwrap
CMD procwrap -v