自建镜像启动报："no such file or directory"

工作中编写prometheus的vsphere vcenter的exporter之后，进行容器化部署的实践，就参照prometheus的Dockerfile写了一个

FROM        quay.io/prometheus/busybox:latest
LABEL maintainer "QHCloud Observer Exporter"
USER       root
EXPOSE     3871
COPY observer_vcenter_exporter /bin/observer_vcenter_exporter
#WORKDIR    /
ENTRYPOINT [ "/bin/observer_vcenter_exporter" ]
CMD        [ "--config-file=/etc/observer/vcenter.yml"]

但启动的时候报如下错误：

standard_init_linux.go:190: exec user process caused "no such file or directory"

经过不停的测试，发现是打出来的二进制文件在busybox中无法运行，但prometheus能运行，就通过阅读promu的源码并通过增加-v参数打印出了prometheus编译的参数

go build -o /home/chensl004/Workspace/go/src/github.com/prometheus/prometheus/prometheus -ldflags -X github.com/prometheus/prometheus/vendor/github.com/prometheus/common/version.Version=2.3.0.1 -X github.com/prometheus/prometheus/vendor/github.com/prometheus/common/version.Revision=3cf878f9079773ced3461ae3c4b2516e47c07264 -X github.com/prometheus/prometheus/vendor/github.com/prometheus/common/version.Branch=2.3.0 -X github.com/prometheus/prometheus/vendor/github.com/prometheus/common/version.BuildUser=chensl004@chensl004 -X github.com/prometheus/prometheus/vendor/github.com/prometheus/common/version.BuildDate=20180620-06:55:23  -extldflags '-static' -a -tags netgo github.com/prometheus/prometheus/cmd/prometheus

经过尝试发现增加-tags netgo之后镜像启动正常，在网上找了一下对go build -tags的描述比较少，依然不清楚为什么。后面发现网上有对比-tags netgo 和CGO_ENABLED，通过设置CGO_ENABLED=0环境变量，发现镜像启动也是没问题的。

个人猜测，golang默认使用cgo编译，但busybox中没有c相关的环境导致二进制文件无法正常运行。因此，将cgo编译关闭之后就没问题了。