如何解决Golang Docker文件进行调试
我有以下适用于我的应用程序的docker文件。我能够访问简单的Web应用程序服务器。
FROM golang:1.14.7 AS builder
RUN go get github.com/go-delve/delve/cmd/dlv
RUN mkdir /app
ADD . /app
WORKDIR /app
RUN CGO_ENABLED=0 GOOS=linux go build -gcflags="all=-N -l" -o main ./...
FROM alpine:3.12.0 AS production
COPY --from=builder /app .
EXPOSE 8000 40000
ENV PORT=8000
CMD ["./main"]
像下面这样采用它时,我无法将其成功部署到Kubernetes。容器因一些一般性错误而崩溃,而不是我可以使用的错误。
standard_init_linux.go:190: exec user process caused "no such file or directory"
这不起作用
FROM golang:1.14.7 AS builder
RUN go get github.com/go-delve/delve/cmd/dlv
RUN mkdir /app
ADD . /app
WORKDIR /app
RUN CGO_ENABLED=0 GOOS=linux go build -gcflags="all=-N -l" -o main ./...
FROM alpine:3.12.0 AS production
COPY --from=builder /app .
COPY --from=builder /go/bin/dlv /
EXPOSE 8000 40000
ENV PORT=8000
CMD ["/dlv","--listen=:40000","--headless=true","--api-version=2","--accept-multiclient","exec","./main"]
如果有人想尝试一下,这是简单的程序(这是最小的可复制示例),如果您获取第一个docker文件,它将为您工作,而第二个则无效。
package main
import (
"fmt"
"net/http"
"os"
)
func main() {
fmt.Println("app is starting!")
var port string
if port = os.Getenv("PORT"); len(port) == 0 {
port = "8080"
}
http.HandleFunc("/",handler)
http.ListenAndServe(":"+port,nil)
}
func handler(w http.ResponseWriter,r *http.Request) {
fmt.Fprintf(w,"Hi there,%s!",r.URL.Path[1:])
}
解决方法
您需要使用静态链接标志来编译dlv
本身。否则,dlv
将具有指向libc的动态链接,而该链接在高山图像中不存在。其他选项包括将生产映像切换为基于debian的(FROM debian
)或将golang映像切换为基于albian的(FROM golang:1.14.7-alpine
)。要在没有动态链接的情况下编译dlv
,可以使用以下Dockerfile:
FROM golang:1.14.7 AS builder
RUN CGO_ENABLED=0 go get -ldflags '-s -w -extldflags -static' github.com/go-delve/delve/cmd/dlv
RUN mkdir /app
ADD . /app
WORKDIR /app
RUN CGO_ENABLED=0 GOOS=linux go build -gcflags="all=-N -l" -o main ./...
FROM alpine:3.12.0 AS production
COPY --from=builder /app .
COPY --from=builder /go/bin/dlv /
EXPOSE 8000 40000
ENV PORT=8000
CMD ["/dlv","--listen=:40000","--headless=true","--api-version=2","--accept-multiclient","exec","./main"]
要查看动态链接,请构建您的构建器映像并针对输出二进制文件运行ldd
:
$ docker build --target builder -t test-63403272 .
[+] Building 4.6s (11/11) FINISHED
=> [internal] load build definition from Dockerfile 0.0s
=> => transferring dockerfile: 570B 0.0s
=> [internal] load .dockerignore 0.0s
=> => transferring context: 2B 0.0s
=> [internal] load metadata for docker.io/library/golang:1.14.7 0.2s
=> [builder 1/6] FROM docker.io/library/golang:1.14.7@sha256:1364cfbbcd1a5f38bdf8c814f02ebbd2170c93933415480480104834341f283e 0.0s
=> [internal] load build context 0.0s
=> => transferring context: 591B 0.0s
=> CACHED [builder 2/6] RUN go get github.com/go-delve/delve/cmd/dlv 0.0s
=> CACHED [builder 3/6] RUN mkdir /app 0.0s
=> [builder 4/6] ADD . /app 0.1s
=> [builder 5/6] WORKDIR /app 0.0s
=> [builder 6/6] RUN CGO_ENABLED=0 GOOS=linux go build -gcflags="all=-N -l" -o main ./... 4.0s
=> exporting to image 0.2s
=> => exporting layers 0.2s
=> => writing image sha256:d2ca7bbc0bb6659d0623e1b8a3e1e87819d02d0c7f0a0762cffa02601799c35e 0.0s
=> => naming to docker.io/library/test-63403272 0.0s
$ docker run -it --rm test-63403272 ldd /go/bin/dlv
linux-vdso.so.1 (0x00007ffda66ee000)
libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007faa4824d000)
libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007faa4808c000)
/lib64/ld-linux-x86-64.so.2 (0x00007faa48274000)
Libc是切换到高山时常见的缺少库,因为默认情况下它使用musl。
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