为什么找不到二进制 dlv - 没有这样的文件或目录

Question

我有一个工作正常的 docker 文件。但是要远程调试它，我读到我需要在它上面安装dlv然后我需要运行 dlv 并传递我正在尝试调试的应用程序的参数。因此，在其上安装 dlv 并尝试运行它之后。我得到错误exec /dlv: no such file or directory这是泊坞窗文件    FROM golang:1.18-alpine AS builder# Build Delve for debuggingRUN go install github.com/go-delve/delve/cmd/dlv@latest# Create and change to the app directory.WORKDIR /appENV CGO_ENABLED=0# Retrieve application dependencies.COPY go.* ./RUN go mod download# Copy local code to the container image.COPY . ./# Build the binary.RUN go build -gcflags="all=-N -l" -o fooapp# Use the official Debian slim image for a lean production container.FROM debian:buster-slimEXPOSE 8000 40000RUN set -x && apt-get update && DEBIAN_FRONTEND=noninteractive apt-get install -y \    ca-certificates && \    rm -rf /var/lib/apt/lists/*# Copy the binary to the production image from the builder stage.#COPY --from=builder /app/fooapp /app/fooapp #commented this out  COPY --from=builder /go/bin/dlv /dlv# Run dlv as pass fooapp as parameterCMD ["/dlv", "--listen=:40000", "--headless=true", "--api-version=2", "--accept-multiclient", "exec", "/app/fooapp"]以上结果exec /dlv: no such file or directory我不确定为什么会这样。作为 docker 的新手，我尝试了不同的方法来调试它。我试着用它dive来检查图像是否dlv在路径中/dlv，它确实如此。我还附上了它的图片

Answer 1

您构建了dlv基于alpine- 的发行版。dlv可执行文件链接到libc.musl：

# ldd dlv 

        linux-vdso.so.1 (0x00007ffcd251d000)

        libc.musl-x86_64.so.1 => not found

但是后来你切换到glibc基于图像debian:buster-slim。该图像没有所需的库。

# find / -name libc.musl*                                        

<nothing found>

这就是您无法执行的原因dlv- 动态链接器无法找到正确的库。

您需要构建glibc基于 - 的 docker。例如，替换第一行

FROM golang:bullseye AS builder

顺便提一句。构建后，您需要以特权模式运行容器

$ docker build . -t try-dlv

...

$ docker run --privileged --rm try-dlv

API server listening at: [::]:40000

2022-10-30T10:51:02Z warning layer=rpc Listening for remote connections (connections are not authenticated nor encrypted)

在非特权容器中dlv不允许产生子进程。

$ docker run --rm try-dlv

API server listening at: [::]:40000

2022-10-30T10:55:46Z warning layer=rpc Listening for remote connections (connections are not authenticated nor encrypted)

could not launch process: fork/exec /app/fooapp: operation not permitted

真正最小的图像

你用来debian:buster-slim最小化图像，它的大小是 80 MB。但是如果你需要一个非常小的图像，使用busybox，它只有 4.86 MB 的开销。

FROM golang:bullseye AS builder

# Build Delve for debugging

RUN go install github.com/go-delve/delve/cmd/dlv@latest

# Create and change to the app directory.

WORKDIR /app

ENV CGO_ENABLED=0

# Retrieve application dependencies.

COPY go.* ./

RUN go mod download

# Copy local code to the container image.

COPY . ./

# Build the binary.

RUN go build -o fooapp .

# Download certificates

RUN set -x && apt-get update && DEBIAN_FRONTEND=noninteractive apt-get install -y \

    ca-certificates 

# Use the official Debian slim image for a lean production container.

FROM busybox:glibc

EXPOSE 8000 40000

# Copy the binary to the production image from the builder stage.

COPY --from=builder /app/fooapp /app/fooapp 

# COPY --from=builder /app/ /app

COPY --from=builder /go/bin/dlv /dlv

COPY --from=builder /etc/ssl /etc/ssl

# Run dlv as pass fooapp as parameter

CMD ["/dlv", "--listen=:40000", "--headless=true", "--api-version=2", "--accept-multiclient", "exec", "/app/fooapp"]

# ENTRYPOINT ["/bin/sh"]

图像大小为 25 MB，其中 18 MB 来自应用程序dlv，2 MB 来自Hello World应用程序。

在选择图像时，应注意具有相同风格的libc. golang:bullseye针对glibc. 因此，最小图像必须glibc基于。

但是，如果您想要更舒适一些，请使用已安装的alpine软件包gcompat。与busybox.

FROM golang:bullseye AS builder

# Build Delve for debugging

RUN go install github.com/go-delve/delve/cmd/dlv@latest

# Create and change to the app directory.

WORKDIR /app

ENV CGO_ENABLED=0

# Copy local code to the container image.

COPY . ./

# Retrieve application dependencies.

RUN go mod tidy

# Build the binary.

RUN go build -o fooapp .

# Use alpine lean production container.

# FROM busybox:glibc

FROM alpine:latest

# gcompat is the package to glibc-based apps

# ca-certificates contains trusted TLS CA certs

# bash is just for the comfort, I hate /bin/sh

RUN apk add gcompat ca-certificates bash

EXPOSE 8000 40000

# Copy the binary to the production image from the builder stage.

COPY --from=builder /app/fooapp /app/fooapp 

# COPY --from=builder /app/ /app

COPY --from=builder /go/bin/dlv /dlv

# Run dlv as pass fooapp as parameter

CMD ["/dlv", "--listen=:40000", "--headless=true", "--api-version=2", "--accept-multiclient", "exec", "/app/fooapp"]

# ENTRYPOINT ["/bin/bash"]

Answer 2

长话短说

运行apt-get install musl，然后/dlv应该按预期工作。

解释

按着这些次序：

1. docker run -it <image-name> sh

2. apt-get install file

3. file /dlv

然后你可以看到如下输出：

/dlv: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib/ld-musl-x86_64.so.1, Go BuildID=xV8RHgfpp-zlDlpElKQb/DOLzpvO_A6CJb7sj1Nxf/aCHlNjW4ruS1RXQUbuCC/JgrF83mgm55ntjRnBpHH, not stripped

令人困惑no such file or directory（有关相关讨论，请参阅此问题）是由 missing 引起的/lib/ld-musl-x86_64.so.1。

因此，解决方案是musl按照其文档安装库。

我的回答是受这个答案的启发。