我有一个运行良好的 docker 文件。然而,要远程调试它,我读到我需要在其上安装
dlv
,然后我需要运行 dlv 并传递我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。我收到错误了
exec /dlv: no such file or directory
这是 docker 文件
FROM golang:1.18-alpine 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 -gcflags="all=-N -l" -o fooapp
# Use the official Debian slim image for a lean production container.
FROM debian:buster-slim
EXPOSE 8000 40000
RUN 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 parameter
CMD ["/dlv", "--listen=:40000", "--headless=true", "--api-version=2", "--accept-multiclient", "exec", "/app/fooapp"]
以上结果为
exec /dlv: no such file or directory
我不确定为什么会发生这种情况。作为 docker 的新手,我尝试了不同的方法来调试它。我尝试使用
dive
检查并查看图像在路径 dlv
中是否有 /dlv
,确实如此。我还附上了它的图片
您在基于
dlv
的发行版中构建了 alpine
。 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
但随后您切换到基于
glibc
的图像 debian:buster-slim
。该图像没有所需的库。
# find / -name libc.musl*
<nothing found>
这就是为什么你无法执行
dlv
- 动态链接器无法找到正确的库。
您需要构建基于
glibc
的 docker。例如,替换第一行
FROM golang:bullseye AS builder
顺便说一句。构建后,您需要在特权模式下运行容器
$ 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
不允许生成子进程。
$ 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
非常小的图像
您可以使用
debian:buster-slim
来最小化图像,它的大小为 80 MB。但如果您需要非常小的图像,请使用busybox
,它的开销仅为 4.86 MB。
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
dlv
,2 MB来自Hello World
应用程序。
在选择图像时,应注意具有相同的
libc
风格。 golang:bullseye
链接到 glibc
。因此,最小图像必须是基于 glibc
的。
但是如果您想要更舒适一点,请使用安装了
alpine
软件包的 gcompat
。这是一个相当丰富的 Linux,有很多外部软件包,与 busybox
相比,只需额外 6 MB。
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"]
运行
apt-get install musl
,然后 /dlv
应该按预期工作。
请按照以下步骤操作:
docker run -it <image-name> sh
apt-get install file
file /dlv
然后你可以看到以下输出:
/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
令人困惑的
no such file or directory
(相关讨论请参阅这个问题)是由于缺少/lib/ld-musl-x86_64.so.1
造成的。
因此,解决方案是按照
其文档安装
musl
库。
我的答案受到这个答案的启发。
no such file or directory
错误表示您的二进制文件不存在,或者您的二进制文件动态链接到不存在的库。
正如这个answer中所说,delve 与 libc.musl 链接。因此,对于您的 delve 构建,您可以禁用
CGO
,因为这可能会导致动态链接到 libc/libmusl:
# Build Delve for debugging
RUN CGO_ENABLED=0 go install github.com/go-delve/delve/cmd/dlv@latest
...
这甚至允许您稍后为最终目标映像使用临时构建,并且不需要您安装任何其他软件包(例如
musl
)或使用任何基于 glibc
的映像,并且要求您在特权模式下运行。