Pick the Right Distroless Base Image For Your Application

docker challenge https://labs.iximiuz.com/challenges/pick-the-right-distroless-base-image

使用 logs 来查看容器的日志
- exec /server: no such file or directory
- 暂时看不出来啥问题，猜测是 CMD 位置错误，后面意识到理解错误了
使用 dive 来查看 container 信息

使用 cp 来复制二进制 server 文件到本地运行，没有报错（8080 端口）
- docker cp status-checker:/server .
根据提示使用 file 和 ldd 来查看文件动态链接的 so 文件

root@docker-01:~# file server
server: ELF 64-bit LSB pie executable, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, BuildID[sha1]=016df6500c2c3df1dd3ce82d9e9a5bd547584c97, for GNU/Linux 3.2.0, with debug_info, not stripped

root@docker-01:~# ldd server
        linux-vdso.so.1 (0x00007ffde5df1000)
        libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007fbc097e4000)
        /lib64/ld-linux-x86-64.so.2 (0x00007fbc0a379000)

[!NOTE]

linux-vdso.so.1¹ 没有实体文件，文件 GNU/LINUX 编译，那么需要 libc，动态连接 /lib64/ld-linux-x86-64.so.2

现在根据上面的理解修改成下面的 Dockerfile

FROM scratch

COPY ./server /server
COPY ./libc.so.6 /lib/x86_64-linux-gnu/libc.so.6
COPY ./ld-linux-x86-64.so.2 /lib64/ld-linux-x86-64.so.2

CMD ["/server"]

docker build -t tmp .
- build 的时候 COPY 出现无文件的错误文件必须和 dockerfile 文件的同级目录下 ²
  
  The <src> path must be inside the build context; you can’t use COPY ../something /something, because the builder can only access files from the context, and ../something specifies a parent file or directory of the build context root.
使用 docker run -p 8080:8080 --name status-checker tmp
curl localhost:8080 报错
- tls: failed to verify certificate: x509: certificate signed by unknown authority
- 发现需要安装 ca-certificates
- 重新修改³

FROM golang:alpine as builder
RUN apk update && apk upgrade && apk add --no-cache ca-certificates
RUN update-ca-certificates

FROM scratch

COPY --from=builder /etc/ssl/certs/ca-certificates.crt /etc/ssl/certs/
COPY ./server /server
COPY ./libc.so.6 /lib/x86_64-linux-gnu/libc.so.6
COPY ./ld-linux-x86-64.so.2 /lib64/ld-linux-x86-64.so.2

CMD ["/server"]

重新 build 并运行通过测试

Pick the Right Distroless Base Image For Your Application

Footnotes