无法在nginx中安装bash :alpine

Question

我有以下Dockerfile：

# => Build container
FROM node:14-alpine AS builder
WORKDIR /app

# split the dependecies from our source code so docker builds can cache this step
# (unless we actually change dependencies)
COPY package.json yarn.lock ./
RUN yarn install
COPY . ./
RUN yarn build

# => Run container
FROM nginx:alpine

# Nginx config
WORKDIR /usr/share/nginx/html
RUN rm -rf ./*
COPY ./nginx/nginx.conf /etc/nginx/conf.d/default.conf

# Default port exposure
EXPOSE 8080

# Copy .env file and shell script to container
COPY --from=builder /app/dist .
COPY ./env.sh .
COPY .env .

USER root

# Add bash
RUN apk update && apk add --no-cache bash

# Make our shell script executable
RUN chmod +x env.sh

# Start Nginx server
CMD ["/bin/bash", "-c", "/usr/share/nginx/html/env.sh && nginx -g \"daemon off;\""]

但是，当我尝试运行它时，我在尝试添加bash时得到以下错误

------
 > [stage-1 8/9] RUN apk update && apk add --no-cache bash:
#19 0.294 fetch https://dl-cdn.alpinelinux.org/alpine/v3.14/main/x86_64/APKINDEX.tar.gz
#19 0.358 140186175183688:error:1416F086:SSL routines:tls_process_server_certificate:certificate verify failed:ssl/statem/statem_clnt.c:1914:
#19 0.360 fetch https://dl-cdn.alpinelinux.org/alpine/v3.14/community/x86_64/APKINDEX.tar.gz
#19 0.360 ERROR: https://dl-cdn.alpinelinux.org/alpine/v3.14/main: Permission denied
#19 0.360 WARNING: Ignoring https://dl-cdn.alpinelinux.org/alpine/v3.14/main: No such file or directory
#19 0.405 140186175183688:error:1416F086:SSL routines:tls_process_server_certificate:certificate verify failed:ssl/statem/statem_clnt.c:1914:
#19 0.407 ERROR: https://dl-cdn.alpinelinux.org/alpine/v3.14/community: Permission denied
#19 0.407 WARNING: Ignoring https://dl-cdn.alpinelinux.org/alpine/v3.14/community: No such file or directory
#19 0.408 2 errors; 42 distinct packages available
------
executor failed running [/bin/sh -c apk update && apk add --no-cache bash]: exit code: 2

我需要添加它来执行此脚本：

#!/bin/bash

# Recreate config file
rm -rf ./env-config.js
touch ./env-config.js

# Add assignment 
echo "window._env_ = {" >> ./env-config.js

# Read each line in .env file
# Each line represents key=value pairs
while read -r line || [[ -n "$line" ]];
do
  # Split env variables by character `=`
  if printf '%s\n' "$line" | grep -q -e '='; then
    varname=$(printf '%s\n' "$line" | sed -e 's/=.*//')
    varvalue=$(printf '%s\n' "$line" | sed -e 's/^[^=]*=//')
  fi

  # Read value of current variable if exists as Environment variable
  value=$(printf '%s\n' "${!varname}")
  # Otherwise use value from .env file
  [[ -z $value ]] && value=${varvalue}
  
  # Append configuration property to JS file
  echo "  $varname: \"$value\"," >> ./env-config.js
done < .env

echo "}" >> ./env-config.js

根据我所读到的，添加USER root应该可以解决这个问题，但在这种情况下它不会。

对如何修复有什么建议吗？

Answer 1

您应该能够将/bin/sh用作标准的Bourne shell；而且，您应该能够避免在CMD行中使用sh -c包装器。

首先，使用POSIX shell syntax重写脚本。浏览一下脚本，看起来几乎没问题；将第一行改为#!/bin/sh，并更正非标准的${!varname}扩展(请参阅Dynamic variable names in Bash)

# Read value of current variable if exists as Environment variable
value=$(sh -c "echo \$$varname")
# Otherwise use value from .env file
[[ -z $value ]] && value=${varvalue}

您可以尝试使用具有更多限制的shell的alpine或busybox映像来测试它，或者使用bash设置POSIXLY_CORRECT环境变量。

其次，using ENTRYPOINT and CMD together有一个合理的标准模式。CMD作为参数传递给ENTRYPOINT，因此如果ENTRYPOINT以exec "$@"结尾，它将用该命令替换它自己。

#!/bin/sh
#      ^^ not bash

# Recreate config file
...
echo "window._env_ = {" >> ./env-config.js
...
echo "}" >> ./env-config.js

# Run the main container CMD
exec "$@"

现在，在您的do文件中，您不需要安装GNU bash，因为您没有使用它，但是您确实需要正确地拆分ENTRYPOINT和CMD。

ENTRYPOINT ["/usr/share/nginx/html/env.sh"] # must be JSON-array syntax
CMD ["nginx", "-g", "daemon off;"]          # can be either syntax

另外，Docker语法是基本的shell语法，而不是cmd1 && cmd2扩展，因此您可以编写CMD ["/bin/sh", "-c", "cmd1 && cmd2"]；但是，如果您编写的命令没有使用JSON数组语法，Docker将为您插入sh -c包装器。您几乎不需要在Dockerfile文件中写出sh -c。