E: 包‘ mysql-client’在使用 docker Comose 构建 php-fpm 映像时没有安装候选项

我相当新的码头，所以我试图了解更多关于它使用幼鱼项目，我下面这个教程:

Https://www.digitalocean.com/community/tutorials/how-to-set-up-laravel-nginx-and-mysql-with-docker-compose

我调整了 Dockerfile 的教程有一点，但即使教程文件导致相同的结果。

FROM php:7.3-fpm


# Copy composer.lock and composer.json
COPY composer.lock composer.json /var/www/
# Install dependencies
RUN curl -sL https://deb.nodesource.com/setup_10.x | bash - && \
apt-get update && apt-get install -y mysql-client \
    



RUN npm install -g npm


# Clear cache
RUN apt-get clean && rm -rf /var/lib/apt/lists/*




# Install extensions
RUN docker-php-ext-install pdo pdo_mysql


# Install composer
RUN curl -sS https://getcomposer.org/installer | php -- --install-dir=/usr/local/bin --filename=composer


# Add user for laravel application
RUN groupadd -g 1000 www
RUN useradd -u 1000 -ms /bin/bash -g www www


# Copy existing application directory contents
COPY . /var/www


# Copy existing application directory permissions
COPY --chown=www:www . /var/www


# Change current user to www
USER www
# Set working directory
WORKDIR /var/www
# Expose port 9000 and start php-fpm server
EXPOSE 9000


CMD ["php-fpm"]

但是当我运行 docker-compose up -d时，总是出现以下错误:

E: Package 'mysql-client' has no installation candidate
ERROR: Service 'app' failed to build: The command '/bin/sh -c curl -sL https://deb.nodesource.com/setup_10.x | bash - &&     apt-get update && apt-get install -y mysql-client     nodejs     build-essential     vim     git     curl' returned a non-zero code: 100

我错过了什么吗？

我希望这个工作，因为我正在运行 apt-get update之前安装 mysql-client。

谢谢。