Why can’t docker find copy’s file?

  docker, question

There is one sentence in dockerfile:

COPY supervisord.conf /etc/supervisord.conf

The construction was successful, but the file could not be found when entering the container. Why?

In addition, why can’t this container be entered with doc-composesexephp-workerbash, but with doc-composesexephp-workersh?

The complete dockerfile is as follows:

#
 #--------------------------------------------------------------------------
 # Image Setup
 #--------------------------------------------------------------------------
 #
 
 FROM php:7.1-alpine
 
 MAINTAINER Mahmoud Zalt <mahmoud@zalt.me>
 
 RUN apk --update add wget \
 curl \
 git \
 build-base \
 libmemcached-dev \
 libmcrypt-dev \
 libxml2-dev \
 zlib-dev \
 autoconf \
 cyrus-sasl-dev \
 libgsasl-dev \
 supervisor
 
 RUN docker-php-ext-install mysqli mbstring pdo pdo_mysql mcrypt tokenizer xml
 RUN pecl channel-update  pecl.php.net && pecl install memcached-3.0.4 && docker-php-ext-enable memcached
 
 # Install PostgreSQL drivers:
 ARG INSTALL_PGSQL=false
 RUN if [ ${INSTALL_PGSQL} = true ];  then \
 apk --update add postgresql-dev \
 && docker-php-ext-install pdo_pgsql \
 ;  fi
 
 RUN rm /var/cache/apk/* \
 && mkdir -p /var/www
 
 #
 #--------------------------------------------------------------------------
 # Optional Supervisord Configuration
 #--------------------------------------------------------------------------
 #
 # Modify the ./supervisor.conf file to match your App's requirements.
 # Make sure you rebuild your container with every change.
 #
 
 COPY supervisord.conf /etc/supervisord.conf
 
 ENTRYPOINT ["/usr/bin/supervisord", "-n", "-c",  "/etc/supervisord.conf"]
 
 #
 #--------------------------------------------------------------------------
 # Optional Software's Installation
 #--------------------------------------------------------------------------
 #
 # If you need to modify this image, feel free to do it right here.
 #
 # -- Your awesome modifications go here -- #
 
 
 #
 #--------------------------------------------------------------------------
 # Final Touch
 #--------------------------------------------------------------------------
 #
 
 WORKDIR /etc/supervisor/conf.d/

You should use add instead of copy. In addition, the php image you use is based on alpine. alpine has no bash, only sh