I have made a dockerfile and I was going to run it on AWS ECS but I cant as it requires -t

Question

Here is my docker run and the docker file is there a reason why it requires -t and isnt working on ECS thanks for any help. I dont understand what -t does so if someone could also help with that thanks.

This is just a basic docker that connects to my rds and uses wordpress. I dont have any plugins and shapely is the theme i'm using .

command docker run -t --name wordpress -d -p 80:80 dockcore/wordpress 



FROM ubuntu

#pt-get clean all
RUN apt-get -y update
RUN DEBIAN_FRONTEND=noninteractive apt-get -y install unzip wget mysql-client mysql-server apache2 libapache2-mod-php7.0 pwgen python-setuptools vim-tiny php7.0-mysql  php7.0-lda
RUN rm -fr /var/cashe/*files neeeded
ADD wordpress.conf /etc/apache2/sites-enabled/000-default.conf

# Wordpress install
RUN wget -P /var/www/html/ https://wordpress.org/latest.zip
RUN unzip /var/www/html/latest.zip -d /var/www/html/
RUN rm -fr /var/www/html/latest.zip

# Copy he wp config file
RUN cp /var/www/html/wordpress/wp-config-sample.php /var/www/html/wordpress/wp-config.php

# Expose web port
EXPOSE 80

# wp config for database
RUN sed -ie 's/database_name_here/wordpress/g' /var/www/html/wordpress/wp-config.php
RUN sed -ie 's/username_here/root/g' /var/www/html/wordpress/wp-config.php
RUN sed -ie 's/password_here/password/g' /var/www/html/wordpress/wp-config.php
RUN sed -ie 's/localhost/wordpressrds.xxxxxxxxxxxxxx.ap-southeast-2.rds.amazonaws.com:3306/g' /var/www/html/wordpress/wp-config.php
RUN rm -fr /var/www/html/wordpress/wp-content/themes/*
RUN rm -fr /var/www/html/wordpress/wp-content/plugins/*
ADD /shapely /var/www/html/wordpress/wp-content/themes/

# Start apache on boot
RUN echo "service apache2 start" >> ~/.bashrc

Answer 1

I see a couple problems. First of all your container should never require -t in order to run unless it is a temporary container that you plan to interact with using a shell. Background containers shouldn't require an interactive TTY interface, they just run in the background autonomously.

Second in your docker file I see a lot of RUN statements which are basically the build time commands for setting up the initial state of the container, but you don't have any CMD statement.

You need a CMD which is the process to actually kick off and start in the container when you try to run the container. RUN statements only execute once during the initial docker build, and then the results of those run statements are saved into the container image. When you run a docker container it has the initial state that was setup by the RUN statements, and then the CMD statement kicks off a running process in the container.

So it looks like that last RUN in your Dockerfile should be a CMD since the Apache server is the long running process that you want to run with the container state that you previously setup using all those RUN statements.

Another thing you should do is chain many of those consecutive RUN statements into one. Docker creates a separate layer for each RUN command, where each layer is kind of like a Git commit of the state of the container. So it is very wasteful to have so many RUN statements because it makes way too many container layers. You can do something like this ot chain RUN statements together instead to make a smaller, more efficient container:

RUN apt-get -y update && \
    DEBIAN_FRONTEND=noninteractive apt-get -y install unzip wget mysql-client mysql-server apache2 libapache2-mod-php7.0 pwgen python-setuptools vim-tiny php7.0-mysql  php7.0-lda && \
    rm -fr /var/cashe/*files neeeded

I recommend reading through this guide from Docker that covers best practices for writing a Dockerfile: https://docs.docker.com/engine/userguide/eng-image/dockerfile_best-practices/#cmd