The Dockerfile

In this lesson, we are going to discuss the Dockerfile that we uploaded in the previous lesson. This lesson will show you how to fulfill all the requirements and dependencies of your application if you will run it in a Docker container.

Dockerfile

So here goes the Dockerfile:

Base Image

FROM gcr.io/educative-exec-env/educative:latest

This is an official image made by Educative. It comes with an operating system of Ubuntu:16.04 with Python 2.7 and Node.js 8.x already installed in the container. So now we have Node.js of version 8 built into the container.

Copying Files into Docker environment

Next, we will transfer files from outside of the Docker environment into the Docker environment. So first of all, we create a folder named Basic-MERN-Stack-App in the directory (usr/local/educative):

RUN cd usr/local/educative && mkdir Basic-MERN-Stack-App

Your code can reside anywhere else as well but as a convention, we place the folders in this directory (usr/local/educative).

By using the COPY command, we copy the contents of Basic-MERN-Stack-App into usr/local/educative/Basic-MERN-Stack-App (the folder that we created in the previous step):

## Copying the contents of Basic-MERN-Stack-App to the folder we created in the above command
COPY Basic-MERN-Stack-App  usr/local/educative/Basic-MERN-Stack-App

Now that the files are present in the Docker environment, we install the node_modules by using npm install in the root and the client folder:

RUN cd usr/local/educative/Basic-MERN-Stack-App && \
    npm install && \
    cd client && \ 
    npm install

The above portion is how you copy your code files into the Docker Environment. So far, we have Ubuntu as our OS with Python and Node.js installed on it. We have also transferred our application code into the Docker environment in the following directory:

usr/local/educative/Basic-MERN-Stack-App.

Installing yarn

Let’s look at the requirements left now. As this particular project requires yarn, we install it through the following instructions:

RUN curl -sS https://dl.yarnpkg.com/debian/pubkey.gpg | apt-key add -
RUN echo "deb https://dl.yarnpkg.com/debian/ stable main" | tee /etc/apt/sources.list.d/yarn.list
RUN apt-get update && apt-get install yarn

Fixing etc/hosts

On Educative, the etc/hosts files need to be fixed as it becomes empty in the OS of the Docker container. The /etc/hosts is an operating system file that translates hostnames or domain names to IP addresses Therefore, we append the lines specified using the echo command:

RUN echo "127.0.0.1       localhost" >> /etc/hosts && \
    echo "::1     localhost ip6-localhost ip6-loopback" >> /etc/hosts  && \
    echo "fe00::0 ip6-localnet" >> /etc/hosts && \
    echo "ff00::0 ip6-mcastprefix" >> /etc/hosts && \
    echo "ff02::1 ip6-allnodes" >> /etc/hosts && \
    echo "ff02::2 ip6-allrouters" >> /etc/hosts && \
    echo "172.17.0.3      e2d7ddabb2c5" >> /etc/hosts

Tmux

tmux is not part of the requirement but it will used by us to view both the client and server sessions at once in the same terminal.

RUN  apt-get -y install tmux

MongoDB

Finally, MongoDB is installed in the following way:

RUN apt-get update && rm -rf /var/lib/apt/lists/*
RUN apt-get update && apt-get install -y gnupg2
RUN apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv 9DA31620334BD75D9DCB49F368818C72E52529D4
RUN bash -c 'echo "deb http://repo.mongodb.org/apt/ubuntu xenial/mongodb-org/4.0 multiverse" > /etc/apt/sources.list.d/mongodb-org-4.0.list'
RUN apt-get update
RUN apt-get install -y mongodb-org=4.0.10 mongodb-org-server=4.0.10 mongodb-org-shell=4.0.10 mongodb-org-mongos=4.0.10 mongodb-org-tools=4.0.10 --allow-unauthenticated
RUN mkdir -p /data/db
RUN mongod --smallfiles > /dev/null &

You can modify the versions in the command according to the requirements of your application.

Options to Copy Code

There are two options to copy code files into the container:

1. Cloning from GitHub
2. Copying Files via Dockerfile when the image is built

To clone from GitHub, you can use the git clone <your-repository-link> command. If we didn’t make modifications to the code on GitHub, we would have used the following commands:

RUN cd usr/local/educative && \
    git clone https://github.com/hemakshis/Basic-MERN-Stack-App.git && \
    cd Basic-MERN-Stack-App && \
    npm install && \
    cd client && \ 
    npm install