Docker is a software container platform that helps automate the repetitive tasks of setting up and configuring development environments so that developers can focus on what matters: building great software.
Docker can build an image for your application, and bundle dependencies and your application into a standardized unit, called container that is independent from the host version of Linux kernel, platform distribution, or deployment model. This container can be transferred to another machine that runs Docker, and executed there without compatibility issues.
In short, a container is a stripped-to-basics version of a Linux operating system. An image is software you load into a container.
Digital Ocean is a cloud infrastructure provider that allows developers to deploy and host their programs on virtual private servers called Droplets.
Today we’re going to create a Docker container for the app that we built in Short Assignment 7, and then we’re going to deploy this container on Digital Ocean.
In the first part, you will get familiar with creating and testing a Docker container for your project. In the second part, you will learn how to deploy your container on Digital Ocean.
Be sure to look out for the following notations:
- 💻 run in terminal
- 🚀 this is a key step
⚠️ Follow instructions carefully!!!
Create a Docker container for your project and test:
- Create a Dockerfile and .dockerignore in the local repository of your Short Assignment 7.
- Build a docker container for your Short Assignment 7.
- Pull the mongodb docker container, run it and then link it to your project container.
- Make sure your project work in localhost:8080.
Deploy your project container on Digital Ocean:
- Push your project container to Docker Hub.
- Create a docker droplet in Digital Ocean.
- SSH to your server and pull the mongodb container and your project container.
- Run the mongodb container first then link it to your project container.
- Copy and paste the ip address of your server into your browser and have a look! You made it!
Windows users should download Docker Toolbox (You only need Docker Machine, no need to install any of the other options.)
🚀 Create a Digital Ocean account. It will ask for credit card information, but your Github Education Pack has a promo code that gives you a $50 credit which is much more than you need for this workshop.
Make sure not to miss the promo code option below the credit card form
🚀 After that, head on over to Docker Hub and create a free account there as well.
Now we will work on building a Docker container for the app we built in Short Assignment 7.
🚀 Before continuing, make the following change in server.js:
const mongoURI = `mongodb://${process.env.MONGODB_PORT_27017_TCP_ADDR}:${process.env.MONGODB_PORT_27017_TCP_PORT}/cs52poll`;
We will have our app running in one Docker container, and Mongodb running in another and then link them together, and this is used so that our app is looking in the correct place for the database.
sudo.
🚀 Create an empty file Dockerfile at the top level of your app directory and open it in Atom.
In the file you want the following:
FROM node:latest
# Create app directory
RUN mkdir -p /usr/src/app
WORKDIR /usr/src/app
# Install app dependencies
COPY package.json /usr/src/app/
RUN npm install
# Bundle app source
COPY . /usr/src/app
EXPOSE 9090
CMD [ "npm", "run", "dev" ]
🚀 Now, create a .dockerignore file in the same directory as your Dockerfile with following content:
node_modules
npm-debug.log
💻 Build the image:
$ docker build -t username/sa7-app .
Be prepared for this to download lots of files as it builds your image for you.
💻 Run the container:
$ docker run -p 8080:9090 -d username/sa7-app
But…. this doesn’t work because it is not connected to a database. (You may see a string of letters and numbers displayed on your terminal window. That’s normal! The string is actually the container ID of the container in which this image is running)
The -p option takes port 9090 of the container and exposes it on port 8080 on your localhost. Note that the port 9090 of our image is exposed to the container as we wrote in our DockerFile. The -d option runs it in detached mode so that it can continue even if you log out.
View the running docker containers
$ docker ps
View current and past running docker containers:
$ docker ps -a
Copy the container id from the above output. Print the console log of your app within the container:
$ docker logs <container id>
Note: you will see an error that ends with this:
[nodemon] app crashed - waiting for file changes before starting…
💻 Now halt your app container for now, we’ll start it back up in a few minutes after we set up and run our database container
$ docker stop <container id>
Side Note: You can connect to a running Docker container and run commands within it
$ docker exec -it <container id> bash
Or
$ docker exec -it <container name> bash
Your app wasn’t working in the container before because it was looking for a MongoDB database to connect to, but couldn’t find one. So we’re going to get one running in a separate container and link the two.
💻 Pull the latest Mongo image from Docker Hub:
$ docker pull mongo:latest
💻 Make a data directory in this folder:
$ mkdir $(pwd)/data
💻 Run the Mongo container:
$ docker run -v $(pwd)/data --name mongo -d mongo mongod --smallfiles
Now that you have a container with Mongo up and running. You can see that by running docker ps
Now you can link it to your app.
docker stop to halt your app container in the previous step:
💻 Bring your application alive and connect it to Mongo
$ docker run -p 8080:9090 --link mongo:mongodb -d username/sa7-app
Check your current processes using docker ps, and you can see both your app container and database container are up and running.
You should now be able to go to http://localhost:8080/ and view the app. But wait, isn’t this what we already had? Yes, so now it is time to upload our newly built Docker container to Docker Hub so that we can deploy it anywhere.
🚀 In Docker Hub, click Create Repository button on your right, create a new repository with the same name as your app(sa7-app) and give it whatever description you like. 💻 Then in Terminal, run
$ docker login
and use your Docker Hub credentials.
After you are logged in, push it to Docker Hub with a simple
$ docker push username/sa7-app
(this may take some time depending on your upload speed)
While that is uploading, let’s set up a droplet on Digital Ocean.
After logging in, there should be an option to Create a Droplet. Click that, and we’ll go through the process of setting up a simple Droplet with Docker set up.
🚀 Click the “Create Droplet” button. Then click the tab for “One-click apps” (right below “Choose an image”)
and choose Docker 17.04.0-ce on 16.04.
🚀 Scroll down and choose the $5/mo option, and it is fine to leave the rest at the defaults. Click create and it will bring you back to the Droplets screen and after a few moments the newly created droplet will appear.
💻 You will receive an email with the IP and the root password, which you will use to
$ ssh root@<server ip>
(Wait until your droplet finishes setting up and run the above ssh to login to your droplet. You can find the server ip in your droplet dashboard )
💻 Upon login you will be prompted to enter the root password which you received in the email.
You will see
Changing password for root.
(current) UNIX password:
💻 Just enter that password again and then set up a new password.
Now, if your Docker container has successfully been pushed to Docker Hub, then it is time to set it up here.
💻 Run the following commands while logged into root:
$ docker pull mongo:latest
$ docker pull username/sa7-app
$ mkdir ~/data
$ docker run -v ~/data:/data --name mongo -d mongo mongod --smallfiles
$ docker run -p 80:9090 --link mongo:mongodb -d username/sa7-app
Celebrate!!! This time we are exposing the container on port 80, so if you go to the server ip in your browser then you should be greeted with your app!
✅ Installed Docker and build a Docker container for your sa7.
✅ Tested your project container with the mongodb container locally.
✅ Pushed your project container to Docker Hub.
✅ Set up your Docker Droplet on Digital Ocean.
✅ Pulled your project container and mongo db container in your server and linked them. Then you made it happen!
References:
https://nodejs.org/en/docs/guides/nodejs-docker-webapp/
http://www.ifdattic.com/how-to-mongodb-nodejs-docker/
https://www.thachmai.info/2015/05/10/docker-container-linking-mongo-node/