Updating Containers with Watchtower

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Updating Containers with Watchtower

For the last six months, the Acme Anvil Corporation has been migrating some of their bare metal infrastructure to Docker containers. After the initial implementation, the team has decided that they need a way to manage container updates. After doing some research, the team has discovered Watchtower. Watchtower is a container that updates all running containers when changes are made to the image that it is running. You have been tasked with creating a proof of concept for the team. You will need to create a Dockerfile that will be used to create a Docker image. The image will be pushed to Docker Hub. Next, you will create a container using this image. Once the image is created, you will deploy the Watchtower container. After Watchtower is deployed, you will update the Dockerfile, rebuild the image, and push the changes to Docker Hub. Watchtower checks for changes every 30 seconds. Once it detects the changes, Watchtower will update the running container. For more information on Watchtower you can go [here](https://github.com/v2tec/watchtower).

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Lab Info

Level

Intermediate

Last updated

May 05, 2025

Duration

1h 0m

Challenge

Create the Dockerfile

Create a Dockerfile:

vi Dockerfile

The Dockerfile should contain the following:

FROM node

RUN mkdir -p /var/node
ADD content-express-demo-app/ /var/node/
WORKDIR /var/node
RUN npm install
CMD ./bin/www

Challenge

Build the Docker Image
Build the Docker image:
```
docker build -t USERNAME/express -f Dockerfile .
```
Challenge

Push the Image to Docker Hub
Login to Docker Hub:
```
docker login
```
Push the image to Docker Hub:
```
docker push USERNAME/express
```
Challenge

Create a Demo Container
Create the container that Watchtower will monitor:
```
 docker run -d --name demo-app -p 80:3000 --restart always USERNAME/express
```

Challenge

Create the Watchtower Container

Create the Watchtower container that will monitor the demo-app container:

docker run -d --name watchtower --restart always -v /var/run/docker.sock:/var/run/docker.sock containrrr/watchtower -i 30

Challenge

Update the Docker Image

Update the Docker image:

docker build -t USERNAME/express -f Dockerfile .

Repush the image to Docker Hub:

docker push USERNAME/express:latest

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