How to add Dockerfile and test it locally

runme_dockerfile.md

Step 1: check/create Dockerfile in root

Your repository should have Dockerfile in the root directory. Specification of Dockerfile you can find here: https://docs.docker.com/engine/reference/builder/

For Node.JS application it can be something like this:

FROM node:12.10.0

# Create directory where we will place the application
WORKDIR /usr/src/app

# Copy application source code to the image
COPY . .

RUN npm install && \
    npm run build
# Which port the application expose
EXPOSE <PORT_EXPOSED_BY_APPLICATION>

# How we will run application
ENTRYPOINT npm run start

Where <PORT_EXPOSED_BY_APPLICATION> is a port which application listen inside container.

Step 2: build docker image locally

To build docker image locally ypou already should have installed docker-daemon on your laptop. How to do it you can find here: https://docs.docker.com/engine/install/

Then you need to go to the root of your repository and run command:

docker build -t test-app:latest .

As result you will have docker image with name test-app and tag latest.

Step 3: run docker image locally to test

After previous steps you should check docker image. To do this you have to run docker image on your laptop by command:

docker run --rm -pPORT_INSIDE:80 test-app:latest

Where PORT_INSIDE is port from Dockerfile from line EXPOSE.

After running application should be run on http://localhost, so you can open this URL in your browser and check the application. If you see correct web application there you can add this Dockerfile to the repo.