Dockerfile Build Arguments

In this lesson, we will explore using build arguments to paramerterize an image build.

Use the --build-arg flag when building an image:

--build-arg [NAME]=[VALUE]

Use the ARG instruction in the Dockerfile:

ARG [NAME]=[DEFAULT_VALUE]

Step 1: Navigate to the args directory:

mkdir args

cd args

Step 2: Clone the weather-app:

git clone https://github.com/nishanthkumarpathi/content-weather-app.git src

Step 3: Create the Dockerfile:

vi Dockerfile

Step 4: Create an image for the weather-app

Dockerfile:

FROM node
LABEL org.label-schema.version=v1.1
ARG SRC_DIR=/var/node

RUN mkdir -p $SRC_DIR
ADD src/ $SRC_DIR
WORKDIR $SRC_DIR
RUN npm install
EXPOSE 3000
CMD ./bin/www

Step 5: Build the weather-app image:

docker image build -t nishanthkp/weather-app:v3 --build-arg SRC_DIR=/var/code .

Step 6: Inspect the image:

docker image inspect nishanthkp/weather-app:v3 | grep WorkingDir

Step 7: Create the weather-app container:

docker container run -d --name weather-app3 -p 8085:3000 nishanthkp/weather-app:v3

Step 8: Verify that the container is working by executing curl:

curl localhost:8085

In case if you dont find curl in your system, then do the following.

sudo apt install curl