Dockerfile contd..
- ARG :
- This instruction can be helpful in defining the variable and pass argument during build time
- The arguments can be passed from docker command line “`docker image build –build-arg <arg>=value
- Refer Here for the changes
- ENV: This instruction sets the environmental variable and is available while running the container and this can be changed while running your container
- Refer examples done inthe class
- Exercise: Try to fix the container not starting issue with the following dockerfile
FROM openjdk:11-slim
LABEL author="khaja ibrahim"
LABEL organization="quality thought"
ARG DOWNLOAD_URL="https://referenceapplicationskhaja.s3.us-west-2.amazonaws.com/spring-petclinic-2.4.2.jar"
ENV APPLICATION_PATH="/spring-petclinic.jar"
ENV TEST_ENV="hello"
ADD ${DOWNLOAD_URL} ${APPLICATION_PATH}
EXPOSE 8080
CMD [ "java", "-jar", ${APPLICATION_PATH} ]
- ESCAPE: The escape directive sets the escape characters in the Dockerfile. If not specified the default escape is
\
#escape=`
- Sample dockerfile
#escape=`
FROM ubuntu:bionic
LABEL author='khaja'
RUN export DEBIAN_FRONTEND=noninteractive `
&& apt update && apt install apache2 -y `
&& apt install php libapache2-mod-php php-mysql -y `
&& apt install php-cli -y
COPY info.php /var/www/html/info.php
WORKDIR /var/www/html
EXPOSE 80
ENTRYPOINT [ "echo" ]
CMD [ "helloworld" ]
-
Exercise: There is a sample python code Refer Here
-
Manual Steps:
- Ensure python is installed
- Ensure pip is installed
- clone the code from github
git clone https://github.com/khajasampleapps/basicflask.git - Execute
pip install -r requirements.txt - To run your application
python app.py
-
Try to create a Dockerfile with all the necessary instructions to create an image for basicflask
-
Few sessions earlier we have created a Dockerfile for gameoflife, which needed tomcat to work.
FROM tomcat:jdk8
LABEL author="khaja"
EXPOSE 8080
ADD https://referenceapplicationskhaja.s3.us-west-2.amazonaws.com/gameoflife.war /usr/local/tomcat/webapps/gameoflife.war
- In this Dockerfile we have not written ENTRYPOINT/CMD because we want to use base images CMD.
