docker - pass arguments to the script during build - docker

Question

I would like to pass argument (from the docker command) to the shell script inside the Dockerfile.
This is the docker command line.
docker build --file=DockerfileTest --build-arg docker_image=PX-release-migration --tag=test-image:latest --rm=true .
This is a script that is called inside the Dockerfile.
#!/bin/sh -e
image_name=$1
echo "docker image is $image_name"
if [[ ($image_name == '') || ($image_name == *"-dev-"*) ]]; then
echo "This is development"
cp src/main/resources/application-dev.properties src/main/resources/application.properties
elif [[ $image_name == *"-preprod-"* ]]; then
echo "This is preprod"
cp src/main/resources/application-stg.properties src/main/resources/application.properties
elif [[ $image_name == *"-release-"* ]]; then
echo "This is production"
cp src/main/resources/application-prod.properties src/main/resources/application.properties
fi
When I execute separately the script, it works, but it doe
This is docker file.
ARG spring_env=local
ARG docker_image=-local-
FROM maven:3.6.1-jdk-8
COPY . /apps/demo
WORKDIR /apps/demo
RUN chmod +x /apps/demo/initialize_env.sh
RUN ./initialize_env.sh $docker_image
RUN echo "spring_env is ${spring_env}"
So basically, i would like to use a different spring application properties file during the build depending on the docker_image name. If a docker image name contains 'release', i would like to package application-prod.properties during the build.
This is the error message that I am getting.
Step 1/8 : ARG spring_env=local
Step 2/8 : ARG docker_image=-local-
Step 3/8 : FROM maven:3.6.1-jdk-8
---> 4c81be38db66
Step 4/8 : COPY . /apps/demo
---> 41439197c465
Step 5/8 : WORKDIR /apps/demo
---> Running in 56bd408c2eb1
Removing intermediate container 56bd408c2eb1
---> 4c4025bf5f64
Step 6/8 : RUN chmod +x /apps/demo/initialize_env.sh
---> Running in 18dc3a5c1a54
Removing intermediate container 18dc3a5c1a54
---> 60d2037a0209
Step 7/8 : RUN ./initialize_env.sh $docker_image
---> Running in 2e049b2cf630
docker image is
./initialize_env.sh: 5: ./initialize_env.sh: Syntax error: word unexpected (expecting ")")
The command '/bin/sh -c ./initialize_env.sh $docker_image' returned a non-zero code: 2
When I execute separately the script, it works, but it doesn't inside the docker container.

Answer 1

Tip: Use ShellCheck to check scripts for syntax errors.
#!/bin/sh -e
if [[ ($image_name == '') || ($image_name == *"-dev-"*) ]]; then
[[ is bash syntax but your script is declared to use plain sh. It works on your machine presumably because sh is really symlinked to bash, but inside the container that's not the case. maven:3.6.1-jdk-8 is based on debian:stretch which uses dash instead of bash.
Change the shebang line. You can also delete the parentheses; they're superfluous.
#!/bin/bash -e
if [[ $image_name == '' || $image_name == *"-dev-"* ]]; then
You could also use a case block to simplify the repetitive checks.
case "$image_name" in
''|*-dev-*)
echo "This is development"
cp src/main/resources/application-dev.properties src/main/resources/application.properties
;;
*-preprod-*)
echo "This is preprod"
cp src/main/resources/application-stg.properties src/main/resources/application.properties
;;
*-release-*)
echo "This is production"
cp src/main/resources/application-prod.properties src/main/resources/application.properties
;;
esac