Running a bash script before startup in an NGINX docker container

Question

I'm trying to run a javascript app on localhost:8000 using docker. Part of what I would like to do is swap out some config files based on the docker run command, I'd like to pass an environment variable into the container so that the bash script can use that as a parameter.

What my dockerfile is looking like is this:

FROM nginx
COPY . /usr/share/nginx/html
CMD ["bash","/usr/share/nginx/html/runfile.sh"]

And the bash script looks like this:

#!/bin/bash
if [ "$SECURITY_VERSION" = "OPENAM" ]; then
    sed -i -e 's/localhost/openam/g' authConfig.js
fi

docker run -p 8000:80 missioncontrol:latest -e SECURITY_VERSION="TEST"

Docker gives me an exception saying -e exec command not found.

However if I change the dockerfile to use ENTRYPOINT instead of CMD, the -e flag works but the webserver does not start up.

Is there something I'm missing here? Is the ENTRYPOINT being overriden or something?

EDIT:

So I've updated my dockerfile to use ENTRYPOINT ["bash","/usr/share/nginx/html/runfile.sh", ";", " nginx -g daemon off;"]

But the docker container still shuts down. Is there something I'm missing?

Answer 1

NGINX 1.19 has a folder /docker-entrypoint.d on the root where place startup scripts executed by thedocker-entrypoint.sh script. You can also read the execution on the log.

/docker-entrypoint.sh: /docker-entrypoint.d/ is not empty, will attempt to perform configuration

/docker-entrypoint.sh: Looking for shell scripts in /docker-entrypoint.d/

/docker-entrypoint.sh: Launching

[..........]

/docker-entrypoint.sh: Configuration complete; ready for start up

Answer 2

Update the CMD line as below in the your dockerfile. Please note that if runfile.sh does not succeed (exit 0; inside it) then the next nginx command will not be executed.

FROM nginx
COPY . /usr/share/nginx/html
CMD /usr/share/nginx/html/runfile.sh && nginx -g 'daemon off;'

nginx docker file is using a CMD commnd to start the server on the base image you use. When you use the CMD command in your dockerfile you overwrite the one in their image. As it is mentioned in the dockerfile documentation:

There can only be one CMD instruction in a Dockerfile. If you list more than one CMD then only the last CMD will take effect.