Have troubles figuring out the execution context using Docker and Docker Compose

Question

I have the following docker-compose.yml:

version: '3'
services:
  frontend:
    build: 
      context: ./
      dockerfile: docker/Dockerfile
    image: tsl.web.frontend.image
    container_name: tsl.web.frontend.container
    ports:
      - "8080:80"

Notice the context: ./

And this is my docker-compose command:

docker-compose build --force-rm --build-arg ENVIRONMENT=development frontend

Here is the structure of my src code:

Notice I have red underlined two important aspects of this structure.

Now here is a part of my Dockerfile, I will include the entire Dockerfile below:

# https://stackoverflow.com/a/35774741/1258525
# use changes to package.json to force Docker not to use the cache
# when we change our application's nodejs dependencies:
COPY ./package.json /tmp/package.json
RUN npm --prefix /tmp install /tmp
RUN cp -rn /tmp/node_modules ./
#RUN npm --prefix ./ run build-development ./
RUN npm run build-development #failing here

COPY dist /usr/share/nginx/html

So the RUN npm run build-development command is failing because it cannot find package.json:

This is where I am confused about the execution context of the RUN statement. I was able to copy the package.json file to /tmp in the previous Dockerfile command COPY ./package.json /tmp/package.json. I think my context is still where my docker-compose.yml file lives but obviously it is not...

Complete Dockerfile:

FROM centos:7
MAINTAINER Brian Ogden

# Not currently being used but may come in handy
ARG ENVIRONMENT
ENV NODE_VERSION 6.11.1

RUN yum -y update; yum clean all
RUN yum -y install http://nginx.org/packages/centos/7/noarch/RPMS/nginx-release-centos-7-0.el7.ngx.noarch.rpm; yum -y makecache
RUN yum -y install nginx-1.12.0

# Cleanup some default NGINX configuration files we don’t need
RUN rm /etc/nginx/conf.d/default.conf

COPY ./docker/conf/frontend.conf /etc/nginx/conf.d/frontend.conf
COPY ./docker/conf/nginx.conf /etc/nginx/nginx.conf

#############################################
# NodeJs Install
#############################################
RUN yum install -y \
        wget

#Download NodeJs package
RUN wget https://nodejs.org/dist/v$NODE_VERSION/node-v$NODE_VERSION-linux-x64.tar.gz

#extract the binary package into our system's local package hierarchy with the tar command. 
#The archive is packaged within a versioned directory, which we can get rid of by passing the --strip-components 1 option. 
#We will specify the target directory of our command with the -C command:
#This will install all of the components within the /usr/local branch
RUN tar --strip-components 1 -xzvf node-v* -C /usr/local
#############################################

# https://stackoverflow.com/a/35774741/1258525
# use changes to package.json to force Docker not to use the cache
# when we change our application's nodejs dependencies:
COPY ./package.json /tmp/package.json
RUN npm --prefix /tmp install /tmp
RUN cp -rn /tmp/node_modules ./
#RUN npm --prefix ./ run build-development ./
RUN npm run build-development

COPY dist /usr/share/nginx/html

EXPOSE 8080

CMD ["nginx"]

ALex_hha · Accepted Answer · 2017-12-19 23:18:12Z

1

You can run intermediate container with id 4e14504665eb and explore the filesystem.

$ docker run -it --rm 4e14504665eb  bash

or you can directly run

$ docker run -it --rm 4e14504665eb  ls -la /tmp

But these commands look a little bit weird

RUN npm --prefix /tmp install /tmp
RUN cp -rn /tmp/node_modules ./
RUN npm run build-development

You probably should run build command from /tmp directory

P.S. Your Dockerfile looks not optimal. I would suggest to use more optimized version

answered Dec 19, 2017 at 23:18

ALex_hha

7,4152 gold badges28 silver badges42 bronze badges

thanks for your optimized Docker file, if you look at my answer below I used many of your optimizations, you will probably also see more of what my issue was with npm run build-development

Brian
– Brian

2017-12-20 21:54:28 +00:00
Commented Dec 20, 2017 at 21:54
notice that your version of / && did not work and also CMD ["nginx", "-g", "daemon off;"] did not work for me, nginx did not start up

Brian
– Brian

2017-12-20 22:25:05 +00:00
Commented Dec 20, 2017 at 22:25
Without logs I can't help you

ALex_hha
– ALex_hha

2017-12-21 11:31:12 +00:00
Commented Dec 21, 2017 at 11:31

Add a comment |

Brian · Accepted Answer · 2017-12-20 22:21:32Z

I believe the foundation of my misunderstanding was really the execution context of the Docker COPY command versus the RUN command.

I thought that the RUN command was running in the same execution context as COPY which would be the Dockerfile or the context stated in my docker-compose.yml because COPY was in this context.

That is not the case though, basically COPY knows ./ to the Dockerfile. RUN however does not know about anything outside of the Docker image being built.

I was trying to RUN a command against files I had not copied into the Docker image I was building. This section of my Dockerfile was the secret to success:

WORKDIR /app
COPY . /app

RUN npm run build-$ENVIRONMENT

And here is my complete working Dockerfile, thanks to ALex_hha for some of the syntax optimizations:

FROM centos:7
MAINTAINER Brian Ogden

# Not currently being used but may come in handy
ARG ENVIRONMENT
ENV NODE_VERSION 6.11.1

RUN yum -y update && \
    yum clean all && \
    yum -y install http://nginx.org/packages/centos/7/noarch/RPMS/nginx-release-centos-7-0.el7.ngx.noarch.rpm \
    yum -y makecache && \
    yum -y install nginx-1.12.0 wget

# Cleanup some default NGINX configuration files we don’t need
RUN rm /etc/nginx/conf.d/default.conf

#############################################
# NodeJs Install
#############################################

#Download NodeJs package
RUN wget -q -O - https://nodejs.org/dist/v$NODE_VERSION/node-v$NODE_VERSION-linux-x64.tar.gz \
    | tar --strip-components=1 -xzf - -C /usr/local
#pipe tar is extracting the binary package into our system's local package hierarchy with the tar command. 
#The archive is packaged within a versioned directory, which we can get rid of by passing the --strip-components 1 option. 
#We will specify the target directory of our command with the -C command:
#This will install all of the components within the /usr/local branch

# https://stackoverflow.com/a/35774741/1258525
# use changes to package.json to force Docker not to use the cache
# when we change our application's nodejs dependencies:
COPY ./package.json /tmp/package.json
RUN cd /tmp && npm install
RUN mkdir /app && cp -a /tmp/node_modules /app/

WORKDIR /app
COPY . /app

RUN npm run build-$ENVIRONMENT

RUN cd /app && cp -a dist/* /usr/share/nginx/html
COPY ./docker/conf/frontend.conf /etc/nginx/conf.d/frontend.conf
COPY ./docker/conf/nginx.conf /etc/nginx/nginx.conf


EXPOSE 80

CMD ["nginx"]

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