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Docker build cache issue?


I am injecting build details into a docker image through the dockerfile build, with this code

FROM node:10.15.3

Build information passed in, this can be bound into the application if required



set working directory

RUN mkdir /usr/src/app

WORKDIR /usr/src/app

add /usr/src/app/node_modules/.bin to $PATH

ENV PATH /usr/src/app/node_modules/.bin:$PATH

install and cache app dependencies

COPY ./ /usr/src/app/

COPY package.json /usr/src/app/package.json

RUN echo “{ “buildDate”: “$BUILD_DATE” }” > /usr/src/app/src/build-date.json

RUN echo “{ “buildVersion”: “$BUILD_TAG” }” > /usr/src/app/src/build-version.json

RUN npm install --silent

RUN npm install react-scripts@1.1.1 -g --silent

RUN npm run build

start app

CMD [“npm”, “start”]

This works so that if I run

docker run -it imageName bash

I can see the files and verify the content. Starting the image using docker-compose also works and I can show the build details in and about box widget. All good so far.

If I rebuild the image using the same scripts. and check the files with docker run -it again they are correct, however, when I start the image with docker-compose and execute
docker exec -it containerName bash

and cat the files they are still the files from the original build. It is as though they are cached but I can’t see where. The docker build command is;

docker build --no-cache --build-arg BUILD_TAG=$localTag --build-arg BUILD_DATE="$localTimeStamp" -t $localImage .

I hope I have explained that, in summary docker run image seems to give the correct information, docker exec container shows an old file.

Any suggestions?