webpack cache-at-build-time Dockerfile example

docker-entrypoint.sh

#!/bin/bash

# read in WEBPACK_BUILD_ENV that was written at build time in the Dockerfile (above)
. /webpack-environment.env

if [[ "$1" = "myapp" ]]; then
  if [[ -z "$ENV" || "$WEBPACK_BUILD_ENV" != "$ENV" ]]; then
    npm run "build:${environment}"
  fi
  exec myapp
fi

exec "$@"

Dockerfile

# build webpack at runtime and write the build envionment name to a file
FROM whatever
ARG WEBPACK_BUILD_ENV=dev
RUN npm run build:${WEBPACK_BUILD_ENV && echo ${WEBPACK_BUILD_ENV} > /webpack-environment.env
ENTRYPOINT ["/docker-entrypoint.sh"]
CMD ["myapp"]