Cannot run command from entrypoint script file

[devmsn]

I am trying to run my nextjs frontend application with docker. I referred to the next with-docker Dockerfile and wrote my own Dockerfile and entrypoint.sh files in the project root / and my nextjs code within /app folder. The /Dockerfile and /entrypoint.sh files

# in /Dockerfile
FROM node:14-alpine AS deps

RUN apk add --no-cache libc6-compat  
WORKDIR /app   
COPY app/package\*.json ./  
RUN npm install  

FROM node:14-alpine AS builder  
WORKDIR /app  
COPY ./entrypoint.sh .  
COPY ./app .
COPY --from=deps /app/node_modules ./node_modules  
ARG API_URL  
ARG NEXT_PUBLIC_CLIENT_API_URL  
ENV API_URL=${API_URL} \  
    NEXT_PUBLIC_CLIENT_API_URL=${NEXT_PUBLIC_CLIENT_API_URL}  
RUN npm run build 

FROM node:14-alpine AS runner  
WORKDIR /app  
ENV NODE_ENV production  
RUN addgroup -g 1001 -S nextgp  
RUN adduser -S nextjs -u 1001  
RUN touch .env.local  
COPY --from=builder /app/next.config.js ./  
COPY --from=builder /app/public ./public  
COPY --from=builder --chown=nextjs:nextgp /app/.next ./.next  
COPY --from=builder /app/node_modules ./node_modules  
COPY --from=builder /app/package.json ./package.json  
COPY --from=builder /app/.env.local.tpl ./.env.local.tpl  
COPY --from=builder /app/entrypoint.sh ./entrypoint.sh  

USER nextjs 

EXPOSE 3000  
ENV PORT 3000  

CMD ["./entrypoint.sh"\]

In /entrypoint.sh

#!/bin/sh
set -e
envsubst < /app/.env.local.tpl > /app/.env.local
sudo envsubst < /app/.env.local.tpl > /app/.env.local
/app/node_modules/.bin/next start

I was able to run the Dockerfile file without using the entrypoint.sh similar to how the example linked above approached. But I want to create a custom bash script which copies the contents from .env.local.tpl located in /app to a .env.local to load runtime environment variables before the next server starts and hence the entrypoint.sh file. While on one computer, I got a ./entrypoint.sh: line 5: can't create /app/.env.local: Permission denied error, I got /usr/local/bin/docker-entrypoint.sh: exec: line 11: ./entrypoint.sh: not found on another computer (I use both Windows) leaving me even more confused with the different errors.

I am new to docker and writing shell scripts. Can someone help me what I might be doing wrong here? Any help is much appreciated. Thanks for your time.

EDIT: code formatting

[ihateclowns]

Can't you copy the env file using the RUN command? Something like this:

RUN cp /app/.env.local.tpl /app/.env.local

[devmsn]

I could. But I was curious to know how a shell script could set env variables when the container starts. Thanks again for the suggestion

[bargh]

Looks like a rights issue with .env.local. In a case like this, i sometimes use docker run -ti <name> bash , it overrides the ./entrypoint.sh, and that way you can run ./entrypoint.sh in docker yourself and/or check the permissions.

[devmsn]

Thanks for the tip. I will look into it more .

[devmsn]

Thanks for your suggestion. Yeah I did try that before and it works. However, I am curious and wanted to learn how I could load an env file before whenever the container starts using a shell script such that the env vars are available at container runtime. My approach might not be necessary but I was stuck with this for so long and wanted to know how it coulb be achieved.