Railway•14mo ago

Build keeps hitting cache -> ENV variable is not changing

Hello! I have a github repo w/ a Dockerfile set up. On Railway, I changed the enviornment variable and redeployed, and am currently getting an error related to the fact that this environment variable was not updated. Specifically it is a Next.js project and the ENV variable is NEXT_PUBLIC_API_URL. Likewise, the env variable is updated to my production API url. Because this environment variable is not changed, my frontend can't reach the backend, and it errors.

Solution:

after line 6 of your dockerfile add

ARG NEXT_PUBLIC_API_URL

ARG NEXT_PUBLIC_API_URL

this needs to come after the FROM build phase instruction because this variable is used during the build...

Jump to solution

41 Replies

Percy•14mo ago

Project ID: b3d6999c-60f7-4134-8803-08aa389195aa

celestial•14mo ago

b3d6999c-60f7-4134-8803-08aa389195aa

Brody•14mo ago

what is the value you have set in that variable

celestial•14mo ago

Original value is http://host.docker.internal:3000 and the new value should have been along the lines of https://myserver-production.up.railway.app The reason why I know the environment variable is the problem is because my fetch error gets printed out to the console. It says it can't reach the url at "host.docker.internal"

Brody•14mo ago

can you please update it once again to use a reference variable? https://docs.railway.app/develop/variables#reference-variables

celestial•14mo ago

NEXT_PUBLIC_API_URL=https://${{RAILWAY_SERVICE_server_URL}} does this look right?

Brody•14mo ago

nope this is the format you want

API_URL=https://${{backend.RAILWAY_PUBLIC_DOMAIN}}

API_URL=https://${{backend.RAILWAY_PUBLIC_DOMAIN}}

so let's see what you got

celestial•14mo ago

gimme a sec Same error

TypeError: fetch failed] {
cause:  [Error: getaddrinfo ENOTFOUND host.docker.internal] {
errno: -3008,
code: 'ENOTFOUND',
syscall: 'getaddrinfo',
hostname: 'host.docker.internal'
}
}
[Error: An error occurred in the Server Components render. The specific message is omitted in production builds to avoid leaking sensitive details. A digest property is included on this error instance which may provide additional details about the nature of the error.] {
digest: '561305779'
}

TypeError: fetch failed] {
cause:  [Error: getaddrinfo ENOTFOUND host.docker.internal] {
errno: -3008,
code: 'ENOTFOUND',
syscall: 'getaddrinfo',
hostname: 'host.docker.internal'
}
}
[Error: An error occurred in the Server Components render. The specific message is omitted in production builds to avoid leaking sensitive details. A digest property is included on this error instance which may provide additional details about the nature of the error.] {
digest: '561305779'
}

celestial•14mo ago

my variables

Brody•14mo ago

what's the value set to

celestial•14mo ago

${{shared.NEXT_PUBLIC_API_URL}}

Brody•14mo ago

that's definitely not the correct value this format we will sort out why the build is still using that host.docker.internal url, but we first need to use the proper reference variable

celestial•14mo ago

Same error NEXT_PUBLIC_API_URL=https://${{server.RAILWAY_PUBLIC_DOMAIN}}

Brody•14mo ago

and the api service is named "server" right?

celestial•14mo ago

yes

Brody•14mo ago

okay looks good then

celestial•14mo ago

i guess i could also try the internal railway URL but

Brody•14mo ago

so you said you where using a dockerfile, could you send it?

celestial•14mo ago

sure

FROM node:18-alpine AS base 

RUN apk add --no-cache libc6-compat

# Build
FROM base AS builder 
WORKDIR /app
COPY package*.json ./
RUN npm install
COPY . .
RUN npm run build

# Production
FROM base AS production
WORKDIR /app

RUN addgroup --system --gid 1001 nodejs
RUN adduser --system --uid 1001 nextjs

# Set the correct permission for prerender cache
RUN mkdir .next
RUN chown nextjs:nodejs .next


COPY --from=builder /app/package*.json ./
COPY --from=builder /app/.next ./.next
COPY --from=builder /app/public ./public
COPY --from=builder /app/node_modules ./node_modules

USER nextjs
EXPOSE 3000

ENV PORT 3000
ENV HOSTNAME "0.0.0.0"

CMD ["npm", "start"]

FROM node:18-alpine AS base 

RUN apk add --no-cache libc6-compat

# Build
FROM base AS builder 
WORKDIR /app
COPY package*.json ./
RUN npm install
COPY . .
RUN npm run build

# Production
FROM base AS production
WORKDIR /app

RUN addgroup --system --gid 1001 nodejs
RUN adduser --system --uid 1001 nextjs

# Set the correct permission for prerender cache
RUN mkdir .next
RUN chown nextjs:nodejs .next


COPY --from=builder /app/package*.json ./
COPY --from=builder /app/.next ./.next
COPY --from=builder /app/public ./public
COPY --from=builder /app/node_modules ./node_modules

USER nextjs
EXPOSE 3000

ENV PORT 3000
ENV HOSTNAME "0.0.0.0"

CMD ["npm", "start"]

This is essentially the same Dockerfile provided by next.js's examples

Brody•14mo ago

that depends, the internal network is not available at build time, so if you only call this api at run time then you can call the internal domain

celestial•14mo ago

Judging from the build logs i assumed that this being cached was the issue (but im not very good at infra stuff so idk)

Brody•14mo ago

I have ideas, need to know some more information to come to any real conclusions where do you get this error from, build logs or deployment logs

celestial•14mo ago

deployment logs

Solution

Brody•14mo ago

after line 6 of your dockerfile add

ARG NEXT_PUBLIC_API_URL

ARG NEXT_PUBLIC_API_URL

this needs to come after the FROM build phase instruction because this variable is used during the build

Brody•14mo ago

show me the dockerfile before you push anything though please

celestial•14mo ago

FROM node:18-alpine as base 

WORKDIR /server 

FROM base as build
ARG NEXT_PUBLIC_API_URL
COPY package*.json ./
RUN npm ci

COPY . ./
RUN npx prisma generate
RUN npm run build

FROM base as production

COPY --from=build /server/build /server/build
COPY --from=build /server/node_modules /server/node_modules
COPY --from=build /server/prisma /server/prisma
COPY --from=build /server/.env* /server/
COPY --from=build /server/startup.sh /server/

EXPOSE 8080
ENV PORT 8080
CMD ["node", "/server/build/index.js"]

FROM node:18-alpine as base 

WORKDIR /server 

FROM base as build
ARG NEXT_PUBLIC_API_URL
COPY package*.json ./
RUN npm ci

COPY . ./
RUN npx prisma generate
RUN npm run build

FROM base as production

COPY --from=build /server/build /server/build
COPY --from=build /server/node_modules /server/node_modules
COPY --from=build /server/prisma /server/prisma
COPY --from=build /server/.env* /server/
COPY --from=build /server/startup.sh /server/

EXPOSE 8080
ENV PORT 8080
CMD ["node", "/server/build/index.js"]

Brody•14mo ago

cleaned up that dockerfile nicely too, nice job push it

celestial•14mo ago

👀 currently deploying. I noticed there was no cache message though

Brody•14mo ago

interesting I see a .env copy, can you elaborate on that? are you using .env files in production?

celestial•14mo ago

ope that was the wrong dockerfile i copy/pasted. that was my backend 😅 sorry bout that. the correct dockerfile is updated tho 👍 But yeah im using .env files is that a bad practice

Brody•14mo ago

yes it is, you would want to use service variables

celestial•14mo ago

Brody•14mo ago

then there's no need for a .env file since the service variables are injected into the environment automatically

celestial•14mo ago

do .env files override serivce variables? can that might be the issue

Brody•14mo ago

yes the dotenv package would indeed overwrite variables from the environment

celestial•14mo ago

😮 OH WAIT ITS WORKING Thank you Brody 🤝 I would not have thought that the ARG would be what I needed

Brody•14mo ago

no problem but please use service variables going forward, you should not have an .env file in your repo as that is a massive security issue even if the repo is private, I've seen way too many .env files in repos that used to be private

celestial•14mo ago

Will do my friend

Brody•14mo ago

and the ARG <variable name> is only needed in the dockerfile if that specific variable is being used during build in your case it is technically used during runtime, but it's also used during build because the value of that variable is getting baked in to your app during build, therefore it is needed during build so you have to bring it in with ARG

celestial•14mo ago

Ahh that makes more sense

Brody•14mo ago

awesome

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Build keeps hitting cache -> ENV variable is not changing