Issues passing Docker build args

1

Hi!

I’ve a simple Dockerfile containing an Angular build:

FROM node:alpine AS build-env
WORKDIR /app

ARG BUILD_COMMAND

COPY package.json ./
COPY package-lock.json ./

RUN npm i

COPY projects ./projects
COPY config ./config
COPY angular.json ./
COPY tsconfig.json ./
COPY tailwind.config.js ./

RUN $BUILD_COMMAND

As you can see, I’ve an ARG to run a certain build command that will be a bit different depending on deploying to production or staging environment.

Locally, when I test the Dockerfile, I run:

docker build --build-arg "BUILD_COMMAND=npm run build:prod" -t frontend .

It works as expected.

The Render documentation then tells me:

As I understand this, I can simply set up an environment variable and use it as a build arg in my Dockerfile.

Therefore, I’ve setup the environment variable like this:

image

But when I run a deployment, the following log is outputted:

Oct 4 04:04:41 PM  #19 [build-env 10/11] COPY tailwind.config.js ./
Oct 4 04:04:41 PM  #19 DONE 0.1s
Oct 4 04:04:41 PM  
Oct 4 04:04:41 PM  #20 [build-env 11/11] RUN $BUILD_COMMAND
Oct 4 04:04:41 PM  #20 DONE 0.2s
Oct 4 04:04:41 PM  
Oct 4 04:04:41 PM  #21 [stage-1 3/4] COPY --from=build-env /app/dist/smudgy /usr/share/nginx/html
Oct 4 04:04:41 PM  #21 ERROR: failed to calculate checksum of ref u1af40o4ezjdscs8wd738ils6::mn7wero8o7q9bempjeowvxorf: failed to walk /home/user/.local/tmp/buildkit-mount2121883536/app/dist: lstat /home/user/.local/tmp/buildkit-mount2121883536/app/dist: no such file or directory
Oct 4 04:04:41 PM  ------
Oct 4 04:04:41 PM   > [stage-1 3/4] COPY --from=build-env /app/dist/smudgy /usr/share/nginx/html:
Oct 4 04:04:41 PM  ------
Oct 4 04:04:41 PM  Dockerfile:24

It looks like the arg BUILD_COMMAND has not been set. Not sure, if I should see that in the build log, but I can tell from the running duration of the command that I was not executed properly.

As said, it works locally on my machine when setting the build arg.

Any idea what I’m missing to make it work on render?

Thanks!

2

Hmm,

I would expect that that work - can you try add RUN echo $BUILD_COMMAND after the ARG to see if the value is output in the build as a first debug step here,

John B

3

Good idea, I updated my Dockerfile to be:

# Build Env
FROM node:alpine AS build-env
WORKDIR /app

ARG BUILD_COMMAND
RUN echo $BUILD_COMMAND

# [...]

And the output is this one here:

image

This does not look correct, right?

4

Ok, I investigated a bit further.

As soon as I have a space in the value of my environment variable, it will not be translated to a build arg.

I tried some escaping with quotes, backslashes etc., but I haven’t found a working one, yet.

My intermediate solution is now to define BUILD_COMMAND with a value of build:staging instead of npm run build:staging and move the npm run part directly into the Dockerfile.

But I think it should work with spaces as well, right?

5

What about putting quotes around the environment variable?

$ export VAR=FOO

$ echo $VAR
FOO
$ export VAR=FOO BAH
$ echo $VAR
FOO
$ echo "$VAR"
FOO
$ export VAR="FOO BAH"
$ echo $VAR
FOO BAH

John B

6

In the Render settings? If so, as I mentioned, I’ve already tried that with no luck.

Is your code sample badly formatted? Should I put that into the Dockerfile?

7

Hi I’m having the same issue, too. I’m pulling an env variable:

ARG RENDER_HOSTNAME

FROM node:16.17.1
…
RUN NEXT_PUBLIC_API_HOST=https://$RENDER_HOSTNAME.onrender.com npm run build

Screen Shot 2022-10-19 at 9.39.37 PM
Screen Shot 2022-10-19 at 9.39.37 PM1970×110 10.7 KB

But my app always shows “https://.onrender.com”. It looks like the env var is never transformed to the build arg.

8

Hi there,
We’ve identified and issue with how we were passing build args which should have fixed build args containing spaces.

John B

9

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