Using files from the "source" in "output"

[gothy]

Hi there

I have a need to provide my backend code with GOOGLE_APPLICATION_CREDENTIALS env var that should point to the file containing firebase app creds.
I have that file in the root of the sources dir. Listing this file with ./ prefix path in the Now env vars doesn't make much difference, i think it's because the output is missing most of the files from the source.
Is there a way to specify which files i want to move to "output" during the build process?

[lucleray]

Hi @gothy ,

You can use custom Build Command and Output Directory to add custom logic to your Build and copy source files over to the output directory.

For example, if you are using Next.js, you can set your Build Command to next build && cp my-firebase-creds.txt output/my-firebase-creds.txt and your Output Directory to output.

Note that this will publish your file and your file will be exposed to your visitors.

If you want to keep your file content secret, you will need to find a way to pass the content of the file instead of a file path to the firebase library you are using.

[rafinskipg]

I am not using firebase, but normal google cloud. Google cloud authentication

In my use case I am using Google Cloud storage (https://www.npmjs.com/package/@google-cloud/storage)

Diving into the code i can see that there are another options available, like using keyFileName, but it also requires a File, and that means having it copied to your vercel project.

 new Storage({ projectId:
   'your-project-id', keyFilename: '/path/to/keyfile.json'
 });

Another option would be to use "credentials" and passing a "client_email" and a "private_key". This would be awesome if it worked. I also tried passing the whole configuration object here, but nothing.

I used my client_email and private_key from my service account, but it does not work. See here and here
https://googleapis.dev/nodejs/storage/latest/global.html#StorageOptions

@lucleray , what i also tried todo is doing the following

1. Override build command in Vercel, and make a git clone from a repository with my credentials
2. Try to set the environment variable pointing to that repository files. But it does not work, maybe the absolute path i am using is wrong. It is not clearly explained in the documentation which is the absolute path of the deployment. I have tried this GOOGLE_APPLICATION_CREDENTIALS=~/mycloned-repo/file.json and also ./mycloned-repo/file.json. Both failing

UPDATE:

This may fail in the future, but at the end it worked by generating a new service account file and introducing it into the credentials options in the storage constructor. But i fear that this method will only work for 60 minutes. The previous file i was using it worked fine when set as GOOGLE_APPLICATION_CREDENTIALS but failed when used as a credentials property, saying that the token was short lived and already expired.
My guess is that setting GOOGLE_APPLCIATION_CREDENTIALS will do a refresh token, but using credentials will not.

Lets see. I will come back to update

[rafinskipg]

The app it's been running for a couple of hours with no problem.

Final solution:

const storage = new Storage({
  credentials: {
    client_email: process.env.GOOGLE_CLIENT_EMAIL,
    private_key: process.env.GOOGLE_PRIVATE_KEY.replace(/\\n/g, '\n')
  },
  projectId: process.env.GOOGLE_PROJECTID
})

[cdock1029]

@rafinskipg Following this blog post, here's possibly a cleaner way to do it without worrying about newlines and such. You can base64 encode/decode the file from a secret

https://dev.to/parondeau/gcp-credentials-next-js-3a0d

[rafinskipg]

Wow @cdock1029 thanks for sharing! I will keep it in my list of resources.

[saitodisse]

@rafinskipg Following this blog post, here's possibly a cleaner way to do it without worrying about newlines and such. You can base64 encode/decode the file from a secret

dev.to/parondeau/gcp-credentials-next-js-3a0d

this is the best way. Use JSON.parse to get the privatekey: vercel/vercel#749 (comment)