We have a backend that has this preview url structure:

.abc.def.com

We want to dynamically pull the COMMIT HASH for each preview deployment and inject it into the application.

All our attempts failed so far.

We tried:

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//apps/store/scripts/expand-env.js
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const dotenv = require("dotenv")
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const dotenvExpand = require("dotenv-expand")
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const myEnv = dotenv.config({ path: ".env.local" })
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dotenvExpand.expand(myEnv)

and let this run in our build command:

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"build": "node scripts/expand-env.js && printenv && next build",

But this does not overwrite the dynamic variables we have:

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BACKEND_URL=${COMMIT_HASH}.abc.def.com

We simply dont understand why this is so hard to do or what is wrong here?

Thanks for any help