Fix Library ? Docker
Docker troubleshooting

Fix Docker Environment Variables Not Available at Runtime

Build args and runtime environment variables are different. Pass runtime secrets when starting the container or through the host platform environment.

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Common symptoms

  • Variables are available during docker build but undefined in the app.
  • Container runs locally but production secrets are missing.
  • Frontend values are baked but server secrets are absent.

What to check first

Platform: Docker
Error: Runtime env vars missing

Build args and runtime environment variables are different. Pass runtime secrets when starting the container or through the host platform environment.

Step-by-step fix

  1. Use ARG only for build-time values.
  2. Pass runtime variables with docker run -e or platform settings.
  3. Use --env-file for local testing.
  4. Avoid baking private secrets into the image.
docker run -e DATABASE_URL="$DATABASE_URL" my-app
docker run --env-file .env my-app

Common mistake to avoid

Do not store production secrets in the Dockerfile.

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