Hello,

I am trying to setup our medusajs project on railway. I started with trying to deploy the Medusa backend server, but I keep getting the error: undefined variable 'npm'.
I could not find much about this issue. What could be going wrong?

build config:
[build]

builder = "NIXPACKS"

buildCommand = "npm run build:backend"

[build.nixpacksPlan.phases.setup]

nixPkgs = ["nodejs", "npm"]

[variables]

MEDUSA_WORKER_MODE = 'server'

[build.nixpacksPlan.phases.install]

cmds=["npm install --legacy-peer-deps"]

[deploy]

startCommand = "medusa migrations run && medusa start"

Error log:

Sep 23 11:23:54

#8 21.36 installing 'e05605ec414618eab4a7a6aea8b38f6fbbcc8f08-env'

Sep 23 11:23:54

Sep 23 11:23:54

#8 21.86 error:

Sep 23 11:23:54

#8 21.86 … while calling the 'derivationStrict' builtin

Sep 23 11:23:54

#8 21.86 at <nix/derivation-internal.nix>:34:12:

Sep 23 11:23:54

#8 21.86 33|

Sep 23 11:23:54

#8 21.86 34| strict = derivationStrict drvAttrs;

Sep 23 11:23:54

#8 21.86 | ^

Sep 23 11:23:54

#8 21.86 35|

Sep 23 11:23:54

#8 21.86

Sep 23 11:23:54

#8 21.86 … while evaluating derivation 'e05605ec414618eab4a7a6aea8b38f6fbbcc8f08-env'

Sep 23 11:23:54

#8 21.86 whose name attribute is located at /nix/store/m8klxk6j3r647r0kiw9qfk9r81gdhyvk-source/pkgs/stdenv/generic/make-derivation.nix:334:7

Sep 23 11:23:54

#8 21.86

Sep 23 11:23:54

#8 21.86 … while evaluating attribute 'passAsFile' of derivation 'e05605ec414618eab4a7a6aea8b38f6fbbcc8f08-env'

Sep 23 11:23:54

Sep 23 11:23:54

#8 21.86 at /nix/store/m8klxk6j3r647r0kiw9qfk9r81gdhyvk-source/pkgs/build-support/trivial-builders/default.nix:69:9:

Sep 23 11:23:54

#8 21.86 68| inherit buildCommand name;

Sep 23 11:23:54

#8 21.86 69| passAsFile = [ "buildCommand" ]

Sep 23 11:23:54

#8 21.86 | ^

Sep 23 11:23:54

#8 21.86 70| ++ (derivationArgs.passAsFile or [ ]);

Sep 23 11:23:54

#8 21.86

Sep 23 11:23:54

#8 21.86 (stack trace truncated; use '--show-trace' to show the full, detailed trace)

Sep 23 11:23:54

#8 21.86

Sep 23 11:23:54

#8 21.86 error: undefined variable 'npm'

Sep 23 11:23:54

#8 21.86 at /app/.nixpacks/nixpkgs-e05605ec414618eab4a7a6aea8b38f6fbbcc8f08.nix:19:16:

Sep 23 11:23:54

#8 21.86 18| '')

Sep 23 11:23:54

#8 21.86 19| nodejs npm

Sep 23 11:23:54

#8 21.86 | ^

Sep 23 11:23:54

#8 21.86 20| ];

Sep 23 11:23:54

Sep 23 11:23:55

#8 ERROR: process "/bin/bash -ol pipefail -c nix-env -if .nixpacks/nixpkgs-e05605ec414618eab4a7a6aea8b38f6fbbcc8f08.nix && nix-collect-garbage -d" did not complete successfully: exit code: 1

Sep 23 11:23:55

Sep 23 11:23:55

-----

Sep 23 11:23:55

> [stage-0 4/10] RUN nix-env -if .nixpacks/nixpkgs-e05605ec414618eab4a7a6aea8b38f6fbbcc8f08.nix && nix-collect-garbage -d:

Sep 23 11:23:55

21.86 70| ++ (derivationArgs.passAsFile or [ ]);

Sep 23 11:23:55

21.86

Sep 23 11:23:55

21.86 (stack trace truncated; use '--show-trace' to show the full, detailed trace)

Sep 23 11:23:55

21.86

Sep 23 11:23:55

21.86 error: undefined variable 'npm'

Sep 23 11:23:55

21.86 at /app/.nixpacks/nixpkgs-e05605ec414618eab4a7a6aea8b38f6fbbcc8f08.nix:19:16:

Sep 23 11:23:55

21.86 18| '')

Sep 23 11:23:55

21.86 19| nodejs npm

Sep 23 11:23:55

21.86 | ^

Sep 23 11:23:55

21.86 20| ];

Sep 23 11:23:55

-----

Sep 23 11:23:55

Sep 23 11:23:55

Dockerfile:8

Sep 23 11:23:55

-------------------

Sep 23 11:23:55

6 |

Sep 23 11:23:55

7 | COPY .nixpacks/nixpkgs-e05605ec414618eab4a7a6aea8b38f6fbbcc8f08.nix .nixpacks/nixpkgs-e05605ec414618eab4a7a6aea8b38f6fbbcc8f08.nix

Sep 23 11:23:55

8 | >>> RUN nix-env -if .nixpacks/nixpkgs-e05605ec414618eab4a7a6aea8b38f6fbbcc8f08.nix && nix-collect-garbage -d

Sep 23 11:23:55

9 |

Sep 23 11:23:55

10 |

Sep 23 11:23:55

-------------------

Sep 23 11:23:55

ERROR: failed to solve: process "/bin/bash -ol pipefail -c nix-env -if .nixpacks/nixpkgs-e05605ec414618eab4a7a6aea8b38f6fbbcc8f08.nix && nix-collect-garbage -d" did not complete successfully: exit code: 1

Sep 23 11:23:55

Sep 23 11:23:55

Error: Docker build failed