Allow running nix with --impure

src/common/utils.py

@@ -172,7 +172,7 @@ def exit_unless_nix_artifact(path, force_realise=False):
         sys.exit(1)
 
 
-def try_resolve_flakeref(flakeref, force_realise=False):
+def try_resolve_flakeref(flakeref, force_realise=False, impure=False):
     """
     Resolve flakeref to out-path, force-realising the output if `force_realise`
     is True. Returns resolved path if flakeref can be resolved to out-path,
@@ -181,7 +181,8 @@ def try_resolve_flakeref(flakeref, force_realise=False):
     LOG.info("Evaluating '%s'", flakeref)
     exp = "--extra-experimental-features flakes "
     exp += "--extra-experimental-features nix-command"
-    cmd = f"nix eval --raw {flakeref} {exp}"
+    extra_args = "--impure" if impure else ""
+    cmd = f"nix eval --raw {flakeref} {exp} {extra_args}"
     ret = exec_cmd(cmd.split(), raise_on_error=False)
     if not ret:
         LOG.debug("not a flakeref: '%s'", flakeref)
@@ -191,7 +192,7 @@ def try_resolve_flakeref(flakeref, force_realise=False):
     if not force_realise:
         return nixpath
     LOG.info("Try force-realising flakeref '%s'", flakeref)
-    cmd = f"nix build --no-link {flakeref} {exp}"
+    cmd = f"nix build --no-link {flakeref} {exp} {extra_args}"
     ret = exec_cmd(cmd.split(), raise_on_error=False, return_error=True)
     if not ret:
         LOG.fatal("Failed force_realising %s: %s", flakeref, ret.stderr)

src/sbomnix/main.py

@@ -59,6 +59,8 @@ def getargs():
     group.add_argument("--cdx", nargs="?", help=helps, default="sbom.cdx.json")
     helps = "Path to spdx json output file (default: ./sbom.spdx.json)"
     group.add_argument("--spdx", nargs="?", help=helps, default="sbom.spdx.json")
+    helps = "Run nix command with --impure"
+    parser.add_argument("--impure", help=helps, action="store_true")
 
     return parser.parse_args()
 
@@ -72,7 +74,7 @@ def main():
     set_log_verbosity(args.verbose)
     runtime = args.buildtime is False
     flakeref = None
-    target_path = try_resolve_flakeref(args.NIXREF, force_realise=runtime)
+    target_path = try_resolve_flakeref(args.NIXREF, force_realise=runtime, impure=args.impure)
     if target_path:
         flakeref = args.NIXREF
     else: