add flake evaluator, make hydraJob outputs optional

Signed-off-by: ahuston-0 <aliceghuston@gmail.com>

flupdt/flake_show.py

@@ -3,9 +3,16 @@
 import json
 from flupdt.common import bash_wrapper
 import shutil
+import logging
+import re
+
+output_regexes = [
+    re.compile(r'checking derivation (.*)...'),
+    re.compile(r'checking NixOS configuration \'(nixosConfigurations.*)\'\.\.\.')
+]
 
 
-def traverse_json_base(json_dict: dict, path: list[str]):
+def traverse_json_base(json_dict: dict, path: list[str]) -> list[str]:
     final_paths = []
     for key, value in json_dict.items():
         if isinstance(value, dict):
@@ -14,21 +21,46 @@ def traverse_json_base(json_dict: dict, path: list[str]):
                 "nixos-configuration",
                 "derivation",
             ]:
-                final_paths += [".".join(path + [key])]
+                output = ".".join(path + [key])
+                final_paths += [output]
             else:
                 final_paths += traverse_json_base(value, path + [key])
     return final_paths
 
 
-def traverse_json(json_dict: dict):
+def traverse_json(json_dict: dict) -> list[str]:
     return traverse_json_base(json_dict, [])
 
-
-def get_derivations(path_to_flake: str):
-    nix_path = shutil.which("nix")
-    flake_show = bash_wrapper(f"{nix_path} flake show --json", path=path_to_flake)
-    if flake_show[1] != 0:
-        raise RuntimeError("flake show returned non-zero exit code")
-    flake_show_json = json.loads(flake_show[0])
-    derivations = traverse_json(flake_show_json)
+def get_derivations_from_check(nix_path:str,path_to_flake:str)-> list[str]:
+    flake_check = bash_wrapper(f"{nix_path} flake check --verbose --keep-going", path=path_to_flake)
+    if flake_check[2] != 0:
+        logging.warn("nix flake check returned non-zero exit code, collecting all available outputs")
+    error_out = flake_check[1].split('\n')
+    possible_outputs = filter(lambda s: s.startswith("checking"), error_out)
+    derivations = []
+    for output in possible_outputs:
+        for r in output_regexes:
+            logging.debug(f"{output} {r.pattern}")
+            match = r.match(output)
+            if match is not None:
+                logging.debug(match.groups())
+                derivations += [match.groups()[0]]
+    return derivations
+
+def get_derivations(path_to_flake: str) -> list[str]:
+    nix_path = shutil.which("nix")
+    derivations = []
+    if nix_path is None:
+        raise RuntimeError("nix is not available in the PATH, please verify that it is installed")
+    flake_show = bash_wrapper(f"{nix_path} flake show --json", path=path_to_flake)
+    if flake_show[2] != 0:
+        logging.error("flake show returned non-zero exit code")
+        logging.warn("falling back to full evaluation via nix flake check")
+        derivations =  get_derivations_from_check(nix_path, path_to_flake)
+    else:
+        flake_show_json = json.loads(flake_show[0])
+        derivations = traverse_json(flake_show_json)
+    for i in range(len(derivations)):
+        if derivations[i].startswith("nixosConfigurations"):
+             derivations[i] += ".config.system.build.toplevel"
     return derivations