Allow configuring gen_build_info.py through environment variables

This makes the life of forks slightly easier by letting you pass an
environment variable instead of having to maintain this file yourself.

Tools/gen_build_info.py

@@ -19,11 +19,11 @@
     "SS14.Server_osx-x64.zip"
 ]
 
-VERSION = os.environ['GITHUB_SHA']
-FORK_ID = "wizards"
-BUILD_URL = f"https://cdn.centcomm.spacestation14.com/builds/wizards/builds/{{FORK_VERSION}}/{FILE}"
-MANIFEST_URL = f"https://cdn.centcomm.spacestation14.com/cdn/version/{{FORK_VERSION}}/manifest"
-MANIFEST_DOWNLOAD_URL = f"https://cdn.centcomm.spacestation14.com/cdn/version/{{FORK_VERSION}}/download"
+FORK_ID = os.environ.get("CDN_FORK_ID", "wizards")
+HOSTNAME = os.environ.get("CDN_HOSTNAME", "cdn.centcomm.spacestation14.com")
+BUILD_URL = f"https://{HOSTNAME}/builds/{FORK_ID}/builds/{{FORK_VERSION}}/{FILE}"
+MANIFEST_URL = f"https://{HOSTNAME}/version/{{FORK_VERSION}}/manifest"
+MANIFEST_DOWNLOAD_URL = f"https://{HOSTNAME}/version/{{FORK_VERSION}}/download"
 
 def main() -> None:
     client_file = os.path.join("release", FILE)
@@ -38,24 +38,33 @@ def inject_manifest(zip_path: str, manifest: str) -> None:
         z.writestr("build.json", manifest)
 
 
+def get_git_sha() -> str:
+    proc = subprocess.run(["git", "rev-parse", "HEAD"], stdout=subprocess.PIPE, check=True, encoding="UTF-8")
+    tag = proc.stdout.strip()
+    return tag
+
 def generate_build_json(file: str) -> str:
     # Env variables set by Jenkins.
 
     hash = sha256_file(file)
     engine_version = get_engine_version()
     manifest_hash = generate_manifest_hash(file)
+    version = os.environ.get("GITHUB_SHA")
+    if not version:
+        version = get_git_sha()
 
     return json.dumps({
         "download": BUILD_URL,
         "hash": hash,
-        "version": VERSION,
+        "version": version,
         "fork_id": FORK_ID,
         "engine_version": engine_version,
         "manifest_url": MANIFEST_URL,
         "manifest_download_url": MANIFEST_DOWNLOAD_URL,
         "manifest_hash": manifest_hash
     })
 
+
 def generate_manifest_hash(file: str) -> str:
     zip = ZipFile(file)
     infos = zip.infolist()
@@ -83,7 +92,6 @@ def get_engine_version() -> str:
     assert tag.startswith("v")
     return tag[1:] # Cut off v prefix.
 
-
 def sha256_file(path: str) -> str:
     with open(path, "rb") as f:
         h = hashlib.sha256()