refactor: rewrite JWT generation from python to bash

Replaced generate_jwt.py with generate_jwt.sh using only openssl and coreutils. Updated SKILL.md to remove the python fallback section and use grep/cut for JSON parsing instead of python3.
2026-03-25 21:46:02 -04:00
parent f425b5191e
commit dedb35953b
3 changed files with 49 additions and 109 deletions
@@ -1,84 +0,0 @@
-#!/usr/bin/env python3
-"""Generate a JWT for GitHub App authentication.
-
-Reads from environment variables:
-  GITHUB_APP_ID       - The GitHub App's numeric ID
-  GITHUB_APP_PEM_FILE - Path to the PEM-encoded private key file
-
-Prints the signed JWT to stdout.
-"""
-
-import json
-import os
-import sys
-import time
-import base64
-
-try:
-    from cryptography.hazmat.primitives import hashes, serialization
-    from cryptography.hazmat.primitives.asymmetric import padding
-
-    USE_CRYPTOGRAPHY = True
-except ImportError:
-    import subprocess
-
-    USE_CRYPTOGRAPHY = False
-
-
-def b64url(data: bytes) -> str:
-    return base64.urlsafe_b64encode(data).rstrip(b"=").decode("ascii")
-
-
-def sign_with_cryptography(unsigned: str, pem_contents: str) -> str:
-    """Sign using the cryptography library. Handles both PKCS#1 and PKCS#8 PEM formats."""
-    private_key = serialization.load_pem_private_key(pem_contents.encode(), password=None)
-    signature = private_key.sign(unsigned.encode(), padding.PKCS1v15(), hashes.SHA256())
-    return b64url(signature)
-
-
-def sign_with_openssl(unsigned: str, pem_file: str) -> str:
-    """Sign using the openssl CLI. Reads the key from the file path directly."""
-    result = subprocess.run(
-        ["openssl", "dgst", "-sha256", "-sign", pem_file, "-binary"],
-        input=unsigned.encode(),
-        capture_output=True,
-    )
-    if result.returncode != 0:
-        print(f"error: openssl signing failed: {result.stderr.decode()}", file=sys.stderr)
-        sys.exit(1)
-    return b64url(result.stdout)
-
-
-def main():
-    app_id = os.environ.get("GITHUB_APP_ID")
-    pem_file = os.environ.get("GITHUB_APP_PEM_FILE")
-
-    if not app_id:
-        print("error: GITHUB_APP_ID is not set", file=sys.stderr)
-        sys.exit(1)
-    if not pem_file:
-        print("error: GITHUB_APP_PEM_FILE is not set", file=sys.stderr)
-        sys.exit(1)
-    if not os.path.isfile(pem_file):
-        print(f"error: PEM file not found: {pem_file}", file=sys.stderr)
-        sys.exit(1)
-
-    now = int(time.time())
-    header = b64url(json.dumps({"alg": "RS256", "typ": "JWT"}).encode())
-    payload = b64url(
-        json.dumps({"iat": now - 60, "exp": now + 600, "iss": app_id}).encode()
-    )
-    unsigned = f"{header}.{payload}"
-
-    if USE_CRYPTOGRAPHY:
-        with open(pem_file, "r") as f:
-            pem_contents = f.read()
-        signature = sign_with_cryptography(unsigned, pem_contents)
-    else:
-        signature = sign_with_openssl(unsigned, pem_file)
-
-    print(f"{unsigned}.{signature}")
-
-
-if __name__ == "__main__":
-    main()
@@ -0,0 +1,41 @@
+#!/usr/bin/env bash
+# Generate a JWT for GitHub App authentication.
+#
+# Required environment variables:
+#   GITHUB_APP_ID       - The GitHub App's numeric ID
+#   GITHUB_APP_PEM_FILE - Path to the PEM-encoded private key file
+#
+# Prints the signed JWT to stdout.
+
+set -euo pipefail
+
+if [[ -z "${GITHUB_APP_ID:-}" ]]; then
+  echo "error: GITHUB_APP_ID is not set" >&2
+  exit 1
+fi
+
+if [[ -z "${GITHUB_APP_PEM_FILE:-}" ]]; then
+  echo "error: GITHUB_APP_PEM_FILE is not set" >&2
+  exit 1
+fi
+
+if [[ ! -f "${GITHUB_APP_PEM_FILE}" ]]; then
+  echo "error: PEM file not found: ${GITHUB_APP_PEM_FILE}" >&2
+  exit 1
+fi
+
+## Build JWT
+
+header=$(printf '{"alg":"RS256","typ":"JWT"}' | openssl base64 -e -A | tr '+/' '-_' | tr -d '=')
+
+now=$(date +%s)
+iat=$((now - 60))
+exp=$((now + 600))
+
+payload=$(printf '{"iat":%d,"exp":%d,"iss":"%s"}' "$iat" "$exp" "$GITHUB_APP_ID" | openssl base64 -e -A | tr '+/' '-_' | tr -d '=')
+
+unsigned="${header}.${payload}"
+
+signature=$(printf '%s' "$unsigned" | openssl dgst -sha256 -sign "${GITHUB_APP_PEM_FILE}" -binary | openssl base64 -e -A | tr '+/' '-_' | tr -d '=')
+
+echo "${unsigned}.${signature}"