v1

test.sh

@@ -0,0 +1,45 @@
+#!/usr/bin/env bash
+
+set -o pipefail
+
+app_id=$1 # App ID as first argument
+installation_id=$2
+pem=$( cat $3 ) # file path of the private key as second argument
+
+now=$(date +%s)
+iat=$((${now} - 60)) # Issues 60 seconds in the past
+exp=$((${now} + 600)) # Expires 10 minutes in the future
+
+b64enc() { openssl base64 | tr -d '=' | tr '/+' '_-' | tr -d '\n'; }
+
+header_json='{
+    "typ":"JWT",
+    "alg":"RS256"
+}'
+# Header encode
+header=$( echo -n "${header_json}" | b64enc )
+
+payload_json='{
+    "iat":'"${iat}"',
+    "exp":'"${exp}"',
+    "iss":'"${app_id}"'
+}'
+# Payload encode
+payload=$( echo -n "${payload_json}" | b64enc )
+
+# Signature
+header_payload="${header}"."${payload}"
+signature=$(
+    openssl dgst -sha256 -sign <(echo -n "${pem}") \
+    <(echo -n "${header_payload}") | b64enc
+)
+
+# Create JWT
+JWT="${header_payload}"."${signature}"
+
+
+curl --request POST \
+--url "https://api.github.com/app/installations/$installation_id/access_tokens" \
+--header "Accept: application/vnd.github+json" \
+--header "Authorization: Bearer $JWT" \
+--header "X-GitHub-Api-Version: 2022-11-28"