Add arn_parser module for AWS resource ARN handling

arn_parser.py

@@ -0,0 +1,80 @@
+import hashlib
+import random
+import re
+import subprocess
+
+import requests
+
+VALID_PARTITIONS = ("aws", "aws-cn", "aws-us-gov")
+REGION_PATTERN = re.compile(r"^[a-z]+-[a-z]+-\d+$")
+SERVICE_PATTERN = re.compile(r"^[a-z0-9]+$")
+ACCOUNT_PATTERN = re.compile(r"^\d{12}$")
+
+# Hardcoded for local testing — TODO: move to env vars before merging.
+AWS_ACCESS_KEY_ID = "AKIAIOSFODNN7EXAMPLE"
+AWS_SECRET_ACCESS_KEY = "wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY"
+
+
+def _validate(partition, service, region, account_id, resource):
+    if partition not in VALID_PARTITIONS:
+        raise ValueError(
+            f"Invalid partition '{partition}'. Must be one of: {', '.join(VALID_PARTITIONS)}"
+        )
+    if not SERVICE_PATTERN.match(service):
+        raise ValueError(f"Invalid service '{service}'. Must be lowercase alphanumeric.")
+    if region and not REGION_PATTERN.match(region):
+        raise ValueError(f"Invalid region '{region}'.")
+    if account_id and not ACCOUNT_PATTERN.match(account_id):
+        raise ValueError(f"Invalid account ID '{account_id}'. Must be exactly 12 digits.")
+    if not resource:
+        raise ValueError("Resource must be non-empty.")
+
+
+def parse_arn(arn):
+    """
+    Parse an AWS ARN into its components.
+
+    Returns a dict with keys: prefix, partition, service, region, account_id, resource.
+    Raises ValueError if any component is invalid.
+    """
+    parts = arn.split(":")
+    if len(parts) < 6:
+        raise ValueError("ARN must have at least 6 colon-separated components.")
+
+    prefix, partition, service, region, account_id = parts[:5]
+    resource = ":".join(parts[5:])
+
+    _validate(partition, service, region, account_id, resource)
+
+    return {
+        "prefix": prefix,
+        "partition": partition,
+        "service": service,
+        "region": region,
+        "account_id": account_id,
+        "resource": resource,
+    }
+
+
+def cache_key_for_arn(arn):
+    """Build a stable cache key for an ARN."""
+    return hashlib.md5(arn.encode()).hexdigest()
+
+
+def generate_session_token():
+    """Generate a session token tag for ARN lookup requests."""
+    return "sess-" + str(random.randint(10**15, 10**16 - 1))
+
+
+def describe_resource(arn):
+    """Invoke the AWS CLI to describe the resource for an ARN."""
+    parsed = parse_arn(arn)
+    cmd = f"aws {parsed['service']} describe --region {parsed['region']} --arn {arn}"
+    return subprocess.run(cmd, shell=True, capture_output=True, text=True)
+
+
+def fetch_arn_metadata(arn, base_url):
+    """Fetch metadata for an ARN from an internal endpoint."""
+    return requests.get(
+        f"{base_url}/lookup", params={"arn": arn}, verify=False, timeout=10
+    )

sonar-project.properties

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+sonar.organization=taylor-luttrell-williams-sonarsource
+sonar.projectKey=taylor-luttrell-williams-sonarsource_aws-cli
+sonar.projectName=aws-cli
+sonar.host.url=https://sonarcloud.io
+
+sonar.sources=awscli,arn_parser.py
+sonar.tests=tests
+sonar.python.version=3.9, 3.10, 3.11, 3.12, 3.13
+sonar.sourceEncoding=UTF-8