fix Juniper parsing issue when CLI banner is appended to the XML output [skip ci]

hyperglass/parsing/juniper.py

@@ -1,6 +1,7 @@
 """Parse Juniper XML Response to Structured Data."""
 
 # Standard Library
+import re
 from typing import Dict, Iterable
 
 # Third Party
@@ -14,14 +15,42 @@ from hyperglass.configuration import params
 from hyperglass.models.parsing.juniper import JuniperRoute
 
 
+def clean_xml_output(output: str) -> str:
+    """Remove Juniper-specific patterns from output."""
+    patterns = (
+        """
+        The XML response can a CLI banner appended to the end of the XML
+        string. For example:
+
+        ```
+        <rpc-reply>
+        ...
+        <cli>
+          <banner>{master}</banner>
+        </cli>
+        </rpc-reply>
+
+        {master}
+        ```
+
+        This pattern will remove anything inside braces, including the braces.
+        """
+        r"\{.+\}",
+    )
+    lines = (line.strip() for line in output.split())
+    scrubbed_lines = (re.sub(pat, "", line) for pat in patterns for line in lines)
+    return "\n".join(scrubbed_lines)
+
+
 def parse_juniper(output: Iterable) -> Dict:  # noqa: C901
     """Parse a Juniper BGP XML response."""
     data = {}
 
     for i, response in enumerate(output):
+        cleaned = clean_xml_output(response)
         try:
             parsed = xmltodict.parse(
-                response, force_list=("rt", "rt-entry", "community")
+                cleaned, force_list=("rt", "rt-entry", "community")
             )
 
             log.debug("Initially Parsed Response: \n{}", parsed)
@@ -49,7 +78,7 @@ def parse_juniper(output: Iterable) -> Dict:  # noqa: C901
 
         except xmltodict.expat.ExpatError as err:
             log.critical(str(err))
-            raise ParsingError("Error parsing response data")
+            raise ParsingError("Error parsing response data") from err
 
         except KeyError as err:
             log.critical("{} was not found in the response", str(err))