Bicep: Missing parser support for extension keyword #7364
Description
Describe the issue
The bicep parser doesn't support the extension keyword and throws a parsing error when it encounters it in a file.
I've created a pull request fixing the issue at the pycep repo.
Error ouput:
2025-11-10 09:09:05,065 [MainThread ] [INFO ] [bicep] start to parse 1 files
2025-11-10 09:09:05,084 [MainThread ] [DEBUG] [bicep] Couldn't parse main.bicep
Traceback (most recent call last):
File ".../.cache/uv/archive-v0/byuoiA4g8gpozKNsrLhzc/lib/python3.12/site-packages/lark/lexer.py", line 689, in lex
yield lexer.next_token(lexer_state, parser_state)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File ".../.cache/uv/archive-v0/byuoiA4g8gpozKNsrLhzc/lib/python3.12/site-packages/lark/lexer.py", line 622, in next_token
raise UnexpectedCharacters(lex_state.text.text, line_ctr.char_pos, line_ctr.line, line_ctr.column,
lark.exceptions.UnexpectedCharacters: No terminal matches 'e' in the current parser context, at line 8 col 1
extension microsoftGraphV1
^
Expected one of:
* VAR
* TYPE
* OUTPUT
* _CPP_COMMENT_NL
* MODULE
* AT
* TARGETSCOPE
* PARAM
* METADATA
* RESOURCE
Previous tokens: Token('_CPP_COMMENT_NL', '// Enable Microsoft Graph extension\n')
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File ".../.cache/uv/archive-v0/byuoiA4g8gpozKNsrLhzc/lib/python3.12/site-packages/checkov/bicep/parser.py", line 24, in parse
template = self.bicep_parser.parse(text=content)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File ".../.cache/uv/archive-v0/byuoiA4g8gpozKNsrLhzc/lib/python3.12/site-packages/pycep/main.py", line 29, in parse
tree = self._create_tree(text=text, file_path=file_path)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File ".../.cache/uv/archive-v0/byuoiA4g8gpozKNsrLhzc/lib/python3.12/site-packages/pycep/main.py", line 53, in _create_tree
return self.lark_parser.parse(bicep_text)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File ".../.cache/uv/archive-v0/byuoiA4g8gpozKNsrLhzc/lib/python3.12/site-packages/lark/lark.py", line 677, in parse
return self.parser.parse(text, start=start, on_error=on_error)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File ".../.cache/uv/archive-v0/byuoiA4g8gpozKNsrLhzc/lib/python3.12/site-packages/lark/parser_frontends.py", line 131, in parse
return self.parser.parse(stream, chosen_start, **kw)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File ".../.cache/uv/archive-v0/byuoiA4g8gpozKNsrLhzc/lib/python3.12/site-packages/lark/parsers/lalr_parser.py", line 42, in parse
return self.parser.parse(lexer, start)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File ".../.cache/uv/archive-v0/byuoiA4g8gpozKNsrLhzc/lib/python3.12/site-packages/lark/parsers/lalr_parser.py", line 88, in parse
return self.parse_from_state(parser_state)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File ".../.cache/uv/archive-v0/byuoiA4g8gpozKNsrLhzc/lib/python3.12/site-packages/lark/parsers/lalr_parser.py", line 111, in parse_from_state
raise e
File ".../.cache/uv/archive-v0/byuoiA4g8gpozKNsrLhzc/lib/python3.12/site-packages/lark/parsers/lalr_parser.py", line 100, in parse_from_state
for token in state.lexer.lex(state):
^^^^^^^^^^^^^^^^^^^^^^
File ".../.cache/uv/archive-v0/byuoiA4g8gpozKNsrLhzc/lib/python3.12/site-packages/lark/lexer.py", line 698, in lex
raise UnexpectedToken(token, e.allowed, state=parser_state, token_history=[last_token], terminals_by_name=self.root_lexer.terminals_by_name)
lark.exceptions.UnexpectedToken: Unexpected token Token('STRING', 'extension') at line 8, column 1.
Expected one of:
* VAR
* TYPE
* OUTPUT
* _CPP_COMMENT_NL
* MODULE
* AT
* TARGETSCOPE
* PARAM
* METADATA
* RESOURCE
* $END
Previous tokens: [Token('_CPP_COMMENT_NL', '// Enable Microsoft Graph extension\n')]
Example Value
// Simple extension
extension microsoftGraphV1
// Extension with config and alias
extension kubernetes with {
namespace: 'default'
kubeConfig: 'someKubeConfig'
} as k8s
// ... Do something with it