[WIP] CLI-227: add implicit context_mount to Image docker methods

modal/_utils/docker_utils.py

@@ -0,0 +1,104 @@
+# Copyright Modal Labs 2024
+import re
+import shlex
+from pathlib import Path
+from typing import Optional, Sequence
+
+from ..exception import InvalidError
+
+
+def extract_copy_command_patterns(dockerfile_lines: Sequence[str]) -> list[str]:
+    """
+    Extract all COPY command sources from a Dockerfile.
+    Combines multiline COPY commands into a single line.
+    """
+    copy_source_patterns: set[str] = set()
+    current_command = ""
+    copy_pattern = re.compile(r"^\s*COPY\s+(.+)$", re.IGNORECASE)
+
+    # First pass: handle line continuations and collect full commands
+    for line in dockerfile_lines:
+        line = line.strip()
+        if not line or line.startswith("#"):
+            # ignore comments and empty lines
+            continue
+
+        if current_command:
+            # Continue previous line
+            current_command += " " + line.rstrip("\\").strip()
+        else:
+            # Start new command
+            current_command = line.rstrip("\\").strip()
+
+        if not line.endswith("\\"):
+            # Command is complete
+
+            match = copy_pattern.match(current_command)
+            if match:
+                args = match.group(1)
+                parts = shlex.split(args)
+
+                if len(parts) >= 2:
+                    # Last part is destination, everything else is a mount source
+                    sources = parts[:-1]
+
+                    for source in sources:
+                        special_pattern = re.compile(r"^\s*--|\$\s*")
+                        if special_pattern.match(source):
+                            raise InvalidError(
+                                f"COPY command: {source} using special flags/arguments/variables are not supported"
+                            )
+
+                        if source == ".":
+                            copy_source_patterns.add("./**")
+                        else:
+                            copy_source_patterns.add(source)
+
+            current_command = ""
+
+    return list(copy_source_patterns)
+
+
+def find_dockerignore_file(context_directory: Path, dockerfile_path: Optional[Path] = None) -> Optional[Path]:
+    """
+    Find dockerignore file relative to current context directory
+    and if dockerfile path is provided, check if specific <dockerfile_name>.dockerignore
+    file exists in the same directory as <dockerfile_name>
+
+    Finds the most specific dockerignore file that exists.
+    """
+
+    def valid_dockerignore_file(fp):
+        # fp has to exist
+        if not fp.exists():
+            return False
+        # fp has to be subpath to current working directory
+        if not fp.is_relative_to(context_directory):
+            return False
+
+        return True
+
+    generic_name = ".dockerignore"
+    possible_locations = []
+    if dockerfile_path:
+        specific_name = f"{dockerfile_path.name}.dockerignore"
+        # 1. check if specific <dockerfile_name>.dockerignore file exists in the same directory as <dockerfile_name>
+        possible_locations.append(dockerfile_path.parent / specific_name)
+        # 2. check if generic .dockerignore file exists in the same directory as <dockerfile_name>
+        possible_locations.append(dockerfile_path.parent / generic_name)
+
+    # 3. check if generic .dockerignore file exists in current working directory
+    possible_locations.append(context_directory / generic_name)
+
+    return next((e for e in possible_locations if valid_dockerignore_file(e)), None)
+
+
+class _AutoDockerIgnoreSentinel:
+    def __repr__(self) -> str:
+        return f"{__name__}.AUTO_DOCKERIGNORE"
+
+    def __call__(self, _: Path) -> bool:
+        raise NotImplementedError("This is only a placeholder. Do not call")
+
+
+AUTO_DOCKERIGNORE = _AutoDockerIgnoreSentinel()