feat: Path Resolver and Validator (#55)

The function "which" at aws_lambda_builders/utils.py was copied from
https://github.com/python/cpython/blob/3.7/Lib/shutil.py
SPDX-License-Identifier: Python-2.0
Copyright 2019 by the Python Software Foundation

.appveyor.yml

@@ -18,13 +18,14 @@ install:
 # To run Nodejs workflow integ tests
 - ps: Install-Product node 8.10
 
-- "set PATH=%PYTHON%\\Scripts;%PYTHON%\\bin;%PATH%"
+- "set PATH=%PYTHON%;%PYTHON%\\Scripts;%PYTHON%\\bin;%PATH%"
 - "%PYTHON%\\python.exe -m pip install -r requirements/dev.txt"
 - "%PYTHON%\\python.exe -m pip install -e ."
 - "set PATH=C:\\Ruby25-x64\\bin;%PATH%"
 - "gem --version"
 - "gem install bundler -v 1.17.3 --no-ri --no-rdoc"
 - "bundler --version"
+- "echo %PATH%"
 
 # setup go
 - rmdir c:\go /s /q

.pylintrc

@@ -9,7 +9,7 @@
 
 # Add files or directories to the blacklist. They should be base names, not
 # paths.
-ignore=compat.py
+ignore=compat.py, utils.py
 
 # Pickle collected data for later comparisons.
 persistent=yes
@@ -360,4 +360,4 @@ int-import-graph=
 
 # Exceptions that will emit a warning when being caught. Defaults to
 # "Exception"
-overgeneral-exceptions=Exception
+overgeneral-exceptions=Exception

.travis.yml

@@ -15,6 +15,9 @@ install:
   # To run Nodejs workflow integ tests
   - nvm install 8.10.0
   - nvm use 8.10.0
+  # To run Ruby workflow integ tests
+  - rvm install ruby-2.5.3
+  - rvm use ruby-2.5.3
 
   # Go workflow integ tests require Go 1.11+
   - eval "$(gimme 1.11.2)"

NOTICE

@@ -1,2 +1,6 @@
 AWS Lambda Builders
 Copyright 2018 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+
+The function "which" at aws_lambda_builders/utils.py was copied from https://github.com/python/cpython/blob/3.7/Lib/shutil.py
+SPDX-License-Identifier: Python-2.0
+Copyright 2019 by the Python Software Foundation

aws_lambda_builders/binary_path.py

@@ -0,0 +1,21 @@
+"""
+Class containing resolved path of binary given a validator and a resolver and the name of the binary.
+"""
+
+
+class BinaryPath(object):
+
+    def __init__(self, resolver, validator, binary, binary_path=None):
+        self.resolver = resolver
+        self.validator = validator
+        self.binary = binary
+        self._binary_path = binary_path
+        self.path_provided = True if self._binary_path else False
+
+    @property
+    def binary_path(self):
+        return self._binary_path
+
+    @binary_path.setter
+    def binary_path(self, binary_path):
+        self._binary_path = binary_path

aws_lambda_builders/builder.py

@@ -7,7 +7,6 @@
 import logging
 
 from aws_lambda_builders.registry import get_workflow, DEFAULT_REGISTRY
-from aws_lambda_builders.validate import RuntimeValidator
 from aws_lambda_builders.workflow import Capability
 
 LOG = logging.getLogger(__name__)
@@ -91,8 +90,6 @@ def build(self, source_dir, artifacts_dir, scratch_dir, manifest_path,
         :param options:
             Optional dictionary of options ot pass to build action. **Not supported**.
         """
-        if runtime:
-            self._validate_runtime(runtime)
 
         if not os.path.exists(scratch_dir):
             os.makedirs(scratch_dir)
@@ -107,16 +104,5 @@ def build(self, source_dir, artifacts_dir, scratch_dir, manifest_path,
 
         return workflow.run()
 
-    def _validate_runtime(self, runtime):
-        """
-        validate runtime and local runtime version to make sure they match
-
-        :type runtime: str
-        :param runtime:
-            String matching a lambda runtime eg: python3.6
-        """
-        RuntimeValidator.validate_runtime(required_language=self.capability.language,
-                                          required_runtime=runtime)
-
     def _clear_workflows(self):
         DEFAULT_REGISTRY.clear()

aws_lambda_builders/exceptions.py

@@ -18,7 +18,7 @@ class UnsupportedManifestError(LambdaBuilderError):
 class MisMatchRuntimeError(LambdaBuilderError):
     MESSAGE = "{language} executable found in your path does not " \
               "match runtime. " \
-              "\n Expected version: {required_runtime}, Found version: {found_runtime}. " \
+              "\n Expected version: {required_runtime}, Found version: {runtime_path}. " \
               "\n Possibly related: https://github.com/awslabs/aws-lambda-builders/issues/30"
 
 

aws_lambda_builders/path_resolver.py

@@ -0,0 +1,28 @@
+"""
+Basic Path Resolver that looks for the executable by runtime first, before proceeding to 'language' in PATH.
+"""
+
+from aws_lambda_builders.utils import which
+
+
+class PathResolver(object):
+
+    def __init__(self, binary, runtime):
+        self.binary = binary
+        self.runtime = runtime
+        self.executables = [self.runtime, self.binary]
+
+    def _which(self):
+        exec_paths = []
+        for executable in [executable for executable in self.executables if executable is not None]:
+            paths = which(executable)
+            exec_paths.extend(paths)
+
+        if not exec_paths:
+            raise ValueError("Path resolution for runtime: {} of binary: "
+                             "{} was not successful".format(self.runtime, self.binary))
+        return exec_paths
+
+    @property
+    def exec_paths(self):
+        return self._which()

aws_lambda_builders/utils.py

@@ -3,6 +3,7 @@
 """
 
 import shutil
+import sys
 import os
 import logging
 
@@ -57,3 +58,77 @@ def copytree(source, destination, ignore=None):
             copytree(new_source, new_destination, ignore=ignore)
         else:
             shutil.copy2(new_source, new_destination)
+
+# NOTE: The below function is copied from Python source code and modified
+# slightly to return a list of paths that match a given command
+#  instead of returning just the first match
+
+# The function "which" at aws_lambda_builders/utils.py was copied from https://github.com/python/cpython/blob/3.7/Lib/shutil.py
+# SPDX-License-Identifier: Python-2.0
+# Copyright 2019 by the Python Software Foundation
+
+
+def which(cmd, mode=os.F_OK | os.X_OK, path=None):  # pragma: no cover
+    """Given a command, mode, and a PATH string, return the paths which
+    conforms to the given mode on the PATH, or None if there is no such
+    file.
+    `mode` defaults to os.F_OK | os.X_OK. `path` defaults to the result
+    of os.environ.get("PATH"), or can be overridden with a custom search
+    path.
+    Note: This function was backported from the Python 3 source code.
+    """
+    # Check that a given file can be accessed with the correct mode.
+    # Additionally check that `file` is not a directory, as on Windows
+    # directories pass the os.access check.
+
+    def _access_check(fn, mode):
+        return os.path.exists(fn) and os.access(fn, mode) and not os.path.isdir(fn)
+
+    # If we're given a path with a directory part, look it up directly
+    # rather than referring to PATH directories. This includes checking
+    # relative to the current directory, e.g. ./script
+    if os.path.dirname(cmd):
+        if _access_check(cmd, mode):
+            return cmd
+
+        return None
+
+    if path is None:
+        path = os.environ.get("PATH", os.defpath)
+    if not path:
+        return None
+
+    path = path.split(os.pathsep)
+
+    if sys.platform == "win32":
+        # The current directory takes precedence on Windows.
+        if os.curdir not in path:
+            path.insert(0, os.curdir)
+
+        # PATHEXT is necessary to check on Windows.
+        pathext = os.environ.get("PATHEXT", "").split(os.pathsep)
+        # See if the given file matches any of the expected path
+        # extensions. This will allow us to short circuit when given
+        # "python.exe". If it does match, only test that one, otherwise we
+        # have to try others.
+        if any(cmd.lower().endswith(ext.lower()) for ext in pathext):
+            files = [cmd]
+        else:
+            files = [cmd + ext for ext in pathext]
+    else:
+        # On other platforms you don't have things like PATHEXT to tell you
+        # what file suffixes are executable, so just pass on cmd as-is.
+        files = [cmd]
+
+    seen = set()
+    paths = []
+
+    for dir in path:
+        normdir = os.path.normcase(dir)
+        if normdir not in seen:
+            seen.add(normdir)
+            for thefile in files:
+                name = os.path.join(dir, thefile)
+                if _access_check(name, mode):
+                    paths.append(name)
+    return paths

aws_lambda_builders/validator.py

@@ -0,0 +1,18 @@
+"""
+No-op validator that does not validate the runtime_path for a specified language.
+"""
+
+import logging
+
+LOG = logging.getLogger(__name__)
+
+
+class RuntimeValidator(object):
+
+    def __init__(self, runtime):
+        self.runtime = runtime
+        self._runtime_path = None
+
+    def validate(self, runtime_path):
+        self._runtime_path = runtime_path
+        return runtime_path