Make pandas, numpy, and matplotlib optional dependencies with lazy loading and helpful error messages

README.md

@@ -11,6 +11,18 @@ To install the latest release:
 
 `pip install prometheus-api-client`
 
+To install with all optional dependencies (pandas, numpy, matplotlib):
+
+`pip install prometheus-api-client[all]`
+
+**Note:** Starting from version 0.6.0, pandas, numpy, and matplotlib are optional dependencies. 
+If you only need `PrometheusConnect` without DataFrame support or plotting capabilities, you can install the minimal version which significantly reduces memory footprint and installation time, especially on Alpine-based Docker images.
+
+To install only specific extras:
+- For DataFrame support: `pip install prometheus-api-client[dataframe]`
+- For numpy support: `pip install prometheus-api-client[numpy]`
+- For plotting support: `pip install prometheus-api-client[plot]`
+
 To install directly from this branch:
 
 `pip install https://github.com/4n4nd/prometheus-api-client-python/zipball/master`

prometheus_api_client/prometheus_connect.py

@@ -4,7 +4,6 @@
 import os
 import json
 import logging
-import numpy
 from datetime import datetime, timedelta
 import requests
 from requests.adapters import HTTPAdapter
@@ -569,6 +568,8 @@ def get_metric_aggregation(
                 'max': 6.009373
              }
         """
+        import numpy
+
         if not isinstance(operations, list):
             raise TypeError("Operations can be only of type list")
         if len(operations) == 0:

requirements-core.txt

@@ -0,0 +1,2 @@
+requests
+dateparser

setup.py

@@ -7,8 +7,8 @@
 
 
 def get_install_requires():
-    """Get requirements from requirements.txt."""
-    with open("requirements.txt", "r") as requirements_file:
+    """Get core requirements from requirements-core.txt."""
+    with open("requirements-core.txt", "r") as requirements_file:
         res = requirements_file.readlines()
         return [req.split(" ", maxsplit=1)[0] for req in res if req]
 
@@ -36,6 +36,12 @@ def get_version():
     long_description_content_type="text/markdown",
     url="https://github.com/4n4nd/prometheus-api-client-python",
     install_requires=get_install_requires(),
+    extras_require={
+        "dataframe": ["pandas>=1.4.0"],
+        "numpy": ["numpy"],
+        "plot": ["matplotlib"],
+        "all": ["pandas>=1.4.0", "numpy", "matplotlib"],
+    },
     packages=setuptools.find_packages(),
     package_data={"prometheus-api-client": ["py.typed"]},
     tests_require=["httmock"],

tests/test_lazy_imports.py

@@ -0,0 +1,81 @@
+"""Test lazy imports to ensure pandas/matplotlib are not loaded unnecessarily."""
+import unittest
+import sys
+import importlib
+
+
+class TestLazyImports(unittest.TestCase):
+    """Test that PrometheusConnect can be imported without loading heavy dependencies."""
+
+    @staticmethod
+    def _remove_modules(module_names):
+        """Remove specified modules and their submodules from sys.modules.
+
+        Args:
+            module_names: List of module names to remove
+        """
+        for module_name in module_names:
+            modules_to_remove = [
+                key for key in sys.modules.keys()
+                if key == module_name or key.startswith(module_name + '.')
+            ]
+            for module in modules_to_remove:
+                del sys.modules[module]
+
+    @staticmethod
+    def _is_module_loaded(module_name):
+        """Check if a module is loaded in sys.modules.
+
+        Args:
+            module_name: Name of the module to check
+
+        Returns:
+            bool: True if module is loaded, False otherwise
+        """
+        return any(m == module_name or m.startswith(module_name + '.') for m in sys.modules.keys())
+
+    def test_prometheus_connect_import_without_pandas_matplotlib_numpy(self):
+        """Test that importing PrometheusConnect doesn't load pandas, matplotlib, or numpy."""
+        # Remove any previously loaded modules
+        self._remove_modules(['prometheus_api_client', 'numpy', 'pandas', 'matplotlib'])
+
+        # Import PrometheusConnect
+        from prometheus_api_client import PrometheusConnect
+
+        # Check that pandas, matplotlib, and numpy are not loaded
+        self.assertFalse(self._is_module_loaded('pandas'), 
+                        "pandas should not be loaded when importing PrometheusConnect")
+        self.assertFalse(self._is_module_loaded('matplotlib'), 
+                        "matplotlib should not be loaded when importing PrometheusConnect")
+        self.assertFalse(self._is_module_loaded('numpy'), 
+                        "numpy should not be loaded when importing PrometheusConnect")
+
+    def test_prometheus_connect_instantiation_without_numpy(self):
+        """Test that PrometheusConnect can be instantiated without loading numpy."""
+        # Remove any previously loaded modules
+        self._remove_modules(['prometheus_api_client', 'numpy'])
+
+        # Import and instantiate PrometheusConnect
+        from prometheus_api_client import PrometheusConnect
+        pc = PrometheusConnect(url='http://test.local:9090')
+
+        # Check that numpy is still not loaded after instantiation
+        self.assertFalse(self._is_module_loaded('numpy'), 
+                        "numpy should not be loaded when instantiating PrometheusConnect")
+        self.assertIsNotNone(pc, "PrometheusConnect should be instantiated successfully")
+
+    def test_metric_import_loads_pandas(self):
+        """Test that importing Metric does load pandas (expected behavior)."""
+        # Remove any previously loaded modules
+        self._remove_modules(['prometheus_api_client', 'pandas'])
+
+        # Import Metric
+        from prometheus_api_client import Metric
+
+        # Check that pandas is loaded (this is expected for Metric)
+        self.assertTrue(self._is_module_loaded('pandas'), 
+                       "pandas should be loaded when importing Metric")
+
+
+if __name__ == '__main__':
+    unittest.main()