add function to parse canonical quantities (e.g. resources)

kubernetes/test/test_quantity.py

@@ -0,0 +1,112 @@
+# coding: utf-8
+# Copyright 2019 The Kubernetes Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import absolute_import
+
+import unittest
+from kubernetes.utils import parse_quantity
+from decimal import Decimal
+
+
+class TestQuantity(unittest.TestCase):
+    def test_parse(self):
+        self.assertIsInstance(parse_quantity(2.2), Decimal)
+        # input, expected output
+        tests = [
+            (0, 0),
+            (2, 2),
+            (2, Decimal("2")),
+            (2., 2),
+            (Decimal("2.2"), Decimal("2.2")),
+            (2., Decimal(2)),
+            (Decimal("2."), 2),
+            ("123", 123),
+            ("2", 2),
+            ("2n", Decimal("2") * Decimal(1000)**-3),
+            ("2u", Decimal("0.000002")),
+            ("2m", Decimal("0.002")),
+            ("0m", Decimal("0")),
+            ("0M", Decimal("0")),
+            ("223k", 223000),
+            ("002M", 2 * 1000**2),
+            ("2M", 2 * 1000**2),
+            ("4123G", 4123 * 1000**3),
+            ("2T", 2 * 1000**4),
+            ("2P", 2 * 1000**5),
+            ("2E", 2 * 1000**6),
+
+            ("223Ki", 223 * 1024),
+            ("002Mi", 2 * 1024**2),
+            ("2Mi", 2 * 1024**2),
+            ("2Gi", 2 * 1024**3),
+            ("4123Gi", 4123 * 1024**3),
+            ("2Ti", 2 * 1024**4),
+            ("2Pi", 2 * 1024**5),
+            ("2Ei", 2 * 1024**6),
+
+            ("2.34n", Decimal("2.34") * Decimal(1000)**-3),
+            ("2.34u", Decimal("2.34") * Decimal(1000)**-2),
+            ("2.34m", Decimal("2.34") * Decimal(1000)**-1),
+            ("2.34Ki", Decimal("2.34") * 1024),
+            ("2.34", Decimal("2.34")),
+            (".34", Decimal("0.34")),
+            ("34.", 34),
+            (".34M", Decimal("0.34") * 1000**2),
+
+            ("2e2K", Decimal("2e2") * 1000),
+            ("2e2Ki", Decimal("2e2") * 1024),
+            ("2e-2Ki", Decimal("2e-2") * 1024),
+            ("2.34E1", Decimal("2.34E1")),
+            (".34e-2", Decimal("0.34e-2")),
+        ]
+
+        for inp, out in tests:
+            self.assertEqual(parse_quantity(inp), out)
+            if isinstance(inp, (int, float, Decimal)):
+                self.assertEqual(parse_quantity(-1 * inp), -out)
+            else:
+                self.assertEqual(parse_quantity("-" + inp), -out)
+                self.assertEqual(parse_quantity("+" + inp), out)
+
+    def test_parse_invalid(self):
+        self.assertRaises(ValueError, parse_quantity, [])
+        self.assertRaises(ValueError, parse_quantity, "")
+        self.assertRaises(ValueError, parse_quantity, "-")
+        self.assertRaises(ValueError, parse_quantity, "i")
+        self.assertRaises(ValueError, parse_quantity, "2i")
+        self.assertRaises(ValueError, parse_quantity, "2mm")
+        self.assertRaises(ValueError, parse_quantity, "2mmKi")
+        self.assertRaises(ValueError, parse_quantity, "2KKi")
+        self.assertRaises(ValueError, parse_quantity, "2e")
+        self.assertRaises(ValueError, parse_quantity, "2.2i")
+        self.assertRaises(ValueError, parse_quantity, "bla")
+        self.assertRaises(ValueError, parse_quantity, "Ki")
+        self.assertRaises(ValueError, parse_quantity, "M")
+        self.assertRaises(ValueError, parse_quantity, "2ki")
+        self.assertRaises(ValueError, parse_quantity, "2Ki ")
+        self.assertRaises(ValueError, parse_quantity, "20Ki ")
+        self.assertRaises(ValueError, parse_quantity, "20B")
+        self.assertRaises(ValueError, parse_quantity, "20Bi")
+        self.assertRaises(ValueError, parse_quantity, "20.2Bi")
+        self.assertRaises(ValueError, parse_quantity, "2MiKi")
+        self.assertRaises(ValueError, parse_quantity, "2MK")
+        self.assertRaises(ValueError, parse_quantity, "2MKi")
+        self.assertRaises(ValueError, parse_quantity, "234df")
+        self.assertRaises(ValueError, parse_quantity, "df234")
+        self.assertRaises(ValueError, parse_quantity, tuple())
+
+
+if __name__ == '__main__':
+    unittest.main()

kubernetes/utils/__init__.py

@@ -16,3 +16,4 @@
 
 from .create_from_yaml import (FailToCreateError, create_from_dict,
                                create_from_yaml)
+from .quantity import parse_quantity

kubernetes/utils/quantity.py

@@ -0,0 +1,75 @@
+# Copyright 2019 The Kubernetes Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+from decimal import Decimal, InvalidOperation
+
+
+def parse_quantity(quantity):
+    """
+    Parse kubernetes canonical form quantity like 200Mi to a decimal number.
+    Supported SI suffixes:
+    base1024: Ki | Mi | Gi | Ti | Pi | Ei
+    base1000: n | u | m | "" | k | M | G | T | P | E
+
+    See https://github.com/kubernetes/apimachinery/blob/master/pkg/api/resource/quantity.go
+
+    Input:
+    quanity: string. kubernetes canonical form quantity
+
+    Returns:
+    Decimal
+
+    Raises:
+    ValueError on invalid or unknown input
+    """
+    if isinstance(quantity, (int, float, Decimal)):
+        return Decimal(quantity)
+
+    exponents = {"n": -3, "u": -2, "m": -1, "K": 1, "k": 1, "M": 2,
+                 "G": 3, "T": 4, "P": 5, "E": 6}
+
+    quantity = str(quantity)
+    number = quantity
+    suffix = None
+    if len(quantity) >= 2 and quantity[-1] == "i":
+        if quantity[-2] in exponents:
+            number = quantity[:-2]
+            suffix = quantity[-2:]
+    elif len(quantity) >= 1 and quantity[-1] in exponents:
+        number = quantity[:-1]
+        suffix = quantity[-1:]
+
+    try:
+        number = Decimal(number)
+    except InvalidOperation:
+        raise ValueError("Invalid number format: {}".format(number))
+
+    if suffix is None:
+        return number
+
+    if suffix.endswith("i"):
+        base = 1024
+    elif len(suffix) == 1:
+        base = 1000
+    else:
+        raise ValueError("{} has unknown suffix".format(quantity))
+
+    # handly SI inconsistency
+    if suffix == "ki":
+        raise ValueError("{} has unknown suffix".format(quantity))
+
+    if suffix[0] not in exponents:
+        raise ValueError("{} has unknown suffix".format(quantity))
+
+    exponent = Decimal(exponents[suffix[0]])
+    return number * (base ** exponent)