#6: Implement "docker-container-log" check

docs/source/reference.rst

@@ -132,3 +132,7 @@ Parameters:
 .. include:: ../../infracheck/checks/postgres-replica-status
    :start-after: <sphinx>
    :end-before: </sphinx>
+
+.. include:: ../../infracheck/checks/docker-container-log
+   :start-after: <sphinx>
+   :end-before: </sphinx>

infracheck/checks/docker-container-log

@@ -0,0 +1,85 @@
+#!/usr/bin/env python3
+
+"""
+<sphinx>
+docker-container-log
+--------------------
+
+Searches docker container logs for matching given regular expression.
+
+Parameters:
+
+- container: Docker container name
+- regexp: Regular expression
+- max_lines: Number of last lines to check (defaults to 5)
+- since_seconds: Get only logs since this time (eg. last 5 minutes = 5 * 60 = 300) (defaults to 300)
+- present: Boolean, if the string should be present in the output or not
+</sphinx>
+"""
+
+import os
+import sys
+import re
+from subprocess import check_output
+from subprocess import CalledProcessError
+from subprocess import STDOUT
+
+
+def parse_bool(boolean: str) -> bool:
+    return bool(int(boolean.lower().replace('true', "1").replace('false', "0")))
+
+
+class DockerContainerLogCheck(object):
+    def _check_output(self, *args, **kwargs):
+        return check_output(*args, **kwargs)
+
+    def main(self, container: str, regexp: str, max_lines: int, since: int, should_be_present: bool):
+        opts = []
+
+        if since > 0:
+            opts.append('--since={}s'.format(since))
+
+        try:
+            out = self._check_output(
+                ['docker', 'logs', container, '--tail="{}"'.format(max_lines)] + opts, stderr=STDOUT).decode('utf-8')
+
+        except CalledProcessError as e:
+            out = e.output.decode('utf-8')
+
+        is_present_in_output = re.findall(regexp, out)
+
+        if should_be_present and is_present_in_output:
+            return True, "The container last {} lines of output has a match, as expected".format(max_lines)
+
+        if not should_be_present and is_present_in_output:
+            return False, "The container output is matching the pattern but should not, " \
+                          "looked at {} lines since {} in {}"\
+                .format(max_lines, str(since) + 's', container)
+
+        if should_be_present and not is_present_in_output:
+            return False, "The container last {} lines of output are not matching, expecting they were"\
+                .format(max_lines)
+
+        if not should_be_present and not is_present_in_output:
+            return True, "The container last {} lines of output are not matching, as expected".format(max_lines)
+
+        return False, "Unknown error"
+
+
+if __name__ == '__main__':
+    app = DockerContainerLogCheck()
+
+    try:
+        status, message = app.main(
+            container=os.environ['CONTAINER'],
+            regexp=os.environ['REGEXP'],
+            max_lines=int(os.getenv('MAX_LINES', '5')),
+            since=int(os.getenv('SINCE_SECONDS', '300')),
+            should_be_present=parse_bool(os.environ['PRESENT'])
+        )
+    except KeyError as attribute:
+        print('Missing environment variable: {}'.format(attribute))
+        sys.exit(1)
+
+    print(message)
+    sys.exit(0 if status else 1)

tests/functional_test_docker_container_log_check.py

@@ -0,0 +1,91 @@
+import unittest
+import os
+import inspect
+from typing import Tuple
+
+# import a script with "-" in filename
+path = os.path.dirname(os.path.abspath(inspect.getfile(inspect.currentframe()))) + '/../'
+with open(path + '/infracheck/checks/docker-container-log', 'r') as script:
+    exec(script.read())
+
+
+class DockerContainerLogCheckTest(unittest.TestCase):
+    @staticmethod
+    def _run_mocked_check(container: str, regexp: str, max_lines: int, since: int, should_be_present: bool) \
+            -> Tuple[bool, str, list]:
+
+        check = DockerContainerLogCheck()
+        called = []
+
+        def check_output(*args, **kwargs):
+            called.append(args)
+
+            return b"""
+            Hello
+            World
+            
+            This
+            Is
+            A
+            Test
+            """
+
+        check._check_output = check_output
+        result, message = check.main(
+            container,
+            regexp,
+            max_lines,
+            since,
+            should_be_present
+        )
+
+        return result, message, called
+
+    def test_expecting_exact_match_and_have_match(self) -> None:
+        result, message, called = self._run_mocked_check(
+            container='container_1',
+            regexp='Hello',
+            max_lines=15,
+            since=5,
+            should_be_present=True
+        )
+
+        self.assertTrue(result)
+        self.assertEqual('The container last 15 lines of output has a match, as expected', message)
+
+    def test_expecting_that_will_not_match(self) -> None:
+        result, message, called = self._run_mocked_check(
+            container='container_1',
+            regexp='This text will not be found',
+            max_lines=15,
+            since=5,
+            should_be_present=True
+        )
+
+        self.assertFalse(result)
+        self.assertEqual('The container last 15 lines of output are not matching, expecting they were', message)
+
+    def test_expecting_to_not_find_text_and_will_not_find(self) -> None:
+        result, message, called = self._run_mocked_check(
+            container='container_1',
+            regexp='This text will not be found',
+            max_lines=15,
+            since=5,
+            should_be_present=False
+        )
+
+        self.assertTrue(result)
+        self.assertEqual('The container last 15 lines of output are not matching, as expected', message)
+
+    def test_expecting_to_not_find_but_will_find(self) -> None:
+        result, message, called = self._run_mocked_check(
+            container='container_1',
+            regexp='Hello',
+            max_lines=15,
+            since=5,
+            should_be_present=False
+        )
+
+        self.assertFalse(result)
+        self.assertEqual('The container output is matching the pattern but should not, '
+                         'looked at 15 lines since 5s in container_1', message)