Merge ~ballot/content-cache-charm/+git/content-cache-charm:site_unique into content-cache-charm:master

[Benjamin Allot]

dcdc954... by Benjamin Allot on 2021-03-18

WIP

Unmerged commits

dcdc954... by Benjamin Allot on 2021-03-18

WIP

7971dd9... by Benjamin Allot on 2020-05-12

Duplicate keys of the same node level will now return an error.

This will block the charm.

diff --git a/lib/utils.py b/lib/utils.py
index f06effc..c8ef458 100644
--- a/lib/utils.py
+++ b/lib/utils.py
@@ -6,6 +6,14 @@ import re
 import shutil
 import subprocess
 
+from yaml.constructor import ConstructorError
+
+try:
+    from yaml import CLoader as Loader
+except ImportError:
+    from yaml import Loader
+
+
 BASE_CACHE_PORT = 6080
 BASE_BACKEND_PORT = 8080
 BACKEND_PORT_LIMIT = 61000  # sysctl net.ipv4.ip_local_port_range
@@ -218,3 +226,33 @@ def package_version(package):
     if not version:
         return None
     return version
+
+
+class SafeDuplicateKeysLoader(yaml.SafeLoader):
+    """A YAML Loader refusing to load duplicate keys."""
+
+    def construct_mapping(self, node: yaml.nodes.MappingNode, deep=False: bool) -> dict:
+        """Construct the dict without duplicate keys.
+
+        This is a redefinition of :py:function:`yaml.constructor.BaseConstructor.construct_mapping`.
+        It throws a :py:class:`yaml.constructor.ConstructorError` exception if duplicate keys are present at any level.
+
+        :param node: The yaml representation to load.
+        :param deep: Do a deep copy of the yaml node.
+        :returns: The dictionary representing the yaml
+
+
+
+def no_duplicates_constructor(loader, node, deep=False):
+    """Check for duplicate keys."""
+
+    mapping = {}
+    for key_node, value_node in node.value:
+        key = loader.construct_object(key_node, deep=deep)
+        value = loader.construct_object(value_node, deep=deep)
+        if key in mapping:
+            raise ConstructorError("while constructing a mapping", node.start_mark,
+                                   "found duplicate key (%s)" % key, key_node.start_mark)
+        mapping[key] = value
+
+    return loader.construct_mapping(node, deep)
diff --git a/reactive/content_cache.py b/reactive/content_cache.py
index d396779..b80fb60 100644
--- a/reactive/content_cache.py
+++ b/reactive/content_cache.py
@@ -22,6 +22,8 @@ from lib import haproxy as HAProxy
 
 SYSCTL_CONF_PATH = '/etc/sysctl.d/90-content-cache.conf'
 
+yaml.add_constructor(yaml.resolver.BaseResolver.DEFAULT_MAPPING_TAG, utils.no_duplicates_constructor)
+
 
 @reactive.hook('upgrade-charm')
 def upgrade_charm():
@@ -580,9 +582,14 @@ def ports_map_lookup(ports_map, site, base_port, blacklist_ports=None, key=None)
 
 
 def sites_from_config(sites_yaml, sites_secrets=None, blacklist_ports=None):
-    conf = yaml.safe_load(sites_yaml)
-    # 'configs' is special and used to host YAML anchors so let's remove it
-    conf.pop('configs', '')
+    try:
+        conf = yaml.safe_load(sites_yaml)
+        # 'configs' is special and used to host YAML anchors so let's remove it
+        conf.pop('configs', '')
+    except yaml.constructor.ConstructorError as exc:
+        hookenv.log(str(exc))
+        return False
+
     sites = interpolate_secrets(conf, sites_secrets)
     cache_port = 0
     backend_port = 0