new lookup plugin: LMDB - allow wildcard searches - make dbname configurable for with_lmdb_kv: - added built-in documentation - incorporate suggested changes by dw - comment spaces - outdent for the bot

lib/ansible/plugins/lookup/lmdb_kv.py

@@ -0,0 +1,107 @@
+# (c) 2017-2018, Jan-Piet Mens <jpmens(at)gmail.com>
+# (c) 2018 Ansible Project
+# GNU General Public License v3.0+ (see COPYING or https://www.gnu.org/licenses/gpl-3.0.txt)
+from __future__ import (absolute_import, division, print_function)
+__metaclass__ = type
+
+DOCUMENTATION = """
+    lookup: lmdb
+    author:
+      - Jan-Piet Mens (@jpmens) <jpmens(at)gmail.com>
+      - Ansible Core
+    version_added: "2.5"
+    short_description: fetch data from LMDB
+    description:
+      - This lookup returns a list of results from an LMDB DB corresponding to a list of items given to it
+    requirements:
+      - lmdb (python library https://lmdb.readthedocs.io/en/release/)
+    options:
+      _terms:
+        description: list of keys to query
+      db:
+        description: path to LMDB database
+        default: 'ansible.mdb'
+"""
+
+EXAMPLES = """
+- name: query LMDB for a list of country codes
+  debug: msg="{{ lookup('lmdb_kv', 'nl', 'be', 'lu', db='jp.mdb') }}"
+
+- name: use list of values in a loop
+  debug: msg="Hello from {{ item.0 }} a.k.a. {{ item.1 }}"
+  with_lmdb_kv:
+     - "n*"
+
+"""
+
+RETURN = """
+_raw:
+  description: value(s) stored in LMDB
+"""
+
+
+from ansible.errors import AnsibleError
+from ansible.plugins.lookup import LookupBase
+
+HAVE_LMDB = True
+try:
+    import lmdb
+except ImportError:
+    HAVE_LMDB = False
+
+
+class LookupModule(LookupBase):
+
+    def run(self, terms, variables, **kwargs):
+
+        '''
+        terms contain any number of keys to be retrieved.
+        If terms is None, all keys from the database are returned
+        with their values, and if term ends in an asterisk, we
+        start searching there
+
+        The LMDB database defaults to 'ansible.mdb' if Ansible's
+        variable 'lmdb_kv_db' is not set:
+
+              vars:
+                - lmdb_kv_db: "jp.mdb"
+        '''
+
+        if HAVE_LMDB is False:
+            raise AnsibleError("Can't LOOKUP(lmdb_kv): this module requires lmdb to be installed")
+
+        db = variables.get('lmdb_kv_db', None)
+        if db is None:
+            db = kwargs.get('db', 'ansible.mdb')
+        db = str(db)
+
+        try:
+            env = lmdb.open(db, readonly=True)
+        except Exception as e:
+            raise AnsibleError("LMDB can't open database %s: %s" % (db, str(e)))
+
+        ret = []
+        if len(terms) == 0:
+            with env.begin() as txn:
+                cursor = txn.cursor()
+                cursor.first()
+                for key, value in cursor:
+                    ret.append((key, value))
+
+        else:
+            for term in terms:
+                with env.begin() as txn:
+                    if term.endswith('*'):
+                        cursor = txn.cursor()
+                        prefix = term[:-1]           # strip asterisk
+                        # cursor.set_range(prefix)
+                        cursor.set_range(term)
+                        while cursor.key().startswith(prefix):
+                            ret.append(cursor.item())
+                            cursor.next()
+                    else:
+                        value = txn.get(term)
+                        if value is not None:
+                            ret.append(value)
+
+        return ret