Fix #1376 - Initialise ub_ctx in views on usage, not import

interface/views/connection.py

@@ -19,7 +19,7 @@
 from checks.scoring import STATUS_FAIL, STATUS_INFO, STATUS_NOT_TESTED, STATUS_NOTICE, STATUS_SUCCESS
 from checks.tasks.routing import TeamCymruIPtoASN, BGPSourceUnavailableError
 from interface import redis_id
-from interface.views.shared import get_client_ip, get_javascript_retries, ub_ctx
+from interface.views.shared import get_client_ip, get_javascript_retries, get_ub_ctx
 
 probe_ipv6 = Probe("ipv6", "conn", scorename="ipv6", nourl=True, maxscore=100)
 probe_resolver = Probe("resolver", "conn", scorename="dnssec", nourl=True, maxscore=100, reportfield="reportdnssec")
@@ -354,6 +354,7 @@ def find_AS_by_IP(ip):
     :returns: AS number or None on error
 
     """
+    ub_ctx = get_ub_ctx()
     try:
         asns_prefixes = TeamCymruIPtoASN.asn_prefix_pairs_for_ip(None, ip)
         (asn, _) = asns_prefixes[0]
@@ -407,6 +408,7 @@ def unbound_ptr(qname):
     Return the PTR records for `qname` from unbound.
 
     """
+    ub_ctx = get_ub_ctx()
     status, result = ub_ctx.resolve(qname, unbound.RR_TYPE_PTR, unbound.RR_CLASS_IN)
     if status == 0 and result.havedata:
         return result.data.domain_list

interface/views/shared.py

@@ -28,24 +28,38 @@
 
 from statshog.defaults.django import statsd
 
-ub_ctx = unbound.ub_ctx()
-ub_ctx.set_fwd(settings.IPV4_IP_RESOLVER_INTERNAL_PERMISSIVE)
+_ub_ctx = None
 
-if settings.INTEGRATION_TESTS:
-    # forward the .test zone used in integration tests
-    ub_ctx.zone_add("test.", "transparent")
 
-if settings.DEBUG_LOG_UNBOUND:
-    ub_ctx.set_option("log-queries:", "yes")
-    ub_ctx.set_option("verbosity:", "2")
+def get_ub_ctx():
+    """
+    Wrapper around ub_ctx initialisation for https://github.com/internetstandards/Internet.nl/issues/1376
+    """
+    global _ub_ctx
+    if _ub_ctx:
+        return _ub_ctx
+
+    _ub_ctx = unbound.ub_ctx()
+    _ub_ctx.set_fwd(settings.IPV4_IP_RESOLVER_INTERNAL_PERMISSIVE)
+
+    if settings.INTEGRATION_TESTS:
+        # forward the .test zone used in integration tests
+        _ub_ctx.zone_add("test.", "transparent")
 
-# XXX: Remove for now; inconsistency with applying settings on celery.
-# YYY: Removal caused infinite waiting on pipe to unbound. Added again.
-ub_ctx.set_async(True)
-ub_ctx.set_option("rrset-roundrobin:", "no")
+    if settings.DEBUG_LOG_UNBOUND:
+        _ub_ctx.set_option("log-queries:", "yes")
+        _ub_ctx.set_option("verbosity:", "2")
+
+    # XXX: Remove for now; inconsistency with applying settings on celery.
+    # YYY: Removal caused infinite waiting on pipe to unbound. Added again.
+    _ub_ctx.set_async(True)
+    _ub_ctx.set_option("rrset-roundrobin:", "no")
+
+    # fire an initial DNS query to start unbound background worker and prevent race conditions that can occur
+    _ub_ctx.resolve_async("internet.nl", {}, lambda x, y, z: None, unbound.RR_TYPE_A, unbound.RR_CLASS_IN)
+
+    return _ub_ctx
 
-# fire an initial DNS query to start unbound background worker and prevent race conditions that can occur
-ub_ctx.resolve_async("internet.nl", {}, lambda x, y, z: None, unbound.RR_TYPE_A, unbound.RR_CLASS_IN)
 
 # See: https://stackoverflow.com/a/53875771 for a good summary of the various
 # RFCs and other rulings that combine to define what is a valid domain name.
@@ -286,6 +300,8 @@ def get_retest_time(report):
 
 @statsd.timer("ub_resolve_with_timeout")
 def ub_resolve_with_timeout(qname, qtype, rr_class, timeout):
+    ub_ctx = get_ub_ctx()
+
     def ub_callback(data, status, result):
         if status == 0 and result.havedata:
             data["data"] = result.data