DTLS server: Only run when explicitly enabled

Author: chrysn

aiocoap/defaults.py

@@ -88,7 +88,8 @@ def get_default_servertransports(*, loop=None, use_env=True):
         yield 'oscore'
 
     if not dtls_missing_modules():
-        yield 'tinydtls_server'
+        if 'AIOCOAP_DTLSSERVER_ENABLED' in os.environ:
+            yield 'tinydtls_server'
         yield 'tinydtls'
 
     yield 'tcpserver'

aiocoap/transports/tinydtls_server.py

@@ -11,6 +11,15 @@
 
 Bear in mind that the aiocoap CoAPS support is highly experimental and
 incomplete.
+
+Unlike other transports this is *not* enabled automatically in general, as it
+is limited to servers bound to a single address for implementation reasons.
+(Basically, because it is built on the simplesocketserver rather than the udp6
+server -- that can change in future, though). Until either the implementation
+is changed or binding arguments are (allowing different transports to bind to
+per-transport addresses or ports), a DTLS server will only be enabled if the
+AIOCOAP_DTLSSERVER_ENABLED environment variable is set, or tinydtls_server is
+listed explicitly in AIOCOAP_SERVER_TRANSPORT.
 """
 
 # Comparing this to the tinydtls transport, things are a bit easier as we don't

tests/common.py

@@ -21,6 +21,10 @@
     import gbulb
     gbulb.install()
 
+# All test servers are bound to loopback; if for any reason one'd want to run
+# with particular transports, just set them explicitly.
+os.environ['AIOCOAP_DTLSSERVER_ENABLED'] = '1'
+
 if 'coverage' in sys.modules:
     PYTHON_PREFIX = [sys.executable, '-m', 'coverage', 'run', '--parallel-mode']
 else: