fix: format of IPv6 address logged at PostgREST startup

The IPv6 address logged at the startup like `::1:80` was
wrong because the port isn't clearly separated. This commit
corrects it, now logging as `[::1]:80`.

This is done in accordance to RFC 3986. In short, we did this
have a clear separation between the port and host because
the components of an IPv6 are separated with the ':' character.

Signed-off-by: Taimoor Zaeem <taimoorzaeem@gmail.com>

test/io/postgrest.py

@@ -97,7 +97,9 @@ def run(
         if port:
             env["PGRST_SERVER_PORT"] = str(port)
             env["PGRST_SERVER_HOST"] = host or "localhost"
-            baseurl = f"http://localhost:{port}"
+            # When constructing IPv6 address, host address should be bracketed like [host]
+            apihost = f"[{host}]" if host and is_ipv6(host) else "localhost"
+            baseurl = f"http://{apihost}:{port}"
         else:
             socketfile = pathlib.Path(tmpdir) / "postgrest.sock"
             env["PGRST_SERVER_UNIX_SOCKET"] = str(socketfile)
@@ -105,7 +107,8 @@ def run(
 
         adminport = freeport(port)
         env["PGRST_ADMIN_SERVER_PORT"] = str(adminport)
-        adminurl = f"http://localhost:{adminport}"
+        adminhost = f"[{host}]" if host and is_ipv6(host) else "localhost"
+        adminurl = f"http://{adminhost}:{adminport}"
 
         command = [POSTGREST_BIN]
         env["HPCTIXFILE"] = hpctixfile()
@@ -219,3 +222,11 @@ def sleep_pool_connection(url, seconds):
         session.get(url + f"/rpc/sleep?seconds={seconds}", timeout=0.1)
     except requests.exceptions.ReadTimeout:
         pass
+
+
+def is_ipv6(addr):
+    try:
+        socket.inet_pton(socket.AF_INET6, addr)
+        return True
+    except OSError:
+        return False

test/io/test_io.py

@@ -1362,9 +1362,9 @@ def test_log_postgrest_version(defaultenv):
         assert "Starting PostgREST %s..." % version in output[0]
 
 
-def test_log_postgrest_host_and_port(defaultenv):
+@pytest.mark.parametrize("host", ["127.0.0.1", "::1"])
+def test_log_postgrest_host_and_port(host, defaultenv):
     "PostgREST should output the host and port it is bound to."
-    host = "127.0.0.1"
     port = freeport()
 
     with run(
@@ -1372,7 +1372,10 @@ def test_log_postgrest_host_and_port(defaultenv):
     ) as postgrest:
         output = postgrest.read_stdout(nlines=10)
 
-        assert f"API server listening on {host}:{port}" in output[2]  # output-sensitive
+        if is_ipv6(host):  # IPv6
+            assert f"API server listening on [{host}]:{port}" in output[2]
+        else:  # IPv4
+            assert f"API server listening on {host}:{port}" in output[2]
 
 
 def test_succeed_w_role_having_superuser_settings(defaultenv):