diff options
Diffstat (limited to 'erts')
| -rw-r--r-- | erts/doc/src/Makefile | 1 | ||||
| -rw-r--r-- | erts/doc/src/alt_disco.xml | 93 | ||||
| -rw-r--r-- | erts/doc/src/part.xml | 1 | ||||
| -rw-r--r-- | erts/emulator/test/distribution_SUITE.erl | 7 |
4 files changed, 101 insertions, 1 deletions
diff --git a/erts/doc/src/Makefile b/erts/doc/src/Makefile index 5fa8b0673a..96cc4413a9 100644 --- a/erts/doc/src/Makefile +++ b/erts/doc/src/Makefile @@ -74,6 +74,7 @@ XML_CHAPTER_FILES = \ match_spec.xml \ crash_dump.xml \ alt_dist.xml \ + alt_disco.xml \ driver.xml \ absform.xml \ inet_cfg.xml \ diff --git a/erts/doc/src/alt_disco.xml b/erts/doc/src/alt_disco.xml new file mode 100644 index 0000000000..d04221b9b3 --- /dev/null +++ b/erts/doc/src/alt_disco.xml @@ -0,0 +1,93 @@ +<?xml version="1.0" encoding="utf-8" ?> +<!DOCTYPE chapter SYSTEM "chapter.dtd"> + +<chapter> + <header> + <copyright> + <year>2018</year><year>2018</year> + <holder>Ericsson AB. All Rights Reserved.</holder> + </copyright> + <legalnotice> + Licensed under the Apache License, Version 2.0 (the "License"); + you may not use this file except in compliance with the License. + You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, software + distributed under the License is distributed on an "AS IS" BASIS, + WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + See the License for the specific language governing permissions and + limitations under the License. + + </legalnotice> + + <title>How to Implement an Alternative Service Discovery for Erlang Distribution + </title> + <prepared>Timmo Verlaan</prepared> + <responsible></responsible> + <docno></docno> + <approved></approved> + <checked></checked> + <date>2018-04-25</date> + <rev>PA1</rev> + <file>alt_disco.xml</file> + </header> + <p> + This section describes how to implement an alternative discovery mechanism + for Erlang distribution. Discovery is normally done using DNS and the + Erlang Port Mapper Daemon (EPMD) for port discovery. + </p> + + <note><p> + Support for alternative service discovery mechanisms was added in Erlang/OTP + 21. + </p></note> + + + <section> + <title>Introduction</title> + <p>To implement your own service discovery module you have to write your own + EPMD module. The <seealso marker="kernel:erl_epmd">EPMD module</seealso> is + responsible for providing the location of another node. The distribution + modules (<c>inet_tcp_dist</c>/<c>inet_tls_dist</c>) call the EPMD module to + get the IP address and port of the other node. The EPMD module that is part + of Erlang/OTP will resolve the hostname using DNS and uses the EPMD unix + process to get the port of another node. The EPMD unix process does this by + connecting to the other node on a well-known port, port 4369.</p> + </section> + + <section> + <title>Discovery module</title> + <p>The discovery module needs to implement the same API as the regular + <seealso marker="kernel:erl_epmd">EPMD module</seealso>. However, instead of + communicating with EPMD you can connect to any service to find out + connection details of other nodes. A discovery module is enabled + by setting <seealso marker="erts:erl#epmd_module">-epmd_module</seealso> + when starting erlang. The discovery module must implement the following + callbacks:</p> + + <taglist> + <tag><seealso marker="kernel:erl_epmd#start_link/0">start_link/0</seealso></tag> + <item>Start any processes needed by the discovery module.</item> + <tag><seealso marker="kernel:erl_epmd#names/1">names/1</seealso></tag> + <item>Return node names held by the registrar for the given host.</item> + <tag><seealso marker="kernel:erl_epmd#register_node/2">register_node/2</seealso></tag> + <item>Register the given node name with the registrar.</item> + <tag><seealso marker="kernel:erl_epmd#port_please/3">port_please/3</seealso></tag> + <item>Return the distribution port used by the given node.</item> + </taglist> + + <p>The discovery module may implement the following callback:</p> + + <taglist> + <tag><seealso marker="kernel:erl_epmd#address_please/3">address_please/3</seealso></tag> + <item><p>Return the address of the given node. + If not implemented, <seealso marker="kernel:inet#gethostbyname/1"> + inet:gethostbyname/1</seealso> will be used instead</p> + <p>This callback may also return the port of the given node. In that case + <seealso marker="kernel:erl_epmd#port_please/3">port_please/3</seealso> + may be omitted.</p></item> + </taglist> + </section> +</chapter> diff --git a/erts/doc/src/part.xml b/erts/doc/src/part.xml index d583b873a0..fc39cb30e6 100644 --- a/erts/doc/src/part.xml +++ b/erts/doc/src/part.xml @@ -37,6 +37,7 @@ <xi:include href="match_spec.xml"/> <xi:include href="crash_dump.xml"/> <xi:include href="alt_dist.xml"/> + <xi:include href="alt_disco.xml"/> <xi:include href="absform.xml"/> <xi:include href="tty.xml"/> <xi:include href="driver.xml"/> diff --git a/erts/emulator/test/distribution_SUITE.erl b/erts/emulator/test/distribution_SUITE.erl index e40d346e10..b8b84e91a0 100644 --- a/erts/emulator/test/distribution_SUITE.erl +++ b/erts/emulator/test/distribution_SUITE.erl @@ -73,7 +73,7 @@ dist_evil_parallel_receiver/0]). %% epmd_module exports --export([start_link/0, register_node/2, register_node/3, port_please/2]). +-export([start_link/0, register_node/2, register_node/3, port_please/2, address_please/3]). suite() -> [{ct_hooks,[ts_install_cth]}, @@ -2086,6 +2086,11 @@ port_please(_Name, _Ip) -> {port, Port, Version} end. +address_please(_Name, _Address, _AddressFamily) -> + %% Use localhost. + IP = {127,0,0,1}, + {ok, IP}. + %%% Utilities timestamp() -> |