Add mod_libcluster

mod_libcluster/README.md

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+mod_libcluster - Join nodes into cluster
+========================================
+
+Requires:
+- ejabberd 24.xx or higher compiled with Elixir support
+
+
+This small module connects this ejabberd node to other nodes
+using [libcluster](https://github.com/bitwalker/libcluster).
+
+Options
+-------
+
+This module supports several configurable options.
+There are some example configuration files in the `test/` directory.
+Options supported by this module:
+
+* `strategy`
+
+  Sets the clustering strategy to use.
+
+  Supported values are:
+  - `local_epmd`: connect to all nodes managed by the local epmd program
+  - `epmd`: connect to the nodes you specify in the `config: hosts` option
+  - `kubernetes`
+
+  Default value: `local_epmd`.
+
+* `hosts`
+
+  List of erlang node names to connect.
+  This is required, and only useful, when using the `epmd` strategy.
+  Default value: `[]`.
+
+* `timeut`
+
+  Timeout to connect to a node, expressed in milliseconds.
+  This is only useful when using the `epmd` strategy.
+  Default value: `infinity`.
+
+For details of options supported please check the
+[libcluster documentation](https://hexdocs.pm/libcluster).
+
+Test
+----
+
+There's a test script in `test/test.sh` that you can run.
+It compiles ejabberd, installs in `/tmp/` several nodes,
+and builds a cluster using the desired strategy.

mod_libcluster/conf/mod_libcluster.yml

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+#modules:
+#  'ModLibcluster':
+
+    # Connect with any other local node
+    #strategy: local_epmd
+
+    # Connect only to those specific nodes
+    #strategy: epmd
+    #config:
+    #  hosts:
+    #    - [email protected]
+    #    - [email protected]
+    #    - [email protected]
+
+    #strategy: kubernetes
+    #config:
+    #  mode: hostname
+    #  kubernetes_ip_lookup_mode: pods
+    #  kubernetes_namespace: "ejabberd"
+    #  kubernetes_selector: "app=ejabberd"
+    #  kubernetes_node_basename: "ejabberd"
+    #  kubernetes_service_name: "ejabberd-headless"
+    #  polling_interval: 10000
+

mod_libcluster/lib/mod_libcluster.ex

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+defmodule ModLibcluster do
+  use Ejabberd.Module
+
+  def start(_host, opts) do
+
+    strategy = case opts[:strategy] do
+      :local_epmd ->
+        :"Elixir.Cluster.Strategy.LocalEpmd"
+      :epmd ->
+        :"Elixir.Cluster.Strategy.Epmd"
+      :kubernetes ->
+        :"Elixir.Cluster.Strategy.Kubernetes"
+      other_strategy ->
+        other_strategy
+    end
+    info("Starting ejabberd module Libcluster with stategy #{inspect(strategy)}")
+
+    config = [
+      hosts: opts[:hosts],
+      timeout: opts[:timeout]
+    ]
+    info("Starting ejabberd module Libcluster with config #{inspect(config)}")
+
+    topologies = [
+      ejabberd_cluster: [
+        strategy: strategy,
+        config: config,
+        connect: {:ejabberd_admin, :join_cluster, []},
+        disconnect: {:ejabberd_admin, :leave_cluster, []}
+      ]
+    ]
+    children = [
+      {Cluster.Supervisor, [topologies, [name: Ejabberd.ClusterSupervisor]]},
+    ]
+    Supervisor.start_link(children, strategy: :one_for_one, name: Ejabberd.Supervisor)
+    info("Started ejabberd module Libcluster Demo")
+    :ok
+  end
+
+  def stop(_host) do
+    info("Stopping ejabberd module Libcluster Demo")
+    :ok
+  end
+
+  def depends(_host, _opts) do
+    []
+  end
+
+  def mod_opt_type(:hosts) do
+    :econf.list(:econf.atom)
+  end
+
+  def mod_opt_type(:strategy) do
+    :econf.atom
+  end
+
+  def mod_opt_type(:timeout) do
+    :econf.either(:infinity, :econf.int());
+  end
+
+  def mod_options(_host) do
+    [
+     {:hosts, []},
+     {:strategy, :local_epmd},
+     {:timeout, :infinity}
+    ]
+  end
+
+  def mod_doc() do
+    %{:desc => "This is just an empty string."}
+  end
+
+end

mod_libcluster/mod_libcluster.spec

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+author: "Badlop <badlop at process-one.net>"
+category: "cluster"
+summary: "Join nodes into cluster"
+home: "https://github.com/processone/ejabberd-contrib/tree/master/"
+url: "[email protected]:processone/ejabberd-contrib.git"

mod_libcluster/rebar.config

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+{deps, [
+        {jason, "1.5.0-alpha.2", {git, "https://github.com/michalmuskala/jason", {branch, "master"}}},
+        {libcluster, "3.3.3", {git, "https://github.com/bitwalker/libcluster", {branch, "main"}}}
+       ]}.

mod_libcluster/test/epmd.yml

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+modules:
+  'ModLibcluster':
+    # Connect only to those specific nodes
+    strategy: epmd
+    timeout: 5000
+    hosts:
+      - [email protected]
+      - [email protected]
+      - [email protected]

mod_libcluster/test/local_epmd.yml

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+modules:
+  'ModLibcluster':
+    # Connect with any other local node
+    strategy: local_epmd

mod_libcluster/test/test.sh

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+#!/bin/bash
+
+COLOUR="\e[1;49;33m"
+NEUTRAL="\033[00m"
+
+log() {
+    echo ""
+    echo -e $COLOUR"==> $1"$NEUTRAL
+}
+
+MOD=$(pwd)
+
+TOOL=$1
+STR=$2
+SRC=$3
+if [ -n "$TOOL" ] && [ -n "$STR" ] && [ -n "$SRC" ] ; then
+    log "Using tool: $TOOL"
+    log "Using strategy: $STR"
+    log "Using ejabberd source code from: $SRC"
+else
+    echo "Usage: $0 <tool> <strategy> <path>"
+    echo "  <tool> = mix | rebar3"
+    echo "  <strategy> = local_epmd | epmd"
+    echo "  <path> = path to the ejabberd source code"
+    echo "For example: $0 mix local_epmd /home/user1/git/ejabberd/"
+    exit 1
+fi
+
+cd "$SRC" || exit 1
+
+log "Compile ejabberd release..."
+
+compile() {
+    ./autogen.sh
+    ./configure \
+        --with-rebar=$TOOL \
+        --enable-all
+    make
+    rm _build/prod/*.tar.gz
+    make rel
+}
+
+compile
+
+log "Preparing ejabberd nodes..."
+
+case "$TOOL" in
+    mix)
+        echo "Setting up 'mix' tool..."
+        FILE=$(ls -1 _build/prod/*.tar.gz)
+        ;;
+    rebar3)
+        echo "Setting up 'rebar3' tool..."
+        FILE=$(ls -1 _build/prod/rel/ejabberd/*.tar.gz)
+        ;;
+esac
+
+create_node() {
+    N=$1
+    log "Preparing node $N using file $FILE..."
+    rm -rf /tmp/libcluster/"$N"
+    mkdir -p /tmp/libcluster/"$N"
+    tar -xzf "$FILE" -C /tmp/libcluster/"$N"
+    sed -i "s|#' POLL|EJABBERD_BYPASS_WARNINGS=true\n\n#' POLL|g" /tmp/libcluster/"$N"/conf/ejabberdctl.cfg
+    sed -i "s|#ERLANG_NODE=.*|ERLANG_NODE=ejabberd$N@127.0.0.1|" /tmp/libcluster/"$N"/conf/ejabberdctl.cfg
+    sed -i "s| port: \([0-9]*\)| port: \1$N|g" /tmp/libcluster/"$N"/conf/ejabberd.yml
+    sed -i "s|mod_proxy65:|mod_proxy65:\n    port: 777$N|" /tmp/libcluster/"$N"/conf/ejabberd.yml
+    node[N]=/tmp/libcluster/"$N"/bin/ejabberdctl
+}
+
+create_node 1
+create_node 2
+create_node 3
+
+FIRST=${node[1]}
+SECOND=${node[2]}
+THIRD=${node[3]}
+
+log "Let's start the first node..."
+
+echo "first: $FIRST"
+$FIRST start
+$FIRST started
+$FIRST set_master self
+
+log "Uninstall and install mod_libcluster:"
+
+$FIRST module_uninstall mod_libcluster
+rm -rf $MOD/deps/
+rm -rf $MOD/ebin/
+$FIRST module_install mod_libcluster || exit 1
+
+log "Configure mod_libcluster:"
+
+case "$STR" in
+    local_epmd)
+        echo "Setting up 'local_epmd' config..."
+        cp "$MOD"/test/local_epmd.yml \
+           "$HOME"/.ejabberd-modules/mod_libcluster/conf/mod_libcluster.yml
+        ;;
+    epmd)
+        echo "Setting up 'epmd' config..."
+        cp "$MOD"/test/epmd.yml \
+           "$HOME"/.ejabberd-modules/mod_libcluster/conf/mod_libcluster.yml
+        ;;
+esac
+
+log "Initial cluster of first node (should be just this node):"
+
+$FIRST list_cluster
+
+log "Let's start the second node, it should connect automatically to the first node..."
+
+$SECOND start
+$SECOND started
+sleep 5 # wait a few seconds to let the second node join the cluster properly
+$SECOND set_master [email protected]
+
+log "Let's start the third node, it should connect automatically to the first node..."
+
+$THIRD start
+$THIRD started
+sleep 5 # wait a few seconds to let the second node join the cluster properly
+
+log "Cluster as seen by first node:"
+
+$FIRST list_cluster
+
+log "Cluster as seen by second node:"
+
+$SECOND list_cluster
+
+log "Cluster as seen by third node:"
+
+$THIRD list_cluster
+
+log "Stop first node, and check cluster as seen by second node:"
+
+$FIRST stop
+$FIRST stopped
+$SECOND list_cluster
+
+log "... as seen by third node:"
+
+$THIRD list_cluster
+
+log "Start again first node, and check cluster as seen by all the nodes:"
+
+$FIRST start
+$FIRST started
+sleep 5
+echo "First: "
+$FIRST list_cluster
+echo "Second: "
+$SECOND list_cluster
+echo "Third: "
+$THIRD list_cluster
+
+log "Stopping all nodes..."
+
+$FIRST stop
+$SECOND stop
+$THIRD stop