Add relx configuration for an hypothetic 3.10.0 Erlang release

In rabbitmq-defaults, compute $SYS_PREFIX when started from an Erlang
release. The behavior is the same as in a generic-unix package: data &
log dirs will be derived from the release root directory.

8 files changed, 110 insertions, 17 deletions

diff --git a/.gitignore b/.gitignore
index f71d98b114..05e7a03339 100644
--- a/.gitignore
+++ b/.gitignore
@@ -61,6 +61,7 @@ erl_crash.dump
 .envrc
 *.plt
 *.lock
+_rel
 
 /topic-branch-scratch/
 
diff --git a/Makefile b/Makefile
index 13139bb496..9fb9def5c8 100644
--- a/Makefile
+++ b/Makefile
@@ -29,6 +29,9 @@ DEP_PLUGINS = rabbit_common/mk/rabbitmq-dist.mk \
 
 DISABLE_DISTCLEAN = 1
 
+# Newer version of relx(1) with fixes in the extended start script.
+RELX_URL := https://storage.googleapis.com/rmq/erlang-releases/relx-v3.29.0
+
 # FIXME: Use erlang.mk patched for RabbitMQ, while waiting for PRs to be
 # reviewed and merged.
 
diff --git a/deps/rabbit/scripts/rabbitmq-defaults b/deps/rabbit/scripts/rabbitmq-defaults
index 41d72c7da4..7ba61db428 100755
--- a/deps/rabbit/scripts/rabbitmq-defaults
+++ b/deps/rabbit/scripts/rabbitmq-defaults
@@ -7,7 +7,12 @@
 ##
 
 ### next line potentially updated in package install steps
-SYS_PREFIX=
+if test -f "$RABBITMQ_HOME/bin/RabbitMQ"; then
+    SYS_PREFIX=$RABBITMQ_HOME/$RABBITMQ_NODENAME
+else
+    SYS_PREFIX=
+fi
+export SYS_PREFIX
 
 CLEAN_BOOT_FILE=start_clean
 SASL_BOOT_FILE=start_sasl
diff --git a/deps/rabbit/src/rabbit_feature_flags.erl b/deps/rabbit/src/rabbit_feature_flags.erl
index 66e9dd49eb..d8e03cb581 100644
--- a/deps/rabbit/src/rabbit_feature_flags.erl
+++ b/deps/rabbit/src/rabbit_feature_flags.erl
@@ -1480,9 +1480,9 @@ try_to_write_enabled_feature_flags_list(FeatureNames) ->
 %% @returns the path to the file.
 
 enabled_feature_flags_list_file() ->
-    case application:get_env(rabbit, feature_flags_file) of
-        {ok, Val} -> Val;
-        undefined -> throw(feature_flags_file_not_set)
+    case rabbit_prelaunch:get_context() of
+        #{feature_flags_file := File} -> File;
+        _                             -> throw(feature_flags_file_not_set)
     end.
 
 %% -------------------------------------------------------------------
@@ -2232,9 +2232,10 @@ get_forced_feature_flag_names_from_env() ->
 %% @private
 
 get_forced_feature_flag_names_from_config() ->
-    Value = application:get_env(rabbit,
-                                forced_feature_flags_on_init,
-                                undefined),
+    Value = maps:get(
+              forced_feature_flags_on_init,
+              rabbit_prelaunch:get_context(),
+              undefined),
     case Value of
         undefined ->
             Value;
@@ -2441,12 +2442,13 @@ on_load() ->
             %% application environment variable is defined. With a
             %% feature-flags-enabled node, this application environment
             %% variable is defined by rabbitmq-server(8).
-            case application:get_env(rabbit, feature_flags_file) of
-                {ok, _} ->
-                    %% This is a feature-flags-enabled version. Loading
-                    %% the module is permitted.
-                    ok;
-                _ ->
+            try
+                _ = enabled_feature_flags_list_file(),
+                %% This is a feature-flags-enabled version. Loading
+                %% the module is permitted.
+                ok
+            catch
+                _:_:_ ->
                     %% This is a pre-feature-flags version. We deny the
                     %% load and report why, possibly specifying the
                     %% version of RabbitMQ.
diff --git a/deps/rabbit/src/rabbit_plugins.erl b/deps/rabbit/src/rabbit_plugins.erl
index a631f07884..37868df584 100644
--- a/deps/rabbit/src/rabbit_plugins.erl
+++ b/deps/rabbit/src/rabbit_plugins.erl
@@ -90,9 +90,9 @@ plugins_dir() ->
 
 -spec enabled_plugins_file() -> file:filename().
 enabled_plugins_file() ->
-     case application:get_env(rabbit, enabled_plugins_file) of
-        {ok, Val} ->
-            Val;
+    case rabbit_prelaunch:get_context() of
+        #{enabled_plugins_file := File} ->
+            File;
         _ ->
             filename:join([rabbit_mnesia:dir(), "enabled_plugins"])
     end.
diff --git a/deps/rabbitmq_management_agent/src/rabbit_mgmt_external_stats.erl b/deps/rabbitmq_management_agent/src/rabbit_mgmt_external_stats.erl
index 6f3846de61..3fb5f7a54d 100644
--- a/deps/rabbitmq_management_agent/src/rabbit_mgmt_external_stats.erl
+++ b/deps/rabbitmq_management_agent/src/rabbit_mgmt_external_stats.erl
@@ -289,7 +289,7 @@ i(net_ticktime, State) ->
 i(persister_stats, State) ->
     {State, persister_stats(State)};
 i(enabled_plugins, State) ->
-    {ok, Dir} = application:get_env(rabbit, enabled_plugins_file),
+    Dir = rabbit_plugins:enabled_plugins_file(),
     {State, rabbit_plugins:read_enabled(Dir)};
 i(auth_mechanisms, State) ->
     {ok, Mechanisms} = application:get_env(rabbit, auth_mechanisms),
diff --git a/relx.config b/relx.config
new file mode 100644
index 0000000000..bc28f6294d
--- /dev/null
+++ b/relx.config
@@ -0,0 +1,37 @@
+%% vim:ft=erlang:
+{release,
+ {"RabbitMQ", "3.10.0"},
+ [{mnesia, none},
+
+  rabbit,
+
+  {amqp_client, none},
+  {rabbitmq_management_agent, none},
+  {rabbitmq_web_dispatch, none},
+  {rabbitmq_management, none},
+
+  {prometheus, none},
+  {rabbitmq_prometheus, none},
+
+  {rabbitmq_stream_common, none},
+  {rabbitmq_stream, none},
+  {rabbitmq_stream_management, none},
+  {rabbitmq_top, none}]}.
+
+{extended_start_script, true}.
+
+{vm_args, "./vm.args.src"}.
+
+{overlay, [{copy, "escript", "escript"},
+           {copy, "sbin/rabbitmq-defaults", "bin"},
+           {copy, "sbin/rabbitmq-env", "bin"},
+           {copy, "sbin/rabbitmq-plugins", "bin"},
+           {copy, "sbin/rabbitmq-diagnostics", "bin"},
+           {copy, "sbin/rabbitmq-queues", "bin"},
+           {copy, "sbin/rabbitmq-streams", "bin"},
+           {copy, "sbin/rabbitmq-upgrade", "bin"},
+           {copy, "sbin/rabbitmqctl", "bin"},
+           {mkdir, "etc"},
+           {mkdir, "etc/rabbitmq"}]}.
+
+{extended_start_script_hooks, [{pre_start, [{custom, "rabbitmq-env"}]}]}.
diff --git a/vm.args.src b/vm.args.src
new file mode 100644
index 0000000000..37f9b486a3
--- /dev/null
+++ b/vm.args.src
@@ -0,0 +1,45 @@
+## Name of the node
+-sname rabbit
+
+## Cookie for distributed erlang
+#-setcookie rabbit
+
+## Heartbeat management; auto-restarts VM if it dies or becomes unresponsive
+## (Disabled by default..use with caution!)
+##-heart
+
+## Enable kernel poll and a few async threads
+##+K true
+##+A 5
+
+## Increase number of concurrent ports/sockets
+##-env ERL_MAX_PORTS 4096
+
+## Tweak GC to run more often
+##-env ERL_FULLSWEEP_AFTER 10
+
+# +B [c | d | i]
+# Option c makes Ctrl-C interrupt the current shell instead of invoking the emulator break
+# handler. Option d (same as specifying +B without an extra option) disables the break handler. # Option i makes the emulator ignore any break signal.
+# If option c is used with oldshell on Unix, Ctrl-C will restart the shell process rather than
+# interrupt it.
+# Disable the emulator break handler
+# it easy to accidentally type ctrl-c when trying
+# to reach for ctrl-d. ctrl-c on a live node can
+# have very undesirable results
++Bi
+
++W w
+
+-syslog logger []
+-syslog syslog_error_logger false
+
+-env ERL_MAX_ETS_TABLES 50000
+
++P 1048576
++t 5000000
++stbt db
++zdbbl 128000
++sbwt none
++sbwtdcpu none
++sbwtdio none