Add 'generate-upgrade' command

To support OTP release upgrades I have added support for building
upgrade packages. Support for this is included in the
rebar_upgrade module, specifically generate_upgrade/2. It requires
one variable to be set on the command line 'previous_release' which
is the absolute path or relative path from 'rel/' to the previous
release one is upgrading from. Running an upgrade will create the
needed files, including a relup and result in a tarball containing
the upgrade being written to 'rel/'. When done it cleans up the
temporary files systools created.

Usage:
$ rebar generate-upgrade previous_release=/path/to/old/version

This also includes a dummy application that can be used to test
upgrades as well as an example.

Special thanks to Daniel Reverri, Jesper Louis Andersen and
Richard Jones for comments and patches.

1 files changed, 116 insertions, 0 deletions

diff --git a/test/upgrade_project/rel/files/nodetool b/test/upgrade_project/rel/files/nodetool
new file mode 100755
index 0000000..cb524ce
--- /dev/null
+++ b/test/upgrade_project/rel/files/nodetool
@@ -0,0 +1,116 @@
+%% -*- mode:erlang;tab-width:4;erlang-indent-level:4;indent-tabs-mode:nil -*-
+%% ex: ft=erlang ts=4 sw=4 et
+%% -------------------------------------------------------------------
+%%
+%% nodetool: Helper Script for interacting with live nodes
+%%
+%% -------------------------------------------------------------------
+
+main(Args) ->
+    %% Extract the args
+    {RestArgs, TargetNode} = process_args(Args, [], undefined),
+
+    %% See if the node is currently running  -- if it's not, we'll bail
+    case {net_kernel:hidden_connect_node(TargetNode), net_adm:ping(TargetNode)} of
+        {true, pong} ->
+            ok;
+        {_, pang} ->
+            io:format("Node ~p not responding to pings.\n", [TargetNode]),
+            halt(1)
+    end,
+
+    case RestArgs of
+        ["ping"] ->
+            %% If we got this far, the node already responsed to a ping, so just dump
+            %% a "pong"
+            io:format("pong\n");
+        ["stop"] ->
+            io:format("~p\n", [rpc:call(TargetNode, init, stop, [], 60000)]);
+        ["restart"] ->
+            io:format("~p\n", [rpc:call(TargetNode, init, restart, [], 60000)]);
+        ["reboot"] ->
+            io:format("~p\n", [rpc:call(TargetNode, init, reboot, [], 60000)]);
+        ["rpc", Module, Function | RpcArgs] ->
+            case rpc:call(TargetNode, list_to_atom(Module), list_to_atom(Function),
+                          [RpcArgs], 60000) of
+                ok ->
+                    ok;
+                {badrpc, Reason} ->
+                    io:format("RPC to ~p failed: ~p\n", [TargetNode, Reason]),
+                    halt(1);
+                _ ->
+                    halt(1)
+            end;
+        ["rpcterms", Module, Function, ArgsAsString] ->
+            case rpc:call(TargetNode, list_to_atom(Module), list_to_atom(Function),
+                          consult(ArgsAsString), 60000) of
+                {badrpc, Reason} ->
+                    io:format("RPC to ~p failed: ~p\n", [TargetNode, Reason]),
+                    halt(1);
+                Other ->
+                    io:format("~p\n", [Other])
+            end;
+        Other ->
+            io:format("Other: ~p\n", [Other]),
+            io:format("Usage: nodetool {ping|stop|restart|reboot}\n")
+    end,
+    net_kernel:stop().
+
+process_args([], Acc, TargetNode) ->
+    {lists:reverse(Acc), TargetNode};
+process_args(["-setcookie", Cookie | Rest], Acc, TargetNode) ->
+    erlang:set_cookie(node(), list_to_atom(Cookie)),
+    process_args(Rest, Acc, TargetNode);
+process_args(["-name", TargetName | Rest], Acc, _) ->
+    ThisNode = append_node_suffix(TargetName, "_maint_"),
+    {ok, _} = net_kernel:start([ThisNode, longnames]),
+    process_args(Rest, Acc, nodename(TargetName));
+process_args(["-sname", TargetName | Rest], Acc, _) ->
+    ThisNode = append_node_suffix(TargetName, "_maint_"),
+    {ok, _} = net_kernel:start([ThisNode, shortnames]),
+    process_args(Rest, Acc, nodename(TargetName));
+process_args([Arg | Rest], Acc, Opts) ->
+    process_args(Rest, [Arg | Acc], Opts).
+
+
+nodename(Name) ->
+    case string:tokens(Name, "@") of
+        [_Node, _Host] ->
+            list_to_atom(Name);
+        [Node] ->
+            [_, Host] = string:tokens(atom_to_list(node()), "@"),
+            list_to_atom(lists:concat([Node, "@", Host]))
+    end.
+
+append_node_suffix(Name, Suffix) ->
+    case string:tokens(Name, "@") of
+        [Node, Host] ->
+            list_to_atom(lists:concat([Node, Suffix, os:getpid(), "@", Host]));
+        [Node] ->
+            list_to_atom(lists:concat([Node, Suffix, os:getpid()]))
+    end.
+
+
+%%
+%% Given a string or binary, parse it into a list of terms, ala file:consult/0
+%%
+consult(Str) when is_list(Str) ->
+    consult([], Str, []);
+consult(Bin) when is_binary(Bin)->
+    consult([], binary_to_list(Bin), []).
+
+consult(Cont, Str, Acc) ->
+    case erl_scan:tokens(Cont, Str, 0) of
+        {done, Result, Remaining} ->
+            case Result of
+                {ok, Tokens, _} ->
+                    {ok, Term} = erl_parse:parse_term(Tokens),
+                    consult([], Remaining, [Term | Acc]);
+                {eof, _Other} ->
+                    lists:reverse(Acc);
+                {error, Info, _} ->
+                    {error, Info}
+            end;
+        {more, Cont1} ->
+            consult(Cont1, eof, Acc)
+    end.