From 11ed58c24190a4bb98334c803984ac648dc0c139 Mon Sep 17 00:00:00 2001
From: Christian Sunesson <christian.sunesson@kivra.com>
Date: Tue, 5 Oct 2021 10:40:14 +0200
Subject: [PATCH 1/3] extract meta merge function

---
 src/jsonformat.erl | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/jsonformat.erl b/src/jsonformat.erl
index 8994544..472a5c7 100644
--- a/src/jsonformat.erl
+++ b/src/jsonformat.erl
@@ -43,7 +43,7 @@ format(#{msg:={report, #{format:=Format, args:=Args, label:={error_logger, _}}}}
   Report = #{text => io_lib:format(Format, Args)},
   format(Map#{msg := {report, Report}}, Config);
 format(#{level:=Level, msg:={report, Msg}, meta:=Meta}, Config) when is_map(Msg) ->
-  Data0 = maps:merge(Msg, Meta#{level => Level}),
+  Data0 = merge_meta(Msg, Meta#{level => Level}, Config),
   Data1 = apply_key_mapping(Data0, Config),
   Data2 = apply_format_funs(Data1, Config),
   encode(pre_encode(Data2, Config), Config);
@@ -75,6 +75,9 @@ pre_encode(Data, Config) ->
     maps:new(),
     Data).
 
+merge_meta(Msg, Meta, _Config) ->
+  maps:merge(Msg, Meta).
+
 encode(Data, Config) ->
   Json = jsx:encode(Data),
   case new_line(Config) of

From 356476a149fcac8fe867c8010684a5947d12f498 Mon Sep 17 00:00:00 2001
From: Christian Sunesson <christian.sunesson@kivra.com>
Date: Tue, 5 Oct 2021 11:29:56 +0200
Subject: [PATCH 2/3] feat: config to opt in/out from meta fields

---
 src/jsonformat.erl | 47 ++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 45 insertions(+), 2 deletions(-)

diff --git a/src/jsonformat.erl b/src/jsonformat.erl
index 472a5c7..a444206 100644
--- a/src/jsonformat.erl
+++ b/src/jsonformat.erl
@@ -75,8 +75,10 @@ pre_encode(Data, Config) ->
     maps:new(),
     Data).
 
-merge_meta(Msg, Meta, _Config) ->
-  maps:merge(Msg, Meta).
+merge_meta(Msg, Meta0, Config) ->
+  Meta1 = meta_without(Meta0, Config),
+  Meta2 = meta_with(Meta1, Config),
+  maps:merge(Msg, Meta2).
 
 encode(Data, Config) ->
   Json = jsx:encode(Data),
@@ -124,6 +126,15 @@ apply_key_mapping(Data, _) ->
 
 new_line(Config) -> maps:get(new_line, Config, ?NEW_LINE).
 
+meta_without(Meta, Config) ->
+    maps:without(maps:get(meta_without, Config, [report_cb]), Meta).
+
+meta_with(Meta, #{ meta_with := Ks}) ->
+    maps:with(Ks, Meta);
+meta_with(Meta, _ConfigNotPresent) ->
+    Meta.
+
+
 %%%_* Tests ============================================================
 -ifdef(TEST).
 -include_lib("eunit/include/eunit.hrl").
@@ -174,6 +185,38 @@ list_format_test() ->
     ?assertEqual( <<"{\"level\":\"error\",\"report\":\"[{hej,\\\"hopp\\\"}]\",\"time\":1}">>
                 , format(ErrorReport, #{})).
 
+meta_without_test() ->
+    Error = #{ level => info
+             , msg => {report, #{answer => 42}}
+             , meta => #{secret => xyz}},
+    ?assertEqual([ {<<"answer">>, 42}
+                 , {<<"level">>, <<"info">>}
+                 , {<<"secret">>, <<"xyz">>}
+                 ],
+        jsx:decode(format(Error, #{}))),
+    Config2 = #{ meta_without => [secret]},
+    ?assertEqual([ {<<"answer">>, 42}
+                 , {<<"level">>, <<"info">>}
+                 ],
+        jsx:decode(format(Error, Config2))),
+    ok.
+
+meta_with_test() ->
+    Error = #{ level => info
+             , msg => {report, #{answer => 42}}
+             , meta => #{secret => xyz}},
+    ?assertEqual([ {<<"answer">>, 42}
+                 , {<<"level">>, <<"info">>}
+                 , {<<"secret">>, <<"xyz">>}
+                 ],
+        jsx:decode(format(Error, #{}))),
+    Config2 = #{ meta_with => [level]},
+    ?assertEqual([ {<<"answer">>, 42}
+                 , {<<"level">>, <<"info">>}
+                 ],
+        jsx:decode(format(Error, Config2))),
+    ok.
+
 -endif.
 
 %%%_* Emacs ============================================================

From 4b230c42737d5af83a61f5b6290bd06cbe775c05 Mon Sep 17 00:00:00 2001
From: Christian Sunesson <christian.sunesson@kivra.com>
Date: Wed, 6 Oct 2021 10:14:20 +0200
Subject: [PATCH 3/3] add README doc

---
 README.md | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/README.md b/README.md
index 48e0c70..8eaec57 100644
--- a/README.md
+++ b/README.md
@@ -39,6 +39,15 @@ To print each json object to a new line, set `new_line` to `true`:
 #{formatter => {jsonformat, #{ new_line => true }}}
 ```
 
+To control what is being included in the log object from the metadata, there
+are two ways. One can opt-out from fields. Default opts out is `[report_cb]`.
+
+    #{ meta_without => [report_cb, gl, file, domain] }
+
+Or for very detailed control there is instead opt-in.
+
+    #{ meta_with => [time, mfa, line, user_key, client_key] }
+
 To rename keys in the resulting json object, provide a `key_mapping`. For
 example, to rename the `time` and `level` keys to `timestamp` and `lvl`
 respectively, use: