First working version with devise+rails_admin

Gemfile.lock

@@ -86,6 +86,8 @@ GEM
       responders
       warden (~> 1.2.3)
     erubi (1.9.0)
+    faraday (1.0.1)
+      multipart-post (>= 1.2, < 3)
     ffi (1.13.1)
     ffi (1.13.1-x64-mingw32)
     globalid (0.4.2)
@@ -93,6 +95,7 @@ GEM
     haml (5.1.2)
       temple (>= 0.8.0)
       tilt
+    hashie (4.1.0)
     i18n (1.8.5)
       concurrent-ruby (~> 1.0)
     jbuilder (2.10.0)
@@ -103,6 +106,7 @@ GEM
       thor (>= 0.14, < 2.0)
     jquery-ui-rails (6.0.1)
       railties (>= 3.2.16)
+    jwt (2.2.2)
     kaminari (1.2.1)
       activesupport (>= 4.1.0)
       kaminari-actionview (= 1.2.1)
@@ -132,12 +136,39 @@ GEM
     minitest (5.14.1)
     msgpack (1.3.3)
     msgpack (1.3.3-x64-mingw32)
+    multi_json (1.15.0)
+    multi_xml (0.6.0)
+    multipart-post (2.1.1)
     nested_form (0.3.2)
     nio4r (2.5.2)
     nokogiri (1.10.10)
       mini_portile2 (~> 2.4.0)
     nokogiri (1.10.10-x64-mingw32)
       mini_portile2 (~> 2.4.0)
+    oauth2 (1.4.4)
+      faraday (>= 0.8, < 2.0)
+      jwt (>= 1.0, < 3.0)
+      multi_json (~> 1.3)
+      multi_xml (~> 0.5)
+      rack (>= 1.2, < 3)
+    omniauth (1.9.1)
+      hashie (>= 3.4.6)
+      rack (>= 1.6.2, < 3)
+    omniauth-facebook (6.0.0)
+      omniauth-oauth2 (~> 1.2)
+    omniauth-github (1.4.0)
+      omniauth (~> 1.5)
+      omniauth-oauth2 (>= 1.4.0, < 2.0)
+    omniauth-google-oauth2 (0.8.0)
+      jwt (>= 2.0)
+      omniauth (>= 1.1.1)
+      omniauth-oauth2 (>= 1.6)
+    omniauth-oauth2 (1.7.0)
+      oauth2 (~> 1.4)
+      omniauth (~> 1.9)
+    omniauth-openid (1.0.1)
+      omniauth (~> 1.0)
+      rack-openid (~> 1.3.1)
     orm_adapter (0.5.0)
     pg (1.2.3)
     pg (1.2.3-x64-mingw32)
@@ -145,6 +176,9 @@ GEM
     puma (4.3.5)
       nio4r (~> 2.0)
     rack (2.2.3)
+    rack-openid (1.3.1)
+      rack (>= 1.1.0)
+      ruby-openid (>= 2.1.8)
     rack-pjax (1.1.0)
       nokogiri (~> 1.5)
       rack (>= 1.1)
@@ -199,6 +233,7 @@ GEM
     responders (3.0.1)
       actionpack (>= 5.0)
       railties (>= 5.0)
+    ruby-openid (2.9.2)
     rubyzip (2.3.0)
     sass-rails (6.0.0)
       sassc-rails (~> 2.1, >= 2.1.1)
@@ -270,6 +305,10 @@ DEPENDENCIES
   devise (~> 4.7)
   jbuilder (~> 2.7)
   listen (~> 3.2)
+  omniauth-facebook
+  omniauth-github
+  omniauth-google-oauth2
+  omniauth-openid
   pg (>= 0.18, < 2.0)
   puma (~> 4.1)
   rails (~> 6.0.3, >= 6.0.3.2)