I have an Exception notifier set up in my rails application. So today I got the second notification, that the index template is missing:
An ActionView::MissingTemplate occurred in products#index:
Missing template products/index, application/index with {:locale=>[:en, :de], :formats=>["text/html;text/plain"], :variants=>[], :handlers=>[:erb, :builder, :raw, :ruby, :coffee, :slim, :arb, :jbuilder]}. Searched in:
* "/home/releases/20160518143810/app/views"
-------------------------------
Request:
-------------------------------
* URL : http://example.com/shop
* HTTP Method: GET
* IP address : xx.xx.xx.xx
* Parameters : {"controller"=>"products", "action"=>"index"}
* Timestamp : 2016-06-07 08:19:13 +0200
* Server : vintage-shop.ch
* Rails root : /home/releases/20160518143810
* Process: 15714
I know for a fact, that the product's index template is there on the server and checked in in VCS and the application has been running for month now. So I really wonder, why this can happen:
$ ls /home/releases/20160518143810/app/views/products/index.html.slim
# -> /home/releases/20160518143810/app/views/products/index.html.slim
How is this exception possible?
Update: I looked up the IP Address and it is not from the region where I would expect my customers to be from. So I am wondering if this is some sort of attack, but then the question still remains how an exception can be triggered, even though the template is present.
It might be an attack attempt or (more probably I guess) some random noise. The problem seems to be in the format that Rails parsed out from the request headers. Normally, you should see something like: :formats=>[:html, :text, :js, :css, :ics] in the exception message.
The format is generally determined in rails using the request URI (usually everything after a dot '.' is considered a format specification) or using the Accept header. In your case it is the header I guess (you should be able to see the header in the exception notification). The Accept header should contain comma-separated content types, not semicolon-separated, so I guess this is the actual source of the exception.
Take a look at this very insightful blog post if you want more details about Rails format resolution.