Review comments

[kfigiela]

• Command parsing

vcr-proxy/src/Network/VCR.hs

Line 29 in 1251545

[mode, endpoint, filePath, port] -> run (read mode) endpoint filePath (read port)

Several notes:

• I'd go for optparse-applicative instead manual pattern matching.

• endpoint argument is not used for replaying at all, confusing

• Pokemon exception handling?
  

  vcr-proxy/src/Network/VCR.hs

  Line 46 in 1251545

  . Warp.setOnException (\ _ _ -> return ())

  
  Maybe at least print exception to the console?

• Use 502 as default error handler (minor)
  

  vcr-proxy/src/Network/VCR.hs

  Line 51 in 1251545

  defaultExceptionResponse e =

  
  

  vcr-proxy/src/Network/VCR/Middleware.hs

  Line 86 in 1251545

  respond $ Wai.responseLBS HT.status500

• Endpoint not stored in the casette
  

  vcr-proxy/src/Network/VCR/Types.hs

  Line 39 in 1251545

  data Cassette = Cassette

  
  I'd add it for future reference.

• UTF-8 handling
  Not sure if this will be a problem in practice, but AFARI there is no standard that tells that urls have to be UTF-8 encoded. Perhaps we should operate on ByteStrings?
  

  vcr-proxy/src/Network/VCR/Middleware.hs

  Line 104 in 1251545

  modifyPath = TE.encodeUtf8 . T.append scheme . T.append "://" . T.append (TE.decodeUtf8 host) . TE.decodeUtf8

• Executable name
  

  vcr-proxy/package.yaml

  Line 48 in 1251545

  vcr-proxy-exe:

  
  Perhaps we could just call it vcr-proxy?

[kozak]

UTF-8 Handling

While in this particular place (ie. modifyPath) this makes total sense, I am not sure what to do about storage in the cassette yaml file.
Maybe I am misunderstanding but if we don't know the encoding apriori, then the only safe way of encoding the URL (and also headers, query, body etc) would be to treat them as binary, which would result in a unreadable cassette file.
I would be in favour of leaving the rest of the code as is for the moment and fixing the problem if we run into it. (The most probable first occurrence of the problem would be with a binary request body or response).

[kozak]

Stuff left todo (from slack):

• Clients using the proxy will need to wait for the proxy process to start

• we could add a test endpoint so that the client can poll to see if proxy is up
• output something to stdout when the proxy has started

• Env variables

Kamil had the idea to use environment variables to switch the mode to Record, so it could be used in tests like:
VCR_MODE=Record stack test --ta "-m dotpay"

[kfigiela]

which would result in a unreadable cassette file

Hmm… welcome to world of encoding or escaping stuff. We can leave this for now if it works. Did you check what happens if we get gzipped response?