Ruby HTTP client is not sophisticated enough to handle errors gracefully. I came across a well-designed client for a web service at [AppSignal].
(https://blog.appsignal.com/2018/05/16/ensure-retry-and-reraise-exceptions-in-ruby.html)
The code for the client is as following:
| require 'uri' | |
| require 'net/http' | |
| def get_server_connection(arg1, arg2) | |
| http = nil | |
| retries = 0 | |
| uri = URI("http://localhost:8089/") | |
| begin | |
| unless http | |
| puts "Opening TCP connection..." | |
| http = Net::HTTP.start(uri.host, uri.port, read_timeout: 5) | |
| end | |
| puts "Executing HTTP request..." | |
| res = http.request_get(uri.path) | |
| puts res.code, res.body | |
| return res | |
| rescue Errno::ECONNREFUSED, Net::ReadTimeout => e | |
| # timeout would throw ReadTimeout exception | |
| if (retries+=1) <= 3 | |
| puts "Timeout (#{e}), retrying in 1 second..." | |
| sleep(retries) # Sleep more with each failure | |
| retry # re-run the code!! | |
| else | |
| raise # All retries failed, raise the `last` seen exception | |
| end | |
| ensure | |
| if http | |
| puts "Closing the TCP connection..." | |
| http.finish | |
| end | |
| end | |
| end | |
| def handle_backend_response(arg1, arg2) | |
| res = get_server_connection(arg1, arg2) | |
| unless res.nil? # did we get a response? | |
| puts res.code, res.body | |
| if res.code == "200" | |
| return get_body_from_response(res.body) | |
| end | |
| if res.code == "404" | |
| # handle 404 as you wish | |
| return nil | |
| else | |
| puts "service unavailable" | |
| return nil | |
| end | |
| end | |
| end |
The code has the following logic:
- Try to establish a connection with the server.
- The request has a timeout and connection refused exceptions.
- If retries fail, code raise the last seen exception.
- Each retry has increased timeout.
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