faas

README

timeaway

version v0.7.8 : 18 March 2025 (fix svg calendar sizing)

A small web app to calculate if the compound length of trips to Schengen countries by non-EU visitors conform with Regulation (EU) No 610/2013 limiting the total length of stays to no more than 90 days in any 180 day window.

See the example gif.

You can find out more about the 90 in 180 day rule on the GOV.UK Travelling to the EU and Schengen area web page.

Run It

Run the provided web app after cloning the repo:

~/src/go-timeaway$ go run cmd/main.go
> 2025/03/10 19:38:31 serving on 127.0.0.1:8000

And then visit http://127.0.0.1:8000 in your browser. See the example gif below.

The url parameters each time a calculation is made, allowing calculations to be conveniently saved or bookmarked.

Calculation

The trips go module provides the means for calculation.

The calculation method uses a 180 day moving window to calculate the longest compound trip length (daysAway). Where more than one window has the same daysAway the window with the earliest start date is reported.

API

The /trips POST endpoint can be interacted with over json. This command:

curl -s -X POST -d '
[{"Start":"2022-12-01","End":"2022-12-02"},
 {"Start":"2023-01-02","End":"2023-03-30"},
 {"Start":"2023-04-01","End":"2023-04-02"},
 {"Start":"2023-09-03","End":"2023-09-12"}
]' 127.0.0.1:8000/trips | jq .

gives the following output, assuming the server is running on 127.0.0.1:8000/:

{
  "start": "2022-12-01T00:00:00Z",
  "end": "2023-05-29T00:00:00Z",
  "daysAway": 92,
  "overlaps": 3,
  "holidays": [
    {
      "start": "2022-12-01T00:00:00Z", "end": "2022-12-02T00:00:00Z", "duration": 2,
      "overlap": {"start": "2022-12-01T00:00:00Z", "end": "2022-12-02T00:00:00Z", "duration": 2}
    },
    {
      "start": "2023-01-02T00:00:00Z", "end": "2023-03-30T00:00:00Z", "duration": 88,
      "overlap": {"start": "2023-01-02T00:00:00Z", "end": "2023-03-30T00:00:00Z", "duration": 88}
    },
    {
      "start": "2023-04-01T00:00:00Z", "end": "2023-04-02T00:00:00Z", "duration": 2,
      "overlap": {"start": "2023-04-01T00:00:00Z", "end": "2023-04-02T00:00:00Z", "duration": 2}
    },
    {
      "start": "2023-09-03T00:00:00Z", "end": "2023-09-12T00:00:00Z", "duration": 10
    }
  ],
  "error": null,
  "breach": true
}

Note that the last holiday has no overlap with the longest window of 2022-12-01 to 2023-05-29.

Info

This app has also turned into a github actions/workflows experiment inspired by the book "Shipping Go" by Joel Holmes, and trying out htmx and hyperscript. These experiments partly accounts for the large number of commits and releases in this repo!

Example

Licence

This project is licensed under the MIT Licence.

Documentation

Overview

faas is an entry point for GCP serverless function, which cheekily supports other urls too

Index

• func GCPServer(w http.ResponseWriter, r *http.Request)

Functions

func GCPServer

func GCPServer(w http.ResponseWriter, r *http.Request)

GCPServer is the entry point for a FAAS application as set out in section 4.5 of Joel Holmes' "Shipping Go". The idea for multiple endpoints is discussed at https://medium.com/google-cloud/hack-use-cloud-functions-as-a-webserver-with-golang-42edc7935247