GVAT

German vat id validator

Introduction

GVAT is a REST service for validating the German VAT ID numbers against the EU/VIES online database. These can be found in .env file in the project root.

Configuration

all application configurations are provided as environment variables.

Variable	Description	Default
SERVER_PORT	Server port	8080
EU_VIES_BASE_URL	eu/vies service base url	none
EU_VIES_TIMEOUT	eu/vies service call timeout (ms)	5000
EU_VIES_MAX_RETRIES	maximum number of retries per call	2
POOL_MAX_WORKERS	concurrenct number of eu/vies calls	10
POOL_QUEUE_SIZE	buffer size for eu/vies requests	1000
POOL_WORKER_BUFFER	worker buffer size for eu/vies calls	10
SERVER_READ_TIMEOUT	server read timeout milli (ms)	10000
SERVER_WRITE_TIMEOUT	server write timeout milli (ms)	10000

How to build and run

Using go build

On Linux

• make sure go 1.17.1 or above is installed
• clone the repository using git

git clone https://github.com/wishperera/GVAT.git

• enter the root directory and run the following command.

cd GVAT
sh cmd/build_and_run.sh

On other operating systems

• make sure go 1.17.1 or above is installed
• clone the repository using git
• set the GOOS and GOARCH env variables
• edit .env and source the env config to environment or manullay set them.

go build -o gvat
./gvat

Using docker

• make sure the latest version of docker is installed
• clone the repository using git

git clone https://github.com/wishperera/GVAT.git

• enable the docker containers to reach external networks as follows

sudo sysctl net.ipv4.conf.all.forwarding=1
sudo iptables -P FORWARD ACCEPT

• enter the root directory and run the following command. Edit the .env file if you need to change the configurations

cd GVAT
sh cmd/docker_build_and_run.sh

• verify the container is running

docker ps

• if everyting goes smooth you should see something like below

Verification of functionality

Use the following curl call to verify the functionality.

curl --location --request GET 'http://localhost:{PORT}/validate/DE129357125' \
--header 'trace-id: a27c776a-341e-11ec-8d3d-0242ac130000'

NOTE : replace the {PORT} field with the value you configured for SERVICE_PORT

default example:

curl --location --request GET 'http://localhost:8080/validate/{VAT_ID}' \
--header 'trace-id: a27c776a-341e-11ec-8d3d-0242ac130000'

NOTE : replace the {VAT_ID} with a valid vat id

if your VAT id is valid you should receive a response similar to below

{
    "vatId": "DE129357125",
    "valid": true
}

The full API reference can be found here. Postman collection can be found here.

Room for improvement

• use exponential backoff while calling the eu/vies api
• integrate metrics