gluetun/internal/provider/example/updater/api.go

package updater

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"net/http"
)

var errHTTPStatusCodeNotOK = errors.New("HTTP status code not OK")

type apiData struct {
	Servers []apiServer `json:"servers"`
}

type apiServer struct {
	OpenVPNHostname   string `json:"openvpn_hostname"`
	WireguardHostname string `json:"wireguard_hostname"`
	Country           string `json:"country"`
	Region            string `json:"region"`
	City              string `json:"city"`
	WgPubKey          string `json:"wg_public_key"`
}

func fetchAPI(ctx context.Context, client *http.Client) (
	data apiData, err error,
) {
	// TODO: adapt this URL and the structures above to match the real
	// API models you have.
	const url = "https://example.com/servers"

	request, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
	if err != nil {
		return data, err
	}

	response, err := client.Do(request)
	if err != nil {
		return data, err
	}

	if response.StatusCode != http.StatusOK {
		_ = response.Body.Close()
		return data, fmt.Errorf("%w: %d %s",
			errHTTPStatusCodeNotOK, response.StatusCode, response.Status)
	}

	decoder := json.NewDecoder(response.Body)
	if err := decoder.Decode(&data); err != nil {
		_ = response.Body.Close()
		return data, fmt.Errorf("decoding response body: %w", err)
	}

	if err := response.Body.Close(); err != nil {
		return data, fmt.Errorf("closing response body: %w", err)
	}

	return data, nil
}