image/resources/netapp-exports/volumes.go

/*
 Copyright 2022 Google LLC

 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
 You may obtain a copy of the License at

      https://www.apache.org/licenses/LICENSE-2.0

 Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
*/

package main

import (
	"encoding/json"
	"fmt"
	"net/http"
	"net/url"
)

type API struct {
	Client   *http.Client
	BaseURL  string
	User     string
	Password string
}

type VolumePathList struct {
	Paths    []string
	NextPage string
}

func resolveURL(base string, ref string) (string, error) {
	baseURL, err := url.Parse(base)
	if err != nil {
		return "", err
	}

	refURL, err := url.Parse(ref)
	if err != nil {
		return "", err
	}

	return baseURL.ResolveReference(refURL).String(), nil
}

func (api *API) FetchPage() (result VolumePathList, err error) {
	url, err := resolveURL(api.BaseURL, "storage/volumes?nas.path=!null&fields=nas.path&max_records=100")
	if err != nil {
		return
	}
	result, err = api.FetchNextPage(url)
	return
}

func (api *API) FetchNextPage(url string) (result VolumePathList, err error) {
	if url == "" {
		err = fmt.Errorf("url not specified")
		return
	}

	req, err := http.NewRequest(http.MethodGet, url, nil)
	if err != nil {
		return
	}
	req.SetBasicAuth(api.User, api.Password)

	response, err := api.Client.Do(req)
	if err != nil {
		return
	}
	defer response.Body.Close()

	if response.StatusCode != http.StatusOK {
		err = fmt.Errorf("get %s: server responded with %d", url, response.StatusCode)
		return
	}

	var raw struct {
		Records []struct {
			Nas struct {
				Path string
			}
		}
		Links struct {
			Next struct {
				Href string
			}
		} `json:"_links"`
	}

	decoder := json.NewDecoder(response.Body)
	err = decoder.Decode(&raw)
	if err != nil {
		return
	}

	if raw.Records != nil {
		result.Paths = make([]string, 0, len(raw.Records))
		for _, r := range raw.Records {
			path := r.Nas.Path
			if path != "" {
				result.Paths = append(result.Paths, path)
			}
		}
	}

	nextPage := raw.Links.Next.Href
	if nextPage != "" {
		nextPage, err = resolveURL(url, nextPage)
	}
	result.NextPage = nextPage

	return
}

func (api *API) FetchAll() (paths []string, err error) {
	page, err := api.FetchPage()
	for {
		paths = append(paths, page.Paths...)
		if err != nil {
			return
		}
		if page.NextPage == "" {
			return
		}
		page, err = api.FetchNextPage(page.NextPage)
	}
}