Add trident-acp api client

This commit adds a new API client to enable proprietary workflows in Trident.

acp/client.go

@@ -0,0 +1,144 @@
+// Copyright 2023 NetApp, Inc. All Rights Reserved.
+
+package acp
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"time"
+
+	"github.com/netapp/trident/utils/version"
+)
+
+// Client is a concrete reference for interfacing directly with ACP REST APIs.
+type Client struct {
+	baseURL    string
+	httpClient http.Client
+}
+
+// NewAPI accepts a base URL and timeout and returns a reference for interfacing directly with trident-acp REST APIs.
+func NewAPI(baseURL string, timeout time.Duration) (*Client, error) {
+	if _, err := url.Parse(baseURL); baseURL == "" || err != nil {
+		return nil, fmt.Errorf("invalid URL [%s] specified for trident-acp API client; %v", baseURL, err)
+	} else if timeout < 1 {
+		return nil, fmt.Errorf("invalid timeout [%v] specified for trident-acp API client", timeout)
+	}
+
+	return &Client{
+		baseURL:    baseURL,
+		httpClient: http.Client{Timeout: timeout},
+	}, nil
+}
+
+type getVersionResponse struct {
+	Version string `json:"version"`
+	Error   string `json:"error,omitempty"`
+}
+
+// GetVersion gets the installed ACP version.
+// Example: http://<host>:<port>/trident-acp/v1/version
+func (c *Client) GetVersion(ctx context.Context) (*version.Version, error) {
+	// Create a new HTTP request.
+	url := c.baseURL + versionEndpoint
+	req, err := c.newRequest(ctx, http.MethodGet, url, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	// Assign headers.
+	req.Header.Set("User-Agent", userAgent())
+
+	// Make the request.
+	res, data, err := c.invokeAPI(req)
+	if err != nil {
+		return nil, err
+	} else if res.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("non-ok status code: [%v]; status %v", res.StatusCode, res.Status)
+	}
+
+	// Parse the response data into a struct.
+	var versionResponse getVersionResponse
+	if err := json.Unmarshal(data, &versionResponse); err != nil {
+		return nil, fmt.Errorf("failed to unmarshal response body; %v", err)
+	} else if versionResponse.Error != "" {
+		return nil, fmt.Errorf("failed to get trident-acp version; %v", err)
+	}
+
+	return version.ParseDate(versionResponse.Version)
+}
+
+// Entitled accepts a feature and makes a request to ACP APIs to check if the supplied feature in Trident is allowed.
+// Example: http://<host>:<port>/trident-acp/v1/entitled?feature=<feature>
+func (c *Client) Entitled(ctx context.Context, feature string) (bool, error) {
+	// Create a new HTTP request.
+	url := c.baseURL + entitledEndpoint
+	req, err := c.newRequest(ctx, http.MethodGet, url, nil)
+	if err != nil {
+		return false, nil
+	}
+
+	// Assign headers.
+	req.Header.Set("User-Agent", userAgent())
+
+	// Add or Set query parameters.
+	params := req.URL.Query()
+	params.Set("feature", feature)
+	req.URL.RawQuery = params.Encode()
+
+	// Make the request.
+	// TODO: Inspect the response body when the Entitled API changes.
+	res, _, err := c.invokeAPI(req)
+	if err != nil {
+		return false, err
+	} else if res.StatusCode != http.StatusOK {
+		return false, fmt.Errorf("non-OK status code: [%v]; status %v", res.StatusCode, res.Status)
+	}
+
+	return true, nil
+}
+
+// newRequest accepts necessary fields to construct a new http request.
+// It returns a new http request or an error if one occurs.
+func (c *Client) newRequest(ctx context.Context, method, url string, data []byte) (*http.Request, error) {
+	// Ideally, the context should never be empty. If it is, set it to the default value used in new requests.
+	if ctx == nil {
+		ctx = context.Background()
+	}
+
+	// Construct a new http request.
+	var body io.Reader
+	if data != nil {
+		body = bytes.NewBuffer(data)
+	}
+
+	req, err := http.NewRequestWithContext(ctx, method, url, body)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create new request: [%s, %s]; %v", method, url, err)
+	}
+
+	return req, nil
+}
+
+// invokeAPI accepts a http request, makes the request, and parses the response.
+// It returns the http response, the response body or an error if one occurs.
+func (c *Client) invokeAPI(req *http.Request) (*http.Response, []byte, error) {
+	// Make the request.
+	res, err := c.httpClient.Do(req)
+	if err != nil {
+		return nil, nil, fmt.Errorf("error making request: [%s]; %v", req.URL.String(), err)
+	}
+	defer func() { _ = res.Body.Close() }()
+
+	// Read the response body.
+	data, err := io.ReadAll(res.Body)
+	if err != nil {
+		return res, nil, fmt.Errorf("failed to parse response body; %v", err)
+	}
+
+	return res, data, nil
+}