MM-17023: Plugin Marketplace (#12183)

* MM-17149 - Extend config.json for marketplace settings (#11933)

* MM-17149 - Extend config.json for marketplace settings

* Renamed MarketplaceUrl, tracking default marketplace url

* Added EnableMarketplace to the client config

* Revert "Added EnableMarketplace to the client config"

This reverts commit 0f982c4c661c2cd9bb96264e9a01a2363c40d9c5.

* MM-17149 - Added EnableMarketplace to the client config (#11958)

* Added EnableMarketplace to the client config

* Moved EnableMarketplace setting out of limited client configuration

* MM-17150, MM-17545, MM-18100 - Implement GET /api/v4/plugins/m… (#11977)

* MM-17150 - Implement GET /api/v4/plugins/marketplace proxying upstream
MM-17545 - Merge locally installed plugins into GET /api/v4/plugins/marketplace

* Replaced MarketplacePluginState with Installed

* Setting InstalledVersion instead of Installed

* marketplace client setting per_page if non zero

* Creating insecure client for marketplace url

* Fixed trailing slash for default marketplace url

* Adding filtering

* Fixed function names

* Renamed Manifest() to GetManifest(), added godoc for BaseMarketplacePlugin

* Handling plugin.ErrNotFound correctly

* Checking err == nil instead when a plugin is installed

* MM-18450 - Local-only plugin search (#12152)

* MM-17846: plugin icons (#12157)

* MM-17846: add support for plugin icons

Extend the model definitions to support plugin icons from the marketplace.

* s/IconURL/IconData

* MM-18475 - Converge on snake_case responses from the marketplace (#12179)

* MM-18520 - MM-Server should forward server version to marketplace server (#12181)

* Renamed request to filter client4.GetMarketplacePlugins

* Renamed request to filter

* Guarding against bad marketplace server response

services/marketplace/client.go

@@ -0,0 +1,79 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See License.txt for license information.
+
+package marketplace
+
+import (
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"net/url"
+
+	"github.com/mattermost/mattermost-server/model"
+	"github.com/mattermost/mattermost-server/services/httpservice"
+	"github.com/pkg/errors"
+)
+
+// Client is the programmatic interface to the marketplace server API.
+type Client struct {
+	address    string
+	httpClient *http.Client
+}
+
+// NewClient creates a client to the marketplace server at the given address.
+func NewClient(address string, httpService httpservice.HTTPService) (*Client, error) {
+	var httpClient *http.Client
+	addressUrl, err := url.Parse(address)
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to parse marketplace address")
+	}
+	if addressUrl.Hostname() == "localhost" || addressUrl.Hostname() == "127.0.0.1" {
+		httpClient = httpService.MakeClient(true)
+	} else {
+		httpClient = httpService.MakeClient(false)
+	}
+
+	return &Client{
+		address:    address,
+		httpClient: httpClient,
+	}, nil
+}
+
+// GetPlugins fetches the list of plugins from the configured server.
+func (c *Client) GetPlugins(request *model.MarketplacePluginFilter) ([]*model.BaseMarketplacePlugin, error) {
+	u, err := url.Parse(c.buildURL("/api/v1/plugins"))
+	if err != nil {
+		return nil, err
+	}
+
+	request.ApplyToURL(u)
+
+	resp, err := c.doGet(u.String())
+	if err != nil {
+		return nil, err
+	}
+	defer closeBody(resp)
+
+	switch resp.StatusCode {
+	case http.StatusOK:
+		return model.BaseMarketplacePluginsFromReader(resp.Body)
+	default:
+		return nil, errors.Errorf("failed with status code %d", resp.StatusCode)
+	}
+}
+
+// closeBody ensures the Body of an http.Response is properly closed.
+func closeBody(r *http.Response) {
+	if r.Body != nil {
+		_, _ = ioutil.ReadAll(r.Body)
+		_ = r.Body.Close()
+	}
+}
+
+func (c *Client) buildURL(urlPath string, args ...interface{}) string {
+	return fmt.Sprintf("%s%s", c.address, fmt.Sprintf(urlPath, args...))
+}
+
+func (c *Client) doGet(u string) (*http.Response, error) {
+	return c.httpClient.Get(u)
+}