Growth spike: Get latest MM version (#19366)

* tools updates

* Revert "tools updates"

This reverts commit 6293297b55803c5a263e200ebd80192899666ae9.

* new endpoint to fetch the latest release information

* adding unit tests

* fixing tests and adding check for github response

* error translations

* fixing translations

* chaning error log

* changing cache size

* empty strings for translations

* changing size to 1

Co-authored-by: Benjamin Cooke <benjamincooke@Benjamins-MacBook-Pro.local>
Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

app/admin.go

@@ -4,6 +4,7 @@
 package app
 
 import (
+	"encoding/json"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -14,11 +15,16 @@ import (
 
 	"github.com/mattermost/mattermost-server/v6/config"
 	"github.com/mattermost/mattermost-server/v6/model"
+	"github.com/mattermost/mattermost-server/v6/services/cache"
 	"github.com/mattermost/mattermost-server/v6/shared/i18n"
 	"github.com/mattermost/mattermost-server/v6/shared/mail"
 	"github.com/mattermost/mattermost-server/v6/shared/mlog"
 )
 
+var latestVersionCache = cache.NewLRU(cache.LRUOptions{
+	Size: 1,
+})
+
 func (s *Server) GetLogs(page, perPage int) ([]string, *model.AppError) {
 	var lines []string
 
@@ -241,3 +247,43 @@ func (s *Server) serverBusyStateChanged(sbs *model.ServerBusyState) {
 		mlog.Info("server busy state cleared via cluster event - non-critical services enabled")
 	}
 }
+
+func (a *App) GetLatestVersion(latestVersionUrl string) (*model.GithubReleaseInfo, *model.AppError) {
+	var cachedLatestVersion *model.GithubReleaseInfo
+	if cacheErr := latestVersionCache.Get("latest_version_cache", &cachedLatestVersion); cacheErr == nil {
+		return cachedLatestVersion, nil
+	}
+
+	res, err := http.Get(latestVersionUrl)
+	if err != nil {
+		return nil, model.NewAppError("GetLatestVersion", "app.admin.latest_version_external_error.failure", nil, "", http.StatusInternalServerError)
+	}
+
+	defer res.Body.Close()
+
+	responseData, err := ioutil.ReadAll(res.Body)
+	if err != nil {
+		return nil, model.NewAppError("GetLatestVersion", "app.admin.latest_version_read_all.failure", nil, "", http.StatusInternalServerError)
+	}
+
+	var releaseInfoResponse *model.GithubReleaseInfo
+	err = json.Unmarshal(responseData, &releaseInfoResponse)
+	if err != nil {
+		return nil, model.NewAppError("GetLatestVersion", "app.admin.latest_version_unmarshal.failure", nil, "", http.StatusInternalServerError)
+	}
+
+	if validErr := releaseInfoResponse.IsValid(); validErr != nil {
+		return nil, model.NewAppError("GetLatestVersion", "app.admin.latest_version_external_error.failure", nil, "", http.StatusInternalServerError)
+	}
+
+	err = latestVersionCache.Set("latest_version_cache", releaseInfoResponse)
+	if err != nil {
+		return nil, model.NewAppError("GetLatestVersion", "app.admin.latest_version_set_cache.failure", nil, "", http.StatusInternalServerError)
+	}
+
+	return releaseInfoResponse, nil
+}
+
+func (a *App) ClearLatestVersionCache() {
+	latestVersionCache.Remove("latest_version_cache")
+}