Backend image rendering as plugin (#11966)

* rendering: headless chrome progress

* renderer: minor change

* grpc: version hell

* updated grpc libs

* wip: minor progess

* rendering: new image rendering plugin is starting to work

* feat: now phantomjs works as well and updated alerting to use new rendering service

* refactor: renamed renderer package and service to rendering to make renderer name less confusing (rendering is internal service that handles the renderer plugin now)

* rendering: now render key is passed and render auth is working in plugin mode

* removed unneeded lines from gitignore

* rendering: now plugin mode supports waiting for all panels to complete rendering

* fix: LastSeenAt fix for render calls, was not set which causes a lot of updates to Last Seen at during rendering, this should fix sqlite db locked issues in seen in previous releases

* change: changed render tz url parameter to use proper timezone name as chrome does not handle UTC offset TZ values

* fix: another update to tz param generation

* renderer: added http mode to renderer service, new ini setting [rendering] server_url

pkg/services/rendering/rendering.go

@@ -0,0 +1,99 @@
+package rendering
+
+import (
+	"context"
+	"fmt"
+	"path/filepath"
+
+	plugin "github.com/hashicorp/go-plugin"
+
+	pluginModel "github.com/grafana/grafana-plugin-model/go/renderer"
+	"github.com/grafana/grafana/pkg/log"
+	"github.com/grafana/grafana/pkg/middleware"
+	"github.com/grafana/grafana/pkg/models"
+	"github.com/grafana/grafana/pkg/plugins"
+	"github.com/grafana/grafana/pkg/registry"
+	"github.com/grafana/grafana/pkg/setting"
+	"github.com/grafana/grafana/pkg/util"
+)
+
+func init() {
+	registry.RegisterService(&RenderingService{})
+}
+
+type RenderingService struct {
+	log          log.Logger
+	pluginClient *plugin.Client
+	grpcPlugin   pluginModel.RendererPlugin
+	pluginInfo   *plugins.RendererPlugin
+	renderAction renderFunc
+
+	Cfg *setting.Cfg `inject:""`
+}
+
+func (rs *RenderingService) Init() error {
+	rs.log = log.New("rendering")
+	return nil
+}
+
+func (rs *RenderingService) Run(ctx context.Context) error {
+	if rs.Cfg.RendererUrl != "" {
+		rs.log.Info("Backend rendering via external http server")
+		rs.renderAction = rs.renderViaHttp
+		<-ctx.Done()
+		return nil
+	}
+
+	if plugins.Renderer == nil {
+		rs.renderAction = rs.renderViaPhantomJS
+		<-ctx.Done()
+		return nil
+	}
+
+	rs.pluginInfo = plugins.Renderer
+
+	if err := rs.startPlugin(ctx); err != nil {
+		return err
+	}
+
+	rs.renderAction = rs.renderViaPlugin
+
+	err := rs.watchAndRestartPlugin(ctx)
+
+	if rs.pluginClient != nil {
+		rs.log.Debug("Killing renderer plugin process")
+		rs.pluginClient.Kill()
+	}
+
+	return err
+}
+
+func (rs *RenderingService) Render(ctx context.Context, opts Opts) (*RenderResult, error) {
+	if rs.renderAction != nil {
+		return rs.renderAction(ctx, opts)
+	} else {
+		return nil, fmt.Errorf("No renderer found")
+	}
+}
+
+func (rs *RenderingService) getFilePathForNewImage() string {
+	pngPath, _ := filepath.Abs(filepath.Join(rs.Cfg.ImagesDir, util.GetRandomString(20)))
+	return pngPath + ".png"
+}
+
+func (rs *RenderingService) getURL(path string) string {
+	// &render=1 signals to the legacy redirect layer to
+	return fmt.Sprintf("%s://%s:%s/%s&render=1", setting.Protocol, rs.getLocalDomain(), setting.HttpPort, path)
+}
+
+func (rs *RenderingService) getLocalDomain() string {
+	if setting.HttpAddr != setting.DEFAULT_HTTP_ADDR {
+		return setting.HttpAddr
+	}
+
+	return "localhost"
+}
+
+func (rs *RenderingService) getRenderKey(orgId, userId int64, orgRole models.RoleType) string {
+	return middleware.AddRenderAuthKey(orgId, userId, orgRole)
+}