global: split Akvorado into 3 services

console/root.go

@@ -0,0 +1,122 @@
+// Package console exposes a web interface.
+package console
+
+import (
+	"fmt"
+	"html/template"
+	"io/fs"
+	"log"
+	netHTTP "net/http"
+	"net/http/httputil"
+	"net/url"
+	"os"
+	"path"
+	"path/filepath"
+	"runtime"
+	"sync"
+
+	"github.com/rs/zerolog"
+	"gopkg.in/tomb.v2"
+
+	"akvorado/common/daemon"
+	"akvorado/common/http"
+	"akvorado/common/reporter"
+)
+
+// Component represents the console component.
+type Component struct {
+	r      *reporter.Reporter
+	d      *Dependencies
+	t      tomb.Tomb
+	config Configuration
+
+	templates     map[string]*template.Template
+	templatesLock sync.RWMutex
+}
+
+// Dependencies define the dependencies of the console component.
+type Dependencies struct {
+	Daemon daemon.Component
+	HTTP   *http.Component
+}
+
+// New creates a new console component.
+func New(reporter *reporter.Reporter, config Configuration, dependencies Dependencies) (*Component, error) {
+	c := Component{
+		r:      reporter,
+		d:      &dependencies,
+		config: config,
+	}
+	c.d.Daemon.Track(&c.t, "console")
+	if err := c.loadTemplates(); err != nil {
+		return nil, err
+	}
+
+	// Grafana proxy
+	if c.config.GrafanaURL != "" {
+		// Provide a proxy for Grafana
+		url, err := url.Parse(config.GrafanaURL)
+		if err != nil {
+			return nil, fmt.Errorf("unable to parse Grafana URL %q: %w", config.GrafanaURL, err)
+		}
+		proxy := httputil.NewSingleHostReverseProxy(url)
+		proxy.Transport = &netHTTP.Transport{
+			Proxy: nil, // Disable proxy
+		}
+		proxy.ErrorLog = log.New(c.r.With().
+			Str("proxy", "grafana").
+			Str("level", zerolog.LevelWarnValue).
+			Logger(), "", 0)
+		proxyHandler := netHTTP.HandlerFunc(
+			func(w netHTTP.ResponseWriter, r *netHTTP.Request) {
+				proxy.ServeHTTP(w, r)
+			})
+		c.d.HTTP.AddHandler("/grafana/", proxyHandler)
+	}
+
+	c.d.HTTP.AddHandler("/docs/", netHTTP.HandlerFunc(c.docsHandlerFunc))
+	c.d.HTTP.AddHandler("/assets/", netHTTP.HandlerFunc(c.assetsHandlerFunc))
+
+	return &c, nil
+}
+
+// Start starts the web component.
+func (c *Component) Start() error {
+	c.r.Info().Msg("starting console component")
+	if err := c.watchTemplates(); err != nil {
+		return err
+	}
+	c.t.Go(func() error {
+		select {
+		case <-c.t.Dying():
+			return nil
+		}
+	})
+	return nil
+}
+
+// Stop stops the console component.
+func (c *Component) Stop() error {
+	c.r.Info().Msg("stopping console component")
+	defer c.r.Info().Msg("console component stopped")
+	c.t.Kill(nil)
+	return c.t.Wait()
+}
+
+// embedOrLiveFS returns a subset of the provided embedded filesystem,
+// except if the component is configured to use the live filesystem.
+// Then, it returns the provided tree.
+func (c *Component) embedOrLiveFS(embed fs.FS, p string) fs.FS {
+	var fileSystem fs.FS
+	if c.config.ServeLiveFS {
+		_, src, _, _ := runtime.Caller(0)
+		fileSystem = os.DirFS(filepath.Join(path.Dir(src), p))
+	} else {
+		var err error
+		fileSystem, err = fs.Sub(embed, p)
+		if err != nil {
+			panic(err)
+		}
+	}
+	return fileSystem
+}