Simplify Bundling of UI assets

CONTRIBUTING.md

@@ -76,12 +76,6 @@ the source code for the UI assets (requires Node.js 6+).
 The assets must be compiled first with `make build-ui`, which runs Node.js build and then
 packages the assets into a Go file that is `.gitignore`-ed.
 
-The packaged assets can be enabled by providing a build tag `ui`, for example:
-
-```
-$ go run -tags ui ./cmd/all-in-one/main.go
-```
-
 `make run-all-in-one` essentially runs Jaeger all-in-one by combining both of the above
 steps into a single `make` command.
 

Makefile

@@ -176,7 +176,7 @@ lint-go: $(LINT)
 
 .PHONY: run-all-in-one
 run-all-in-one: build-ui
-	go run -tags ui ./cmd/all-in-one --log-level debug
+	go run ./cmd/all-in-one --log-level debug
 
 .PHONY: changelog
 changelog:

Makefile.BuildBinaries.mk

@@ -74,13 +74,11 @@ _build-a-binary-%:
 
 .PHONY: build-jaeger
 build-jaeger: BIN_NAME = jaeger
-build-jaeger: GO_TAGS = -tags ui
 build-jaeger: BUILD_INFO = $(BUILD_INFO_V2)
 build-jaeger: build-ui _build-a-binary-jaeger$(SUFFIX)-$(GOOS)-$(GOARCH)
 
 .PHONY: build-all-in-one
 build-all-in-one: BIN_NAME = all-in-one
-build-all-in-one: GO_TAGS = -tags ui
 build-all-in-one: build-ui _build-a-binary-all-in-one$(SUFFIX)-$(GOOS)-$(GOARCH)
 
 .PHONY: build-agent
@@ -89,7 +87,6 @@ build-agent: _build-a-binary-agent$(SUFFIX)-$(GOOS)-$(GOARCH)
 
 .PHONY: build-query
 build-query: BIN_NAME = query
-build-query: GO_TAGS = -tags ui
 build-query: build-ui _build-a-binary-query$(SUFFIX)-$(GOOS)-$(GOARCH)
 
 .PHONY: build-collector

cmd/query/app/static_handler.go

@@ -76,7 +76,7 @@ type loadedConfig struct {
 
 // NewStaticAssetsHandler returns a StaticAssetsHandler
 func NewStaticAssetsHandler(staticAssetsRoot string, options StaticAssetsHandlerOptions) (*StaticAssetsHandler, error) {
-	assetsFS := ui.StaticFiles
+	assetsFS := ui.GetStaticFiles()
 	if staticAssetsRoot != "" {
 		assetsFS = http.Dir(staticAssetsRoot)
 	}

cmd/query/app/ui/assets.go

@@ -0,0 +1,29 @@
+// Copyright (c) 2024 The Jaeger Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+package ui
+
+import (
+	"embed"
+	"net/http"
+
+	"github.com/jaegertracing/jaeger/pkg/gzipfs"
+	"github.com/jaegertracing/jaeger/pkg/httpfs"
+)
+
+//go:embed actual/*
+var actualAssetsFS embed.FS
+
+//go:embed placeholder/index.html
+var placeholderAssetsFS embed.FS
+
+// GetStaticFiles gets the static assets that the Jaeger UI will serve. If the actual
+// assets are available, then this function will return them. Otherwise, a
+// non-functional index.html is returned to be used as a placeholder.
+func GetStaticFiles() http.FileSystem {
+	if _, err := actualAssetsFS.ReadFile("actual/index.html.gz"); err != nil {
+		return httpfs.PrefixedFS("placeholder", http.FS(placeholderAssetsFS))
+	}
+
+	return httpfs.PrefixedFS("actual", http.FS(gzipfs.New(actualAssetsFS)))
+}

cmd/query/app/ui/doc.go

@@ -2,7 +2,7 @@
 // SPDX-License-Identifier: Apache-2.0
 
 // Package ui bundles UI assets packaged with stdlib/embed.
-// By default it imports the placeholder, non-functional index.html.
-// When building with "-tags ui", it imports the real UI assets
-// generated in build-ui Makefile target.
+// If the real UI assets are available, they are used in the
+// build-ui Makefile target. Otherwise, the non-functional
+// index.html is used.
 package ui

cmd/query/app/ui/placeholder/index.html

@@ -7,7 +7,7 @@
         <h1>🥋: This is not the Jaeger UI you are looking for!</h1>
         <p>
             This is a placeholder for the Jaeger UI home page.
-            If you are seeing this, you are running a binary that was not compiled with the UI assets (<code>-tags ui</code>).
+            If you are seeing this, you are running a binary that was not compiled with the UI assets.
             See <a href="https://github.com/jaegertracing/jaeger/blob/main/CONTRIBUTING.md#running-local-build-with-the-ui">these instructions</a>.
         </p>
         <h1>UI configuration</h1>