milestone 8: web server, rest api, sse, auth, metrics and static assets

build.zig

@@ -21,6 +21,14 @@ pub fn build(b: *std.Build) void {
     const fuzz = b.option(bool, "fuzz", "Build the fuzz targets with the LLVM backend (required for --fuzz)") orelse false;
     const version_string = b.option([]const u8, "version-string", "Version reported by `nxdns version`") orelse "0.1.0-dev";
     const git_commit = b.option([]const u8, "git-commit", "Git commit reported by `nxdns version`") orelse "unknown";
+    const web_dist = b.option([]const u8, "web-dist", "Built web UI directory to embed (default: the placeholder page)") orelse "web/dist-placeholder";
+
+    // `b.path` panics on absolute paths, and a CI artifact directory is one.
+    const web_dist_path: std.Build.LazyPath = if (std.fs.path.isAbsolute(web_dist))
+        .{ .cwd_relative = web_dist }
+    else
+        b.path(web_dist);
+    const web_assets = webAssetsIndex(b, web_dist_path);
 
     const options = b.addOptions();
     options.addOption(bool, "integration", integration);
@@ -29,7 +37,7 @@ pub fn build(b: *std.Build) void {
     options.addOption([]const u8, "git_commit", git_commit);
     options.addOption([]const u8, "zig_version_string", builtin.zig_version_string);
 
-    const exe = addExecutable(b, target, optimize, options);
+    const exe = addExecutable(b, target, optimize, options, web_assets);
     b.installArtifact(exe);
 
     const run = b.addRunArtifact(exe);
@@ -53,6 +61,7 @@ pub fn build(b: *std.Build) void {
     tests.root_module.addAnonymousImport("test_fixtures", .{
         .root_source_file = b.path("tests/fixtures/fixtures.zig"),
     });
+    tests.root_module.addAnonymousImport("web_assets", .{ .root_source_file = web_assets });
     const test_step = b.step("test", "Run the test suite");
     test_step.dependOn(&b.addRunArtifact(tests).step);
 
@@ -102,7 +111,7 @@ pub fn build(b: *std.Build) void {
         const query = std.Target.Query.parse(.{ .arch_os_abi = triple }) catch |err| {
             std.debug.panic("invalid cross target '{s}': {t}", .{ triple, err });
         };
-        const cross_exe = addExecutable(b, b.resolveTargetQuery(query), optimize, options);
+        const cross_exe = addExecutable(b, b.resolveTargetQuery(query), optimize, options, web_assets);
         cross_exe.linkage = .static;
         const install = b.addInstallArtifact(cross_exe, .{
             .dest_dir = .{ .override = .{ .custom = b.fmt("cross/{s}", .{triple}) } },
@@ -116,6 +125,7 @@ fn addExecutable(
     target: std.Build.ResolvedTarget,
     optimize: std.builtin.OptimizeMode,
     options: *std.Build.Step.Options,
+    web_assets: std.Build.LazyPath,
 ) *std.Build.Step.Compile {
     const exe = b.addExecutable(.{
         .name = "nxdns",
@@ -127,11 +137,43 @@ fn addExecutable(
         }),
     });
     exe.root_module.addOptions("build_options", options);
+    exe.root_module.addAnonymousImport("web_assets", .{ .root_source_file = web_assets });
     exe.root_module.linkLibrary(sqliteLibrary(b, target, optimize));
     exe.root_module.linkLibrary(mbedtlsLibrary(b, target, optimize));
     return exe;
 }
 
+/// The embedded web UI (milestone-8 ruling 24): the dist directory plus the
+/// generated `assets.zig` index and build-time gzip siblings, merged into one
+/// WriteFiles directory so every `@embedFile` path resolves inside the module
+/// root. Returns the index file, the root of the `web_assets` module.
+///
+/// The dist is staged through its own WriteFiles step before it reaches the
+/// tool because a Run step hashes only the resolved path string of a directory
+/// argument, not its contents; the staged copy lives at a content-hashed path,
+/// so editing an asset re-runs the tool instead of replaying a stale cache.
+fn webAssetsIndex(b: *std.Build, dist: std.Build.LazyPath) std.Build.LazyPath {
+    const staged = b.addWriteFiles().addCopyDirectory(dist, ".", .{});
+
+    const tool = b.addExecutable(.{
+        .name = "gen_web_assets",
+        .root_module = b.createModule(.{
+            .root_source_file = b.path("tools/gen_web_assets.zig"),
+            .target = b.graph.host,
+            .optimize = .ReleaseSafe,
+        }),
+    });
+
+    const run = b.addRunArtifact(tool);
+    run.addDirectoryArg(staged);
+    const generated = run.addOutputDirectoryArg("web_assets");
+
+    const merged = b.addWriteFiles();
+    _ = merged.addCopyDirectory(staged, ".", .{});
+    _ = merged.addCopyDirectory(generated, ".", .{});
+    return merged.getDirectory().path(b, "assets.zig");
+}
+
 /// SQLite 3.53.4 amalgamation (see build.zig.zon for the pinned URL and hash).
 fn sqliteLibrary(
     b: *std.Build,