feat(builtin): support for substitutions

Author: thesayyn

internal/pkg_web/BUILD.bazel

@@ -21,7 +21,10 @@ filegroup(
 
 nodejs_binary(
     name = "assembler",
-    data = ["assembler.js"],
+    data = [
+        "assembler.js",
+        "//third_party/github.com/gjtorikian/isBinaryFile",
+    ],
     entry_point = ":assembler.js",
     node_modules = ":node_modules_none",
 )
@@ -32,6 +35,7 @@ jasmine_node_test(
     srcs = ["assembler_spec.js"],
     deps = [
         "assembler.js",
+        "//third_party/github.com/gjtorikian/isBinaryFile",
     ],
 )
 

internal/pkg_web/assembler.js

@@ -17,6 +17,7 @@
 
 const fs = require('fs');
 const path = require('path');
+const isBinary = require('isbinaryfile').isBinaryFileSync;
 
 /**
  * Create a new directory and any necessary subdirectories
@@ -29,9 +30,47 @@ function mkdirp(p) {
   }
 }
 
+function getMappingsFromVolatileFile(volatileFilePath) {
+  const stampFileLines = fs.readFileSync(volatileFilePath, {encoding: 'utf-8'}).trim().split('\n');
+  const stampMap = {};
+  for (const line of stampFileLines) {
+    const [key, value] = line.split(' ');
+    stampMap[key] = value;
+  }
+  return stampMap;
+}
+
+function normalizeSubstitutions(substitutionsArg, volatileFilePath) {
+  const substitutions = JSON.parse(substitutionsArg);
+  const stampMap = getMappingsFromVolatileFile(volatileFilePath);
+
+  const normalizedSubstitutions = {};
+
+  for (const occurrence in substitutions) {
+    let substituteWith = substitutions[occurrence];
+    if (substituteWith.match(/^{.*?}$/)) {
+      substituteWith = substituteWith.replace(/^{(.*?)}$/, '$1');
+      if (!stampMap[substituteWith]) {
+        throw new Error(`Could not find ${substituteWith} key in volatile-status file.`);
+      }
+      substituteWith = stampMap[substituteWith];
+    }
+    normalizedSubstitutions[occurrence] = substituteWith;
+  }
+  return normalizedSubstitutions;
+}
+
 function main(params) {
   const outdir = params.shift();
 
+  const volatileFilePath = params.shift();
+
+  const rawSubstitutions = params.shift().replace(/^'(.*)'$/, '$1');
+
+  const normalizedSubstitutions = normalizeSubstitutions(rawSubstitutions, volatileFilePath)
+
+  const substitutions = Object.entries(normalizedSubstitutions);
+
   const rootDirs = [];
   while (params.length && params[0] !== '--assets') {
     let r = params.shift();
@@ -42,6 +81,7 @@ function main(params) {
   }
   // Always trim the longest prefix
   rootDirs.sort((a, b) => b.length - a.length);
+
   params.shift(); // --assets
 
   function relative(execPath) {
@@ -56,12 +96,20 @@ function main(params) {
     return execPath;
   }
 
-  function copy(f) {
+  function copy(f, substitutions) {
     if (fs.statSync(f).isDirectory()) {
       for (const file of fs.readdirSync(f)) {
         // Change paths to posix
-        copy(path.join(f, file).replace(/\\/g, '/'));
+        copy(path.join(f, file).replace(/\\/g, '/'), substitutions);
       }
+    } else if (!isBinary(f)) {
+      const dest = path.join(outdir, relative(f));
+      let content = fs.readFileSync(f, {encoding: 'utf-8'});
+      substitutions.forEach(([occurrence, replaceWith]) => {
+        content = content.replace(occurrence, replaceWith);
+      });
+      fs.mkdirSync(path.dirname(dest), {recursive: true});
+      fs.writeFileSync(dest, content);
     } else {
       const dest = path.join(outdir, relative(f));
       mkdirp(path.dirname(dest));
@@ -75,7 +123,7 @@ function main(params) {
   // copied from within bazel-bin.
   // See https://github.com/bazelbuild/rules_nodejs/pull/546.
   for (const f of new Set(params)) {
-    copy(f);
+    copy(f, substitutions);
   }
   return 0;
 }

internal/pkg_web/assembler_spec.js

@@ -4,6 +4,7 @@ const fs = require('fs');
 
 describe('assembler', () => {
     const outdir = 'output';
+    const volatilePath = 'path/to/volatile-status.txt';
     let testCount = 0;
     beforeEach(() => {
       const now = Date.now() + String(testCount++);
@@ -14,21 +15,42 @@ describe('assembler', () => {
       fs.mkdirSync('path');
       fs.mkdirSync('path/to');
       fs.writeFileSync('path/to/thing1.txt', 'some content', {encoding: 'utf-8'});
+      fs.writeFileSync(volatilePath, 'TEST_KEY 41561')
     });
 
     it('should copy files', () => {
-        assembler.main([outdir, '--assets', 'path/to/thing1.txt']);
-        expect(fs.readdirSync('output/path/to')).toContain('thing1.txt');
-        expect(fs.readFileSync('output/path/to/thing1.txt', {encoding: 'utf-8'})).toBe('some content');
+      assembler.main([outdir, volatilePath, '{}', '--assets', 'path/to/thing1.txt']);
+      expect(fs.readdirSync('output/path/to')).toContain('thing1.txt');
+      expect(fs.readFileSync('output/path/to/thing1.txt', {
+        encoding: 'utf-8'
+      })).toBe('some content');
     });
 
     it('should strip longest rootdir', () => {
-        assembler.main([outdir, 'path', 'path/to', '--assets', 'path/to/thing1.txt']);
-        expect(fs.readdirSync('output')).toContain('thing1.txt');
+      assembler.main(
+          [outdir, volatilePath, '{}', 'path', 'path/to', '--assets', 'path/to/thing1.txt']);
+      expect(fs.readdirSync('output')).toContain('thing1.txt');
     });
 
     it('should handle nested directories', () => {
-        assembler.main([outdir, 'path', '--assets', 'path/to']);
-        expect(fs.readdirSync('output/to')).toContain('thing1.txt');
+      assembler.main([outdir, volatilePath, '{}', 'path', '--assets', 'path/to']);
+      expect(fs.readdirSync('output/to')).toContain('thing1.txt');
     });
+
+    it('should replace contents with static text', () => {
+      assembler.main([
+        outdir, volatilePath, '{"some content":"some other content"}', '--assets',
+        'path/to/thing1.txt'
+      ]);
+      expect(fs.readFileSync('output/path/to/thing1.txt', {
+        encoding: 'utf-8'
+      })).toBe('some other content');
+    })
+
+
+    it('should replace contents with dynamic text from volatile file', () => {
+      assembler.main(
+          [outdir, volatilePath, '{"content":"{TEST_KEY}"}', '--assets', 'path/to/thing1.txt']);
+      expect(fs.readFileSync('output/path/to/thing1.txt', {encoding: 'utf-8'})).toBe('some 41561');
+    })
 });

internal/pkg_web/pkg_web.bzl

@@ -25,14 +25,17 @@ _ATTRS = {
         allow_files = True,
         doc = """Files which should be copied into the package""",
     ),
+    "substitutions": attr.string_dict(
+        doc = """Key-value pairs which are replaced in all the files while building the package.""",
+    ),
     "_assembler": attr.label(
         default = "@build_bazel_rules_nodejs//internal/pkg_web:assembler",
         executable = True,
         cfg = "host",
     ),
 }
 
-def move_files(output_name, files, action_factory, var, assembler, root_paths):
+def move_files(output_name, substitutions, version_file, files, action_factory, var, assembler, root_paths):
     """Moves files into an output directory
 
     Args:
@@ -48,12 +51,15 @@ def move_files(output_name, files, action_factory, var, assembler, root_paths):
     www_dir = action_factory.declare_directory(output_name)
     args = action_factory.args()
     args.add(www_dir.path)
+    args.add(version_file.path)
+    args.add(substitutions)
     args.add_all(root_paths)
     args.add("--assets")
     args.add_all([f.path for f in files])
     args.use_param_file("%s", use_always = True)
+
     action_factory.run(
-        inputs = files,
+        inputs = files + [version_file],
         outputs = [www_dir],
         executable = assembler,
         arguments = [args],
@@ -89,6 +95,8 @@ def _impl(ctx):
 
     package_layout = move_files(
         ctx.label.name,
+        ctx.attr.substitutions,
+        ctx.version_file,
         ctx.files.srcs,
         ctx.actions,
         ctx.var,

internal/pkg_web/test3/BUILD.bazel

@@ -0,0 +1,26 @@
+load("@build_bazel_rules_nodejs//:index.bzl", "pkg_web")
+load("@npm_bazel_jasmine//:index.from_src.bzl", "jasmine_node_test")
+
+package(default_visibility = ["//visibility:public"])
+
+pkg_web(
+    name = "pkg",
+    srcs = [
+        "index.html",
+    ],
+    substitutions = {
+        "THIS_SHOULD_BE_REPLACED": "THIS_SHOULD_BE_REPLACED_WITH_THIS",
+    },
+)
+
+jasmine_node_test(
+    name = "test",
+    srcs = ["spec.js"],
+    data = [
+        "index_golden.html_",
+        ":pkg",
+    ],
+    tags = [
+        "fix-windows",
+    ],
+)

internal/pkg_web/test3/index.html

@@ -0,0 +1 @@
+<html>THIS_SHOULD_BE_REPLACED</html>

internal/pkg_web/test3/index_golden.html_

@@ -0,0 +1 @@
+<html>THIS_SHOULD_BE_REPLACED_WITH_THIS</html>

internal/pkg_web/test3/spec.js

@@ -0,0 +1,15 @@
+const fs = require('fs');
+const path = require('path');
+
+process.chdir(path.join(process.env['TEST_SRCDIR'], 'build_bazel_rules_nodejs'));
+console.error(fs.readdirSync('.'));
+describe('pkg_web', () => {
+  it('should match the golden file', () => {
+    const output = 'build_bazel_rules_nodejs/internal/pkg_web/test/pkg/index.html';
+    const golden = 'build_bazel_rules_nodejs/internal/pkg_web/test/index_golden.html_';
+    const actual = fs.readFileSync(require.resolve(output), {encoding: 'utf-8'});
+    const expected = fs.readFileSync(require.resolve(golden), {encoding: 'utf-8'});
+    // make the input hermetic by replacing the cache-buster timestamp
+    expect(actual.replace(/\?v=\d+/g, '?v=123')).toBe(expected);
+  });
+});