bazel sync: add an option to only sync a particular set of repositories

Add an option --only to `bazel sync` allowing to specify that only a specified
set of external repositories be synced. Still, all repositories (or only the
configure-like ones, if --configure is given) are considered out of date; so if
the specified repository depends one of those, those are fetched as well.

Change-Id: I1712963077081452fbaca0f34e2ab9415d80f880
PiperOrigin-RevId: 290583672

src/main/java/com/google/devtools/build/lib/bazel/commands/SyncCommand.java

@@ -180,7 +180,7 @@ public BlazeCommandResult exec(CommandEnvironment env, OptionsParsingResult opti
           // fetch anyway. So the only task remaining is to record the use of "bind" for whoever
           // collects resolved information.
           env.getReporter().post(resolveBind(rule));
-        } else if (shouldSync(rule, syncOptions.configure)) {
+        } else if (shouldSync(rule, syncOptions)) {
           // TODO(aehlig): avoid the detour of serializing and then parsing the repository name
           try {
             repositoriesToFetch.add(
@@ -221,12 +221,16 @@ public BlazeCommandResult exec(CommandEnvironment env, OptionsParsingResult opti
     return BlazeCommandResult.exitCode(exitCode);
   }
 
-  private static boolean shouldSync(Rule rule, boolean configure) {
+  private static boolean shouldSync(Rule rule, SyncOptions options) {
     if (!rule.getRuleClassObject().getWorkspaceOnly()) {
       // We should only sync workspace rules
       return false;
     }
-    if (configure) {
+    if (options.only != null && !options.only.isEmpty() && !options.only.contains(rule.getName())) {
+      // There is a whitelist of what to sync, but the rule is not in this white list
+      return false;
+    }
+    if (options.configure) {
       // If this is only a configure run, only sync Starlark rules that
       // declare themselves as configure-like.
       return SkylarkRepositoryFunction.isConfigureRule(rule);

src/main/java/com/google/devtools/build/lib/bazel/commands/SyncOptions.java

@@ -17,6 +17,7 @@
 import com.google.devtools.common.options.OptionDocumentationCategory;
 import com.google.devtools.common.options.OptionEffectTag;
 import com.google.devtools.common.options.OptionsBase;
+import java.util.List;
 
 /** Defines the options specific to Bazel's sync command */
 public class SyncOptions extends OptionsBase {
@@ -27,4 +28,15 @@ public class SyncOptions extends OptionsBase {
       effectTags = {OptionEffectTag.CHANGES_INPUTS},
       help = "Only sync repositories marked as 'configure' for system-configuration purpose.")
   public boolean configure;
+
+  @Option(
+      name = "only",
+      defaultValue = "null",
+      allowMultiple = true,
+      documentationCategory = OptionDocumentationCategory.EXECUTION_STRATEGY,
+      effectTags = {OptionEffectTag.CHANGES_INPUTS},
+      help =
+          "If this option is given, only sync the repositories specified with this option."
+              + " Still consider all (or all configure-like, of --configure is given) outdated.")
+  public List<String> only;
 }

src/test/shell/bazel/skylark_repository_test.sh

@@ -1413,6 +1413,55 @@ EOF
       || fail "expected success after successful sync"
 }
 
+function test_sync_only() {
+  # Set up two repositories that count how often they are fetched
+  cat >environ.bzl <<'EOF'
+def environ(r_ctx, var):
+  return r_ctx.os.environ[var] if var in r_ctx.os.environ else "undefined"
+EOF
+  cat <<'EOF' >bar.tpl
+FOO=%{FOO} BAR=%{BAR} BAZ=%{BAZ}
+EOF
+  write_environ_skylark "${TEST_TMPDIR}/executionFOO" ""
+  mv test.bzl testfoo.bzl
+  write_environ_skylark "${TEST_TMPDIR}/executionBAR" ""
+  mv test.bzl testbar.bzl
+  cat > WORKSPACE <<'EOF'
+load("//:testfoo.bzl", foorepo="repo")
+load("//:testbar.bzl", barrepo="repo")
+foorepo(name="foo")
+barrepo(name="bar")
+EOF
+  touch BUILD
+  bazel clean --expunge
+  echo 0 > "${TEST_TMPDIR}/executionFOO"
+  echo 0 > "${TEST_TMPDIR}/executionBAR"
+
+  # Normal sync should hit both repositories
+  echo; echo bazel sync; echo
+  bazel sync
+  assert_equals 1 $(cat "${TEST_TMPDIR}/executionFOO")
+  assert_equals 1 $(cat "${TEST_TMPDIR}/executionBAR")
+
+  # Only foo
+  echo; echo bazel sync --only foo; echo
+  bazel sync --only foo
+  assert_equals 2 $(cat "${TEST_TMPDIR}/executionFOO")
+  assert_equals 1 $(cat "${TEST_TMPDIR}/executionBAR")
+
+  # Only bar
+  echo; echo bazel sync --only bar; echo
+  bazel sync --only bar
+  assert_equals 2 $(cat "${TEST_TMPDIR}/executionFOO")
+  assert_equals 2 $(cat "${TEST_TMPDIR}/executionBAR")
+
+  # Only bar
+  echo; echo bazel sync --only bar; echo
+  bazel sync --only bar
+  assert_equals 2 $(cat "${TEST_TMPDIR}/executionFOO")
+  assert_equals 3 $(cat "${TEST_TMPDIR}/executionBAR")
+}
+
 function test_download_failure_message() {
   # Regression test for #7850
   # Verify that the for a failed downlaod, it is clearly indicated