Compress Blimp engine bundle using gzip in blimp_engine_bundle target.

Fastest compression mode is used, which takes on average around 12 seconds on my workstation.

BUG=582519

Review URL: https://codereview.chromium.org/1641343002

Cr-Commit-Position: refs/heads/master@{#373401}

2 files changed, 23 insertions, 15 deletions

diff --git a/blimp/engine/BUILD.gn b/blimp/engine/BUILD.gn
index 7752536..313d0b4 100644
--- a/blimp/engine/BUILD.gn
+++ b/blimp/engine/BUILD.gn
@@ -247,7 +247,7 @@ if (is_linux) {
     _rebased_dockerfile = rebase_path("//blimp/engine/Dockerfile")
     _rebased_startup_script = rebase_path("//blimp/engine/start_engine.sh")
     _rebased_manifest = rebase_path("//blimp/engine/engine-manifest.txt")
-    _bundle = "$root_out_dir/blimp_engine_bundle.tar"
+    _bundle = "$root_out_dir/blimp_engine_bundle.tar.gz"
 
     # Detail the target & "source"-file dependencies, and output, for GN.
     deps = [
diff --git a/blimp/tools/bundle-engine.py b/blimp/tools/bundle-engine.py
index 9fd266e..4c3aa04 100755
--- a/blimp/tools/bundle-engine.py
+++ b/blimp/tools/bundle-engine.py
@@ -6,7 +6,7 @@
 '''Bundles the Blimp Engine and its runtime dependencies into a tarball.
 
    The created bundle can be passed as input to docker build.  E.g.
-   docker build - < ../../out-linux/Debug/blimp_engine_deps.tar
+   docker build - < ../../out-linux/Debug/blimp_engine_deps.tar.gz
 '''
 
 
@@ -15,7 +15,6 @@ import errno
 import os
 import subprocess
 import sys
-import tarfile
 
 def ReadDependencies(manifest):
   """Read the manifest and return the list of dependencies.
@@ -56,18 +55,27 @@ def main():
 
   deps = ReadDependencies(args.manifest)
 
-  # Add the deps to the tarball along with the Dockerfile.
-  with tarfile.open(args.output, 'w') as tarball:
-    tarball.add(args.dockerfile, arcname='Dockerfile')
-    tarball.add(args.startup_script, arcname='start_engine.sh')
-    os.chdir(args.build_dir)
-    for dep in deps:
-      try:
-        tarball.add(dep)
-      except OSError as e:
-        if e.errno == errno.ENOENT:
-          print >> sys.stderr, dep + " not found (did you build the engine?)"
-          exit(1)
+  dockerfile_dirname, dockerfile_basename = os.path.split(args.dockerfile)
+  startup_script_dirname, startup_script_basename = os.path.split(
+      args.startup_script)
+
+  try:
+    env = os.environ.copy()
+    # Use fastest possible mode when gzipping.
+    env["GZIP"] = "-1"
+    subprocess.check_output(
+        ["tar",
+         "-zcf", args.output,
+         "-C", dockerfile_dirname, dockerfile_basename,
+         "-C", startup_script_dirname, startup_script_basename,
+         "-C", args.build_dir] + deps,
+        # Redirect stderr to stdout, so that its output is captured.
+        stderr=subprocess.STDOUT,
+        env=env)
+  except subprocess.CalledProcessError as e:
+    print >> sys.stderr, "Failed to create tarball:"
+    print >> sys.stderr, e.output
+    sys.exit(1)
 
 if __name__ == "__main__":
   main()