Merge pull request #132 from google/upstream-1544753093

Add docker cache directory

Author: KaylaNguyen

README.md

@@ -71,7 +71,6 @@ optional arguments:
                         from DOCKER_CONFIG
   --stderrthreshold STDERRTHRESHOLD
                         Write log events at or above this level to stderr.
-
 ```
 
 ## pusher.par
@@ -107,7 +106,6 @@ optional arguments:
                         from DOCKER_CONFIG
   --stderrthreshold STDERRTHRESHOLD
                         Write log events at or above this level to stderr.
-
 ```
 
 ## importer.par

client/v2_2/save_.py

@@ -18,6 +18,7 @@
 
 from __future__ import print_function
 
+import errno
 import io
 import json
 import os
@@ -140,8 +141,10 @@ def tarball(name, image,
   multi_image_tarball({name: image}, tar, {})
 
 
-def fast(image, directory,
-         threads = 1):
+def fast(image,
+         directory,
+         threads = 1,
+         cache_directory = None):
   """Produce a FromDisk compatible file layout under the provided directory.
 
   After calling this, the following filesystem will exist:
@@ -162,6 +165,7 @@ def fast(image, directory,
     image: a docker image to save.
     directory: an existing empty directory under which to save the layout.
     threads: the number of threads to use when performing the upload.
+    cache_directory: directory that stores file cache.
 
   Returns:
     A tuple whose first element is the path to the config file, and whose second
@@ -174,6 +178,38 @@ def write_file(name, accessor,
     with io.open(name, u'wb') as f:
       f.write(accessor(arg))
 
+  def write_file_and_store(name, accessor,
+                           arg, cached_layer):
+    write_file(cached_layer, accessor, arg)
+    link(cached_layer, name)
+
+  def link(source, dest):
+    """Creates a symbolic link dest pointing to source.
+
+    Unlinks first to remove "old" layers if needed
+    e.g., image A latest has layers 1, 2 and 3
+    after a while it has layers 1, 2 and 3'.
+    Since in both cases the layers are named 001, 002 and 003,
+    unlinking promises the correct layers are linked in the image directory.
+
+    Args:
+      source: image directory source.
+      dest: image directory destination.
+    """
+    try:
+      os.symlink(source, dest)
+    except OSError as e:
+      if e.errno == errno.EEXIST:
+        os.unlink(dest)
+        os.symlink(source, dest)
+      else:
+        raise e
+
+  def valid(cached_layer, digest):
+    with io.open(cached_layer, u'rb') as f:
+      current_digest = docker_digest.SHA256(f.read(), '')
+    return current_digest == digest
+
   with concurrent.futures.ThreadPoolExecutor(max_workers=threads) as executor:
     future_to_params = {}
     config_file = os.path.join(directory, 'config.json')
@@ -192,18 +228,30 @@ def write_file(name, accessor,
     layers = []
     for blob in reversed(image.fs_layers()):
       # Create a local copy
+      layer_name = os.path.join(directory, '%03d.tar.gz' % idx)
       digest_name = os.path.join(directory, '%03d.sha256' % idx)
+      # Strip the sha256: prefix
+      digest = blob[7:].encode('utf8')
       f = executor.submit(
           write_file,
           digest_name,
-          # Strip the sha256: prefix
           lambda blob: blob[7:].encode('utf8'),
           blob)
       future_to_params[f] = digest_name
 
-      layer_name = os.path.join(directory, '%03d.tar.gz' % idx)
-      f = executor.submit(write_file, layer_name, image.blob, blob)
-      future_to_params[f] = layer_name
+      if cache_directory:
+        # Search for a local cached copy
+        cached_layer = os.path.join(cache_directory, digest)
+        if os.path.exists(cached_layer) and valid(cached_layer, digest):
+          f = executor.submit(link, cached_layer, layer_name)
+          future_to_params[f] = layer_name
+        else:
+          f = executor.submit(write_file_and_store, layer_name, image.blob,
+                              blob, cached_layer)
+          future_to_params[f] = layer_name
+      else:
+        f = executor.submit(write_file, layer_name, image.blob, blob)
+        future_to_params[f] = layer_name
 
       layers.append((digest_name, layer_name))
       idx += 1

puller_test.sh

@@ -19,6 +19,8 @@
 # Trick to chase the symlink before the docker build.
 cp -f puller.par puller2.par
 
+timing=-1
+
 # Test pulling an image by just invoking the puller
 function test_puller() {
   local image=$1
@@ -81,6 +83,53 @@ function test_image() {
   test_base "${image}" python2.7 gcr.io/cloud-builders/bazel
 }
 
+function test_puller_with_cache() {
+  local image=$1
+
+   # Test it in our current environment.
+  puller.par --name="${image}" --directory=/tmp/ --cache=/tmp/containerregistry_docker_cache_dir
+}
+ function test_image_with_cache() {
+  local image=$1
+
+  test_image_with_timing "${image}"
+  local first_pull_timing=$timing
+  echo "TIMING: ${image} - First pull took ${first_pull_timing} seconds"
+
+  test_image_with_timing "${image}"
+  local second_pull_timing=$timing
+  echo "TIMING: ${image} - Second pull took ${second_pull_timing} seconds"
+   # TODO - is there a better way to test that the cache was used beside asserting the first_pull > second_pull???
+}
+
+ function test_image_with_timing() {
+  local image=$1
+
+  echo "TESTING: ${image}"
+  local pull_start=$(date +%s)
+  test_puller_with_cache "${image}"
+  local pull_end=$(date +%s)
+  timing=$(($pull_end-$pull_start))
+
+  test_base "${image}" python2.7 python:2.7
+  test_base "${image}" python2.7 gcr.io/cloud-builders/bazel
+}
+
+ function clear_cache_directory() {
+  rm -fr /tmp/containerregistry_docker_cache_dir
+}
+
+ function create_cache_directory() {
+  mkdir -p /tmp/containerregistry_docker_cache_dir
+}
+
+clear_cache_directory
+
+create_cache_directory
+
+ # Test pulling with cache
+test_image_with_cache gcr.io/google-appengine/python:latest
+
 # Test pulling a trivial image.
 test_image gcr.io/google-containers/pause:2.0
 
@@ -125,3 +174,6 @@ test_puller_multiplatform index.docker.io/library/busybox:1.29.3 \
 # TODO: add multiplatform test cases on --os-features and --features
 
 # TODO(user): Add an authenticated pull test.
+
+clear_cache_directory
+

tools/fast_puller_.py

@@ -60,6 +60,8 @@
     action='store',
     help='The path to the directory where the client configuration files are '
     'located. Overiddes the value from DOCKER_CONFIG')
+parser.add_argument(
+    '--cache', action='store', help='Image\'s files cache directory.')
 
 _THREADS = 8
 
@@ -108,20 +110,32 @@ def main():
         platform = platform_args.FromArgs(args)
         # pytype: disable=wrong-arg-types
         with img_list.resolve(platform) as default_child:
-          save.fast(default_child, args.directory, threads=_THREADS)
+          save.fast(
+              default_child,
+              args.directory,
+              threads=_THREADS,
+              cache_directory=args.cache)
           return
         # pytype: enable=wrong-arg-types
 
     logging.info('Pulling v2.2 image from %r ...', name)
     with v2_2_image.FromRegistry(name, creds, transport, accept) as v2_2_img:
       if v2_2_img.exists():
-        save.fast(v2_2_img, args.directory, threads=_THREADS)
+        save.fast(
+            v2_2_img,
+            args.directory,
+            threads=_THREADS,
+            cache_directory=args.cache)
         return
 
     logging.info('Pulling v2 image from %r ...', name)
     with v2_image.FromRegistry(name, creds, transport) as v2_img:
       with v2_compat.V22FromV2(v2_img) as v2_2_img:
-        save.fast(v2_2_img, args.directory, threads=_THREADS)
+        save.fast(
+            v2_2_img,
+            args.directory,
+            threads=_THREADS,
+            cache_directory=args.cache)
         return
   # pylint: disable=broad-except
   except Exception as e:

transform/v2_2/metadata_.py

@@ -160,7 +160,7 @@ def Override(data,
 
   output['config'] = defaults.get('config', {})
 
-  # pytype: disable=attribute-error
+  # pytype: disable=attribute-error,unsupported-operands
   if options.entrypoint:
     output['config']['Entrypoint'] = options.entrypoint
   if options.cmd:
@@ -204,7 +204,7 @@ def Override(data,
 
   if options.workdir:
     output['config']['WorkingDir'] = options.workdir
-  # pytype: enable=attribute-error
+  # pytype: enable=attribute-error,unsupported-operands
 
   # diff_ids are ordered from bottom-most to top-most
   diff_ids = defaults.get('rootfs', {}).get('diff_ids', [])