Hash the uncompressed contents of docker context tar

src/taskgraph/docker.py

@@ -122,7 +122,7 @@ def build_image(name, tag, args=None):
     tag = tag or docker.docker_image(name, by_tag=True)
 
     buf = BytesIO()
-    docker.stream_context_tar(".", image_dir, buf, "", args)
+    docker.stream_context_tar(".", image_dir, buf, args)
     cmdargs = ["docker", "image", "build", "--no-cache", "-"]
     if tag:
         cmdargs.insert(-1, f"-t={tag}")

src/taskgraph/util/archive.py

@@ -7,6 +7,7 @@
 import os
 import stat
 import tarfile
+from contextlib import contextmanager
 
 # 2016-01-01T00:00:00+0000
 DEFAULT_MTIME = 1451606400
@@ -104,14 +105,14 @@ def create_tar_from_files(fp, files):
             tf.addfile(ti, f)
 
 
-def create_tar_gz_from_files(fp, files, filename=None, compresslevel=9):
-    """Create a tar.gz file deterministically from files.
+@contextmanager
+def gzip_compressor(fp, filename=None, compresslevel=9):
+    """Create a deterministic GzipFile writer.
 
-    This is a glorified wrapper around ``create_tar_from_files`` that
-    adds gzip compression.
+    This is a glorified wrapper around ``GzipFile`` that adds some
+    determinism.
 
     The passed file handle should be opened for writing in binary mode.
-    When the function returns, all data has been written to the handle.
     """
     # Offset 3-7 in the gzip header contains an mtime. Pin it to a known
     # value so output is deterministic.
@@ -123,4 +124,17 @@ def create_tar_gz_from_files(fp, files, filename=None, compresslevel=9):
         mtime=DEFAULT_MTIME,
     )
     with gf:
+        yield gf
+
+
+def create_tar_gz_from_files(fp, files, filename=None, compresslevel=9):
+    """Create a tar.gz file deterministically from files.
+
+    This is a glorified wrapper around ``create_tar_from_files`` that
+    adds gzip compression.
+
+    The passed file handle should be opened for writing in binary mode.
+    When the function returns, all data has been written to the handle.
+    """
+    with gzip_compressor(fp, filename, compresslevel) as gf:
         create_tar_from_files(gf, files)

src/taskgraph/util/docker.py

@@ -10,7 +10,7 @@
 import re
 from typing import Optional
 
-from taskgraph.util.archive import create_tar_gz_from_files
+from taskgraph.util.archive import create_tar_from_files, gzip_compressor
 
 IMAGE_DIR = os.path.join(".", "taskcluster", "docker")
 
@@ -76,10 +76,15 @@ class HashingWriter:
     def __init__(self, writer):
         self._hash = hashlib.sha256()
         self._writer = writer
+        self._written = 0
 
     def write(self, buf):
         self._hash.update(buf)
         self._writer.write(buf)
+        self._written += len(buf)
+
+    def tell(self):
+        return self._written
 
     def hexdigest(self):
         return self._hash.hexdigest()
@@ -108,13 +113,8 @@ def create_context_tar(topsrcdir, context_dir, out_path, args=None):
     Returns the SHA-256 hex digest of the created archive.
     """
     with open(out_path, "wb") as fh:
-        return stream_context_tar(
-            topsrcdir,
-            context_dir,
-            fh,
-            image_name=os.path.basename(out_path),
-            args=args,
-        )
+        with gzip_compressor(fh, filename=os.path.basename(out_path)) as gf:
+            return stream_context_tar(topsrcdir, context_dir, gf, args=args)
 
 
 RUN_TASK_ROOT = os.path.join(os.path.dirname(os.path.dirname(__file__)), "run-task")
@@ -135,7 +135,7 @@ def create_context_tar(topsrcdir, context_dir, out_path, args=None):
 ]
 
 
-def stream_context_tar(topsrcdir, context_dir, out_file, image_name=None, args=None):
+def stream_context_tar(topsrcdir, context_dir, out_file, args=None):
     """Like create_context_tar, but streams the tar file to the `out_file` file
     object."""
     archive_files = {}
@@ -201,7 +201,7 @@ def stream_context_tar(topsrcdir, context_dir, out_file, image_name=None, args=N
     archive_files["Dockerfile"] = io.BytesIO("".join(content).encode("utf-8"))
 
     writer = HashingWriter(out_file)
-    create_tar_gz_from_files(writer, archive_files, image_name)
+    create_tar_from_files(writer, archive_files)
     return writer.hexdigest()
 
 

test/test_util_docker.py

@@ -39,7 +39,7 @@ def test_generate_context_hash(self):
                 docker.generate_context_hash(
                     tmpdir, os.path.join(tmpdir, "docker/my-image"), "my-image"
                 ),
-                "e1649b3427bd7a0387f4508d25057c2e89228748517aad6c70e3df54f47bd13a",
+                "ab46d51b191eb6c595cccf1fa02485b4e1decc6ba9737a8b8613038d3661be52",
             )
         finally:
             shutil.rmtree(tmpdir)
@@ -98,9 +98,9 @@ def test_create_context_tar_basic(self):
             os.chmod(os.path.join(d, "extra"), MODE_STANDARD)
 
             tp = os.path.join(tmp, "tar")
-            h = docker.create_context_tar(tmp, d, tp, "my_image")
+            h = docker.create_context_tar(tmp, d, tp)
             self.assertEqual(
-                h, "6c1cc23357625f64f775a08eace7bbc3877dd08d2f3546e0f2e308bac8491865"
+                h, "3134fa88c39a604132b260c2c3cf09f6fe4a8234475a4272fd9438aac47caaae"
             )
 
             # File prefix should be "my_image"
@@ -131,9 +131,9 @@ def test_create_context_topsrcdir_files(self):
             os.chmod(os.path.join(extra, "file0"), MODE_STANDARD)
 
             tp = os.path.join(tmp, "tar")
-            h = docker.create_context_tar(tmp, d, tp, "test_image")
+            h = docker.create_context_tar(tmp, d, tp)
             self.assertEqual(
-                h, "e7f14044b8ec1ba42e251d4b293af212ad08b30ec8ab6613abbdbe73c3c2b61f"
+                h, "56657d2f428fe268cc3b0966649a3bf8477dcd2eade7a1d4accc5c312f075a2f"
             )
 
             with tarfile.open(tp, "r:gz") as tf:
@@ -158,7 +158,7 @@ def test_create_context_absolute_path(self):
                 fh.write(b"# %include /etc/shadow\n")
 
             with self.assertRaisesRegex(Exception, "cannot be absolute"):
-                docker.create_context_tar(tmp, d, os.path.join(tmp, "tar"), "test")
+                docker.create_context_tar(tmp, d, os.path.join(tmp, "tar"))
         finally:
             shutil.rmtree(tmp)
 
@@ -172,7 +172,7 @@ def test_create_context_outside_topsrcdir(self):
                 fh.write(b"# %include foo/../../../etc/shadow\n")
 
             with self.assertRaisesRegex(Exception, "path outside topsrcdir"):
-                docker.create_context_tar(tmp, d, os.path.join(tmp, "tar"), "test")
+                docker.create_context_tar(tmp, d, os.path.join(tmp, "tar"))
         finally:
             shutil.rmtree(tmp)
 
@@ -186,7 +186,7 @@ def test_create_context_missing_extra(self):
                 fh.write(b"# %include does/not/exist\n")
 
             with self.assertRaisesRegex(Exception, "path does not exist"):
-                docker.create_context_tar(tmp, d, os.path.join(tmp, "tar"), "test")
+                docker.create_context_tar(tmp, d, os.path.join(tmp, "tar"))
         finally:
             shutil.rmtree(tmp)
 
@@ -214,10 +214,10 @@ def test_create_context_extra_directory(self):
             os.chmod(os.path.join(tmp, "file0"), MODE_STANDARD)
 
             tp = os.path.join(tmp, "tar")
-            h = docker.create_context_tar(tmp, d, tp, "my_image")
+            h = docker.create_context_tar(tmp, d, tp)
 
             self.assertEqual(
-                h, "d2a3363b15d0eb547a6c81a72ddf3980e2f6e6360c29b4fb6818102896f43180"
+                h, "ba7b62e8f25977e8e6629aee1d121ae92b6007258c90a53fb94c8607e1e96e10"
             )
 
             with tarfile.open(tp, "r:gz") as tf:
@@ -261,11 +261,11 @@ def test_stream_context_tar(self):
             # file objects are BufferedRandom instances
             out_file = BufferedRandom(BytesIO(b""))
             h = docker.stream_context_tar(
-                tmp, d, out_file, "my_image", args={"PYTHON_VERSION": "3.8"}
+                tmp, d, out_file, args={"PYTHON_VERSION": "3.8"}
             )
 
             self.assertEqual(
-                h, "e015aabf2677d90fee777c8813fd69402309a2d49bcdff2c28428134a53e36be"
+                h, "ba7b62e8f25977e8e6629aee1d121ae92b6007258c90a53fb94c8607e1e96e10"
             )
         finally:
             shutil.rmtree(tmp)