Build and tag Dangerzone images

Build Dangerzone images and tag them with a unique ID that stems from
the Git reop. Note that using tags as image IDs instead of regular image
IDs breaks the current Dangerzone expectations, but this will be
addressed in subsequent commits.

install/common/build-image.py

@@ -2,12 +2,13 @@
 import gzip
 import os
 import platform
+import secrets
 import subprocess
 import sys
 from pathlib import Path
 
 BUILD_CONTEXT = "dangerzone/"
-TAG = "dangerzone.rocks/dangerzone:latest"
+IMAGE_NAME = "dangerzone.rocks/dangerzone"
 REQUIREMENTS_TXT = "container-pip-requirements.txt"
 if platform.system() in ["Darwin", "Windows"]:
     CONTAINER_RUNTIME = "docker"
@@ -44,8 +45,31 @@ def main():
     )
     args = parser.parse_args()
 
+    tarball_path = Path("share") / "container.tar.gz"
+    image_id_path = Path("share") / "image-id.txt"
+
     print(f"Building for architecture '{ARCH}'")
 
+    # Designate a unique tag for this image, depending on the Git commit it was created
+    # from:
+    # 1. If created from a Git tag (e.g., 0.8.0), the image tag will be `0.8.0`.
+    # 2. If created from a commit, it will be something like `0.8.0-31-g6bdaa7a`.
+    # 3. If the contents of the Git repo are dirty, we will append a unique identifier
+    #    for this run, something like `0.8.0-31-g6bdaa7a-fdcb` or `0.8.0-fdcb`.
+    dirty_ident = secrets.token_hex(2)
+    tag = (
+        subprocess.check_output(
+            ["git", "describe", "--first-parent", f"--dirty=-{dirty_ident}"],
+        )
+        .decode()
+        .strip()[1:]  # remove the "v" prefix of the tag.
+    )
+    image_name_tagged = IMAGE_NAME + ":" + tag
+
+    print(f"Will tag the container image as '{image_name_tagged}'")
+    with open(image_id_path, "w") as f:
+        f.write(tag)
+
     print("Exporting container pip dependencies")
     with ContainerPipDependencies():
         if not args.use_cache:
@@ -59,8 +83,11 @@ def main():
                 check=True,
             )
 
+        # Build the container image, and tag it with two tags; the one we calculated
+        # above, and the "latest" tag.
         print("Building container image")
         cache_args = [] if args.use_cache else ["--no-cache"]
+        image_name_latest = IMAGE_NAME + ":latest"
         subprocess.run(
             [
                 args.runtime,
@@ -74,7 +101,9 @@ def main():
                 "-f",
                 "Dockerfile",
                 "--tag",
-                TAG,
+                image_name_latest,
+                "--tag",
+                image_name_tagged,
             ],
             check=True,
         )
@@ -85,15 +114,15 @@ def main():
                 [
                     CONTAINER_RUNTIME,
                     "save",
-                    TAG,
+                    image_name_tagged,
                 ],
                 stdout=subprocess.PIPE,
             )
 
             print("Compressing container image")
             chunk_size = 4 << 20
             with gzip.open(
-                "share/container.tar.gz",
+                tarball_path,
                 "wb",
                 compresslevel=args.compress_level,
             ) as gzip_f:
@@ -105,21 +134,6 @@ def main():
                         break
             cmd.wait(5)
 
-    print("Looking up the image id")
-    image_id = subprocess.check_output(
-        [
-            args.runtime,
-            "image",
-            "list",
-            "--format",
-            "{{.ID}}",
-            TAG,
-        ],
-        text=True,
-    )
-    with open("share/image-id.txt", "w") as f:
-        f.write(image_id)
-
 
 class ContainerPipDependencies:
     """Generates PIP dependencies within container"""