(WIP) Check for container updates rather than using image-id.txt

dangerzone/isolation_provider/container.py

@@ -5,7 +5,7 @@ import shlex
 import subprocess
 from typing import List, Tuple
 
-from .. import container_utils, errors
+from .. import container_utils, errors, updater
 from ..container_utils import Runtime
 from ..document import Document
 from ..util import get_resource_path, get_subprocess_startupinfo
@@ -95,23 +95,18 @@ class Container(IsolationProvider):
 
     @staticmethod
     def install() -> bool:
-        """Install the container image tarball, or verify that it's already installed.
+        """Check if an update is available and install it if necessary."""
+        # XXX Do this only if users have optted in to auto-updates
 
-        Perform the following actions:
-        1. Get the tags of any locally available images that match Dangerzone's image
-           name.
-        2. Get the expected image tag from the image-id.txt file.
-           - If this tag is present in the local images, then we can return.
-           - Else, prune the older container images and continue.
-        3. Load the image tarball and make sure it matches the expected tag.
-        """
-        old_tags = container_utils.list_image_tags()
-        expected_tag = container_utils.get_expected_tag()
-
-        if expected_tag not in old_tags:
-            # Prune older container images.
-            log.info(
-                f"Could not find a Dangerzone container image with tag '{expected_tag}'"
+        # # Load the image tarball into the container runtime.
+        update_available, image_digest = updater.is_update_available(
+            container_utils.CONTAINER_NAME
+        )
+        if update_available and image_digest:
+            updater.upgrade_container_image(
+                container_utils.CONTAINER_NAME,
+                image_digest,
+                updater.DEFAULT_PUBKEY_LOCATION,
             )
             for tag in old_tags:
                 tag = container_utils.CONTAINER_NAME + ":" + tag
@@ -119,18 +114,9 @@ class Container(IsolationProvider):
         else:
             return True
 
-        # Load the image tarball into the container runtime.
-        container_utils.load_image_tarball()
-
-        # Check that the container image has the expected image tag.
-        # See https://github.com/freedomofpress/dangerzone/issues/988 for an example
-        # where this was not the case.
-        new_tags = container_utils.list_image_tags()
-        if expected_tag not in new_tags:
-            raise errors.ImageNotPresentException(
-                f"Could not find expected tag '{expected_tag}' after loading the"
-                " container image tarball"
-            )
+        updater.verify_local_image(
+            container_utils.CONTAINER_NAME, updater.DEFAULT_PUBKEY_LOCATION
+        )
 
         return True
 
@@ -214,6 +200,15 @@ class Container(IsolationProvider):
         name: str,
     ) -> subprocess.Popen:
         runtime = Runtime()
+
+        image_digest = container_utils.get_local_image_digest(
+            container_utils.CONTAINER_NAME
+        )
+        updater.verify_local_image(
+            container_utils.CONTAINER_NAME,
+            updater.DEFAULT_PUBKEY_LOCATION,
+            image_digest,
+        )
         security_args = self.get_runtime_security_args()
         debug_args = []
         if self.debug:
@@ -222,9 +217,7 @@ class Container(IsolationProvider):
         enable_stdin = ["-i"]
         set_name = ["--name", name]
         prevent_leakage_args = ["--rm"]
-        image_name = [
-            container_utils.CONTAINER_NAME + ":" + container_utils.get_expected_tag()
-        ]
+        image_name = [container_utils.CONTAINER_NAME + "@sha256:" + image_digest]
         args = (
             ["run"]
             + security_args