feat(remote)!: use craft-application remote build for core22

snapcraft/application.py

@@ -22,7 +22,7 @@
 import os
 import pathlib
 import sys
-from typing import Any
+from typing import Any, Optional
 
 import craft_application.commands as craft_app_commands
 import craft_cli
@@ -62,6 +62,25 @@
 }
 
 
+def _get_esm_error_for_base(base: str) -> None:
+    """Raise an error appropriate for the base under ESM."""
+    channel: Optional[str] = None
+    match base:
+        case "core":
+            channel = "4.x"
+            version = "4"
+        case "core18":
+            channel = "7.x"
+            version = "7"
+        case _:
+            return
+
+    raise RuntimeError(
+        f"ERROR: base {base!r} was last supported on Snapcraft {version} available "
+        f"on the {channel!r} channel."
+    )
+
+
 class Snapcraft(Application):
     """Snapcraft application definition."""
 
@@ -163,11 +182,39 @@ def _get_dispatcher(self) -> craft_cli.Dispatcher:
                 yaml_data = util.safe_yaml_load(file)
             base = yaml_data.get("base")
             build_base = yaml_data.get("build-base")
+            _get_esm_error_for_base(base)
             if "core24" in (base, build_base) or build_base == "devel":
                 # We know for sure that we're handling a core24 project
                 self._known_core24 = True
             elif any(arg in ("version", "--version", "-V") for arg in sys.argv):
                 pass
+            elif "remote-build" in sys.argv and any(
+                b in ("core20", "core22") for b in (base, build_base)
+            ):
+                build_strategy = os.environ.get("SNAPCRAFT_REMOTE_BUILD_STRATEGY", None)
+                if build_strategy not in (
+                    "force-fallback",
+                    "disable-fallback",
+                    "",
+                    None,
+                ):
+                    raise errors.SnapcraftError(
+                        f"Unknown value {build_strategy!r} in environment variable "
+                        "'SNAPCRAFT_REMOTE_BUILD_STRATEGY'. "
+                        "Valid values are 'disable-fallback' and 'force-fallback'."
+                    )
+                # Use legacy snapcraft unless explicitly forced to use craft-application
+                if (
+                    "core20" in (base, build_base)
+                    and build_strategy != "disable-fallback"
+                ):
+                    raise errors.ClassicFallback()
+                # Use craft-application unless explicitly forced to use legacy snapcraft
+                if (
+                    "core22" in (base, build_base)
+                    and build_strategy == "force-fallback"
+                ):
+                    raise errors.ClassicFallback()
             else:
                 raise errors.ClassicFallback()
         return super()._get_dispatcher()

snapcraft/cli.py

@@ -24,12 +24,12 @@
 
 import craft_cli
 import craft_store
+from craft_application.errors import RemoteBuildError
 from craft_cli import ArgumentParsingError, EmitterMode, ProvideHelpException, emit
 from craft_providers import ProviderError
 
 from snapcraft import errors, store, utils
 from snapcraft.parts import plugins
-from snapcraft.remote import RemoteBuildError
 
 from . import commands
 from .legacy_cli import run_legacy
@@ -44,7 +44,6 @@
             commands.core22.StageCommand,
             commands.core22.PrimeCommand,
             commands.core22.PackCommand,
-            commands.core22.RemoteBuildCommand,
             commands.core22.SnapCommand,  # hidden (legacy compatibility)
             commands.core22.PluginsCommand,
             commands.core22.ListPluginsCommand,

snapcraft/commands/core22/__init__.py

@@ -34,7 +34,6 @@
     TryCommand,
 )
 from .lint import LintCommand
-from .remote import RemoteBuildCommand
 
 __all__ = [
     "BuildCommand",
@@ -49,7 +48,6 @@
     "PluginsCommand",
     "PrimeCommand",
     "PullCommand",
-    "RemoteBuildCommand",
     "SnapCommand",
     "StageCommand",
     "TryCommand",