lifecycle: only warn when a default provider snap is missing (#2885)

Snapcraft gained the ability to check for artifacts from snaps listed as plugs
when using the content interface.

The side effect, is that the snap needs to be published on the main Snap Store,
this is a requirement brand stores cannot meet, so instead of failing,
Snapcraft resorts to warning instead.

Signed-off-by: Sergio Schvezov <sergio.schvezov@canonical.com>

snapcraft/internal/lifecycle/_runner.py

@@ -1,6 +1,6 @@
 # -*- Mode:Python; indent-tabs-mode:nil; tab-width:4 -*-
 #
-# Copyright (C) 2015-2018 Canonical Ltd
+# Copyright (C) 2015-2020 Canonical Ltd
 #
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License version 3 as
@@ -83,23 +83,32 @@ def execute(
             "The repo backend is not returning the list of installed packages"
         )
 
+    build_snaps = project_config.build_snaps
     content_snaps = project_config.project._get_content_snaps()
-    required_snaps = project_config.build_snaps | content_snaps
 
-    if common.is_process_container():
-        installed_snaps = []  # type: List[str]
+    if common.is_process_container() and build_snaps:
+        installed_snaps: List[str] = []
         logger.warning(
             (
                 "The following snaps are required but not installed as snapcraft "
                 "is running inside docker or podman container: {}.\n"
                 "Please ensure the environment is properly setup before continuing.\n"
                 "Ignore this message if the appropriate measures have already been taken".format(
-                    ", ".join(required_snaps)
+                    ", ".join(build_snaps)
                 )
             )
         )
     else:
-        installed_snaps = repo.snaps.install_snaps(required_snaps)
+        installed_snaps = repo.snaps.install_snaps(build_snaps)
+        for content_snap in content_snaps:
+            try:
+                installed_snaps += repo.snaps.install_snaps([content_snap])
+            except repo.snaps.errors.SnapUnavailableError:
+                logger.warning(
+                    f"Could not install snap defined in plug {content_snap!r}. "
+                    "The missing library report may have false positives listed if those "
+                    "libraries are provided by the content snap."
+                )
 
     try:
         global_state = states.GlobalState.load(

snapcraft/internal/meta/snap.py

@@ -1,6 +1,6 @@
 # -*- Mode:Python; indent-tabs-mode:nil; tab-width:4 -*-
 #
-# Copyright (C) 2019 Canonical Ltd
+# Copyright (C) 2019-2020 Canonical Ltd
 #
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License version 3 as
@@ -119,6 +119,9 @@ def get_provider_content_directories(self) -> Set[str]:
             provider_path = common.get_installed_snap_path(provider)
             yaml_path = os.path.join(provider_path, "meta", "snap.yaml")
 
+            if not os.path.exists(yaml_path):
+                continue
+
             snap = Snap.from_file(yaml_path)
             for slot in snap.get_content_slots():
                 slot_installed_path = common.get_installed_snap_path(provider)

snapcraft/internal/repo/snaps.py

@@ -1,6 +1,6 @@
 # -*- Mode:Python; indent-tabs-mode:nil; tab-width:4 -*-
 #
-# Copyright (C) 2017-2019 Canonical Ltd
+# Copyright (C) 2017-2020 Canonical Ltd
 #
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License version 3 as

tests/spread/general/content-interface-provider-found/snaps/provider/snap/snapcraft.yaml

@@ -0,0 +1,20 @@
+name: content-test
+version: '0.1'
+summary: snap using a plug with a content interface should install
+description: |
+  Defining a plug using the content interface should install the snap
+  listed under default-provider.
+
+grade: devel
+confinement: devmode
+
+plugs:
+  content-interface:
+    content: content-interface
+    interface: content
+    target: $SNAP/content
+    default-provider: hello
+
+parts:
+  empty:
+    plugin: nil

tests/spread/general/content-interface-provider-found/task.yaml

@@ -0,0 +1,28 @@
+summary: Build a snap that uses the content interface
+
+environment:
+  SNAP_DIR: snaps/provider
+
+prepare: |
+  #shellcheck source=tests/spread/tools/snapcraft-yaml.sh
+  . "$TOOLS_DIR/snapcraft-yaml.sh"
+  set_base "$SNAP_DIR/snap/snapcraft.yaml"
+
+restore: |
+  cd "$SNAP_DIR"
+  snapcraft clean
+
+  #shellcheck source=tests/spread/tools/snapcraft-yaml.sh
+  . "$TOOLS_DIR/snapcraft-yaml.sh"
+  restore_yaml "snap/snapcraft.yaml"
+
+execute: |
+  cd "$SNAP_DIR"
+
+  snapcraft prime
+
+  if ! snap list hello; then
+    echo "snap listed as default provider was not installed"
+    exit 1
+  fi
+

tests/spread/general/content-interface-provider-not-found/snaps/provider/snap/snapcraft.yaml

@@ -0,0 +1,20 @@
+name: content-test
+version: '0.1'
+summary: snap using a plug with a content interface that cannot be found
+description: |
+  Defining a plug using the content interface should only warn when it
+  cannot find the snap listed under default-provider.
+
+grade: devel
+confinement: devmode
+
+plugs:
+  content-interface:
+    content: content-interface
+    interface: content
+    target: $SNAP/content
+    default-provider: unknown-content-snap
+
+parts:
+  empty:
+    plugin: nil

tests/spread/general/content-interface-provider-not-found/task.yaml

@@ -0,0 +1,24 @@
+summary: Build a snap that uses the content interface with a non published snap
+
+environment:
+  SNAP_DIR: snaps/provider
+
+prepare: |
+  #shellcheck source=tests/spread/tools/snapcraft-yaml.sh
+  . "$TOOLS_DIR/snapcraft-yaml.sh"
+  set_base "$SNAP_DIR/snap/snapcraft.yaml"
+
+restore: |
+  cd "$SNAP_DIR"
+  snapcraft clean
+
+  #shellcheck source=tests/spread/tools/snapcraft-yaml.sh
+  . "$TOOLS_DIR/snapcraft-yaml.sh"
+  restore_yaml "snap/snapcraft.yaml"
+
+execute: |
+  cd "$SNAP_DIR"
+
+  output=$(snapcraft prime)
+
+  echo "$output" | MATCH "Could not install snap defined in plug"