lifecycle: only warn when a default provider snap is missing

snapcraft/internal/lifecycle/_runner.py

@@ -82,23 +82,32 @@ 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():
+    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 a plug {content_snap!r}. "
+                    "The missing library report may have false positives listed if those "
+                    "libraries were to be provided by the content snap."
+                )
 
     try:
         global_state = states.GlobalState.load(

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 +1,22 @@
+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"
+
+  snapcraft prime | MATCH "Could not install snap defined in a plug"