From baca55b13a0c4c53f5f10d7d574c2f3a8c576d10 Mon Sep 17 00:00:00 2001
From: CloudBuilder <cloud-image-builders@lists.canonical.com>
Date: Thu, 9 Jul 2020 23:54:45 +0000
Subject: [PATCH] Imported 2.670

No reason for CPC update specified.
---
 debian/changelog     |  6 ++++++
 live-build/functions | 23 +++++++++++++++++++----
 2 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/debian/changelog b/debian/changelog
index 343ce228..78ce248b 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,3 +1,9 @@
+livecd-rootfs (2.670) groovy; urgency=medium
+
+  * snap_preseed: support channel specification with snap name (LP: #1882374)
+
+ -- Dimitri John Ledkov <xnox@ubuntu.com>  Thu, 09 Jul 2020 18:34:43 +0100
+
 livecd-rootfs (2.669) groovy; urgency=medium
 
   * chroot: disable amd64 codepath on riscv64
diff --git a/live-build/functions b/live-build/functions
index ac08d5de..2f847859 100644
--- a/live-build/functions
+++ b/live-build/functions
@@ -631,11 +631,26 @@ snap_prepare() {
 snap_preseed() {
     # Preseed a snap in the image (snap_prepare must be called once prior)
     local CHROOT_ROOT=$1
+    # $2 can be in the form of snap_name/classic=track/risk/branch
     local SNAP=$2
-    local SNAP_NAME=${SNAP%/*}
-    # Per Ubuntu policy, all seeded snaps (with the exception of the core
-    # snap) must pull from stable/ubuntu-$(release_ver) as their channel.
-    local CHANNEL=${3:-"stable/ubuntu-$(release_ver)"}
+    # strip CHANNEL specification
+    local SNAP_NAME=${SNAP%=*}
+    # strip /classic confinement
+    SNAP_NAME=${SNAP_NAME%/*}
+    # Seed from the specified channel (e.g. core18 latest/stable)
+    # Or Channel endcoded in the snap name (e.g. lxd=4.0/stable/ubuntu-20.04)
+    # Or Ubuntu policy default channel latest/stable/ubuntu-$(release_ver)
+    local CHANNEL=$3
+    if [ -z "$CHANNEL" ]; then
+        case $2 in
+            *=*)
+                CHANNEL=${2#*=}
+                ;;
+            *)
+                CHANNEL="stable/ubuntu-$(release_ver)"
+                ;;
+        esac
+    fi
 
     if [ ! -e "$CHROOT_ROOT/var/lib/snapd/seed/assertions/model" ]; then
         echo "ERROR: Snap model assertion not present, snap_prepare must be called"