feat(coreos-update-submodule): add an helper to update submodule

The coreos-update-submodule script help to keep our internal git
mirror of upstream repository in sync by automatically pulling
and pushing the target branch for each submodule

.gitmodules

@@ -1,16 +1,20 @@
 [submodule "bitbake"]
 	path = bitbake
 	url = ssh://git@bitbucket.gad.local:7999/ico/bitbake.git
+	upstream-url = https://git.openembedded.org/bitbake/
 	branch = 2.0
 [submodule "layers/openembedded-core"]
 	path = layers/openembedded-core
 	url = ssh://git@bitbucket.gad.local:7999/ico/openembedded-core.git
+	upstream-url = https://git.openembedded.org/openembedded-core
 	branch = kirkstone
 [submodule "layers/meta-openembedded"]
 	path = layers/meta-openembedded
 	url = ssh://git@bitbucket.gad.local:7999/ico/meta-openembedded.git
+	upstream-url = https://git.openembedded.org/meta-openembedded
 	branch = kirkstone
 [submodule "layers/meta-virtualization"]
 	path = layers/meta-virtualization
 	url = ssh://git@bitbucket.gad.local:7999/ico/meta-virtualization.git
+	upstream-url = https://git.yoctoproject.org/meta-virtualization
 	branch = kirkstone

scripts/_coreos-update-submodule-internal

@@ -0,0 +1,20 @@
+#!/usr/bin/env bash
+
+set -e
+
+# This is run by git submodule foreach inside the coreos-update-submodule script
+# Some info is passed via variable. 
+if [ -z "$sm_path" ]; then
+    echo "This scripts should not be run directly"
+    exit 1
+fi
+
+UPSTREAM_URL=$(git config --file "${toplevel}/.gitmodules"  --get "submodule.${name}.upstream-url")
+DOWNSTREAM_URL=$(git config --file "${toplevel}/.gitmodules"  --get "submodule.${name}.url")
+TRACKING_BRANCH=$(git config --file "${toplevel}/.gitmodules"  --get "submodule.${name}.branch")
+
+echo "Pull $TRACKING_BRANCH from ${UPSTREAM_URL} and pushing to ${DOWNSTREAM_URL}"
+
+git pull "${UPSTREAM_URL}" "${TRACKING_BRANCH}" --ff-only
+git push "${DOWNSTREAM_URL}" "${TRACKING_BRANCH}"
+

scripts/coreos-update-submodule

@@ -0,0 +1,38 @@
+#!/usr/bin/env bash
+
+set -e
+
+echo "Updating layers"
+
+# First we go to the root git repository. This will fail if we are not inside
+# a repository
+gitdir=$(git rev-parse --show-toplevel)
+echo "Root Git directory found at $gitdir"
+cd $gitdir
+
+# Ensure we are inside the CoreOS repository
+
+if ! [ -f "coreos-init-build-env" ]; then
+    echo "We are not inside the CoreOS repository"
+    exit 1
+fi
+
+echo "This script will update each submodule by pulling from the upstream url"
+echo "Then the internal mirror on bitbucket.gad.local will be updated"
+
+printf 'Do you want to proceed (y/n)? '
+read answer
+
+if ! [ "$answer" != "${answer#[Yy]}" ] ; then
+    exit 1
+fi
+
+
+echo "Update all submodule to latest commit, using the tracking branch..."
+
+git submodule foreach "_coreos-update-submodule-internal"
+
+echo "All submodule are updated, internal mirror are up to date"
+echo "You can now use git add and git commit to push changes to CoreOS"
+
+git status