Wait for docker base on env RUNNER_WAIT_FOR_DOCKER_IN_SECONDS. (#2440)

src/Misc/layoutroot/run-helper.sh.template

@@ -18,6 +18,20 @@ while [ -h "$SOURCE" ]; do # resolve $SOURCE until the file is no longer a symli
 done
 DIR="$( cd -P "$( dirname "$SOURCE" )" && pwd )"
 
+# Wait for docker to start
+if [ ! -z "$RUNNER_WAIT_FOR_DOCKER_IN_SECONDS" ]; then
+    if [ "$RUNNER_WAIT_FOR_DOCKER_IN_SECONDS" -gt 0 ]; then
+        echo "Waiting for docker to be ready."
+        for i in $(seq "$RUNNER_WAIT_FOR_DOCKER_IN_SECONDS"); do
+            if docker ps > /dev/null 2>&1; then
+                echo "Docker is ready."
+                break
+            fi
+            "$DIR"/safe_sleep.sh 1
+        done
+    fi
+fi
+
 updateFile="update.finished"
 "$DIR"/bin/Runner.Listener run $*