new: [drone-agent] implemented labels

Once labelled, you can use ``node: {label1: value1}`` in
``.drone.yml`` pipeline.

drone-agent/hooks/init

@@ -20,8 +20,17 @@ capacity="$(options-get capacity)" || true
 
 name=${name:-"$(hostname)/$SERVICE_NAME"}
 capacity=${capacity:-2}
-## YYY should implement labels (see https://docs.drone.io/reference/agent/drone-runner-labels/)
 
+service_def=$(get_compose_service_def "$SERVICE_NAME") || exit 1
+labels_def=$(e "$service_def" | shyaml get-value options.labels) || true
+[ "$labels_def" == None ] && labels_def=""
+if [ "$labels_def" ]; then
+    labels=""
+    while read-0 label value; do
+        var+="$label:$value,"
+    done < <(printf "%s" "$labels_def" | shyaml key-values-0)
+    labels="${var::-1}"
+fi
 
 init-config-add "\
 $MASTER_BASE_SERVICE_NAME:
@@ -30,6 +39,7 @@ $MASTER_BASE_SERVICE_NAME:
     DRONE_RPC_SECRET: $secret
     DRONE_RUNNER_NAME: $name
     DRONE_RUNNER_CAPACITY: $capacity
+    $([ "$labels" ] && echo "DRONE_RUNNER_LABELS: '$labels'")
   volumes:
     - /var/run/docker.sock:/var/run/docker.sock
 "