diff --git a/bin/compose b/bin/compose
index 96e6459..5d714f2 100755
--- a/bin/compose
+++ b/bin/compose
@@ -2218,6 +2218,7 @@ get_compose_yml_content() {
         COMPOSE_YML_CONTENT=""
     fi
 
+    COMPOSE_YML_CONTENT=$(merge_yaml_str "$COMPOSE_YML_CONTENT" "${compose_contents[@]}") || return 1
     output=$(echo "$COMPOSE_YML_CONTENT"| shyaml get-value 2>&1)
     if [ "$?" != 0 ]; then
         outputed_something=
@@ -2437,6 +2438,8 @@ display_help() {
     echo "                              command line will be used."
     echo "  --rebuild-relations-to-service, -R SERVICE"
     echo "                              Will rebuild all relations to given service"
+    echo "  --add-compose-content, -Y YAML"
+    echo "                              Will merge some direct YAML with the current compose"
 
     get_docker_compose_opts_help | remove_options_in_option_help_msg --version --help --verbose |
         filter_docker_compose_help_message
@@ -2663,6 +2666,7 @@ export DOCKER_HOST_NET DOCKER_HOST_IP
 services=()
 remainder_args=()
 compose_opts=()
+compose_contents=()
 action_opts=()
 services_args=()
 pos_arg_ct=0
@@ -2725,6 +2729,11 @@ while read-0 arg; do
                     export VERBOSE=true
                     #compose_opts+=("--verbose" "--log-level" "DEBUG")
                     ;;
+                --add-compose-content|-Y)
+                    read-0 value
+                    compose_contents+=("$value")
+                    shift
+                    ;;
                 --dirs)
                     echo "CACHEDIR: $CACHEDIR"
                     echo "VARDIR: $VARDIR"
@@ -2817,6 +2826,7 @@ while read-0 arg; do
 done < <(cla.normalize "$@")
 
 
+export compose_contents
 [ "${services_args[*]}" ] && debug "  ${DARKWHITE}Services:$NORMAL ${DARKYELLOW}${services_args[*]}$NORMAL"
 [ "${compose_opts[*]}" ] && debug "  ${DARKWHITE}Main docker-compose opts:$NORMAL ${compose_opts[*]}"
 [ "${action_posargs[*]}" ] && debug "  ${DARKWHITE}Main docker-compose pos args:$NORMAL ${action_posargs[*]}"
diff --git a/test/injection b/test/injection
new file mode 100755
index 0000000..36600fe
--- /dev/null
+++ b/test/injection
@@ -0,0 +1,92 @@
+#!/usr/bin/env bash-shlib
+# -*- mode: shell-script -*-
+
+include shunit
+
+depends sed grep git mkdir readlink
+
+export -f matches
+export grep
+
+tmp=/tmp
+tprog="../bin/compose"
+tprog=$(readlink -f $tprog)
+
+
+export PATH=".:$PATH"
+short_tprog=$(basename "$tprog")
+
+
+##
+## Convenience function
+##
+
+init_test() {
+    test_tmpdir=$(mktemp -d -t tmp.XXXXXXXXXX)
+    cd "$test_tmpdir"
+    export CACHEDIR="$test_tmpdir/.cache"
+    export VARDIR="$test_tmpdir/.var"
+    mkdir -p "$CACHEDIR"
+}
+
+
+
+tear_test() {
+    rm -rf "$test_tmpdir"
+}
+
+
+##
+## Tests
+##
+
+
+function test_injection {
+
+    init_test
+
+    export CHARM_STORE=$test_tmpdir
+    mkdir -p  $test_tmpdir/{toto,titi}
+    cat <<EOF2 > $test_tmpdir/toto/metadata.yml
+docker-image: toto
+EOF2
+
+    cat <<EOF2 > $test_tmpdir/titi/metadata.yml
+docker-image: titi
+EOF2
+
+    cat <<EOF2 > $test_tmpdir/compose.yml
+web_site:
+  charm: toto
+EOF2
+
+    export DISABLE_SYSTEM_CONFIG_FILE=true
+
+    assert_list <<EOF
+
+### Testing injection of run-time compose code
+
+## -- simple injection, replacing charm
+
+cd "$test_tmpdir"
+injection='
+web_site:
+  charm: titi
+'
+out=\$("$tprog" -Y "\$injection" config web_site 2>/dev/null) || exit 1
+out=\$(echo "\$out" | shyaml get-value services.web_site.image) || exit 1
+expected="titi"
+
+[ "\$out" == "\$expected" ] || {
+    echo -e "DIFF:\n\$(diff <(echo "\$out") <(echo "\$expected"))"
+    exit 1
+}
+
+EOF
+
+    tear_test
+}
+
+
+
+continue_on_error="0" testbench $*