new: store and keep compiled docker-compose and a mean to use-it for services.

The ``docker-compose.yml`` is saved along with an executable ``dc`` and
``.env`` in a directory to be shared as a volume in case we'd like to
launch a subservice in the same setup from a launched service. For instance,
a ``cron`` charm could want to launch ``run-once`` services.

The charm only need to access the ``dc`` binary, this can be done by
sharing the binary as a volume. This is the recommended way to do this:
``\${DOCKER_COMPOSE_PATH}/bin/dc:/bin/dc:ro``. Notice how we use a
docker-compose level variable here as the DOCKER_COMPOSE_PATH will only
be computed after all ``init`` hooks are done. This is the purpose of
the ``.env`` file that is also generated.

These directories are garbage collected if no containers have volumes
connected to it.

bin/compose-core

@@ -2161,6 +2161,98 @@ get_default_project_name() {
 export -f get_default_project_name
 
 
+get_running_compose_containers() {
+    ## XXXvlab: docker bug: there will be a final newline anyway
+    docker ps --filter label="compose.service" --format='{{.ID}}'
+}
+export -f get_running_compose_containers
+
+
+get_volumes_for_container() {
+    local container="$1"
+
+    docker inspect \
+           --format '{{range $mount := .Mounts}}{{$mount.Source}}{{"\x00"}}{{$mount.Destination}}{{"\x00"}}{{end}}' \
+           "$container"
+}
+export -f get_volumes_for_container
+
+is_volume_used() {
+    local volume="$1" container_id src dst
+
+    while read container_id; do
+        while read-0 src dst; do
+            [[ "$src" == "$volume"/* ]] && return 0
+        done < <(get_volumes_for_container "$container_id")
+    done < <(get_running_compose_containers)
+    return 1
+}
+export -f is_volume_used
+
+
+clean_unused_docker_compose() {
+    for f in /var/lib/compose/docker-compose/*; do
+        [ -e "$f" ] || continue
+        is_volume_used "$f" && continue
+        debug "Cleaning unused docker-compose ${f##*/}"
+        rm -rf "$f" || return 1
+    done
+}
+export -f clean_unused_docker_compose
+
+
+file_get_hash() {
+    local file="$1" sha
+    sha=$(sha256sum "$file")
+    sha=${sha:0:64}
+    echo "$sha"
+}
+export -f file_get_hash
+
+
+docker_compose_store() {
+    local file="$1" sha
+
+    sha=$(file_get_hash "$file") || return 1
+    project=$(get_default_project_name) || return 1
+    dst="/var/lib/compose/docker-compose/$sha/$project"
+    mkdir -p "$dst" || return 1
+    cat <<EOF > "$dst/.env" || return 1
+DOCKER_COMPOSE_PATH=$dst
+EOF
+    cp "$file" "$dst/docker-compose.yml" || return 1
+
+    mkdir -p "$dst/bin" || return 1
+
+    cat <<EOF > "$dst/bin/dc" || return 1
+#!/bin/bash
+
+$(declare -f read-0)
+
+docker_run_opts=()
+
+while read-0 opt; do
+    docker_run_opts+=("\$opt")
+done < <(cat "$COMPOSE_LAUNCHER_OPTS")
+
+docker_run_opts+=(
+  "-w" "$dst"
+  "--entrypoint" "/usr/local/bin/docker-compose"
+)
+[ -t 1 ] && {
+    docker_run_opts+=("-ti")
+}
+
+exec docker run "\${docker_run_opts[@]}" "${COMPOSE_DOCKER_IMAGE:-docker.0k.io/compose}" "\$@"
+
+EOF
+
+    chmod +x "$dst/bin/dc" || return 1
+
+    printf "%s" "$sha"
+}
+
+
 launch_docker_compose() {
     local charm docker_compose_tmpdir docker_compose_dir
     docker_compose_tmpdir=$(mktemp -d -t tmp.XXXXXXXXXX)
@@ -2192,9 +2284,21 @@ launch_docker_compose() {
     # done
     mkdir "$docker_compose_dir/.data"
 
+    if [ -z "$COMPOSE_DISABLE_DOCKER_COMPOSE_STORE" ]; then
+        sha=$(docker_compose_store "$docker_compose_dir/docker-compose.yml") || return 1
+    fi
+
     {
         {
-            cd "$docker_compose_dir"
+            if [ -z "$COMPOSE_DISABLE_DOCKER_COMPOSE_STORE" ]; then
+                cd "/var/lib/compose/docker-compose/$sha/$project"
+            else
+                cd "$docker_compose_dir"
+            fi
+            if [ -f ".env" ]; then
+                debug "${WHITE}.env$NORMAL for $DARKYELLOW$SERVICE_PACK$NORMAL:"
+                debug "$(cat ".env" | prefix "  $GRAY|$NORMAL ")"
+            fi
             debug "${WHITE}docker-compose.yml$NORMAL for $DARKYELLOW$SERVICE_PACK$NORMAL:"
             debug "$(cat "docker-compose.yml" | prefix "  $GRAY|$NORMAL ")"
             debug "${WHITE}Launching$NORMAL: docker-compose $@"
@@ -3086,3 +3190,5 @@ esac || exit 1
 if [ "$post_hook" -a "${#services_args[@]}" != 0 ]; then
     run_service_hook post_deploy "${services_args[@]}" || exit 1
 fi
+
+clean_unused_docker_compose || return 1

test/action

@@ -9,7 +9,7 @@ export -f matches
 export grep
 
 tmp=/tmp
-tprog="../bin/compose"
+tprog="../bin/compose-core"
 tprog=$(readlink -f $tprog)
 
 

test/args

@@ -9,7 +9,7 @@ export -f matches
 export grep
 
 tmp=/tmp
-tprog="../bin/compose"
+tprog="../bin/compose-core"
 tprog=$(readlink -f $tprog)
 
 
@@ -26,6 +26,7 @@ init_test() {
     cd "$test_tmpdir"
     export CACHEDIR="$test_tmpdir/.cache"
     export VARDIR="$test_tmpdir/.var"
+    export COMPOSE_DISABLE_DOCKER_COMPOSE_STORE="1"
     mkdir -p "$CACHEDIR"
 }
 

test/base

@@ -9,7 +9,7 @@ export -f matches
 export grep
 
 tmp=/tmp
-tprog="../bin/compose"
+tprog="../bin/compose-core"
 tprog=$(readlink -f $tprog)
 
 
@@ -26,6 +26,7 @@ init_test() {
     cd "$test_tmpdir"
     export CACHEDIR="$test_tmpdir/.cache"
     export VARDIR="$test_tmpdir/.var"
+    export COMPOSE_DISABLE_DOCKER_COMPOSE_STORE="1"
     mkdir -p "$CACHEDIR"
 }
 

test/injection

@@ -9,7 +9,7 @@ export -f matches
 export grep
 
 tmp=/tmp
-tprog="../bin/compose"
+tprog="../bin/compose-core"
 tprog=$(readlink -f $tprog)
 
 
@@ -26,6 +26,7 @@ init_test() {
     cd "$test_tmpdir"
     export CACHEDIR="$test_tmpdir/.cache"
     export VARDIR="$test_tmpdir/.var"
+    export COMPOSE_DISABLE_DOCKER_COMPOSE_STORE="1"
     mkdir -p "$CACHEDIR"
 }
 

test/wget

@@ -9,7 +9,7 @@ export -f matches
 export grep
 
 tmp=/tmp
-tprog="../bin/compose"
+tprog="../bin/compose-core"
 tprog=$(readlink -f $tprog)