new: [compose-core] add password management function

bin/compose-core

@@ -476,6 +476,121 @@ EOF
 export -f yaml_key_val_str
 
 
+##
+## Intended for charm
+##
+
+
+password:get() {
+    local service="$SERVICE_NAME" label="$1" type="$2" size="${2:-32}"
+
+    local password_file
+    password_file="$(password:get-location "$label" "$type" "$size")"  || return 1
+    cat "$password_file"
+}
+export -f password:get
+
+
+password:get-location() {
+    local service="$SERVICE_NAME" label="$1" type="$2" size="${2:-32}"
+
+    if [ -z "$service" ]; then
+        err "${FUNCNAME[0]}: should be called from a charm hook"
+        return 1
+    fi
+
+    charm=$(get_service_charm "$service") || return 1
+    case "$type" in
+        "internal")
+            :
+            ;;
+        "user")
+            if ! fn.exists "$charm:password:check"; then
+                err "Charm '$charm' doesn't provide a '$charm:password:check' function."
+                echo "  This function is required to check if a user password was changed." >&2
+                return 1
+            fi
+            ;;
+        *)
+            err "${FUNCNAME[0]}: unknown type '$type'"
+            echo "  Should be 'internal' or 'user'." >&2
+            return 1
+            ;;
+    esac
+
+    local password_file="$SERVICE_DATASTORE"/.compose/passwords/"$type"/"$label"
+
+    if ! [ -f "$password_file" ]; then
+        info "Generating password" >&2
+        mkdir -p "${password_file%/*}" &&
+        umask 077 &&
+        openssl rand -base64 32 | tr -d '\n' > "$password_file"
+        e "$password_file"
+        return 0
+    fi
+    if [ "$type" != "user" ]; then
+        info "Using existing secret password" >&2
+        e "$password_file"
+        return 0
+    fi
+    if [ -s "$password_file" ]; then
+        ## password was already set by user through the service
+        e "$password_file"
+        return 0
+    fi
+    if ! out=$("$charm:password:check" "$label" "$password_file"); then
+        err "Failed to check password for '$label' in '$charm'."
+        return 1
+    fi
+    case "$out" in
+        "changed")
+            info "Password for '$label' has changed, forgetting it." >&2
+            e "" > "$password_file"  ## empty file
+            e "$password_file"
+            return 0
+            ;;
+        "ok")
+            e "$password_file"
+            return 0
+            ;;
+        *)
+            err "Unknown return value from '$charm:password:check': $out"
+            return 1
+            ;;
+    esac
+}
+export -f password:get-location
+
+
+passwords:advertise() {
+    local services file label
+    services=("$@")
+    local service
+    complete_msg=""
+    for service in "${services[@]}"; do
+        dir="$DATASTORE"/"$service"/.compose/passwords/user
+        [ -d "$dir" ] || continue
+        msg=""
+        for file in "$dir"/*; do
+            [ -s "$file" ] || continue
+            ls -al "$file" >&2
+            label=${file##*/}
+            msg+="  - $label is $(cat "$file")"$'\n'
+        done
+        if [ -n "$msg" ]; then
+            msg="  ${DARKYELLOW}$service${NORMAL}:"$'\n'"$msg"
+        fi
+        complete_msg+="$msg"
+    done
+    if [ -n "$complete_msg" ]; then
+        echo
+        echo "${WHITE}Compose generated passwords${NORMAL}:"
+        echo "  (Consider changing these password in their respective services)"
+        echo
+        echo "$complete_msg"
+    fi >&2
+}
+
 ##
 ## Docker
 ##