From 0ada34b30b2ce5bf3a2ad6d17a5ccfd8d3679802 Mon Sep 17 00:00:00 2001
From: Shizun Ge <shizunge@gmail.com>
Date: Wed, 17 Jan 2024 21:41:41 -0800
Subject: [PATCH] find self service automatically

---
 README.md         |  4 ++--
 src/lib-gantry.sh | 41 +++++++++++++++++++++++++++++++++++++++--
 2 files changed, 41 insertions(+), 4 deletions(-)

diff --git a/README.md b/README.md
index 5a48fe2..a2e334c 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,6 @@
 # Gantry
 
-[*Gantry*](https://github.com/shizunge/gantry) is a tool to update docker swarm services, enhanced [Shepherd](https://github.com/containrrr/shepherd).
+[*Gantry*](https://github.com/shizunge/gantry) is a tool to update docker swarm services, [enhanced Shepherd](docs/migration.md).
 
 ## Usage
 
@@ -54,7 +54,7 @@ You can configure the most behaviors of *Gantry* via environment variables.
 | GANTRY_SERVICES_EXCLUDED         | | A space separated list of services names that are excluded from updating. |
 | GANTRY_SERVICES_EXCLUDED_FILTERS | | A space separated list of [filters](https://docs.docker.com/engine/reference/commandline/service_ls/#filter). Exclude services which match the given filters from updating. |
 | GANTRY_SERVICES_FILTERS          | | A space separated list of [filters](https://docs.docker.com/engine/reference/commandline/service_ls/#filter) that are accepted by `docker service ls --filter` to select services to update. |
-| GANTRY_SERVICES_SELF             | | A service name to indicate whether a service is *Gantry* itself. *Gantry* will be the first service being updated. The manifest inspection will be always performed on the *Gantry* service to avoid an infinity loop of updating itself. |
+| GANTRY_SERVICES_SELF             | | This is optional. *Gantry* will try to find the service name of itself automatically, and update itself firstly. The manifest inspection will be always performed on the *Gantry* service to avoid an infinity loop of updating itself. User can use this to ask *Gantry* to update another service firstly or in case *Gantry* fails to find the service name of itself. |
 
 ### To check if new images are available
 
diff --git a/src/lib-gantry.sh b/src/lib-gantry.sh
index aab2c5a..46bad91 100755
--- a/src/lib-gantry.sh
+++ b/src/lib-gantry.sh
@@ -1,5 +1,5 @@
 #!/bin/sh
-# Copyright (C) 2023 Shizun Ge
+# Copyright (C) 2023-2024 Shizun Ge
 #
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -246,8 +246,45 @@ in_list() {
   return 1
 }
 
+current_container_name() {
+  local ALL_NETWORKS GWBRIDGE_NETWORK IPS;
+  ALL_NETWORKS=$(docker network ls --format {{.ID}}) || return 1;
+  [ -z "${ALL_NETWORKS}" ] && return 0;
+  GWBRIDGE_NETWORK=$(docker network ls --format {{.ID}} --filter "name=docker_gwbridge") || return 1;
+  IPS=$(ip route | grep src | sed -n "s/.* src \(\S*\).*$/\1/p");
+  [ -z "${IPS}" ] && return 0;
+  local NID;
+  for NID in ${ALL_NETWORKS}; do
+    [ "${NID}" = "${GWBRIDGE_NETWORK}" ] && continue;
+    local ALL_LOCAL_NAME_AND_IP;
+    ALL_LOCAL_NAME_AND_IP=$(docker network inspect ${NID} --format "{{range .Containers}}{{.Name}}={{println .IPv4Address}}{{end}}") || return 1;
+    for NAME_AND_IP in ${ALL_LOCAL_NAME_AND_IP}; do
+      [ -z "${NAME_AND_IP}" ] && continue;
+      for IP in ${IPS}; do
+        [ ! $(echo ${NAME_AND_IP} | grep ${IP}) ] && continue;
+        local NAME=$(echo ${NAME_AND_IP} | sed "s/\(.*\)=${IP}.*$/\1/");
+        echo ${NAME};
+        return 0;
+      done;
+    done;
+  done;
+  return 0;
+}
+
+current_service_name() {
+  local CNAME
+  CNAME=$(current_container_name) || return 1
+  [ -z "${CNAME}" ] && return 0
+  SNAME=$(docker container inspect ${CNAME} --format '{{range $key,$value := .Config.Labels}}{{$key}}={{println $value}}{{end}}' | grep "com.docker.swarm.service.name" | sed "s/com.docker.swarm.service.name=\(.*\)$/\1/") || return 1
+  echo ${SNAME}
+}
+
 service_is_self() {
-  local SELF="${GANTRY_SERVICES_SELF:-""}"
+  if [ -z "${GANTRY_SERVICES_SELF}" ]; then
+    export GANTRY_SERVICES_SELF=$(current_service_name)
+    [ -n "${GANTRY_SERVICES_SELF}" ] && log INFO "Set GANTRY_SERVICES_SELF to ${GANTRY_SERVICES_SELF}."
+  fi
+  local SELF="${GANTRY_SERVICES_SELF}"
   local SERVICE_NAME="${1}"
   [ "${SERVICE_NAME}" = "${SELF}" ]
 }