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 01/13] 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}" ]
 }

From 08949c4663bc281b1fdac2a9f927762626ea1fbf Mon Sep 17 00:00:00 2001
From: Shizun Ge <shizunge@gmail.com>
Date: Wed, 17 Jan 2024 21:57:01 -0800
Subject: [PATCH 02/13] fix shellcheck and update test comments

---
 src/lib-gantry.sh        | 20 +++++++++++---------
 tests/test_entrypoint.sh |  8 +++++++-
 2 files changed, 18 insertions(+), 10 deletions(-)

diff --git a/src/lib-gantry.sh b/src/lib-gantry.sh
index 46bad91..10d6deb 100755
--- a/src/lib-gantry.sh
+++ b/src/lib-gantry.sh
@@ -248,22 +248,23 @@ in_list() {
 
 current_container_name() {
   local ALL_NETWORKS GWBRIDGE_NETWORK IPS;
-  ALL_NETWORKS=$(docker network ls --format {{.ID}}) || return 1;
+  ALL_NETWORKS=$(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;
+  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 ${NID} --format "{{range .Containers}}{{.Name}}={{println .IPv4Address}}{{end}}") || return 1;
+    ALL_LOCAL_NAME_AND_IP=$(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 ${NAME};
+        echo "${NAME_AND_IP}" | grep -q "${IP}" || continue;
+        local NAME;
+        NAME=$(echo "${NAME_AND_IP}" | sed "s/\(.*\)=${IP}.*$/\1/");
+        echo "${NAME}";
         return 0;
       done;
     done;
@@ -275,13 +276,14 @@ current_service_name() {
   local CNAME
   CNAME=$(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 ${SNAME}
+  SNAME=$(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() {
   if [ -z "${GANTRY_SERVICES_SELF}" ]; then
-    export GANTRY_SERVICES_SELF=$(current_service_name)
+    GANTRY_SERVICES_SELF=$(current_service_name)
+    export GANTRY_SERVICES_SELF
     [ -n "${GANTRY_SERVICES_SELF}" ] && log INFO "Set GANTRY_SERVICES_SELF to ${GANTRY_SERVICES_SELF}."
   fi
   local SELF="${GANTRY_SERVICES_SELF}"
diff --git a/tests/test_entrypoint.sh b/tests/test_entrypoint.sh
index e5763ab..9f457f3 100755
--- a/tests/test_entrypoint.sh
+++ b/tests/test_entrypoint.sh
@@ -471,6 +471,10 @@ test_MANIFEST_CMD_none() {
   export GANTRY_UPDATE_OPTIONS="--force"
   STDOUT=$(run_gantry "${FUNCNAME[0]}" 2>&1 | tee >(cat 1>&2))
 
+  # Do not set GANTRY_SERVICES_SELF, it should be set autoamtically
+  # If we are not testing gantry inside a container, it should failed to find the service name.
+  # To test gantry container, we need to use run_gantry_container.
+  expect_no_message "${STDOUT}" ".*GRANTRY_SERVICES_SELF.*"
   # Gantry is still trying to update the service.
   # But it will see no new images.
   expect_no_message "${STDOUT}" "${SKIP_UPDATING_SERVICE}.*${SERVICE_NAME}"
@@ -495,7 +499,7 @@ test_MANIFEST_CMD_none() {
 }
 
 test_MANIFEST_CMD_none_SERVICES_SELF() {
-  # If the service is self, it will always run manifest checking.
+  # If the service is self, it will always run manifest checking. Even if the CMD is set to none
   local IMAGE_WITH_TAG="${1}"
   local SERVICE_NAME STDOUT
   SERVICE_NAME="gantry-test-$(unique_id)"
@@ -505,11 +509,13 @@ test_MANIFEST_CMD_none_SERVICES_SELF() {
   start_replicated_service "${SERVICE_NAME}" "${IMAGE_WITH_TAG}"
   # No image updates after service started.
 
+  # Explicitly set GANTRY_SERVICES_SELF
   export GANTRY_SERVICES_FILTERS="name=${SERVICE_NAME}"
   export GANTRY_SERVICES_SELF="${SERVICE_NAME}"
   export GANTRY_MANIFEST_CMD="none"
   STDOUT=$(run_gantry "${FUNCNAME[0]}" 2>&1 | tee >(cat 1>&2))
 
+  expect_no_message "${STDOUT}" ".*GRANTRY_SERVICES_SELF.*"
   expect_no_message "${STDOUT}" "${SKIP_UPDATING_SERVICE}.*${SERVICE_NAME}"
   expect_message    "${STDOUT}" "${SERVICE_NAME}.*${NO_NEW_IMAGE}"
   expect_no_message "${STDOUT}" "${SERVICE_NAME}.*${UPDATED}"

From b4d9a79f1ea15a208bebd0e57b261a021fce18e6 Mon Sep 17 00:00:00 2001
From: Shizun Ge <shizunge@gmail.com>
Date: Wed, 17 Jan 2024 22:36:27 -0800
Subject: [PATCH 03/13] add provenance: false to avoid unknown images

---
 .github/workflows/on-push.yml    | 1 +
 .github/workflows/on-release.yml | 1 +
 2 files changed, 2 insertions(+)

diff --git a/.github/workflows/on-push.yml b/.github/workflows/on-push.yml
index c808489..e97fb11 100644
--- a/.github/workflows/on-push.yml
+++ b/.github/workflows/on-push.yml
@@ -103,6 +103,7 @@ jobs:
           push: true
           tags: ${{ steps.meta.outputs.tags }}
           labels: ${{ steps.meta.outputs.labels }}
+          provenance: false
       # - name: Post push tests
       #   run: |
       #     echo "Start running tests"
diff --git a/.github/workflows/on-release.yml b/.github/workflows/on-release.yml
index da8af00..efd891c 100644
--- a/.github/workflows/on-release.yml
+++ b/.github/workflows/on-release.yml
@@ -96,6 +96,7 @@ jobs:
           push: true
           tags: ${{ steps.meta.outputs.tags }}
           labels: ${{ steps.meta.outputs.labels }}
+          provenance: false
       # - name: Post push tests
       #   run: |
       #     echo "Start running tests"

From a6372643d470b0f1d3e001efcf3fb6b3809326ef Mon Sep 17 00:00:00 2001
From: Shizun Ge <shizunge@gmail.com>
Date: Wed, 17 Jan 2024 22:48:30 -0800
Subject: [PATCH 04/13] remove image first then report overall status

---
 src/lib-gantry.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/lib-gantry.sh b/src/lib-gantry.sh
index 10d6deb..70e06ea 100755
--- a/src/lib-gantry.sh
+++ b/src/lib-gantry.sh
@@ -586,6 +586,6 @@ gantry_update_services_list() {
 
 gantry_finalize() {
   local STACK="${1:-gantry}"
-  report_services;
   remove_images "${STACK}_image-remover"
+  report_services;
 }

From e3cd279bcd6acfabfe9d95e62090b32a96422dd4 Mon Sep 17 00:00:00 2001
From: Shizun Ge <shizunge@gmail.com>
Date: Wed, 17 Jan 2024 22:49:12 -0800
Subject: [PATCH 05/13] add pre and post update cmd

---
 src/entrypoint.sh | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/src/entrypoint.sh b/src/entrypoint.sh
index 386c8d2..8a51d4e 100755
--- a/src/entrypoint.sh
+++ b/src/entrypoint.sh
@@ -50,6 +50,26 @@ skip_current_node() {
   return 1
 }
 
+run_pre_update_cmd() {
+  local CMD RT
+  CMD=${GANTRY_PRE_UPDATE_CMD:-""}
+  [ -z "${CMD}" ] && return 0
+  log INFO "Run pre update command: ${CMD}"
+  eval "${CMD}"
+  RT=$?
+  log INFO "Finish pre update command. Return value ${RT}."
+}
+
+run_post_update_cmd() {
+  local CMD RT
+  CMD=${GANTRY_POST_UPDATE_CMD:-""}
+  [ -z "${CMD}" ] && return 0
+  log INFO "Run post update command: ${CMD}"
+  eval "${CMD}"
+  RT=$?
+  log INFO "Finish post update command. Return value ${RT}."
+}
+
 gantry() {
   local STACK="${1:-gantry}"
   local START_TIME=
@@ -64,6 +84,8 @@ gantry() {
   local DOCKER_HUB_RATE_USED=
   local TIME_ELAPSED=
 
+  run_pre_update_cmd
+
   log INFO "Starting."
   gantry_initialize "${STACK}"
   ACCUMULATED_ERRORS=$((ACCUMULATED_ERRORS + $?))
@@ -95,6 +117,9 @@ gantry() {
   else
     log INFO "${MESSAGE}"
   fi
+
+  run_post_update_cmd
+
   return ${ACCUMULATED_ERRORS}
 }
 

From c58a0ec50c86a2dee860e369fdf5f52b471cdb33 Mon Sep 17 00:00:00 2001
From: Shizun Ge <shizunge@gmail.com>
Date: Wed, 17 Jan 2024 23:26:35 -0800
Subject: [PATCH 06/13] add a test for pre and post update cmd.

---
 tests/run_all_tests.sh   |  1 +
 tests/test_entrypoint.sh | 38 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 39 insertions(+)

diff --git a/tests/run_all_tests.sh b/tests/run_all_tests.sh
index 478ba52..f2f56c7 100755
--- a/tests/run_all_tests.sh
+++ b/tests/run_all_tests.sh
@@ -102,6 +102,7 @@ main() {
     test_options_LOG_LEVEL_none \
     test_options_UPDATE_OPTIONS \
     test_options_CLEANUP_IMAGES_false \
+    test_options_PRE_POST_UPDATE_CMD \
   "
   local LOGIN_TESTS="\
     test_login_config \
diff --git a/tests/test_entrypoint.sh b/tests/test_entrypoint.sh
index 9f457f3..4df7eb7 100755
--- a/tests/test_entrypoint.sh
+++ b/tests/test_entrypoint.sh
@@ -865,3 +865,41 @@ test_options_CLEANUP_IMAGES_false() {
   prune_local_test_image "${IMAGE_WITH_TAG}"
   finalize_test "${FUNCNAME[0]}"
 }
+
+test_options_PRE_POST_UPDATE_CMD() {
+  local IMAGE_WITH_TAG="${1}"
+  local SERVICE_NAME STDOUT
+  SERVICE_NAME="gantry-test-$(unique_id)"
+
+  initialize_test "${FUNCNAME[0]}"
+  build_and_push_test_image "${IMAGE_WITH_TAG}"
+  start_replicated_service "${SERVICE_NAME}" "${IMAGE_WITH_TAG}"
+
+  export GANTRY_SERVICES_FILTERS="name=${SERVICE_NAME}"
+  export GANTRY_PRE_UPDATE_CMD="echo \"Pre update\""
+  export GANTRY_POST_UPDATE_CMD="echo \"Post update\""
+  STDOUT=$(run_gantry "${FUNCNAME[0]}" 2>&1 | tee >(cat 1>&2))
+
+  expect_message    "${STDOUT}" "Pre update"
+  expect_no_message "${STDOUT}" "${SKIP_UPDATING_SERVICE}.*${SERVICE_NAME}"
+  expect_message    "${STDOUT}" "${SERVICE_NAME}.*${NO_NEW_IMAGE}"
+  expect_no_message "${STDOUT}" "${SERVICE_NAME}.*${UPDATED}"
+  expect_no_message "${STDOUT}" "${SERVICE_NAME}.*${NO_UPDATES}"
+  expect_no_message "${STDOUT}" "${ROLLING_BACK}.*${SERVICE_NAME}"
+  expect_no_message "${STDOUT}" "${FAILED_TO_ROLLBACK}.*${SERVICE_NAME}"
+  expect_no_message "${STDOUT}" "${ROLLED_BACK}.*${SERVICE_NAME}"
+  expect_message    "${STDOUT}" "${NO_SERVICES_UPDATED}"
+  expect_no_message "${STDOUT}" "${NUM_SERVICES_UPDATED}"
+  expect_no_message "${STDOUT}" "${NUM_SERVICES_UPDATE_FAILED}"
+  expect_message    "${STDOUT}" "${NO_IMAGES_TO_REMOVE}"
+  expect_no_message "${STDOUT}" "${REMOVING_NUM_IMAGES}"
+  expect_no_message "${STDOUT}" "${SKIP_REMOVING_IMAGES}"
+  expect_no_message "${STDOUT}" "${REMOVED_IMAGE}.*${IMAGE_WITH_TAG}"
+  expect_no_message "${STDOUT}" "${FAILED_TO_REMOVE_IMAGE}.*${IMAGE_WITH_TAG}"
+  expect_message    "${STDOUT}" "Post update"
+
+  stop_service "${SERVICE_NAME}"
+  prune_local_test_image "${IMAGE_WITH_TAG}"
+  finalize_test "${FUNCNAME[0]}"
+}
+

From 8e9553fe99b45548d0c9513e47dafab1f0296865 Mon Sep 17 00:00:00 2001
From: Shizun Ge <shizunge@gmail.com>
Date: Wed, 17 Jan 2024 23:38:10 -0800
Subject: [PATCH 07/13] update options to PRE_RUN_CMD and POST_RUN_CMD

---
 src/entrypoint.sh        | 30 ++++++++++++++++--------------
 tests/lib-gantry-test.sh |  4 ++++
 tests/run_all_tests.sh   |  2 +-
 tests/test_entrypoint.sh |  6 +++---
 4 files changed, 24 insertions(+), 18 deletions(-)

diff --git a/src/entrypoint.sh b/src/entrypoint.sh
index 8a51d4e..990b362 100755
--- a/src/entrypoint.sh
+++ b/src/entrypoint.sh
@@ -50,24 +50,26 @@ skip_current_node() {
   return 1
 }
 
-run_pre_update_cmd() {
-  local CMD RT
-  CMD=${GANTRY_PRE_UPDATE_CMD:-""}
+exec_pre_run_cmd() {
+  local CMD RT LOG
+  CMD=${GANTRY_PRE_RUN_CMD:-""}
   [ -z "${CMD}" ] && return 0
-  log INFO "Run pre update command: ${CMD}"
-  eval "${CMD}"
+  log INFO "Run pre-run command: ${CMD}"
+  LOG=$(eval "${CMD}")
   RT=$?
-  log INFO "Finish pre update command. Return value ${RT}."
+  log INFO "${LOG}"
+  log INFO "Finish pre-run command. Return value ${RT}."
 }
 
-run_post_update_cmd() {
-  local CMD RT
-  CMD=${GANTRY_POST_UPDATE_CMD:-""}
+exec_post_run_cmd() {
+  local CMD RT LOG
+  CMD=${GANTRY_POST_RUN_CMD:-""}
   [ -z "${CMD}" ] && return 0
-  log INFO "Run post update command: ${CMD}"
-  eval "${CMD}"
+  log INFO "Run post-run command: ${CMD}"
+  LOG=$(eval "${CMD}")
   RT=$?
-  log INFO "Finish post update command. Return value ${RT}."
+  log INFO "${LOG}"
+  log INFO "Finish post-run command. Return value ${RT}."
 }
 
 gantry() {
@@ -84,7 +86,7 @@ gantry() {
   local DOCKER_HUB_RATE_USED=
   local TIME_ELAPSED=
 
-  run_pre_update_cmd
+  exec_pre_run_cmd
 
   log INFO "Starting."
   gantry_initialize "${STACK}"
@@ -118,7 +120,7 @@ gantry() {
     log INFO "${MESSAGE}"
   fi
 
-  run_post_update_cmd
+  exec_post_run_cmd
 
   return ${ACCUMULATED_ERRORS}
 }
diff --git a/tests/lib-gantry-test.sh b/tests/lib-gantry-test.sh
index 6ef7cff..58da6aa 100755
--- a/tests/lib-gantry-test.sh
+++ b/tests/lib-gantry-test.sh
@@ -38,6 +38,8 @@ initialize_test() {
   export GANTRY_SERVICES_SELF=
   export GANTRY_MANIFEST_CMD=
   export GANTRY_MANIFEST_OPTIONS=
+  export GANTRY_PRE_RUN_CMD=
+  export GANTRY_POST_RUN_CMD=
   export GANTRY_ROLLBACK_ON_FAILURE=
   export GANTRY_ROLLBACK_OPTIONS=
   export GANTRY_UPDATE_JOBS=
@@ -334,6 +336,8 @@ run_gantry_container() {
     --env "GANTRY_SERVICES_SELF=${GANTRY_SERVICES_SELF}" \
     --env "GANTRY_MANIFEST_CMD=${GANTRY_MANIFEST_CMD}" \
     --env "GANTRY_MANIFEST_OPTIONS=${GANTRY_MANIFEST_OPTIONS}" \
+    --env "GANTRY_PRE_RUN_CMD=${GANTRY_PRE_RUN_CMD}" \
+    --env "GANTRY_POST_RUN_CMD=${GANTRY_POST_RUN_CMD}" \
     --env "GANTRY_ROLLBACK_ON_FAILURE=${GANTRY_ROLLBACK_ON_FAILURE}" \
     --env "GANTRY_ROLLBACK_OPTIONS=${GANTRY_ROLLBACK_OPTIONS}" \
     --env "GANTRY_UPDATE_JOBS=${GANTRY_UPDATE_JOBS}" \
diff --git a/tests/run_all_tests.sh b/tests/run_all_tests.sh
index f2f56c7..051a9a9 100755
--- a/tests/run_all_tests.sh
+++ b/tests/run_all_tests.sh
@@ -102,7 +102,7 @@ main() {
     test_options_LOG_LEVEL_none \
     test_options_UPDATE_OPTIONS \
     test_options_CLEANUP_IMAGES_false \
-    test_options_PRE_POST_UPDATE_CMD \
+    test_options_PRE_POST_RUN_CMD \
   "
   local LOGIN_TESTS="\
     test_login_config \
diff --git a/tests/test_entrypoint.sh b/tests/test_entrypoint.sh
index 4df7eb7..9b8e66b 100755
--- a/tests/test_entrypoint.sh
+++ b/tests/test_entrypoint.sh
@@ -866,7 +866,7 @@ test_options_CLEANUP_IMAGES_false() {
   finalize_test "${FUNCNAME[0]}"
 }
 
-test_options_PRE_POST_UPDATE_CMD() {
+test_options_PRE_POST_RUN_CMD() {
   local IMAGE_WITH_TAG="${1}"
   local SERVICE_NAME STDOUT
   SERVICE_NAME="gantry-test-$(unique_id)"
@@ -876,8 +876,8 @@ test_options_PRE_POST_UPDATE_CMD() {
   start_replicated_service "${SERVICE_NAME}" "${IMAGE_WITH_TAG}"
 
   export GANTRY_SERVICES_FILTERS="name=${SERVICE_NAME}"
-  export GANTRY_PRE_UPDATE_CMD="echo \"Pre update\""
-  export GANTRY_POST_UPDATE_CMD="echo \"Post update\""
+  export GANTRY_PRE_RUN_CMD="echo \"Pre update\""
+  export GANTRY_POST_RUN_CMD="echo \"Post update\""
   STDOUT=$(run_gantry "${FUNCNAME[0]}" 2>&1 | tee >(cat 1>&2))
 
   expect_message    "${STDOUT}" "Pre update"

From 69db69a3195a0f12bbfb0eb7b8b35871830f6189 Mon Sep 17 00:00:00 2001
From: Shizun Ge <shizunge@gmail.com>
Date: Wed, 17 Jan 2024 23:53:16 -0800
Subject: [PATCH 08/13] export LOG_LEVEL and NODE_NAME in entrypoint.sh

---
 src/entrypoint.sh | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/entrypoint.sh b/src/entrypoint.sh
index 990b362..d3799c4 100755
--- a/src/entrypoint.sh
+++ b/src/entrypoint.sh
@@ -128,6 +128,7 @@ gantry() {
 main() {
   LOG_LEVEL="${GANTRY_LOG_LEVEL:-${LOG_LEVEL}}"
   NODE_NAME="${GANTRY_NODE_NAME:-${NODE_NAME}}"
+  export LOG_LEVEL NODE_NAME
   local SLEEP_SECONDS="${GANTRY_SLEEP_SECONDS:-0}"
   if ! is_number "${SLEEP_SECONDS}"; then 
     log ERROR "GANTRY_SLEEP_SECONDS must be a number. Got \"${GANTRY_SLEEP_SECONDS}\"."

From 1183f72d137b200f4f07469d9c30e13df3c114de Mon Sep 17 00:00:00 2001
From: Shizun Ge <shizunge@gmail.com>
Date: Thu, 18 Jan 2024 00:07:14 -0800
Subject: [PATCH 09/13] [readme] update readme about pre/post run cmd.

---
 README.md                |  6 ++++--
 tests/lib-gantry-test.sh | 10 +++++-----
 2 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/README.md b/README.md
index a2e334c..4ce8043 100644
--- a/README.md
+++ b/README.md
@@ -4,7 +4,7 @@
 
 ## Usage
 
-We release *Gantry* as a container [image](https://hub.docker.com/r/shizunge/gantry). You can create a docker service and run it on a swarm manager node.
+*Gantry* is released as a container [image](https://hub.docker.com/r/shizunge/gantry). You can create a docker service and run it on a swarm manager node.
 
 ```
 docker service create \
@@ -18,7 +18,7 @@ docker service create \
 
 Or with docker compose, see the [example](examples/docker-compose.yml).
 
-You can also run *Gantry* as a script outside the container `source ./src/entrypoint.sh`. *Gantry* is written to work with `busybox ash`. It should also work with `bash`.
+You can also run *Gantry* as a script outside the container `source ./src/entrypoint.sh`. *Gantry* is written to work with `busybox ash` as well as `bash`.
 
 ## Configurations
 
@@ -30,6 +30,8 @@ You can configure the most behaviors of *Gantry* via environment variables.
 |-----------------------|---------|------------|
 | GANTRY_LOG_LEVEL      | INFO | Control how many logs generated by *Gantry*. Valid values are `NONE`, `ERROR`, `WARN`, `INFO`, `DEBUG` (case sensitive). |
 | GANTRY_NODE_NAME      |      | Add node name to logs. |
+| GANTRY_POST_RUN_CMD   |      | Command(s) to eval after each updating iteration. |
+| GANTRY_PRE_RUN_CMD    |      | Command(s) to eval before each updating iteration. |
 | GANTRY_SLEEP_SECONDS  | 0    | Sleep time between two updates. Set it to 0 to run *Gantry* once and then exit. |
 | TZ                    |      | Set timezone for time in logs. |
 
diff --git a/tests/lib-gantry-test.sh b/tests/lib-gantry-test.sh
index 58da6aa..5528d55 100755
--- a/tests/lib-gantry-test.sh
+++ b/tests/lib-gantry-test.sh
@@ -22,7 +22,10 @@ initialize_test() {
   echo "=============================="
   export GANTRY_LOG_LEVEL="DEBUG"
   export GANTRY_NODE_NAME=
+  export GANTRY_POST_RUN_CMD=
+  export GANTRY_PRE_RUN_CMD=
   export GANTRY_SLEEP_SECONDS=
+  export GANTRY_ROLLBACK_ON_FAILURE=
   export GANTRY_REGISTRY_CONFIG=
   export GANTRY_REGISTRY_CONFIG_FILE=
   export GANTRY_REGISTRY_CONFIGS_FILE=
@@ -38,9 +41,6 @@ initialize_test() {
   export GANTRY_SERVICES_SELF=
   export GANTRY_MANIFEST_CMD=
   export GANTRY_MANIFEST_OPTIONS=
-  export GANTRY_PRE_RUN_CMD=
-  export GANTRY_POST_RUN_CMD=
-  export GANTRY_ROLLBACK_ON_FAILURE=
   export GANTRY_ROLLBACK_OPTIONS=
   export GANTRY_UPDATE_JOBS=
   export GANTRY_UPDATE_OPTIONS=
@@ -320,6 +320,8 @@ run_gantry_container() {
     --mount type=bind,source=/var/run/docker.sock,target=/var/run/docker.sock \
     --env "GANTRY_LOG_LEVEL=${GANTRY_LOG_LEVEL}" \
     --env "GANTRY_NODE_NAME=${GANTRY_NODE_NAME}" \
+    --env "GANTRY_POST_RUN_CMD=${GANTRY_POST_RUN_CMD}" \
+    --env "GANTRY_PRE_RUN_CMD=${GANTRY_PRE_RUN_CMD}" \
     --env "GANTRY_SLEEP_SECONDS=${GANTRY_SLEEP_SECONDS}" \
     --env "GANTRY_REGISTRY_CONFIG=${GANTRY_REGISTRY_CONFIG}" \
     --env "GANTRY_REGISTRY_CONFIG_FILE=${GANTRY_REGISTRY_CONFIG_FILE}" \
@@ -336,8 +338,6 @@ run_gantry_container() {
     --env "GANTRY_SERVICES_SELF=${GANTRY_SERVICES_SELF}" \
     --env "GANTRY_MANIFEST_CMD=${GANTRY_MANIFEST_CMD}" \
     --env "GANTRY_MANIFEST_OPTIONS=${GANTRY_MANIFEST_OPTIONS}" \
-    --env "GANTRY_PRE_RUN_CMD=${GANTRY_PRE_RUN_CMD}" \
-    --env "GANTRY_POST_RUN_CMD=${GANTRY_POST_RUN_CMD}" \
     --env "GANTRY_ROLLBACK_ON_FAILURE=${GANTRY_ROLLBACK_ON_FAILURE}" \
     --env "GANTRY_ROLLBACK_OPTIONS=${GANTRY_ROLLBACK_OPTIONS}" \
     --env "GANTRY_UPDATE_JOBS=${GANTRY_UPDATE_JOBS}" \

From 1f16f9a53a6324437962f2e7ce920d6b8146ecea Mon Sep 17 00:00:00 2001
From: Shizun Ge <shizunge@gmail.com>
Date: Thu, 18 Jan 2024 11:41:55 -0800
Subject: [PATCH 10/13] [lib] wait_service_state accepts --running and
 --complete arguments.

---
 src/lib-common.sh | 32 +++++++++++++++++++++-----------
 src/lib-gantry.sh |  2 +-
 2 files changed, 22 insertions(+), 12 deletions(-)

diff --git a/src/lib-common.sh b/src/lib-common.sh
index f462deb..2c0fc04 100755
--- a/src/lib-common.sh
+++ b/src/lib-common.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
@@ -75,6 +75,7 @@ log_docker_time() {
   busybox date -d "@${EPOCH}" -Iseconds 2>&1
 }
 
+# Convert logs from `docker service logs` to `log` format.
 # docker service logs --timestamps --no-task-ids <service>
 # 2023-06-22T01:20:54.535860111Z <task>@<node>    | <msg>
 log_docker_line() {
@@ -188,6 +189,10 @@ swarm_network_arguments() {
   echo "${NETWORK_ARG} --dns=${NETWORK_DNS_IP}"
 }
 
+timezone_arguments() {
+  echo "--env \"TZ=${TZ}\" --mount type=bind,source=/etc/localtime,destination=/etc/localtime,ro"
+}
+
 get_docker_command_name_arg() {
   # get <NAME> from "--name <NAME>" or "--name=<NAME>"
   echo "${@}" | tr '\n' ' ' | sed -E 's/.*--name[ =]([^ ]*).*/\1/'
@@ -244,12 +249,17 @@ docker_service_task_states() {
   done
 }
 
+# Usage: wait_service_state <SERVICE_NAME> [--running] [--complete]
+# Wait for the service, usually a global job or a replicated job, to reach either running or complete state.
+# The function returns immediately when any of the tasks of the service fails.
+# In case of task failing, the function returns a non-zero value.
 wait_service_state() {
-  local SERVICE_NAME="${1}"
-  local WAIT_RUNNING="${2:-"false"}"
-  local WAIT_COMPLETE="${3:-"false"}"
-  local RETURN_VALUE="${4:-0}"
-  local SLEEP_SECONDS="${5:-1}"
+  local SERVICE_NAME="${1}"; shift;
+  local WAIT_RUNNING WAIT_COMPLETE;
+  WAIT_RUNNING=$(echo "${@}" | grep -q -- "--running" && echo "true" || echo "false")
+  WAIT_COMPLETE=$(echo "${@}" | grep -q -- "--complete" && echo "true" || echo "false")
+  local RETURN_VALUE=0
+  local SLEEP_SECONDS=1
   local STATES=
   STATES=$(docker_service_task_states "${SERVICE_NAME}" 2>&1)
   while is_true "${WAIT_RUNNING}" || is_true "${WAIT_COMPLETE}" ; do
@@ -326,16 +336,16 @@ docker_replicated_job() {
   IS_DETACH=$(get_docker_command_detach "${@}")
   # Add "--detach" to work around https://github.com/docker/cli/issues/2979
   # The Docker CLI does not exit on failures.
-  local WAIT_RUNNING="false"
-  local WAIT_COMPLETE=
-  WAIT_COMPLETE=$(if ${IS_DETACH}; then echo "false"; else echo "true"; fi)
   log INFO "Starting service ${SERVICE_NAME}."
   docker service create \
     --mode replicated-job --detach \
     "${@}" >/dev/null
   local RETURN_VALUE=$?
-  # return the code from wait_service_state
-  wait_service_state "${SERVICE_NAME}" "${WAIT_RUNNING}" "${WAIT_COMPLETE}" "${RETURN_VALUE}"
+  # If the command line does not contain '--detach', the function returns til the replicated job is complete.
+  if ! "${IS_DETACH}"; then
+    wait_service_state "${SERVICE_NAME}" --complete || return $?
+  fi
+  return ${RETURN_VALUE}
 }
 
 container_status() {
diff --git a/src/lib-gantry.sh b/src/lib-gantry.sh
index 70e06ea..313e5c1 100755
--- a/src/lib-gantry.sh
+++ b/src/lib-gantry.sh
@@ -161,7 +161,7 @@ remove_images() {
       done;
       log INFO \"Done.\";
       "
-  wait_service_state "${SERVICE_NAME}" "false" "true";
+  wait_service_state "${SERVICE_NAME}" --complete;
   docker_service_logs "${SERVICE_NAME}"
   docker_service_remove "${SERVICE_NAME}"
 }

From e205d06b3899bf98d167a9623a8e23d88dd4849c Mon Sep 17 00:00:00 2001
From: Shizun Ge <shizunge@gmail.com>
Date: Thu, 18 Jan 2024 18:08:37 -0800
Subject: [PATCH 11/13] [examples] add an example for pre and post run command.

---
 README.md                                     |  2 +-
 examples/README.md                            | 10 ++++
 examples/{ => cronjob}/docker-compose.yml     |  3 +-
 examples/prune-and-watchtower/README.md       |  8 +++
 .../prune-and-watchtower/docker-compose.yml   | 53 +++++++++++++++++++
 5 files changed, 74 insertions(+), 2 deletions(-)
 create mode 100644 examples/README.md
 rename examples/{ => cronjob}/docker-compose.yml (79%)
 create mode 100644 examples/prune-and-watchtower/README.md
 create mode 100644 examples/prune-and-watchtower/docker-compose.yml

diff --git a/README.md b/README.md
index 4ce8043..610fb5e 100644
--- a/README.md
+++ b/README.md
@@ -16,7 +16,7 @@ docker service create \
   shizunge/gantry
 ```
 
-Or with docker compose, see the [example](examples/docker-compose.yml).
+Or with docker compose, see the [example](examples/README.md).
 
 You can also run *Gantry* as a script outside the container `source ./src/entrypoint.sh`. *Gantry* is written to work with `busybox ash` as well as `bash`.
 
diff --git a/examples/README.md b/examples/README.md
new file mode 100644
index 0000000..bbabf36
--- /dev/null
+++ b/examples/README.md
@@ -0,0 +1,10 @@
+# Examples
+
+## [cronjob](./cronjob)
+
+Run *gantry* at the specific time.
+
+## [prune-and-watchtower](./prune-and-watchtower)
+
+Run [`docker system prune`](https://docs.docker.com/engine/reference/commandline/system_prune/) and [*watchtower*](https://github.com/containrrr/watchtower) with *gantry*.
+
diff --git a/examples/docker-compose.yml b/examples/cronjob/docker-compose.yml
similarity index 79%
rename from examples/docker-compose.yml
rename to examples/cronjob/docker-compose.yml
index 4e52cd7..b3ac1a0 100644
--- a/examples/docker-compose.yml
+++ b/examples/cronjob/docker-compose.yml
@@ -7,7 +7,8 @@ services:
       - /var/run/docker.sock:/var/run/docker.sock
     environment:
       - "GANTRY_NODE_NAME={{.Node.Hostname}}"
-      - "GANTRY_SERVICES_SELF=${STACK}_gantry"
+      # The gantry service is able to find the name of itself service. Use GANTRY_SERVICES_SELF when you want to set a different value.
+      # - "GANTRY_SERVICES_SELF=${STACK}_gantry"
       - "GANTRY_SLEEP_SECONDS=0"
     deploy:
       replicas: 0
diff --git a/examples/prune-and-watchtower/README.md b/examples/prune-and-watchtower/README.md
new file mode 100644
index 0000000..9389e98
--- /dev/null
+++ b/examples/prune-and-watchtower/README.md
@@ -0,0 +1,8 @@
+# prune and watchtower
+
+This example run `docker system prune` and *watchtower* before updating docker swarm services.
+
+* [`docker system prune`](https://docs.docker.com/engine/reference/commandline/system_prune/) removes all unused containers, networks and images.
+* [*watchtower*](https://github.com/containrrr/watchtower) updates standalone docker containers.
+* [*gantry*](https://github.com/shizunge/gantry) updates docker swarm services.
+
diff --git a/examples/prune-and-watchtower/docker-compose.yml b/examples/prune-and-watchtower/docker-compose.yml
new file mode 100644
index 0000000..1c6a8f0
--- /dev/null
+++ b/examples/prune-and-watchtower/docker-compose.yml
@@ -0,0 +1,53 @@
+version: "3.8"
+
+services:
+  gantry:
+    image: shizunge/gantry
+    volumes:
+      - /var/run/docker.sock:/var/run/docker.sock
+    environment:
+      - "GANTRY_NODE_NAME={{.Node.Hostname}}"
+      - "GANTRY_PRE_RUN_CMD=SERVICE_NAME=gantry-prune;
+                            docker service remove $${SERVICE_NAME} 2>/dev/null;
+                            docker service create --mode global-job --name $${SERVICE_NAME}
+                              --mount type=bind,source=/var/run/docker.sock,destination=/var/run/docker.sock
+                              --entrypoint docker
+                              alpinelinux/docker-cli
+                              system prune -f;
+                            docker service logs $${SERVICE_NAME};
+                            docker service remove $${SERVICE_NAME};
+                            SERVICE_NAME=gantry-container;
+                            docker service remove $${SERVICE_NAME} 2>/dev/null;
+                            docker service create --mode global-job --name $${SERVICE_NAME}
+                              --mount type=bind,source=/var/run/docker.sock,destination=/var/run/docker.sock
+                              ghcr.io/containrrr/watchtower
+                              --cleanup=true
+                              --label-enable
+                              --run-once=true
+                              --stop-timeout=60s
+                              --tlsverify=true;
+                            docker service logs $${SERVICE_NAME};
+                            docker service remove $${SERVICE_NAME};
+        "
+      - "GANTRY_POST_RUN_CMD=echo \"This is a post run command.\";"
+      - "GANTRY_SLEEP_SECONDS=0"
+    deploy:
+      replicas: 0
+      placement:
+        constraints:
+          - node.role==manager
+      restart_policy:
+        condition: none
+      labels:
+        - swarm.cronjob.enable=true
+        - swarm.cronjob.schedule=45 23 0 * * *
+        - swarm.cronjob.skip-running=true
+
+  cronjob:
+    image: crazymax/swarm-cronjob:latest
+    volumes:
+      - /var/run/docker.sock:/var/run/docker.sock
+    deploy:
+      placement:
+        constraints:
+          - node.role==manager

From d678ce04ff2602a33ee998fc7aa1c02dee979d64 Mon Sep 17 00:00:00 2001
From: Shizun Ge <shizunge@gmail.com>
Date: Thu, 18 Jan 2024 18:37:50 -0800
Subject: [PATCH 12/13] [entrypoint] exclude the time spent on updating from
 sleep seconds.

---
 README.md         |  2 +-
 src/entrypoint.sh | 20 ++++++++++++--------
 2 files changed, 13 insertions(+), 9 deletions(-)

diff --git a/README.md b/README.md
index 610fb5e..3ee24cc 100644
--- a/README.md
+++ b/README.md
@@ -32,7 +32,7 @@ You can configure the most behaviors of *Gantry* via environment variables.
 | GANTRY_NODE_NAME      |      | Add node name to logs. |
 | GANTRY_POST_RUN_CMD   |      | Command(s) to eval after each updating iteration. |
 | GANTRY_PRE_RUN_CMD    |      | Command(s) to eval before each updating iteration. |
-| GANTRY_SLEEP_SECONDS  | 0    | Sleep time between two updates. Set it to 0 to run *Gantry* once and then exit. |
+| GANTRY_SLEEP_SECONDS  | 0    | Interval between two updates. Set it to 0 to run *Gantry* once and then exit. Sleep time will exclude the time spent on updating services. |
 | TZ                    |      | Set timezone for time in logs. |
 
 ### To login to registries
diff --git a/src/entrypoint.sh b/src/entrypoint.sh
index d3799c4..0bca75b 100755
--- a/src/entrypoint.sh
+++ b/src/entrypoint.sh
@@ -129,22 +129,26 @@ main() {
   LOG_LEVEL="${GANTRY_LOG_LEVEL:-${LOG_LEVEL}}"
   NODE_NAME="${GANTRY_NODE_NAME:-${NODE_NAME}}"
   export LOG_LEVEL NODE_NAME
-  local SLEEP_SECONDS="${GANTRY_SLEEP_SECONDS:-0}"
-  if ! is_number "${SLEEP_SECONDS}"; then 
+  local INTERVAL_SECONDS="${GANTRY_SLEEP_SECONDS:-0}"
+  if ! is_number "${INTERVAL_SECONDS}"; then 
     log ERROR "GANTRY_SLEEP_SECONDS must be a number. Got \"${GANTRY_SLEEP_SECONDS}\"."
     return 1;
   fi
   local STACK="${1:-gantry}"
   local RETURN_VALUE=0
+  local START_TIME PASSED_SECONDS SLEEP_SECONDS
   while true; do
-    # SC2034 (warning): LOG_SCOPE appears unused. Verify use (or export if used externally).
-    # shellcheck disable=SC2034
-    LOG_SCOPE="${STACK}"
+    export LOG_SCOPE="${STACK}"
+    START_TIME=$(date +%s)
     gantry "${@}"
     RETURN_VALUE=$?
-    [ "${SLEEP_SECONDS}" -le 0 ] && break;
-    log INFO "Sleeping ${SLEEP_SECONDS} seconds before next update."
-    sleep "${SLEEP_SECONDS}"
+    [ "${INTERVAL_SECONDS}" -le 0 ] && break;
+    PASSED_SECONDS=$(difference_between "${START_TIME}" "$(date +%s)")
+    SLEEP_SECONDS=$((INTERVAL_SECONDS - PASSED_SECONDS))
+    if [ "${SLEEP_SECONDS}" -gt 0 ]; then
+      log INFO "Sleeping ${SLEEP_SECONDS} seconds before next update."
+      sleep "${SLEEP_SECONDS}"
+    fi
   done
   return ${RETURN_VALUE}
 }

From 43c12944b27fe13f940317980aa0c062e55e305b Mon Sep 17 00:00:00 2001
From: Shizun Ge <shizunge@gmail.com>
Date: Thu, 18 Jan 2024 18:54:47 -0800
Subject: [PATCH 13/13] [examples] add more links to examples

---
 docs/faq.md                             | 4 ++--
 docs/migration.md                       | 2 ++
 examples/README.md                      | 2 +-
 examples/cronjob/README.md              | 4 ++++
 examples/prune-and-watchtower/README.md | 2 +-
 5 files changed, 10 insertions(+), 4 deletions(-)
 create mode 100644 examples/cronjob/README.md

diff --git a/docs/faq.md b/docs/faq.md
index 19e1887..1f1a721 100644
--- a/docs/faq.md
+++ b/docs/faq.md
@@ -10,7 +10,7 @@ At the end of updating, *Gantry* optionally removes the old images.
 
 ### How to update standalone docker containers?
 
-*Gantry* only works for docker swarm services. If you need to update standalone docker containers, you can try [watchtower](https://github.com/containrrr/watchtower).
+*Gantry* only works for docker swarm services. If you need to update standalone docker containers, you can try [*watchtower*](https://github.com/containrrr/watchtower). *Gantry* can launch *watchtower* via `GANTRY_PRE_RUN_CMD` or `GANTRY_POST_RUN_CMD`. See the [example](../examples/prune-and-watchtower).
 
 ### How to filters multiple services by name?
 
@@ -30,7 +30,7 @@ gantry_finalize;
 
 ### How to run *Gantry* on a cron schedule?
 
-You can start *Gantry* as a docker swarm service and use [`swarm-cronjob`](https://github.com/crazy-max/swarm-cronjob) to run it at a given time. When use `swarm-cronjob`, you need to set `GANTRY_SLEEP_SECONDS` to 0. See the [example](../examples/docker-compose.yml).
+You can start *Gantry* as a docker swarm service and use [`swarm-cronjob`](https://github.com/crazy-max/swarm-cronjob) to run it at a given time. When use `swarm-cronjob`, you need to set `GANTRY_SLEEP_SECONDS` to 0. See the [example](../examples/cronjob).
 
 ### How to update services with no running tasks?
 
diff --git a/docs/migration.md b/docs/migration.md
index d09536a..6b35088 100644
--- a/docs/migration.md
+++ b/docs/migration.md
@@ -52,6 +52,8 @@ The label on the services to select config to enable authentication is renamed t
 | GANTRY_MANIFEST_CMD              |
 | GANTRY_MANIFEST_OPTIONS          |
 | GANTRY_NOTIFICATION_TITLE        |
+| GANTRY_POST_RUN_CMD              |
+| GANTRY_PRE_RUN_CMD               |
 | GANTRY_REGISTRY_CONFIG           |
 | GANTRY_REGISTRY_CONFIG_FILE      |
 | GANTRY_REGISTRY_HOST_FILE        |
diff --git a/examples/README.md b/examples/README.md
index bbabf36..9f21e18 100644
--- a/examples/README.md
+++ b/examples/README.md
@@ -6,5 +6,5 @@ Run *gantry* at the specific time.
 
 ## [prune-and-watchtower](./prune-and-watchtower)
 
-Run [`docker system prune`](https://docs.docker.com/engine/reference/commandline/system_prune/) and [*watchtower*](https://github.com/containrrr/watchtower) with *gantry*.
+Remove unused containers, networks and images. Update standalone docker containers. Update docker swarm services.
 
diff --git a/examples/cronjob/README.md b/examples/cronjob/README.md
new file mode 100644
index 0000000..3ef2def
--- /dev/null
+++ b/examples/cronjob/README.md
@@ -0,0 +1,4 @@
+# cronjob
+
+Use [*swarm-cronjob*](https://github.com/crazy-max/swarm-cronjob) to launch *gantry* at a given time.
+
diff --git a/examples/prune-and-watchtower/README.md b/examples/prune-and-watchtower/README.md
index 9389e98..3996863 100644
--- a/examples/prune-and-watchtower/README.md
+++ b/examples/prune-and-watchtower/README.md
@@ -1,6 +1,6 @@
 # prune and watchtower
 
-This example run `docker system prune` and *watchtower* before updating docker swarm services.
+This example runs `docker system prune` and *watchtower* before updating docker swarm services.
 
 * [`docker system prune`](https://docs.docker.com/engine/reference/commandline/system_prune/) removes all unused containers, networks and images.
 * [*watchtower*](https://github.com/containrrr/watchtower) updates standalone docker containers.