Support graceful shutdown on Synology devices

[magicdude4eva]

Is your feature request related to a problem? Please describe.

The current Watchtower implementation results in Synology containers reporting unexpected stop:

Refer to the discussion and a possible solution via Synology API here: containrrr#1425 (comment)

Describe the solution you'd like

In the provided link containrrr#1425 (comment) I have managed to created a simple bash-script talking to the synology API, which will result in a graceful stop of the container without notifications. I could just not figure out how the life-cycle hooks work to pass on the container name. I thought I could do this in the pre-update to call the script, stop the container and then watchtower will just take over.

Describe alternatives you've considered

Could not find any other than disabling notifications entirely.

Additional context

No response

[beatkind]

Okay, let me see if I got that right:

1. Watchtower is doing its thing, updating the container once a new tag is recognized
2. Watchtower stops the container
3. Synology throws a stupid exception (due to their "interesting" implementation of docker)
4. Watchtower starts the new container

To now get rid of the notification from Synology, you have implemented a script stopping a specific container (and starting it) via the Synology API.

Your feature request in particular is that the lifecycle hooks now also bring an option to include the container's name inside the command, e.g. as a template that is being filled when invoking the command from the lifecycle?

[magicdude4eva]

Yes, unless I missed something and watchtower calls a /hooks/pre-update if enabled. I have a script where I am hoping that the container-name could be exposed as environment variable WATCHTOWER_CONTAINER_NAME, then the hooks/pre-update for Synology could look like this:

#!/bin/bash

LOGFILE="/scripts/watchtower-hook.log"
TIMESTAMP=$(date '+%Y-%m-%d %H:%M:%S')

SYNO_URL="https://MYNAS"
USERNAME="UID"
PASSWORD="PASSWORD"

log() {
  echo "[$(date '+%Y-%m-%d %H:%M:%S')] $1" >> "$LOGFILE"
}

{
  echo ""
  echo "========== [$TIMESTAMP] PRE-UPDATE HOOK =========="
  echo "Container: $WATCHTOWER_CONTAINER_NAME"
} >> "$LOGFILE"

log "[INFO] Authenticating with Synology..."

AUTH_RESPONSE=$(curl -s -X GET \
  "$SYNO_URL/webapi/auth.cgi?api=SYNO.API.Auth&version=6&method=login&account=$USERNAME&passwd=$PASSWORD&enable_syno_token=yes&enable_device_token=no&format=sid")

if [[ $(echo "$AUTH_RESPONSE" | jq -r '.success') == "true" ]]; then
  SID=$(echo "$AUTH_RESPONSE" | jq -r '.data.sid')
  SYNOTOKEN=$(echo "$AUTH_RESPONSE" | jq -r '.data.synotoken')
  log "[AUTH] Success. SID=${SID}"
else
  log "[AUTH] Failed. Response: $AUTH_RESPONSE"
  exit 1
fi

log "[ACTION] Attempting 'stop' on container '$WATCHTOWER_CONTAINER_NAME' via Synology API..."

RESPONSE=$(curl -s -X POST \
  -H "Content-Type: application/x-www-form-urlencoded; charset=UTF-8" \
  -H "X-SYNO-TOKEN: $SYNOTOKEN" \
  -d "name=\"$WATCHTOWER_CONTAINER_NAME\"&api=SYNO.Docker.Container&method=stop&version=1" \
  -b "id=$SID" \
  "$SYNO_URL/webapi/entry.cgi")

log "[ACTION] Synology response: $RESPONSE"

And my Watchtower dockercompose like this:

# Watchtower (automatic docker container updater) - https://github.com/containrrr/watchtower
  watchtower:
....
    environment:
      - WATCHTOWER_CLEANUP=true
      - WATCHTOWER_LABEL_ENABLE=true
      - WATCHTOWER_INCLUDE_STOPPED=false
      - WATCHTOWER_INCLUDE_RESTARTING=true
      - WATCHTOWER_MONITOR_ONLY=false
      - WATCHTOWER_SCHEDULE=0 0 4 * * 6
      - WATCHTOWER_ROLLING_RESTART=true
      - WATCHTOWER_TIMEOUT=30s
      - WATCHTOWER_NOTIFICATIONS_LEVEL=info
      - WATCHTOWER_LIFECYCLE_HOOKS=true
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
      - /etc/localtime:/etc/localtime:ro
      - /volume2/docker/appdata/watchtower/hooks:/hooks:ro
      - /volume2/docker/appdata/watchtower:/scripts:ro
      - /usr/bin/jq:/usr/bin/jq:ro # optional, only if not inside container

I am not sure if there is an easier way to do this? I have not been able to verify this yet as i am on a business trip, but would think the above could work?

[24mu13]

Any update on this?
Is funny we have to design a workaround because of a missing feature in Synology (projects auto update), but still I think this is an elegant one, without reuqiring any relevant change on Watchtower itself.

[telnetdoogie]

this 'warning' that's thrown in DSM is benign and happens any time you stop a container, even if you use compose... so it's not related to watchtower per se. They are being stopped "properly" but DSM just complains. I've learned to ignore the message.

[vbtrek]

If it helps this is the command I use in the console to avoid the warning messages:
sudo synowebapi --exec api=SYNO.Docker.Container version=1 method=stop name='"my-container-name"'