yubiuser / docker-event-monitor Goto Github PK

One of my containers kept restarting because of a typo in its docker-compose.yml file. docker-event-monitor was very useful in figuring this out because my inbox kept filling:

The first one was

Object 'Container' with ID 88085b96 from image containrrr/watchtower reported: stop

All following are:

Object 'Container' with ID 2de67b6b from image containrrr/watchtower reported: start

docker events told me container die which was more helpful at pointing me into the right direction. Maybe docker-event-monitor can be improved in this way.

Consider switching to https://github.com/rs/zerolog

As mentioned in #22 (comment), watchtower has a setting called WATCHTOWER_NOTIFICATION_EMAIL_SUBJECTTAG that injects a server name into the subject, like:

From: ...
Subject: [server.dl6er.de] Container gitea-db-1 restarted
Content: ...

Having such an option would allow me to use docker-event-monitor better as I would be using it on three machines running in three different locations/networks.

What is the problem?

I heavily use docker compose to provide individual services on my servers. When docker-event-monitor sends me a message like

Object 'Container' with ID 2a51bd18 from image postgres:14 reported: stop

it is difficult to know which container was actually affected because years after I have set up my gitea, I might simply have forgotten that postgres is used here. Another possibility would be that it could be used more than once, e.g., when using several provided docker-compose.yml files from various resources on the web.

Background

The structure of my services (all managed using docker compose) is pretty common, like

/home/<user>/docker
/home/<user>/docker/gittea
/home/<user>/docker/gittea/docker-compose.yml
/home/<user>/docker/proxy
/home/<user>/docker/proxy/docker-compose.yml
/home/<user>/docker/bbb
/home/<user>/docker/bbb/docker-compose.yml
/home/<user>/docker/mailserver
/home/<user>/docker/mailserver/docker-compose.yml
/home/<user>/docker/watchtower
/home/<user>/docker/watchtower/docker-compose.yml
... (several more)

(yes, they are intentionally not running as root)

My suggestion

Include details about the docker compose context if applicable. The information should be available through the docker events, e.g.:

2023-09-23T10:29:15.081683269+02:00 container restart 2a51bd189e885381c80d63c8f6d7906a5f220f93412beb9b6eb96e9dfdd2efc4 (com.docker.compose.config-hash=20d8294d54fe37f3c8f4395ba8db4770df004b762180be24af6dcad170c4396c, com.docker.compose.container-number=1, com.docker.compose.depends_on=, com.docker.compose.image=sha256:4d8f13d97fae84ee0f5e9231b89a7957839a8de3ff49b7faab1feac5cab01b6c, com.docker.compose.oneoff=False, com.docker.compose.project=gitea, com.docker.compose.project.config_files=/home/<user>/docker/gitea/docker-compose.yml, com.docker.compose.project.working_dir=/home/<user>/docker/gitea, com.docker.compose.replace=7166e98e5db5339990b54505dd3a62e9b179b53cf0b0a16b0771639aef2ce247, com.docker.compose.service=db, com.docker.compose.version=2.20.2, image=postgres:14, name=gitea-db-1)

Specifically:

• name=gitea-db-1
• com.docker.compose.project=gitea
• com.docker.compose.service=db
• com.docker.compose.project.working_dir=/home/<user>/docker/gitea

To a human consuming the messages generated by docker-event-monitor, name may also be a more obvious choice than the currently printed container ID.

Example message

With docker compose context:

From: ...
Subject: gitea-db-1 container restart
Content: Container gitea-db-1 (gitea:db defined in /home/<user>/docker/gitea) was restarted

Without docker compose:

From: ...
Subject: nginx container restart
Content: Container nginx was restarted

These are the messages I'm referring to in the remainder of this issue ticket:

The first message I ever received contained a timestamp string, nothing else. The title was helpful:

The following messages did not contain a useful title, but what happened was now in the content of the mail:

My suggestions at this point would be to

1. Improve the status message to something like

   Docker event monitor was started at XX-XX-2023 XX:YY:ZZ
   

   (or similar)
2. Change the header from the generic New Docker Event to something dynamic like Container postgres:14: stop. For brevity, you could even skip the leading "Container" and use the title/subject postgres:14: stop and, subsequently, postgres:14: start

I am aware that my suggestion is based on the e-mail reporting where a sender will always be visible allowing to identify the origin immediately. I am not using any of the other notification method your monitor offers, so I cannot speak for them if the same change would be useful over there as well.