Rolling deployments: using update_config - delay does not work

Docker Engine Compose
1

Hello!

We want to achieve proper rolling deployments for our SaaS node app. We have 8 identical node containers running - our docker-compose looks like this (simplified!):

services:
  mysaasapp:
    image: ${MYIMAGE}
    ...
    deploy:
      mode: replicated
      replicas: 8
      update_config:
        parallelism: 1
        delay: 30s
        order: stop-first
      resources:
        limits:
          cpus: '1.5'
          memory: 4096M
        reservations:
          cpus: '0.5'
          memory: 1536M

The thing is … it does not work. When I deploy a new image via MYIMAGE=... docker compose up -d mysaasapp it does NOT delay the startup of the 8 instances - it basically does it all at the same time.

→ no “rolling deployment” is achieved whatsoever.

Can someone help? I don’t understand what I am doing wrong.
Thanks, best,
Patrick

2

I think those settings are mostly for Docker Swarm, not for compose.

You need to deploy Docker Swarm services with docker stack deploy.

3

But it’s documented here for compose no?! Compose Deploy Specification | Docker Docs

4

Of course, the specs support it.

.. but not every implementation of the specs support it. While docker (swarm) stack deployments supported those config-elements from the get go, afaik they have never been implemented for docker compose.

5

Deploy is an optional part of the Compose Specification.

6

It’s unfortunate that docker compose does not output any warnings that it’s unsupported.

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