Files
kamal/test/integration/docker/deployer/app/config/deploy.yml
Donal McBreen 8a41d15b69 Zero downtime deployment with cord file
When replacing a container currently we:
1. Boot the new container
2. Wait for it to become healthy
3. Stop the old container

Traefik will send requests to the old container until it notices that it
is unhealthy. But it may have stopped serving requests before that point
which can result in errors.

To get round that the new boot process is:

1. Create a directory with a single file on the host
2. Boot the new container, mounting the cord file into /tmp and
including a check for the file in the docker healthcheck
3. Wait for it to become healthy
4. Delete the healthcheck file ("cut the cord") for the old container
5. Wait for it to become unhealthy and give Traefik a couple of seconds
to notice
6. Stop the old container

The extra steps ensure that Traefik stops sending requests before the
old container is shutdown.
2023-09-06 14:35:30 +01:00

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YAML

service: app
image: app
servers:
- vm1
- vm2
env:
clear:
CLEAR_TOKEN: '4321'
secret:
- SECRET_TOKEN
registry:
server: registry:4443
username: root
password: root
builder:
multiarch: false
args:
COMMIT_SHA: <%= `git rev-parse HEAD` %>
healthcheck:
cmd: wget -qO- http://localhost > /dev/null || exit 1
traefik:
args:
accesslog: true
accesslog.format: json
image: registry:4443/traefik:v2.9
accessories:
busybox:
image: registry:4443/busybox:1.36.0
cmd: sh -c 'echo "Starting busybox..."; trap exit term; while true; do sleep 1; done'
roles:
- web
stop_wait_time: 1