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78 lines
2.1 KiB
Markdown
78 lines
2.1 KiB
Markdown
---
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title: Use with Docker Swarm
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layout: default
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parent: How Tos
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nav_order: 13
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---
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# Use with Docker Swarm
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{: .note }
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The mechanisms described in this page __do only apply when Docker is running in [Swarm mode][swarm]__.
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[swarm]: https://docs.docker.com/engine/swarm/
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## Stopping containers during backup
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Stopping and restarting containers during backup creation when running Docker in Swarm mode is supported in two ways.
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### Scaling services down to zero before scaling back up
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When labeling a service in the `deploy` section, the following strategy for stopping and restarting will be used:
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- The service is scaled down to zero replicas
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- The backup is created
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- The service is scaled back up to the previous number of replicas
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{: .note }
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This approach will only work for services that are deployed in __replicated mode__.
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Such a service definition could look like:
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```yml
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services:
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app:
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image: myorg/myimage:latest
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deploy:
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labels:
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- docker-volume-backup.stop-during-backup=true
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replicas: 2
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```
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### Stopping the containers
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This approach bypasses the services and stops containers directly, creates the backup and restarts the containers again.
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As Docker Swarm would usually try to instantly restart containers that are manually stopped, this approach only works when using the `on-failure` restart policy.
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A restart policy of `always` is not compatible with this approach.
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Such a service definition could look like:
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```yml
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services:
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app:
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image: myapp/myimage:latest
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labels:
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- docker-volume-backup.stop-during-backup=true
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deploy:
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replicas: 2
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restart_policy:
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condition: on-failure
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```
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---
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## Memory limit considerations
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When running in Swarm mode, it's also advised to set a hard memory limit on your service (~25MB should be enough in most cases, but if you backup large files above half a gigabyte or similar, you might have to raise this in case the backup exits with `Killed`):
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```yml
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services:
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backup:
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image: offen/docker-volume-backup:v2
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deployment:
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resources:
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limits:
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memory: 25M
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```
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