You can use docker swarm (or a better container orchestrator) to have the containers automatically fail over to the second host
this post was submitted on 24 Sep 2023
30 points (94.1% liked)
Selfhosted
39247 readers
311 users here now
A place to share alternatives to popular online services that can be self-hosted without giving up privacy or locking you into a service you don't control.
Rules:
-
Be civil: we're here to support and learn from one another. Insults won't be tolerated. Flame wars are frowned upon.
-
No spam posting.
-
Posts have to be centered around self-hosting. There are other communities for discussing hardware or home computing. If it's not obvious why your post topic revolves around selfhosting, please include details to make it clear.
-
Don't duplicate the full text of your blog or github here. Just post the link for folks to click.
-
Submission headline should match the article title (don’t cherry-pick information from the title to fit your agenda).
-
No trolling.
Resources:
- awesome-selfhosted software
- awesome-sysadmin resources
- Self-Hosted Podcast from Jupiter Broadcasting
Any issues on the community? Report it using the report flag.
Questions? DM the mods!
founded 1 year ago
MODERATORS
Swarm will also spread the load out over both hosts, but all your data would need to be accessible by both hosts
Thanks. That means I need to move all data off the hosts on to, say, a NAS - then the NAS becomes the single point of failure. Can I operate a swarm without doing that but still duplicate everything from host 1 to host 2, so host 2 could take over relatively seamlessly (apart from local DNS and moving port forwarding to nginx on the remaining host)?
I think you can run a ceph or glusterfs cluster for sharing files in a cluster
I think 3 nodes are required for that
Yes could sync the 2 hosts data, you also can use both hosts as nginx upstreams.
Thanks. Can I use my existing, single Docker to start a new swarm, or do I have to start from scratch?
Container orchestration is what you're looking for. Kubernetes is the most popular, but it might be overkill it's hard to say based on your setup. However it's definitely useful experience to know how to run it.
Thanks. Could I achieve a simple 2-host solution with Kubernetes though?
Nothing about k8s is simple. But yes you can achieve that.
Take a look at Rancher for actually running a cluster.
I put my dockers on mirrored zfs pool and have enough spare parts in case of breakdowns.
So you have Docker itself on a single host (with parts) and all the containers in fault tolerant storage, and the most work you'd have to do in the event of host drive failure is to re-install the OS and Docker itself?
I have the OS (with docker) mirrored too. So no reinstalling, just disk or other parts swapping in case of a failure. I hope. A mothboard swap is the worst downtime. I have done this and needed to fiddle with network settings due to changed net interface name to get the server up again.
Learning K8s is a lot to take on, but it will pay off as your needs expand in the long term — and if you decide to go into infra/ops at work.
It might be enough to just rsync stuff to the secondary regularly and the inactive machine monitor the active machine and just start all services as the active machine stops responding.
The issue with orchestration is that you still need a way to share those small databases and config files.
Docker has ok NFS support so you'd want to move the files to NAS shares and have them mount those. Without some way to centralise or spread the files out you won't be covering your SSD failure case. Once you've got that going docker swarm will probably cover your needs just fine.
You could go with K8S but based on you setup that's a bit overkill (unless you're doing it as a learning exercise, in which case go nuts).
Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread:
| Fewer Letters | More Letters |
|---|---|
| DNS | Domain Name Service/System |
| HTTP | Hypertext Transfer Protocol, the Web |
| NAS | Network-Attached Storage |
| k8s | Kubernetes container management package |
| nginx | Popular HTTP server |
4 acronyms in this thread; the most compressed thread commented on today has 8 acronyms.
[Thread #162 for this sub, first seen 24th Sep 2023, 17:15] [FAQ] [Full list] [Contact] [Source code]