Re:Containers Are Not the Future
by mschuster91 on Friday March 20, 2020 @02:28PM
(#22640084)
There do exist things that make it sense for even small shops putting their stuff into containers and then small-ish local/bare metal or even cloud k8s environments:
1) automatic restarts of services when they fail: yes, this is possible with systemd but it's a nightmare to set up compared to a simple HEALTHCHECK command in Docker or an appropriate config section in k8s/rancher.
2) dependency chains (e.g. a java app that depends on mysql database and an external elasticsearch): again, this is possible with systemd, but way easier in k8s.
3) hardware/OS maintenance: in ye olde days, the admin would have to manually shut down services, copy data to new servers, start services there and then pray everything would work to prepare for a large-ish OS update or a longer hardware maintenance without having too much downtime (or buy more expensive software versions such as JIRA/Confluence DC). With k8s/rancher, assuming shared NFS storage, it's as easy as draining and cordoning the node, minimal downtime (essentially the time the software needs to stop/start) and no network/firewall/LB surprises along the way.
4) related to 3), in the cloud, assuming that services have horizontal scalability in mind (which most popular PHP environments have), it's relatively easy and straightforward to use autoscaling to save costs on one side but also prevent your site from going belly-up in case of HN/Reddit mentions. With manual deployments? Ouch.
5) Software upgrades or the creation of stage environments are so much easier, assuming well-written Docker images and software. Again let's take JIRA and Confluence - manually installed it's a lot of fumbling around to upgrade an instance, but with Docker? As easy as incrementing the version tag in the k8s config and 5min later it's updated.
1) automatic restarts of services when they fail: yes, this is possible with systemd but it's a nightmare to set up compared to a simple HEALTHCHECK command in Docker or an appropriate config section in k8s/rancher.
2) dependency chains (e.g. a java app that depends on mysql database and an external elasticsearch): again, this is possible with systemd, but way easier in k8s.
3) hardware/OS maintenance: in ye olde days, the admin would have to manually shut down services, copy data to new servers, start services there and then pray everything would work to prepare for a large-ish OS update or a longer hardware maintenance without having too much downtime (or buy more expensive software versions such as JIRA/Confluence DC). With k8s/rancher, assuming shared NFS storage, it's as easy as draining and cordoning the node, minimal downtime (essentially the time the software needs to stop/start) and no network/firewall/LB surprises along the way.
4) related to 3), in the cloud, assuming that services have horizontal scalability in mind (which most popular PHP environments have), it's relatively easy and straightforward to use autoscaling to save costs on one side but also prevent your site from going belly-up in case of HN/Reddit mentions. With manual deployments? Ouch.
5) Software upgrades or the creation of stage environments are so much easier, assuming well-written Docker images and software. Again let's take JIRA and Confluence - manually installed it's a lot of fumbling around to upgrade an instance, but with Docker? As easy as incrementing the version tag in the k8s config and 5min later it's updated.