Since Docker containers allow to handle almost any service inside, commonly it’s rather hard to automatically predict which node type a particular instance belongs to (i.e. whether it’s application server, DB, cache or storage server, etc). In such a way, it’s a user who defines a particular environment topology and decides which environment layer a container should be placed to.
Thus, in order to integrate the Jelastic automatic horizontal scaling functionality support for Docker-based instances (previously available only for nodes in application server environment layer), the whole Auto Horizontal Scaling section was rebuilt. Now it allows to manually choose a particular node group, where automatic scaling should be applied. This can be done within the appropriate drop-down list in the top-left tools panel corner. Obviously, this list can be used only for Docker-based environments, as such selection has no point for Jelastic native containers, where compute node is always placed within the application server layer.
Beside that, some other amendments were implemented - now, upon switching to the Auto Horizontal Scaling section, you will see a table with all scaling triggers that have been applied to the environment. It provides information on the appropriate Nodes and layers names, with Scaling in (to remove nodes) and Scaling out (to add nodes) conditions you’ve specified. And the Add, Edit, Remove and Refresh buttons above this list allow to easily manage it.
Note: Each new Docker container, added to a layer upon the appropriate trigger execution (i.e. due to increased load), will be created from scratch (i.e. not being cloned from the existing one).
Starting with Jelastic 4.9.1 release, automatic horizontal scaling can be applied to any environment layer, i.e. for all node types including Jelastic certified containers (previously, this was allowed for application server layer only).
Herewith, upon scaling out, new containers are created in the same way as during manual adjustment - i.e. for compute, load balancer and VPS environment layers each newly added instance will be cloned from the master one, and for the rest node types - created from scratch.More info
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