7장. Clustering
Clustering is sharing load between hosts. Each instance must be able to act as an entry point for UI and API access. This must enable the automation controller administrators to use load balancers in front of as many instances as they want and keep good data visibility.
Load balancing is optional, and it is entirely possible to have ingress on one or all instances as needed.
Each instance must be able to join the automation controller cluster and expand its ability to run jobs. This is a simple system where jobs can run anywhere rather than be directed on where to run. Also, you can group clustered instances into different pools or queues, called Instance groups.
Ansible Automation Platform supports container-based clusters by using Kubernetes, meaning you can install new automation controller instances on this platform without any variation or diversion in functionality. You can create instance groups to point to a Kubernetes container. For more information, see the Container and instance groups section.
Supported operating systems
The following operating systems are supported for establishing a clustered environment:
- Red Hat Enterprise Linux 8 or later
Isolated instances are not supported in conjunction with running automation controller in OpenShift.
7.1. Setup considerations
Learn about the initial setup of clusters. To upgrade an existing cluster, see Upgrade Planning in the Ansible Automation Platform Upgrade and Migration Guide.
Note the following important considerations in the new clustering environment:
- PostgreSQL is a standalone instance and is not clustered. Automation controller does not manage replica configuration or database failover (if the user configures standby replicas).
- When you start a cluster, the database node must be a standalone server, and PostgreSQL must not be installed on one of the automation controller nodes.
-
PgBouncer is not recommended for connection pooling with automation controller. Automation controller relies on
pg_notifyfor sending messages across various components, and therefore, PgBouncer cannot readily be used in transaction pooling mode. - All instances must be reachable from all other instances and they must be able to reach the database. It is also important for the hosts to have a stable address or hostname (depending on how the automation controller host is configured).
- All instances must be geographically collocated, with reliable low-latency connections between instances.
-
To upgrade to a clustered environment, your primary instance must be part of the
defaultgroup in the inventory and it needs to be the first host listed in thedefaultgroup. - Manual projects must be manually synced to all instances by the customer, and updated on all instances at once.
-
The
inventoryfile for platform deployments should be saved or persisted. If new instances are to be provisioned, the passwords and configuration options, as well as host names, must be made available to the installer.
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