Distributed Installation Overview¶
Morpheus provides a wide array of options when it comes to deployment architectures. It can start as a simple one machine instance where all services run on the same machine, or it can be split off into individual services per machine and configured in a high availability configuration, either in the same region or cross-region. Naturally, high availability can grow more complicated, depending on the configuration you want to do and this article will cover the basic concepts of the Morpheus HA architecture that can be used in a wide array of configurations.
There are four primary tiers of services represented within the Morpheus appliance. They are the App Tier, Transactional Database Tier, Non-Transactional Database Tier, and Message Tier. Each of these tiers have their own recommendations for High availability deployments that we need to cover.
This is a sample configuration only. Customer configurations and requirements will vary.
The application tier is easily installed with the same debian or yum repository package that Morpheus is normally distributed with. Advanced configuration allows for the additional tiers to be skipped and leave only the “stateless” services that need run. These stateless services include Nginx and Tomcat. These machines should also have at least 8gb of Memory. They can be configured across all regions and placed behind a central load-balancer or Geo based load-balancer. They typically connect to all other tiers as none of the other tiers talk to each other besides through the central application tier. One final piece when it comes to setting up the Application tier is a shared storage means is necessary when it comes to maintaining things like deployment archives, virtual image catalogs, backups, etc. These can be externalized to an object storage service such as Amazon S3 or Openstack Swiftstack as well. If not using those options a simple NFS cluster can also be used to handle the shared storage structure.
Transactional Database Tier¶
The Transactional database tier usually consists of a MySQL compatible database. It is recommended that a lockable clustered configuration be used (Currently Percona XtraDB Cluster is the most recommended in Permissive Mode). There are several documents online related to configuring and setting up an XtraDB Cluster but it most simply can be laid out in a many master configuration. There can be some nodes setup with replication delay as well as some with no replication delay. It is common practice to have no replication delay within the same region and allow some replication delay cross region. This does increase the risk of job run overlap between the 2 regions however, the concurrent operations typically self-correct and this is a non-issue.
Non-Transactional Database Tier¶
The Non-Transactional tier consists of an ElasticSearch (version 7.6.0) cluster. Elastic Search is used for log aggregation data and temporal aggregation data (essentially stats, metrics, and logs). This enables for a high write throughput at scale. ElasticSearch is a Clustered database meaning all nodes no matter the region need to be connected to each other over what they call a “Transport” protocol. It is fairly simple to get setup as all nodes are identical. It is also a java based system and does require a sizable chunk of memory for larger data sets. 8 GB is recommended and more nodes can be added to scale either horizontally or vertically.
The Messaging tier is an AMQP based tier along with STOMP Protocol (used for agent communication). The primary model recommended is to use RabbitMQ for queue services. RabbitMQ is also a cluster-based queuing system and needs at least 3 instances for HA configurations. This is due to elections in the failover scenarios RabbitMQ can manage. If doing a cross-region HA RabbitMQ cluster it is recommended to have at least 3 Rabbit queue clusters per region. Typically to handle HA a RabbitMQ cluster should be placed between a load balancer and the front-end application server to handle cross host connections. The ports necessary to forward in a Rabbit MQ cluster are (5672, and 61613). A rabbitmq cluster can run on smaller memory machines depending on how frequent large request bursts occur. 4 - 8 GB of Memory is recommended to start.