The agent has various configuration options that can be specified via the command-line or via configuration files. All of the configuration options are completely optional. Defaults are specified with their descriptions.

The KV endpoint is used to access Consul's simple key/value store, useful for storing service configuration or other metadata.

We've started our first agent and registered and queried a service on that agent. This showed how easy it is to use Consul but didn't show how this could be extended to a scalable, production-grade service discovery infrastructure. In this step, we'll create our first real cluster with multiple members.

When a Consul agent is started, it begins without knowledge of any other node: it is an isolated cluster of one. To learn about other cluster members, the agent must join an existing cluster. To join an existing cluster, it only needs to know about a single existing member. After it joins, the agent will gossip with this member and quickly discover the other members in the cluster. A Consul agent can join any other agent, not just agents in server mode.

Manage a cluster of Linux containers as a single system to accelerate Dev and simplify Ops.

Developing Distributed Applications that use ZooKeeper

The following options can be set as part of the Galera wsrep_provider_options variable. Dynamic options can be changed while the server is running.

Note that before Galera 3, the repl tag was named replicator.

Raft is a consensus algorithm that is designed to be easy to understand. It's equivalent to Paxos in fault-tolerance and performance. The difference is that it's decomposed into relatively independent subproblems, and it cleanly addresses all major pieces needed for practical systems. We hope Raft will make consensus available to a wider audience, and that this wider audience will be able to develop a variety of higher quality consensus-based systems than are available today.

etcd is a distributed, consistent key value store for shared configuration and service discovery with a focus on being:

Simple: curl'able user facing API (HTTP+JSON)
Secure: optional SSL client cert authentication
Fast: benchmarked 1000s of writes/s per instance
Reliable: properly distributed using Raft

etcd is written in Go and uses the Raft consensus algorithm to manage a highly-available replicated log.

See etcdctl for a simple command line client. Or feel free to just use curl, as in the examples below.

If you're considering etcd for production use, please see: production-ready.md

The aim is showing that it is possible to create a low-cost storage, efficient and scalable, using opensource solutions. In the example below, I am using Ceph for scalability and reliability, combined with EnhanceIO to ensure very good performance.

Slurm is an open-source workload manager designed for Linux clusters of all sizes. It provides three key functions. First it allocates exclusive and/or non-exclusive access to resources (computer nodes) to users for some duration of time so they can perform work. Second, it provides a framework for starting, executing, and monitoring work (typically a parallel job) on a set of allocated nodes. Finally, it arbitrates contention for resources by managing a queue of pending work.