GlossaryΒΆ
- Agent
- The glu agent is an active process that needs to run on every host where applications need to be deployed
- bounce
- In the context of the orchestration engine, bounce means stop followed by start.
- Closure
- In a glu script, a closure is a groovy closure which is essentially a piece of groovy/java code (between curly braces) assigned to an attribute.
- Console
- The webapp/REST api built on top of ZooKeeper which is the orchestrator of the system.
- delta
- The differences between the desired state and the live state.
- deployment plan
- A deployment plan is a set of instructions that the orchestration engine executes to deploy and start (resp. stop and undeploy) applications on various hosts.
- desired state
- The state you want the entire system to be in. It is represented by the model.
- dotted notation
This notation is how groovy allows you to access any entry in a map:
// with the following map Map m = [ p1: 'v1', p2: [ p3: 'v3'] // nested map! ] // the dotted notation allows you to write m.p1 // which would return 'v1' m.p2.p3 // which would return 'v3'
- Fabric
- A fabric defines a group of agents. When an agent starts it is assigned a fabric (a string). A fabric is then defined as the group of agents that were started with the same value for the fabric.
- filter
- A filter is used in the orchestration engine to select a set of entries based on some criteria.
- glu script
- A glu script is a set of instructions backed by a state machine that the agent knows how to run. View more information.
- host
A host represents a physical or virtual instance of a machine running 1 os. Examples
- a laptop with Mac OS X is 1 host
- a unix desktop running 4 Xen virtual machine is 5 hosts (unix destop + 4 VMM)
Note
in a production setup, there is usually one (and only one) glu agent running on each host
- live model
- Representation of the live state as json document. More information about the live model.
- live state
- The state of the live system as reported by the agents in ZooKeeper. This state is dynamically collected by the orchestration engine.
- Metadata
Metadata in the context of glu represents a map that can be represented as a json object:
def goodMetadata = [ p1: 'v1', p2: [1, 2, 3], // array p3: [p31: 'v31'] // another nested map ] // in json format, it would look like this // note that you cannot have comments in json! { "p1": "v1", "p2": [1, 2, 3], "p3": { "p31": "v31" } } // bad because the value is a java object def badMetadata = [ color: java.awt.Color.BLACK ]- model
- The model is a json document which describes what applications need to run, on which host and what it means to deploy and run an application.
- mount point
The unique key on which a glu script get ‘mounted’ on a given agent. It is a String which has a (unix) path like syntax (must start with a /):
Example: /a/b/c
- node
- Synonym for host
- orchestration engine
- The orchestration engine is the process that listens to ZooKeeper updates coming from the agents, compute differences (delta) with the model in order to visualize them and/or execute a deployment plan. The orchestration engine is in charge of orchestrating deployments making sure they happen either sequentially or in parallel (or a combination of both).
- static model
- Synonym for model. More information about the static model.
- system
- The system represents the set of hosts and applications running in a fabric. Its static representation is the model.
- Timer
- A piece of logic that gets executed at a given frequency by the agent. Scheduled/Cancelled by a glu script.
- ZooKeeper
- View more information about ZooKeeper
