orchestrator-in-go

Repository for working through Build An Orchestrator in Go

Details

• Go Version: 1.17

Definitions

• Orchestrator
  • Automates deploying, scaling & managing containers.
• Task
  • Smallest unit of work.
    • Should specify it's needs for memory, CPU & disk.
    • What to do in case of failure (restart_policy).
    • Name of container image used to run the task.
• Job (not included in this implementation)
  • Group of tasks to perform a set of functions.
  • Should specify details at a higher level than tasks.
    • Each task that makes up the job.
    • Which data centers the job should run in.
    • The type of job.
• Scheduler
  • Decides which machine can best host the tasks defined.
  • Could be a process within the machine or possibly a different service.
  • Decisions can vary in model complexity from round-robin to score calculation based on variables and deciding node by best score
    • Detrmine set of candidate machines to run task
    • Score machines from best to worst
    • Pick machine with best score
• Manager
  • Brain of orchestrator & main entry point
  • Jobs go to manager, manager uses scheduler to determine where to run job.
  • Can gather metrics, to use for scheduling.
    • Accept requests from users to start/stop tasks
    • Schedule tasks onto worker machines
    • Keep track of tasks, states & the machine they run on
• Worker
  • Runs the tasks assigned to it, attempts task restarts on failure, makes metrics about task and machine health for master
    • Runs asks as containers
    • Accepts tasks to run from manager
    • provides relevant statistics to the manager to schedule tasks
    • Keeps track of tasks & their state
• Cluster
  • Logical grouping of all above components.
• CLI
  • Main user interface
    • Start/Stop Tasks
    • Get status of tasks
    • See state of machines
    • Start manager
    • Start worker