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Last pushed: 2 years ago
Short Description
Flotilla is an alternative to fleet that uncouples from CoreOS/etcd and couples to AWS.
Full Description

Flotilla - The Petit Fleet

Flotilla is an alternative to fleet that uncouples from CoreOS/etcd and couples to AWS.

Flotilla uses:

  • DynamoDb - for persistence, locking and communication
  • ELB - to reroute traffic during an upgrade
  • IAM - for access control
  • KMS - for encryption of environment variables
  • CloudFormation - for provisioning resources
  • SQS - for communication between components

Like fleet, flotilla distributes systemd units across a cluster of machines.

Unlike fleet, flotilla manages environment variables for scheduled services, and supports weighted distributions of services (for canaries, A/B, load balancing, etc).


Flotilla introduces the concept of a service to distinguish worker instances. An instance is born into a service and advertises membership in DynamoDb.

A scheduler running in the cluster periodically checks for:

  • Which units+configurations are defined for each service? What are their weights?
  • How many instances are currently being used for this service?

Given these inputs, the scheduler updates assignments for instances to satsify the current configuration.

Currently there is a single scheduler for the entire cluster. DynamoDb parallel scans are the intended scaling path for multiple schedulers.


Flotilla workers periodically check for assignments in DynamoDb. If a worker's assignment is changed, it executes the following steps:

  1. Acquire deployment lock for service.
  2. If ELB is defined:
    1. Request deregistration from ELB.
    2. Wait for ELB deregistration (i.e. drain connections)
  3. Stop and unload all existing flotilla units.
  4. Start new flotilla units.
  5. If ELB is defined:
    1. Request registration to ELB.
    2. Wait for ELB registration (i.e. health check).
  6. Release deployment lock for service.


Don't use this in production. This implementation is output from 3x8h "hackathon"s.

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