libcluster_ec2 v0.3.0 ClusterEC2.Strategy.Tags View Source

This clustering strategy works by loading all instances that have the given tag associated with them.

All instances must be started with the same app name and have security groups configured to allow inter-node communication.

config :libcluster,
  topologies: [
    tags_example: [
      strategy: Elixir.ClusterEC2.Strategy.Tags,
      config: [
        ec2_tagname: "mytag",
        ec2_tagvalue: "tagvalue"
        app_prefix: "app"
        ip_type: :private
        polling_interval: 10_000]]]

Configuration Options

KeyRequiredDescription
:ec2_tagnameyesName of the EC2 instance tag to look for.
:ec2_tagvaluenoCan be passed a static value (string), a 0-arity function, or a 1-arity function (which will be passed the value of :ec2_tagname at invocation).
:app_prefixnoWill be appended to the node’s private IP address to create the node name.
:ip_typenoOne of :private or :public, defaults to :private
:polling_intervalnoNumber of milliseconds to wait between polls to the EC2 api. Defaults to 5_000

Link to this section Summary

Functions

Returns a specification to start this module under a supervisor

Invoked when the server is started. start_link/3 or start/3 will block until it returns

Callback implementation for Cluster.Strategy.start_link/1

Link to this section Functions

Returns a specification to start this module under a supervisor.

See Supervisor.

Invoked when the server is started. start_link/3 or start/3 will block until it returns.

args is the argument term (second argument) passed to start_link/3.

Returning {:ok, state} will cause start_link/3 to return {:ok, pid} and the process to enter its loop.

Returning {:ok, state, timeout} is similar to {:ok, state} except handle_info(:timeout, state) will be called after timeout milliseconds if no messages are received within the timeout.

Returning {:ok, state, :hibernate} is similar to {:ok, state} except the process is hibernated before entering the loop. See c:handle_call/3 for more information on hibernation.

Returning :ignore will cause start_link/3 to return :ignore and the process will exit normally without entering the loop or calling c:terminate/2. If used when part of a supervision tree the parent supervisor will not fail to start nor immediately try to restart the GenServer. The remainder of the supervision tree will be (re)started and so the GenServer should not be required by other processes. It can be started later with Supervisor.restart_child/2 as the child specification is saved in the parent supervisor. The main use cases for this are:

  • The GenServer is disabled by configuration but might be enabled later.
  • An error occurred and it will be handled by a different mechanism than the Supervisor. Likely this approach involves calling Supervisor.restart_child/2 after a delay to attempt a restart.

Returning {:stop, reason} will cause start_link/3 to return {:error, reason} and the process to exit with reason reason without entering the loop or calling c:terminate/2.

Callback implementation for GenServer.init/1.

Callback implementation for Cluster.Strategy.start_link/1.