Hot Code Reloading

Coming Soon

This lesson will teach you how to implement hot code reloading for zero-downtime deployments and live system updates. You’ll learn how to:

• Understand Erlang’s hot code reloading mechanisms
• Design modules for safe hot code updates
• Implement version management and rollback strategies
• Handle state migration during code updates
• Build automated deployment pipelines with hot reloading

What You’ll Build

By the end of this lesson, you’ll have implemented:

• Hot code reloading infrastructure
• State migration mechanisms for GenServers
• Version management and rollback capabilities
• Automated deployment with zero downtime
• Testing frameworks for hot code updates

Key Concepts Preview

% Code upgrade callback
code_change(OldVsn, State, Extra) ->
    case OldVsn of
        "1.0.0" -> migrate_state_v1_to_v2(State);
        "1.1.0" -> migrate_state_v11_to_v2(State);
        _ -> {ok, State}
    end.

% Hot code loading
load_new_code(Module, Binary) ->
    case code:load_binary(Module, atom_to_list(Module) ++ ".beam", Binary) of
        {module, Module} -> {ok, loaded};
        {error, Reason} -> {error, Reason}
    end.

% Release upgrade
release_handler:install_release("2.0.0"),
release_handler:make_permanent("2.0.0").

This lesson builds on the fault tolerance from Lesson 28 and prepares you for the advanced security measures we’ll explore in Lesson 30.

This lesson is currently under development. Check back soon for the complete content!