The previous chapter introduced createAsyncThunk and the three actions it generates. This chapter focuses on the lifecycle itself: the shape of each action, the meta fields that carry the request context, the way the slice tracks loading and error state across concurrent requests, and the patterns that prevent the common bugs—stale results overwriting newer ones,…
createAsyncThunk is the Redux Toolkit function that generates an async action creator. It accepts a type prefix and a payload creator function, and it returns a thunk that dispatches three actions automatically: pending when the request starts, fulfilled when it succeeds, and rejected when it fails . The previous chapter covered the extraReducers builder that…
The reducers object in createSlice defines the actions that the slice owns. Every reducer in that object generates an action creator, and the action type is prefixed with the slice’s name. That is the correct place for actions that belong to the feature. But a slice also needs to respond to actions it does not…
An action creator is a function that returns an action object. In classic Redux, every action required a type constant, an action creator, and a reducer case, and the three had to be kept in sync manually. Redux Toolkit’s createAction generates the action creator and the type string from a single call, and the action…
Redux Toolkit includes Immer as a built-in dependency, and createSlice uses it internally. When a reducer is defined inside the reducers object, the state argument is not the plain state object; it is an Immer draft. Assignments to the draft—state.value += 1, state.items.push(item), state.user.name = ‘Ada’—are recorded and converted into an immutable update when the…
Load balancing is the distribution of incoming network traffic across multiple backend servers. The purpose is not to make a single request faster; it is to prevent any one server from becoming a bottleneck, to provide redundancy when a server fails, and to allow the pool to scale by adding more servers rather than upgrading…
Traefik is a reverse proxy that treats configuration as dynamic data. Where Nginx reads its upstream blocks from a file at startup and Caddy reads its Caddyfile, Traefik watches external sources—Docker labels, Kubernetes resources, or a file directory—and updates its routing table at runtime without a restart . The previous chapters covered Nginx and Caddy,…
Caddy’s reverse proxy is configured with a single directive: reverse_proxy. Where Nginx requires an upstream block, a location block, and a set of proxy_set_header directives, Caddy requires the backend address and, optionally, a block of modifiers. The forwarding headers that Nginx requires explicitly are set by default: Caddy passes the incoming Host header to the…
Nginx is the most widely deployed reverse proxy in the Linux ecosystem, and its ngx_http_proxy_module is the component that makes it one. The previous chapter covered the concepts: the request flow, the forwarding headers, the load-balancing algorithms, and the health checks. This chapter covers the Nginx configuration that implements those concepts: the proxy_pass directive, the…
A reverse proxy sits in front of one or more backend servers and forwards client requests to them. The client sees only the proxy; the backend servers are hidden behind it. The proxy terminates the client connection, selects a backend, forwards the request, receives the response, and returns it to the client. The backend sees…