create-stateful-service

Create a stateful service

State management is one of the most common needs of any application: new or legacy, monolith or microservice. Dealing with different databases libraries, testing them, handling retries and faults can be time consuming and hard.

Dapr provides state management capabilities that include consistency and concurrency options. In this guide we'll start of with the basics: Using the key/value state API to allow an application to save, get and delete state.

1. Setup a state store

A state store component represents a resource that Dapr uses to communicate with a database. For the purpose of this how to, we'll use a Redis state store.

See a list of supported state stores here

Using the Dapr CLI

When using Dapr init in Standalone mode, the Dapr CLI automatically provisions a state store (Redis) and creates the relevant YAML when running your app with dapr run. To change the state store being used, replace the YAML under /components with the file of your choice.

Kubernetes

See the instructions here on how to setup different state stores on Kubernetes.

2. Save state

The following example shows how to save two key/value pairs in a single call using the state management API, both of which are saved with the single key1name over http.

The following example is written in Python, but is applicable to any programming language

import requests
import json

stateReq = '[{ "key": "k1", "value": "Some Data"}, { "key": "k2", "value": "Some More Data"}]'
response = requests.post("http://localhost:3500/v1.0/state/key1", json=stateReq)

3. Get state

The following example shows how to get an item by using a key with the state management API over http:

The following example is written in Python, but is applicable to any programming language

import requests
import json

response = requests.get("http://localhost:3500/v1.0/state/key1")
print(response.text)

4. Delete state

The following example shows how to delete an item by using a key with the state management API over http:

The following example is written in Python, but is applicable to any programming language

import requests
import json

response = requests.delete("http://localhost:3500/v1.0/state/key1")