Azure Cache for Redis output binding for Azure Functions

A C# function can be created using one of the following C# modes:

• In-process class library: compiled C# function that runs in the same process as the Functions runtime.
• Isolated process class library: compiled C# function that runs in a process isolated from the runtime. Isolated process is required to support C# functions running on .NET 5.0.
• C# script: used primarily when creating C# functions in the Azure portal.

The following example shows a pub/sub trigger on the set event with an output binding to the same Redis instance. The set event triggers the cache and the output binding returns a delete command for the key that triggered the function.

using Microsoft.Extensions.Logging;

namespace Microsoft.Azure.Functions.Worker.Extensions.Redis.Samples.RedisOutputBinding
{
    internal class SetDeleter
    {
        [Function(nameof(SetDeleter))]
        [RedisOutput(Common.connectionString, "DEL")]
        public static string Run(
            [RedisPubSubTrigger(Common.connectionString, "__keyevent@0__:set")] string key,
            ILogger logger)
        {
            logger.LogInformation($"Deleting recently SET key '{key}'");
            return key;
        }
    }
}

using Microsoft.Extensions.Logging;

namespace Microsoft.Azure.WebJobs.Extensions.Redis.Samples.RedisOutputBinding
{
    internal class SetDeleter
    {
        [FunctionName(nameof(SetDeleter))]
        public static void Run(
            [RedisPubSubTrigger(Common.connectionStringSetting, "__keyevent@0__:set")] string key,
            [Redis(Common.connectionStringSetting, "DEL")] out string[] arguments,
            ILogger logger)
        {
            logger.LogInformation($"Deleting recently SET key '{key}'");
            arguments = new string[] { key };
        }
    }
}

The following example shows a pub/sub trigger on the set event with an output binding to the same Redis instance. The set event triggers the cache and the output binding returns a delete command for the key that triggered the function.

package com.function.RedisOutputBinding;

import com.microsoft.azure.functions.*;
import com.microsoft.azure.functions.annotation.*;
import com.microsoft.azure.functions.redis.annotation.*;

public class SetDeleter {
    @FunctionName("SetDeleter")
    @RedisOutput(
                name = "value",
                connection = "redisConnectionString",
                command = "DEL")
    public String run(
            @RedisPubSubTrigger(
                name = "key",
                connection = "redisConnectionString",
                channel = "__keyevent@0__:set")
                String key,
            final ExecutionContext context) {
        context.getLogger().info("Deleting recently SET key '" + key + "'");
        return key;
    }
}

This example shows a pub/sub trigger on the set event with an output binding to the same Redis instance. The set event triggers the cache and the output binding returns a delete command for the key that triggered the function.

{
    "bindings": [
        {
            "type": "redisPubSubTrigger",
            "connection": "redisConnectionString",
            "channel": "__keyevent@0__:set",
            "name": "key",
            "direction": "in"
        },
        {
            "type": "redis",
            "connection": "redisConnectionString",
            "command": "DEL",
            "name": "$return",
            "direction": "out"
        }
    ],
    "scriptFile": "index.js"
}

module.exports = async function (context, key) {
    context.log("Deleting recently SET key '" + key + "'");
    return key;
}

This example shows a pub/sub trigger on the set event with an output binding to the same Redis instance. The set event triggers the cache and the output binding returns a delete command for the key that triggered the function.

The bindings are defined in this function.json file:

{
    "bindings": [
        {
            "type": "redisPubSubTrigger",
            "connection": "redisLocalhost",
            "channel": "__keyevent@0__:set",
            "name": "key",
            "direction": "in"
        },
        {
            "type": "redis",
            "connection": "redisLocalhost",
            "command": "DEL",
            "name": "retVal",
            "direction": "out"
        }
    ],
    "scriptFile": "run.ps1"
}

This code from the run.ps1 file takes the key from the trigger and passes it to the output binding to delete the cached item.

param($key, $TriggerMetadata)
Write-Host "Deleting recently SET key '$key'"
Push-OutputBinding -Name retVal -Value $key

This example shows a pub/sub trigger on the set event with an output binding to the same Redis instance. The set event triggers the cache and the output binding returns a delete command for the key that triggered the function.

{
    "bindings": [
        {
            "type": "redisPubSubTrigger",
            "connection": "redisLocalhost",
            "channel": "__keyevent@0__:set",
            "name": "key",
            "direction": "in"
        },
        {
            "type": "redis",
            "connection": "redisLocalhost",
            "command": "DEL",
            "name": "$return",
            "direction": "out"
        }
    ],
    "scriptFile": "__init__.py"
}

import logging

def main(key: str) -> str:
    logging.info("Deleting recently SET key '" + key + "'")
    return key

Attributes

The way in which you define an output binding parameter depends on whether your C# functions runs in-process or in an isolated worker process.

The output binding is defined this way:

In this case, the type returned by the method is a key value that the binding uses to execute the command against the specific cache.

When your function has multiple output bindings, you can instead apply the binding attribute to the property of a type that is a key value, which the binding uses to execute the command against the specific cache. For more information, see Multiple output bindings.

Regardless of the C# process mode, the same properties are supported by the output binding attribute:

Annotations

The RedisOutput annotation supports these properties:

Configuration

The following table explains the binding configuration properties that you set in the function.json file.