ElastiCache IAM authentication is not supported in MULTI EXEC commands.

Question

We are trying to use IAM authentication to connect ElastiCache serverless.
But, we notice that in the document point out a limitation: `IAM authentication is not supported in MULTI EXEC commands.`.
May I know more details about this limitation? What exactly happen when we execute MULTI EXEC command over IAM authentication.
We tried to test it. But, we don't see any issue there. Here is our pseudo testing code

```
// c := a redis.UniversalClient
pipe := c.TxPipeline()
pipe.SAdd(ctx, rkey, value)
pipe.Expire(ctx, rkey, expiration)
_, err = pipe.Exec(ctx)
```

re:Post Agent · Answer

You're correct that IAM authentication for ElastiCache has a documented limitation regarding MULTI EXEC commands. This limitation applies to both ElastiCache for Redis/Valkey and MemoryDB services when using IAM authentication.

The limitation specifically means that you cannot use IAM authentication tokens within a Redis transaction block that uses the MULTI and EXEC commands. This is an important distinction from the Redis pipeline functionality you're using in your code example.

Your code is using a transaction pipeline (`TxPipeline()`) which is a client-side implementation that may work differently than direct MULTI/EXEC commands. Many Redis clients implement pipelining as a client-side optimization that batches commands together, which is different from Redis's server-side transactions using MULTI/EXEC.

The key differences:

1. Redis MULTI/EXEC transactions: These are true Redis transactions where commands between MULTI and EXEC are queued on the server and executed atomically.

2. Client-side pipelining: This batches commands to reduce network roundtrips but doesn't necessarily use the MULTI/EXEC commands at the protocol level.

Your code appears to be working because the client library is likely handling the commands in a way that's compatible with IAM authentication, possibly by not using the actual MULTI/EXEC commands at the protocol level.

If you were to directly use MULTI and EXEC commands with IAM authentication (for example, through a raw Redis client or direct protocol interaction), you would likely encounter authentication failures or connection issues.

The IAM authentication token is valid for 15 minutes, and authenticated connections are automatically disconnected after 12 hours. These limitations apply regardless of how you're interacting with the Redis instance.  
**Sources**  
[Authenticating with IAM - Amazon ElastiCache](https://docs.aws.amazon.com/AmazonElastiCache/latest/dg/auth-iam.html)  
[Community | Using IAM authentication for Redis on AWS](https://community.aws/content/2ZCKrwaaaTglCCWISSaKv1d7bI3/using-iam-authentication-for-redis-on-aws)  
[Authenticating with IAM - Amazon MemoryDB](https://docs.aws.amazon.com/memorydb/latest/devguide/auth-iam.html)

ElastiCache IAM authentication is not supported in MULTI EXEC commands.

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