How to run op-alt-da with AWS KMS

Overview

This guide walks through running op-alt-da (da-server) using a Celestia key stored in Amazon Web Services (AWS) key management service (KMS). You will use the localstack, a mock of AWS, to learn how to run the da-server. Once you've done this, you can log in to AWS and use your private key in prod.

Prerequisites

Docker
Go 1.21+
A Celestia RPC endpoint from Quicknode

Getting started

Setup environment

Install awscli:
```
brew install awscli
```

Clone and build op-alt-da (v0.12.0+):

git clone https://github.com/celestiaorg/op-alt-da.git && cd op-alt-da
make

Localstack

Set mock AWS credentials (required even for localstack):

export AWS_ACCESS_KEY_ID=test
export AWS_SECRET_ACCESS_KEY=test
export AWS_DEFAULT_REGION=us-east-1

Start localstack with KMS enabled:

docker run -d \
  --name localstack \
  -p 4566:4566 \
  -e SERVICES=kms \
  localstack/localstack

Verify it's running:

aws --endpoint-url=http://localhost:4566 kms list-keys
# should return: { "Keys": [] }

Create KMS key

Create a KMS key and alias:

KEY_ID=$(aws --endpoint-url=http://localhost:4566 kms create-key \
  --key-spec ECC_SECG_P256K1 \
  --key-usage SIGN_VERIFY \
  --query 'KeyMetadata.KeyId' --output text)
 
aws --endpoint-url=http://localhost:4566 kms create-alias \
  --alias-name alias/op-alt-da/celestia_key --target-key-id $KEY_ID

Configure op-alt-da

Copy config example into config.toml:
```
cp config.toml.example config.toml
```

Edit config.toml with the configs you gathered in the setup:

[celestia]
namespace = "000000000000000000000000000000000000000000000000000000acfe"
keyring_backend = "awskms"
default_key_name = "alias/op-alt-da/celestia_key"
 
bridge_addr = "https://your-endpoint.celestia-mocha.quiknode.pro/your-token/"
bridge_auth_token = ""
bridge_tls_enabled = true
 
core_grpc_addr = "your-endpoint.celestia-mocha.quiknode.pro:9090"
core_grpc_auth_token = "your-token"
core_grpc_tls_enabled = true
 
[celestia.awskms]
region = "us-east-1"
endpoint = "http://localhost:4566"

Note: In v0.12.0+, the default_key_name must include the full alias path (e.g., alias/op-alt-da/celestia_key).

Run the DA server

Run the op-alt-da server:

AWS_ACCESS_KEY_ID=test AWS_SECRET_ACCESS_KEY=test AWS_DEFAULT_REGION=us-east-1 ./bin/da-server -config config.toml

Where this is what the successful start looks like:

INFO [01-20|14:53:56.130] Initializing Stateless Alt-DA server...
INFO [01-20|14:53:56.131] Using celestia storage                   url=https://your-endpoint.celestia-mocha.quiknode.pro/your-token/
INFO [01-20|14:53:56.179] Immediate submission mode (default, no queue)
INFO [01-20|14:53:56.992] Starting HTTP server                     addr=127.0.0.1:3100
INFO [01-20|14:53:56.992] Starting metrics server                  addr=:6060
INFO [01-20|14:53:57.004] Started DA Server

Test a POST request to get your Celestia address:

curl -s -X POST http://127.0.0.1:3100/put \
  -H "Content-Type: application/octet-stream" \
  -d "hello celestia" -o /dev/null

The first request will fail because the account has no funds. Check the server logs for the error message which reveals your Celestia address:

submission failed: account for signer celestia1rwuklcs36jm6wqxk8w9cx9vyja93856nz3sdlf not found

Fund your address at the faucet: https://mocha.celenium.io/faucet

Copy the celestia1... address from the error message and request testnet tokens.

Retry the POST request:

curl -s -X POST http://127.0.0.1:3100/put \
  -H "Content-Type: application/octet-stream" \
  -d "hello celestia" -o /dev/null

A successful POST shows in the server logs:

INFO [01-20|14:54:15.342] celestia: blob successfully submitted    id=74a5940000000000677e645183667f4d9efe506226fd0dd0b70a4144c8fd05c0aa68407ccf886507
INFO [01-20|14:54:15.342] Blob submitted successfully              commitment=010c74a5940000000000677e645183667f4d9efe506226fd0dd0b70a4144c8fd05c0aa68407ccf886507 size=14 duration=11.5436025s

Check your transaction on Celenium by navigating to https://mocha.celenium.io/address/YOUR_CELESTIA_ADDRESS.

Verify your key and alias:

AWS_ACCESS_KEY_ID=test AWS_SECRET_ACCESS_KEY=test AWS_DEFAULT_REGION=us-east-1 aws --endpoint-url=http://localhost:4566 kms list-aliases

You should see your alias pointing to the key:

{
    "Aliases": [
        {
            "AliasName": "alias/op-alt-da/celestia_key",
            "AliasArn": "arn:aws:kms:us-east-1:000000000000:alias/op-alt-da/celestia_key",
            "TargetKeyId": "79b26b15-0635-4b3c-aad0-0ab4406e6754"
        }
    ]
}

Congratulations, you're set up! You should be able to see your blob has been posted successfully using op-alt-da and AWS KMS. Now you can run your OP Stack rollup with AWS KMS, using the Celestia key in AWS.

Production (AWS)

For production AWS KMS usage:

Create a KMS keypair in AWS with key spec ECC_SECG_P256K1 and key usage SIGN_VERIFY.
Create an alias for your key (e.g., alias/op-alt-da/my_celes_key). Per AWS requirements, the alias name must start with alias/.

Configure your IAM policy with the minimum required permissions:

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": [
        "kms:GetPublicKey",
        "kms:Sign"
      ],
      "Resource": "arn:aws:kms:REGION:ACCOUNT_ID:key/KEY_ID"
    }
  ]
}

Update your config.toml:
```
[celestia]
keyring_backend = "awskms"
default_key_name = "alias/op-alt-da/my_celes_key"
 
[celestia.awskms]
region = "us-east-2"
endpoint = ""
```
Note: Leave endpoint empty for production AWS. The default_key_name must include the full alias path (e.g., alias/my_celes_key or alias/op-alt-da/my_celes_key).

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