Storing Kamal secrets in AWS Secrets Manager and deploying to a cheap Hetzner VPS

I ran into a problem with Kamal. My .kamal/secrets file was full of API keys sitting in plaintext on my laptop. Anyone with access could read them all.

TLDR; Use and deploy to a CAX series starts at around 4 euro a month. I use the CX22 with 2 vCPUs and 4GB RAM. Enough for production.

# On your Hetzner server

apt update && apt install -y docker.io



# Copy your SSH key so Kamal can connect

ssh-copy-id root@your-server-ip

Your config/deploy.yml:

servers:

  web:

    hosts:

      - runtime.yourdomain.com



proxy:

  ssl: true

  hosts:

    - runtime.yourdomain.com

  healthcheck:

    path: /health/ready



registry:

  server: docker.io

  username: your-docker-user

  password:

    - KAMAL_REGISTRY_PASSWORD

You need a Console:

1. Go to Secrets Manager > Store a new secret


2. Select "Other type of secret"


3. Switch to plaintext tab and paste your JSON
   

{

  "DEEPGRAM_API_KEY": "your_deepgram_key",

  "ASSEMBLY_AI_API_KEY": "your_assemblyai_key",

  "REDIS_URL": "redis://:password@your-redis:6379",

  "KAMAL_REGISTRY_PASSWORD": "your_docker_token"

}

1. Name it myapp/production/secrets
   


2. Click Store

Pick a region close to your server. If your Hetzner box is in Germany, use eu-central-1 (Frankfurt). Keeps latency low and GDPR happy.

Step 3: IAM user for your laptop

Your laptop needs permission to read the secret during deploy.

1. Go to IAM > Users > Create user


2. Name it kamal-deploy
   


3. Uncheck console access (CLI only)


4. Create a group called secrets-manager with the SecretsManagerReadWrite policy


5. Add an inline policy for batch reading:
   

{

  "Version": "2012-10-17",

  "Statement": [

    {

      "Effect": "Allow",

      "Action": [

        "secretsmanager:GetSecretValue",

        "secretsmanager:DescribeSecret",

        "secretsmanager:BatchGetSecretValue",

        "secretsmanager:ListSecrets"

      ],

      "Resource": "*"

    }

  ]

}

1. Add your user to the group

IAM policies can take a minute to propagate. If it fails at first, wait 30 seconds and try again.

Step 4: Configure AWS CLI

aws configure

# AWS Access Key ID: paste from IAM user

# AWS Secret Access Key: paste

# Default region name: eu-central-1

# Default output format: json

Test it:

aws secretsmanager get-secret-value --secret-id myapp/production/secrets --query SecretString --output text | head -c 50

You should see the start of your JSON.

Step 5: Format your .kamal/secrets file

This is where I got stuck. The --from flag wants one AWS secret per key. Having 20 separate secrets is annoying. Check the , the for keeping hosting affordable. Hope this saves you the same headaches I ran into. Now back to building.