# Tutorial: Running a Relay Server for Fun and Profit
Users that rely on the GSN to access distributed applications (dapps) need to access relays through the Internet to get their messages to the blockchain. Any user can access any relay to communicate with any supported dapp. If you are a dapp developer you can participate in the GSN by running a relay themselves and making it a preferred relay. You can run a Relay Server only to earn from relaying transaction fees.
This article explains how to run a relayer on a cloud VM using Google Cloud Platform Compute (opens new window), though your can use any other hosting provider.
# Running a Relay Server For Profit
Relay Servers get reimbursed by Paymasters for the gas they spend sending transactions for users, plus a transaction fee that is defined by the network.
Profits of a Relay Server vary based on transaction volume, but there is little risk involved in running a Relay Server. Minimal resources are required to run a Relay Server. For example, GCP does not charge you for running a single micro instance (opens new window).
When you want to get your stake back you use the same account you used to register the relayer to unstake and deregister it. After the unstake period, which is about a week, you can withdraw all your locked funds.
- The Relay Server Virtual Machine with docker installed, with a publicly accessible static IP address.
- A DNS service (such as GoDaddy, NameCheap, or DuckDNS) to give your host a DNS name.
- Enough Ether to activate and fund the Relay Server.
- For technical assistance, please use our discord channel (opens new window)
# The Relay Server Virtual Machine
# Initial Setup
First you need to set up the virtual machine (VM) that will run the relay server.
Click CREATE INSTANCE.
Set these parameters (you can accept the default for all the others):
Heading Parameter Value Name Select a meaningful name Machine configuration Machine type e2-micro Boot disk Container Optimized OS Selected Firewall Allow HTTPS traffic Selected Firewall Allow HTTP traffic Selected
Configure the external IP of the relay in the DNS by adding an "A" record for that IP your DNS service. Note: by default, public IP is "ephemeral" and might change after reboot.
# The Docker Container
Now that the VM is running and has a DNS entry, the next step is to actually
run the relay software. It runs inside a docker container. You configure it using
a script called
rdc, which needs to run with more permissions than
the GCP container-optimized OS (opens new window) allows.
So you need to run it from a different computer that is authorized to SSH
into the relayer VM.
If you don't have this permission restriction, you can also download the script directly on the vm, and run the following commands using the "local" option.
- Open SSH to the relayer VM.
- Download the relayer configuration files.
docker-compose.yml file must be placed at the home folder. The
gsn-relay-config.json must be placed inside a
curl https://raw.githubusercontent.com/opengsn/gsn/master/dockers/docker-compose.yml > docker-compose.yml mkdir config curl https://raw.githubusercontent.com/opengsn/gsn/master/dockers/config-sample/gsn-relay-config.json > config/gsn-relay-config.json
Press Ctrl-O and then Enter to save the modified file.
Press Ctrl-X to exit.
Parameter Value relayHubAddress The address for the RelayHub on the network you are using. See this list. managerStakeTokenAddress The address for the ERC-20 token used for stake on the network you are using. See this list. ownerAddress The owner account that will be used by relayer-register, below ethereumNodeUrl The URL to a node on the network you wish to use. If you do not know what to put here, get a free Infura account (opens new window), create a project, and look at KEYS > ENDPOINTS for your network. Use the endpoint that starts with https://
Put the following values in a
Variable Example value Comment HOST my.hostname.com Your Relay Server URL exactly as it is accessed by GSN Clients DEFAULT_EMAIL email@example.com Your e-mail for LetsEncrypt to send SSL alerts to
Download and run the docker images
Note: if there is no 'docker-compose' alias installed on your cloud instance, run it as following:
docker run --rm -v /var/run/docker.sock:/var/run/docker.sock -v "$PWD:$PWD" -w="$PWD" docker/compose:1.27.3 up
To see the progress of the HTTPS server (the slowest component to set up), get the id of the "https-portal" container and run:
docker ps docker logs <https-portal container-id>
When you see this line it means the setup is done. You can close the SSH window.
[services.d](https-portal_1 | ) done.
https://<your-DNS-name>/getaddr/You should receive a JSON file with addresses and status. The
readysetting should be
false, because it isn't registered with the relay hub yet.
You can also check the activity of the relayer when you are on the vm. Get the id of the "jsrelay" container.
docker ps docker logs <jsrelay container-id>
# Relayer Staking and Registration
We need to register the relayer with the Relay Hub. This step has several purposes:
- Stake Ether or any supported ERC-20 token on the relay's honesty, so relays won't try to abuse the system (for example by submitting invalid messages)
- Fund the relayer with the initial account balance for sending transactions. The default is 2 Ether.
- Add the relayer to the on-chain relayers list so clients will know they can use it for free messages
You will need to make transactions from an account specified as
ownerAddress in the Relay Server configuration.
Make sure you have this account selected in MetaMask for the following steps.
- Go to
https://relays.opengsn.org/and click "Register New Relay".
- Enter your Relay Server URL and click "Register".
- Follow the steps on the Relay Registration page.
https://<your-DNS-name>/getaddr/. See that the relayer is now ready. Congratulations.
In order to test your relayer, add its URL to the list of
preferedRelays for your client's RelayProvider.
Otherwise, your client is free to pick any active relay.
The relayer generates its own Ethereum keystores & addresses internally. Do not tamper with the files or use these addresses to any other purpose. The relayer is staked on the network, performing other actions may result in penalization and loss of funds.