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Oasis Web3 Gateway for your EVM ParaTime

This guide will walk you through the steps needed to set up the Oasis Web3 gateway for EVM-compatible ParaTimes, such as Emerald and Sapphire.


Each ParaTime requires its own instance of the Web3 gateway!



In addition to the minimum hardware requirements for running the Oasis node, the following should be added for running the Web3 gateway:

  • CPU:
    • Minimum: 2.0 GHz x86-64 CPU
    • Recommended: 2.0 GHz x86-64 CPU with 2 cores/vCPUs
  • Memory:
    • Minimum: 4 GB of ECC RAM
    • Recommended: 8 GB of ECC RAM
  • Storage:
    • Minimum: 300 GB of SSD or NVMe fast storage
    • Recommended: 500 GB of SSD or NVMe fast storage

To put the figures above into perspective, the Web3 gateway for Emerald with PostgreSQL encountered 210 GB of database growth in ~5 months between Nov 18, 2021 and Apr 11, 2022 (since the Emerald Mainnet launch).

Oasis ParaTime Client Node

The Web3 gateway requires a locally deployed ParaTime-enabled Oasis Node. First, follow the Oasis ParaTime client node guide on how to configure the Oasis client node with one or more ParaTimes. Always use the exact combination of the Oasis node/ParaTime versions as published on the network parameters page for either Mainnet or Testnet.

Apart from the transactions that happen on-chain and produce some effects, there are also a number of read-only queries implemented in the Oasis protocol and EVM. Some of them may be quite resource-hungry such as simulating EVM calls and are disabled by default to avoid DDOS attacks. If your Oasis node instance will only be used by you and your Web3 gateway(s), you can safely enable expensive transactions by adding the following to your Oasis node config:

# ... sections not relevant are omitted ...
mode: client
- {{ emerald_bundle_path }}
- {{ sapphire_bundle_path }}

"{{ emerald_paratime_id }}":
estimate_gas_by_simulating_contracts: true
- all_expensive: true
"{{ sapphire_paratime_id }}":
estimate_gas_by_simulating_contracts: true
- all_expensive: true

In the config above replace {{ ... }} placeholders with actual ParaTime IDs:

  • {{ emerald_paratime_id }}:
    • Emerald on Mainnet: 000000000000000000000000000000000000000000000000e2eaa99fc008f87f
    • Emerald on Testnet: 00000000000000000000000000000000000000000000000072c8215e60d5bca7
  • {{ sapphire_paratime_id }}:
    • Sapphire on Testnet: 000000000000000000000000000000000000000000000000a6d1e3ebf60dff6c


The Web3 gateway stores blockchain data in a PostgreSQL database version 13.3 or higher. Install it by following instructions specific to your operating system and environment.

Because each ParaTime requires its own instance of the Web3 gateway, you will have to create a separate database and a separate user for each Web3 instance.

Download Oasis Web3 Gateway

Check the required version of the Web3 gateway for the network you will be deploying it to: Mainnet, Testnet. Next, download the Oasis-provided binaries from the official GitHub repository.

Alternatively, you can download the source release and compile it yourself. Consult the file for more information.

Running the Web3 Gateway

Copy the content below to the config file of your Web3 gateway.

# Uncomment the runtime_id below.
runtime_id: {{ paratime_id }}
# Path to your internal.sock file in the root Oasis node datadir.
node_address: "unix:{{ oasis_node_unix_socket }}"

# By default, we index the entire blockchain history.
# If you are low on disk space or you use the gateway just for submitting transactions, enable
# pruning below.
enable_pruning: false
pruning_step: 100000
indexing_start: 0

level: debug
format: json

# Change host and port, if PostgreSQL is running somewhere else.
host: ""
port: 5432
# Enter your database name, username and password.
db: {{ postgresql_db }}
user: {{ postgresql_user }}
password: {{ postgresql_password }}
dial_timeout: 5
read_timeout: 10
write_timeout: 5
max_open_conns: 0

chain_id: {{ chain_id }}
# Change host to your external IP address if you have users accessing Web3 from the outside.
host: "localhost"
# Use different port for each Web3 gateway instance, if all run locally.
port: 8545
cors: ["*"]
# Change host to your external IP address if you have users accessing Web3 from the outside.
host: "localhost"
# Use different port for each Web3 gateway instance, if all run locally.
port: 8546
origins: ["*"]
get_logs_max_rounds: 100

Use the following placeholder values:

  • {{ paratime_id }}: The ID of the Emerald or Sapphire ParaTime which you are configuring the Web3 gateway for (see above).
  • {{ oasis_node_unix_socket }}: Path to the internal.sock file created by the Oasis node.
  • {{ postgresql_db }}, {{ postgresql_user }}, {{ postgresql_password }}: Database name and credentials for your PostgreSQL database.
  • {{ chain_id }}: The chain ID of your EVM network:

All configuration settings can also be set via environment variables. For example, instead of setting up the database password in the config file above you can export:


To start the Web3 gateway invoke:

./emerald-web3-gateway --config gateway.yml

The Web3 gateway will connect to your Oasis node and start indexing available blocks (i.e. from the last network upgrade). This may — depending on your hardware and the size of the blockchain — take hours.

If your database contains any tables populated by the previous version of the Web3 gateway, migration scripts will automatically be applied upon startup.

If you want to migrate the database separately, run:

./emerald-web3-gateway migrate-db --config gateway.yml

Above, we are invoking the emerald-web3-gateway process directly from the shell, so you can quickly start using it. If you are setting up a production environment, you should configure the Web3 gateway as a system service and register it in the service manager for your platform.

Archive Web3 Gateway

Each Oasis Web3 gateway can only connect to and synchronize blocks from a single Oasis node instance. To enable access to older EVM blocks, you can configure the Web3 gateway to behave as a proxy to another — archive — instance of the Web3 gateway.

First, set up an instance of the Oasis archive node. Then, repeat the similar process of setting up a Web3 gateway as you would normally do, but configure it to use the newly set up Oasis archive node.

Suppose the archive instances of the Web3 gateway and Oasis nodes are up and running and the archive Web3 gateway is listening on the local port 8543. Enable the proxy for historical blocks by adding the following to your (live) Web3 gateway config and restart it:

# URI of an archive web3 gateway instance for servicing historical queries.
archive_uri: 'http://localhost:8543'

If a query requires information on the block which isn't stored in the live version of the Web3 gateway, the gateway will pass the query to the configured archive instance and return the obtained result.


Historical estimate gas calls are not supported.


Wipe state to force a complete reindex

If you encounter database or hardware issues, you may need to wipe the database and reindex all blocks. First, run the truncate-db subcommand:

emerald-web3-gateway truncate-db --config gateway.yml --unsafe

Then, execute the emerald-web3-gateway normally to start reindexing the blocks.


This will wipe all existing state in the PostgreSQL database and can lead to extended downtime while the Web3 Gateway is reindexing the blocks.