📂 Build an Airnode

# Configuring Airnode

Table of Contents

Tips

Be sure to complete API Integration before configuring your Airnode.

info This icon links to additional field information in the reference section.

An Airnode is deployed or redeployed using configuration values from its config.json and secrets.env files. The config.json specifies the OIS (Oracle Integration Specifications) and other specific configuration details. The secrets.env file holds secrets, such as API keys and chain provider URLs, which are referenced within the config.json file using interpolation.

config-json

  • The config.json file is used during the deployment/redeployment of an Airnode to configure its behavior and to provide mappings of API operations.

  • The secrets.env file holds values for config.json that must be kept secret.

  • The aws.json file holds credentials for deployments targeted to AWS Lambda.

The following example files are useful while reading this doc.

# Creating config.json

Use the config.json template to build your own Airnode configuration file or alter the config.json example file. There are five root level fields in config.json.

# chains

Each row in the chains array represents an Ethereum blockchain the Airnode will serve as identified by the id. Currently Airnode only supports Ethereum blockchains as denoted by type: "evm". There are several supported blockchains, see them in the Airnode contract addresses doc. You can use multiple chain providers for each chain and declare multiple chains each with one of more chain providers. See Chains Providers in Concepts and Definitions.

Below is a simple chain array with a single chain provider.

"chains": [
  {
    "authorizers": [
      "0x5Fgh48...3F6f64180acc"
    ],
    "contracts": {
      "AirnodeRrp": "0xF6d267546...BC9A384fa418"
    },
    "id": "4",
    "providers": [
      "infura_rinkeby": {
        "url": "${INFURA_RINKEBY_PROVIDER_URL}"
      }
    ],
    "type": "evm",
    "blockHistoryLimit": 300,
    "ignoreBlockedRequestsAfterBlocks": 20
  }
],
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19

# authorizers

info The list of authorizer contract addresses the Airnode deployment will set on-chain. See the Authorization doc for more information.

# contracts

info Contains the addresses of the contracts that implement the Airnode protocols. Although you can deploy these contracts yourself, you are recommended to use the ones that were deployed by API3. You can find them in the list above.

# id

info An Airnode can serve multiple chains simultaneously. Set the ID of the desired chain in id (e.g., 4 for Rinkeby test network). See the list of supported chains in the Airnode Contract Addresses doc. See additional definition in the reference section.

# providers

info Airnode can use multiple Ethereum providers per chain. These could be a private Ethereum node, or an Ethereum service provider such as Infura. Accordingly, the providers field is a list which allows for multiple Ethereum providers. Enter a user defined name which identifies the provider and the provider URL which usually is kept in the secrets.env file. The name is used in logs.

# type

info The type of the chain. Only evm is supported at this time. See additional definition in the reference section.

# blockHistoryLimit

info The number of blocks in the past that the Airnode deployment should search for requests. Defaults to 300 (roughly 1 hour for Ethereum).

# ignoreBlockedRequestsAfterBlocks

info The number of blocks that need to pass for the node to start ignoring blocked requests. Defaults to 20.

# nodeSettings

The nodeSettings field holds node-specific (Airnode) configuration parameters.

{
"nodeSettings": {
    "cloudProvider": "aws",
    "airnodeWalletMnemonic": "${AIRNODE_WALLET_MNEMONIC}",
    "heartbeat": {
      "enabled": true,
      "apiKey": "${HEARTBEAT_API_KEY}",
      "id": "${HEARTBEAT_ID}",
      "url": "${HEARTBEAT_URL}"
    },
    "httpGateway": {
      "enabled": true,
      "apiKey": "${HTTP_GATEWAY_API_KEY}"
    },
    "logFormat": "plain",
    "logLevel": "INFO",
    "nodeVersion": "0.2.2",
    "region": "us-east-1",
    "stage": "dev"
  },
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20

# cloudProvider

info Indicates which cloud provider Airnode should be deployed with or if it should be run locally. The deployer currently supports aws or local.

# airnodeWalletMnemonic

info An API provider provides a mnemonic to be used as the Airnode's BIP 44 wallet from which the Airnode's address will be derived. It is not required to fund the wallet to run the Airnode but must be funded to announce the xpub of the Airnode on-chain which is optional.

# heartbeat

info At the end of each of Airnode's runs (every minute), Airnode can make an HTTP POST request to a specified URL. This is both to signal that the Airnode is alive and working (useful especially right after the deployment) and also to send some metrics from its run. Turn on the heartbeat functionality by setting all fields in the config.json section nodeSettings.heartbeat. See the Heartbeat doc for more info.

  • enabled: Enable/disable Airnode's heartbeat.
  • url: The URL to make the heartbeat request to.
  • apiKey: The API key to authenticate against the heartbeat URL.
  • id: The Airnode heartbeat ID for accounting purposes.

# httpGateway

info The gateway allows the testing of defined endpoints without accessing the blockchain. See the HTTP Gateway doc for more info.

  • enabled: Enable/disable Airnode's Access to the HTTP gateway
  • apiKey: A user defined API key to authenticate against the gateway. The key must have a length of between 30 - 120 characters.

# logFormat

info Set one of two possible log formats.

  • json
  • plain

# logLevel

info Set one of four possible log levels.

  • DEBUG
  • INFO
  • WARN
  • ERROR

# nodeVersion

info Of the form #.#.#, this field indicates which node (Airnode) version this config.json is prepared for. Since the config.json format can be expected to change with node versions, using a config.json prepared for one Airnode version with another may result in unexpected issues. See the Releases page of the Airnode repo (opens new window) for available versions.

# region

info This field can be seen as an extension of cloudProvider, it refers to which region of the cloud provider Airnode will be deployed at. An example value for AWS would be us-east-1. Note that transferring a deployment from one region to the other is not trivial at this moment (i.e., it does not take one command like deployment, but rather three). Therefore, try to pick a region and stick to it for this specific deployment.

# stage

info This field allows the deployment of multiple Airnodes with the same provider ID. For example, the provider may deploy one Airnode with the stage api3 to serve API3 dAPIs, and one with the stage public that serves the public. A regular user will have a single deployment, so feel free to set any descriptive name as your stage.

# triggers

The triggers field allows you to expose Airnode endpoints from an OIS selectively. For example, your OIS may include ten endpoints, but you may only want to serve two. Instead of modifying the OIS, you would simply create triggers for the two. List the endpoints that you want to serve with the request–response protocol under triggers.rrp. In most cases, you would create a trigger for each endpoint in your OIS object.

# oisTitle & endpointName

info Each trigger has an oisTitle and endpointName that allow you to refer to one of the endpoints in an OIS object. Remember that an Airnode's config.json file can have more than one OIS object. Fill these in accordingly.

# endpointId

info Add an endpointId to the trigger which is the ID that a requester will use for on-chain requests to reference a specific trigger. Use the admin CLI command derive-endpoint-id to derive endpoint IDs using the oisTitle and endpointName.

npx @api3/airnode-admin derive-endpoint-id \
  --oisTitle "My OIS title..." \
  --endpointName "My endpoint name..."
1
2
3

# ois

The ois field is a list OIS objects that Airnode will be serving. This means that a single instance of an Airnode can serve multiple APIs. You can simply copy paste OIS objects that you will be serving into the ois list. Use the previous guide API Integration to create an OIS object.

# apiCredentials

Each entry in apiCredentials maps to a security scheme defined in an OIS (ois[n].components.securitySchemes.{securitySchemeName} and ois[n].security), where oisTitle is the title field of the related OIS, and securitySchemeName is the name of the respective security scheme. These would be myOisTitle and mySecurityScheme in the example below. securitySchemeValue is the value used for the authentication with the security scheme (e.g., the API key).

Use of apiCredentials is not required, leave its array empty if you don't need any security scheme.

// apiCredentials
[
  {
    "oisTitle": "myOisTitle",
    "securitySchemeName": "mySecurityScheme",
    "securitySchemeValue": "${SS_MY_API_KEY}"
  }
]

// From the OIS object apiCredentials is referencing
// using the oisTitle/securitySchemeName pair.
{
  "title": "myOisTitle",
  ...,
  "components": {
    "securitySchemes": {
      "mySecurityScheme": {
        "in": "header",
        "type": "apiKey",
        "name": "X-api-key"
      }
    }
  },
  "security":{
    "mySecurityScheme": []
  }
  ...
}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28

# oisTitle

info The ois.title of the OIS where the securitySchemeName can be found.

# securitySchemeName

info The name of a security scheme from ois[n].components.securitySchemes.{securitySchemeName}.

# securitySchemeValue

info The value of the security scheme used (as defined by ois[n].components.securitySchemes.{securitySchemeName} for the authentication. Usually stored in secrets.env.

Based on the setup above Airnode will call the API operation with the following header.

headers: {
  "X-api-key": "834989348HHGTDS_8754",
}
1
2
3

# Creating secrets.env

The secrets.env file contains values (secrets) such as blockchain provider urls, chain provider urls, etc. These secrets are embedded in config.json using interpolation.

// Sample interpolation value from config.json
"httpGateway": {
  "enabled": true,
  "apiKey": "${HTTP_GATEWAY_API_KEY}"
},

// Sample variable in secrets.env
HTTP_GATEWAY_API_KEY="FRACZKMH4F32BZ8X5uTd"
1
2
3
4
5
6
7
8

Use the secrets.env template and refer to Reference > Deployment Files > secrets.env as needed.

# Creating aws.env

When it is time to deploy the Airnode to a cloud provider (AWS), the Docker deployer image will need the AWS credentials to build the node on AWS Lambda.

Follow this video (opens new window) if needed. It will show you how to create an IAM user and get security credentials. Put them in the aws.env file as shown below. Note that double quotes (") are not permitted to enclose the values as with the secrets.env file.

AWS_ACCESS_KEY_ID=XYZ...123
AWS_SECRET_ACCESS_KEY=ABC7...89
1
2

Here is an example file that is left blank.

# Summary

In this guide you created the config.json, secrets.env and aws.env files required to deploy an Airnode to a cloud provider (AWS). Note that config.json is user-specific and therefore it is not much use to others.

The secrets.envand aws.env files contains keys, chain provider urls and security credentials, so they should be kept secret. Make sure that you do not push your credentials (secrets.env and aws.env) to a repository or otherwise expose them as these credentials can be used to gain access to your Airnode's private key and AWS account.

The next three steps in this guide are optional.

Last Updated: 3/7/2022, 8:32:47 AM