Configuration | Chainlink

appsettings.json

The node reads its configuration from a Chainlink section:

"Chainlink": {
  "BaseUrl": "https://api.ccip.chain.link/v2/",
  "NetworkRpcUrls": {
    "ethereum-mainnet": "https://your-rpc-provider/...",
    "arbitrum-mainnet": "https://your-rpc-provider/...",
    "base-mainnet": "https://your-rpc-provider/..."
  }
}

Key	Type	Required	Description
`BaseUrl`	text	No	Base URL for the CCIP API v2. Defaults to the real public `https://api.ccip.chain.link/v2/` — a stable production endpoint, so most deployments never need to set this.
`NetworkRpcUrls`	object	Only for `router/isChainSupported` & `router/getFee`	Map of network name → JSON-RPC endpoint URL (e.g. an Alchemy/Infura project URL). Every other operation on this node works with no RPC configuration at all.

No bundled RPC default: Unlike the CCIP API's own stable public BaseUrl, no production default RPC URL ships with this node. An RPC endpoint is deployment-specific infrastructure (often a paid, rate-limited allocation) that must never be hardcoded as a source default. You must supply your own NetworkRpcUrls entry for any network you call isChainSupported or getFee against — see Troubleshooting for what happens when one is missing.

Optional CCIP API Key

The CCIP API v2 works unauthenticated for the vast majority of its surface — every operation this node implements works with no API key at all. An API key is only needed for one gated CCIP API feature (an intents/quote endpoint this node doesn't implement), and it also raises rate-limit headroom on the public endpoints this node does call.

When present, attach the key as this node's credential (an API_KEY-type vault record, the same shape used across this codebase). The node resolves it once per execution via ReadCredentialRawPrimaryAsync and passes it down as a plain per-call parameter — there is no bespoke credential-resolver service class for this node.

Registration

ChainlinkDependency.RegisterDefaults(services) registers everything the node needs:

The ChainlinkApiClientOptions options binding (bound lazily to the Chainlink configuration section)
ChainlinkRateLimitHandler — a Transient DelegatingHandler that retries 429/502/503/504 responses, honoring Retry-After
The CCIP API v2 HTTP client, the message builder, the on-chain reader, and the 3 resource services (Message, Router, Lane)
The executor itself, scoped
The ExecutorRegistry entry for chainlink

Host apps must also add an explicit registration call: alongside the standard DI registration, a new ChainlinkDependency().RegisterDefaults(services); line must be added to Plugins_RegisterAllNodes() in ServiceCollectionExtensionsForAI.cs, plus a ProjectReference from the hosting project to this executor's csproj. Without both, the node type won't appear in the workflow designer even though the package is referenced — this is the same pattern Binance, Ethereum, HashiCorp, and IPFS all use in that same file.

Project Layout

The node ships as three .NET projects (plus a separate Tests project, not part of the shipped package):

Project	Responsibility
`BizFirst.Integration.Chainlink.Domain`	Pure result records and shared value types. Zero logic, zero I/O.
`BizFirst.Integration.Chainlink.Services`	The CCIP API v2 HTTP client, the EVM2AnyMessage/extraArgs ABI encoder, the minimal independent on-chain reader, and the 3 resource services.
`BizFirst.Ai.ExecutionNodes.Blockchain.ChainLink`	The executor: `(resource, operation)` routing, config parsing, operation-info DTOs.

Naming note: the two integration projects use the lowercase spelling Chainlink (BizFirst.Integration.Chainlink.Domain/.Services), while the executor project and this guide's repo use ChainLink. Both spellings refer to the exact same node — this is simply how the three projects were named.