> For the complete documentation index, see [llms.txt](https://chusdrter.gitbook.io/stellar-trade-processor/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://chusdrter.gitbook.io/stellar-trade-processor/developer-guide/environment-and-configuration.md).

# Environment and Configuration

## There are no environment variables

This package reads no environment variables. There is no `.env` file, no config file, no `STELLAR_RPC_URL`, and no hidden defaults picked up from the environment. Nothing is silently configured behind your back.

That is a deliberate consequence of what this is: a library plus a thin CLI, not a hosted service. The CLI is configured entirely by flags, and the library entirely by constructor arguments.

If you want environment-variable configuration for your deployment, put it in your own wrapper:

```sh
processor --mode=stream --rpc-url="$STELLAR_RPC_URL"
```

## The CLI configuration surface

Seven flags, and nothing else. Full details in the [CLI Reference](/stellar-trade-processor/developer-guide/cli-reference.md):

| Flag                   | Default                            |
| ---------------------- | ---------------------------------- |
| `--mode`               | none, required                     |
| `--rpc-url`            | none, required                     |
| `--network-passphrase` | mainnet passphrase                 |
| `--start-ledger`       | `0`                                |
| `--end-ledger`         | `0`                                |
| `--soroswap-router`    | mainnet router address             |
| `--buffer-size`        | `0`, meaning the SDK default of 10 |

Everything is validated before the first network call, and a bad combination exits 2 with one line on stderr.

## The library configuration surface

Configuration is whatever you pass to the constructors:

| What                                   | Where                                                                   |
| -------------------------------------- | ----------------------------------------------------------------------- |
| RPC endpoint, HTTP client, buffer size | `ledgerbackend.RPCLedgerBackendOptions`                                 |
| Ledger range                           | `source.NewBackfillSource(ctx, backend, start, end)`                    |
| Streaming start                        | `source.NewStreamingSource(ctx, backend, start)`                        |
| Network passphrase                     | `ingest.NewLedgerTransactionReaderFromLedgerCloseMeta(passphrase, lcm)` |
| Which venues you extract               | which transformers you put in the slice                                 |
| Which AMMs are decoded                 | `registry.Register(...)`                                                |
| Soroswap router addresses              | `soroban.NewSoroswapAdapter(addresses...)`                              |
| Where events go                        | your `sink.Sink`                                                        |

## Network selection

Two settings must change together when you move between networks, and getting one right while missing the other is the usual mistake.

**The passphrase** is used to compute transaction hashes. Reading testnet ledgers with the mainnet passphrase produces wrong `TxHash` values while everything else looks correct:

| Network | Passphrase                                       |
| ------- | ------------------------------------------------ |
| Mainnet | `Public Global Stellar Network ; September 2015` |
| Testnet | `Test SDF Network ; September 2015`              |

**The Soroswap router address** decides which contract's events are decoded. The default is the mainnet router, `CAG5LRYQ5JVEUI5TEID72EYOVX44TTUJT5BQR2J6J77FH65PCCFAJDDH`. On testnet, pass the testnet router, `CCJUD55AG6W5HAI5LRVNKAE5WDP5XGZBUDS5WNTIVDU7O264UZZE7BRD`, from soroswap/core's `public/testnet.contracts.json`. Verify it before relying on it, because a stale address yields zero AMM events and no error.

```sh
processor --mode=stream \
  --rpc-url=<testnet-rpc-url> \
  --network-passphrase="Test SDF Network ; September 2015" \
  --soroswap-router=CCJUD55AG6W5HAI5LRVNKAE5WDP5XGZBUDS5WNTIVDU7O264UZZE7BRD
```

## Authenticated RPC endpoints

The CLI takes a URL and nothing else, so an endpoint whose key lives in the URL path or query string works as-is. An endpoint that requires a header does not: there is no `--header` flag. Use the library and pass your own `HttpClient`:

```go
backend := ledgerbackend.NewRPCLedgerBackend(ledgerbackend.RPCLedgerBackendOptions{
	RPCServerURL: rpcURL,
	HttpClient:   &http.Client{Transport: authTransport{key: apiKey}},
})
```

A URL containing a key is a secret. It appears in the startup log line the CLI writes to stderr, so treat those logs accordingly.

## Persistent state

There is none. No checkpoint file, no cursor, no cache, no temporary directories. The process writes only to the sink you gave it, which for the CLI means stdout.

Restarting is therefore entirely up to you: pass `--start-ledger` derived from your own output. See the [backfill walkthrough](https://github.com/fadesany/Stellar-Trade-Processor/tree/main/docs/for-library-consumers/backfill-mode-walkthrough.md) and [issue #4](https://github.com/fadesany/Stellar-Trade-Processor/issues/4).

## Resource usage

One ledger is held in memory at a time, plus whatever the backend buffers (`--buffer-size`, default 10). There is no worker pool and no parallelism, so one process uses roughly one core. Memory scales with ledger size and buffer size, not with how long the process has been running.

For higher throughput, run several backfill processes over disjoint ledger ranges rather than looking for a concurrency flag. There isn't one.


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