Implement a cosmos-sdk chain faucet API (#1)

Part of [laconicd testnet validator enrollment](https://www.notion.so/laconicd-testnet-validator-enrollment-6fc1d3cafcc64fef8c5ed3affa27c675)

Co-authored-by: IshaVenikar <ishavenikar7@gmail.com>
Reviewed-on: cerc-io/laconic-faucet#1
Co-authored-by: Prathamesh Musale <prathamesh.musale0@gmail.com>
Co-committed-by: Prathamesh Musale <prathamesh.musale0@gmail.com>

.eslintignore

@@ -0,0 +1,5 @@
+# Don't lint node_modules.
+node_modules
+
+# Don't lint build output.
+dist

.eslintrc.json

@@ -0,0 +1,27 @@
+{
+  "env": {
+    "browser": true,
+    "es2021": true
+  },
+  "extends": [
+    "semistandard",
+    "plugin:@typescript-eslint/recommended"
+  ],
+  "parser": "@typescript-eslint/parser",
+  "parserOptions": {
+    "ecmaVersion": 12,
+    "sourceType": "module"
+  },
+  "plugins": [
+    "@typescript-eslint"
+  ],
+  "rules": {
+    "indent": [
+      "error",
+      2,
+      {
+        "SwitchCase": 1
+      }
+    ]
+  }
+}

.gitignore

@@ -128,3 +128,5 @@ dist
 .yarn/build-state.yml
 .yarn/install-state.gz
 .pnp.*
+
+db

Dockerfile

@@ -0,0 +1,14 @@
+FROM node:20-bullseye
+
+WORKDIR /app
+
+# Copy the application code
+COPY . .
+
+RUN yarn && yarn build
+
+# Expose the required port
+EXPOSE 3000
+
+# Run the app
+CMD ["node", "dist/index.js"]

README.md

@@ -0,0 +1,32 @@
+# laconic-faucet
+
+* Install dependencies and build:
+
+  ```bash
+  yarn && yarn build
+  ```
+
+* Set the private key of a funded faucet account as `faucetKey` in the [config file](./environments/local.toml)
+
+* Run the faucet:
+
+  ```bash
+  yarn start
+
+  # Expected output:
+  # Config:
+  # ...
+  # Faucet server running on port <port>
+  # Using DB directory '/path/to/faucet/data/db'
+  ```
+
+* Example request:
+
+  ```bash
+  curl -X POST http://localhost:3000/faucet \
+    -H "Content-Type: application/json" \
+    -d '{"address": "laconic1cndafgkspae7es7g2j52hmxxukwsy84v6h07w5"}'
+
+  # Expected output:
+  # {"success":true,"txHash":"40405D3CCA8122482C36083762561908E2595A4B765B7457C3995525991D18CE"}
+  ```

environments/local.toml

@@ -0,0 +1,13 @@
+[upstream]
+  rpcEndpoint = "http://localhost:26657"
+  chainId = "laconic_9000-1"
+  denom = "photon"
+  prefix = "laconic"
+  gasPrice = "0.01"
+  faucetKey = ""
+
+[server]
+  port = 3000
+  transferAmount = 1000000
+  periodTransferLimit = 3000000
+  dbDir = "db"

package.json

@@ -0,0 +1,36 @@
+{
+  "name": "laconic-faucet",
+  "version": "0.1.0",
+  "main": "dist/index.js",
+  "license": "UNLICENSED",
+  "private": true,
+  "devDependencies": {
+    "@types/cors": "^2.8.17",
+    "@types/express": "^4.17.21",
+    "@typescript-eslint/eslint-plugin": "^5.47.1",
+    "@typescript-eslint/parser": "^5.47.1",
+    "eslint": "^8.35.0",
+    "eslint-config-semistandard": "^15.0.1",
+    "eslint-config-standard": "^16.0.3",
+    "eslint-plugin-import": "^2.27.5",
+    "eslint-plugin-node": "^11.1.0",
+    "eslint-plugin-promise": "^5.1.0",
+    "eslint-plugin-standard": "^5.0.0",
+    "ts-node": "^10.9.2",
+    "typescript": "^5.5.3"
+  },
+  "dependencies": {
+    "@cosmjs/encoding": "^0.32.4",
+    "@cosmjs/proto-signing": "^0.32.4",
+    "@cosmjs/stargate": "^0.32.4",
+    "@keyv/sqlite": "^3.6.7",
+    "cors": "^2.8.5",
+    "express": "^4.19.2",
+    "toml": "^3.0.0"
+  },
+  "scripts": {
+    "lint": "eslint .",
+    "build": "yarn tsc",
+    "start": "node dist/index.js"
+  }
+}

src/index.ts

@@ -0,0 +1,154 @@
+import express from 'express';
+import Keyv from 'keyv';
+import fs from 'fs';
+import path from 'path';
+import toml from 'toml';
+import cors from 'cors';
+
+import { DirectSecp256k1Wallet } from '@cosmjs/proto-signing';
+import { GasPrice, SigningStargateClient } from '@cosmjs/stargate';
+import { fromBech32 } from '@cosmjs/encoding';
+import KeyvSqlite from '@keyv/sqlite';
+
+const CONFIG_PATH = 'environments/local.toml';
+const FAUCET_DATA_FILE = 'faucet_data.sqlite';
+const FAUCET_DATA_TTL = 86400000; // 24 hrs
+
+interface Config {
+  upstream: {
+    rpcEndpoint: string
+    chainId: string
+    denom: string
+    prefix: string
+    gasPrice: string
+    faucetKey: string
+  },
+  server: {
+    port: number
+    transferAmount: string
+    periodTransferLimit: string
+    dbDir: string
+  }
+}
+
+async function main (): Promise<void> {
+  // Read and parse the configuration
+  const configFile = fs.readFileSync(CONFIG_PATH, 'utf-8');
+  const config: Config = toml.parse(configFile);
+  console.log('Config: ', JSON.stringify(config, null, 2));
+
+  const faucetDataStore = await initKVStore(config.server.dbDir);
+
+  const app = express();
+  app.use(express.json());
+  app.use(cors());
+
+  app.post('/faucet', async (req, res) => {
+    const { address: accountAddress } = req.body;
+
+    if (!accountAddress) {
+      return res.status(400).json({ error: 'address is required' });
+    }
+
+    if (!isValidAddress(accountAddress, config.upstream.prefix)) {
+      return res.status(400).json({ error: 'invalid address' });
+    }
+
+    // Check rate limit
+    const now = Date.now();
+    const today = new Date(now).toISOString().split('T')[0];
+    const faucetStoreKey = `${accountAddress}:${today}`;
+    const amountSentToAddress = await faucetDataStore.get(faucetStoreKey) || '0';
+
+    if (BigInt(amountSentToAddress) + BigInt(config.server.transferAmount) > BigInt(config.server.periodTransferLimit)) {
+      return res.status(429).json({ error: 'Limit exceeded' });
+    }
+
+    try {
+      const txHash = await sendTokens(config, accountAddress, String(config.server.transferAmount));
+      console.log(`Sent tokens to address: ${accountAddress}, txHash: ${txHash}`);
+
+      // Update rate limit
+      await faucetDataStore.set(faucetStoreKey, (BigInt(amountSentToAddress) + BigInt(config.server.transferAmount)).toString(), FAUCET_DATA_TTL);
+
+      res.json({ success: true, txHash });
+    } catch (error) {
+      console.error('Error sending tokens:', error);
+      res.status(500).json({ error: 'Failed to send tokens' });
+    }
+  });
+
+  const port = config.server.port;
+  app.listen(port, () => {
+    console.log(`Faucet server running on port ${port}`);
+  });
+}
+
+async function initKVStore (dbDir: string): Promise<Keyv> {
+  const dbDirPath = path.resolve(dbDir);
+
+  // Create the database dir if it doesn't exist
+  fs.mkdir(dbDirPath, { recursive: true }, (err) => {
+    if (err) {
+      if (err.code !== 'EEXIST') {
+        console.error(`Error creating db directory: ${err.message}`);
+      }
+    }
+
+    console.log(`Using DB directory '${dbDirPath}'`);
+  });
+
+  // Initialize KV store with SQLite backend
+  return new Keyv({
+    store: new KeyvSqlite({
+      uri: `sqlite://${path.resolve(dbDirPath, FAUCET_DATA_FILE)}`,
+      table: 'keyv'
+    })
+  });
+}
+
+async function sendTokens (config: Config, recipientAddress: string, amount: string): Promise<string> {
+  let faucetKey = config.upstream.faucetKey;
+  if (faucetKey.startsWith('0x')) {
+    faucetKey = faucetKey.slice(2);
+  }
+
+  const wallet = await DirectSecp256k1Wallet.fromKey(
+    Buffer.from(faucetKey, 'hex'),
+    config.upstream.prefix
+  );
+  const [faucetAccount] = await wallet.getAccounts();
+
+  const client = await SigningStargateClient.connectWithSigner(
+    config.upstream.rpcEndpoint,
+    wallet,
+    { gasPrice: GasPrice.fromString(`${config.upstream.gasPrice}${config.upstream.denom}`) }
+  );
+
+  const result = await client.sendTokens(
+    faucetAccount.address,
+    recipientAddress,
+    [{ denom: config.upstream.denom, amount: amount }],
+    'auto',
+    'Faucet transfer'
+  );
+
+  return result.transactionHash;
+}
+
+export function isValidAddress (address: string, requiredPrefix: string): boolean {
+  try {
+    const { prefix, data } = fromBech32(address);
+    if (prefix !== requiredPrefix) {
+      return false;
+    }
+
+    return data.length === 20;
+  } catch {
+    return false;
+  }
+}
+
+main().catch(err => {
+  console.log(err);
+});

tsconfig.json

@@ -0,0 +1,110 @@
+{
+  "compilerOptions": {
+    /* Visit https://aka.ms/tsconfig to read more about this file */
+
+    /* Projects */
+    // "incremental": true,                              /* Save .tsbuildinfo files to allow for incremental compilation of projects. */
+    // "composite": true,                                /* Enable constraints that allow a TypeScript project to be used with project references. */
+    // "tsBuildInfoFile": "./.tsbuildinfo",              /* Specify the path to .tsbuildinfo incremental compilation file. */
+    // "disableSourceOfProjectReferenceRedirect": true,  /* Disable preferring source files instead of declaration files when referencing composite projects. */
+    // "disableSolutionSearching": true,                 /* Opt a project out of multi-project reference checking when editing. */
+    // "disableReferencedProjectLoad": true,             /* Reduce the number of projects loaded automatically by TypeScript. */
+
+    /* Language and Environment */
+    "target": "es2016",                                  /* Set the JavaScript language version for emitted JavaScript and include compatible library declarations. */
+    // "lib": [],                                        /* Specify a set of bundled library declaration files that describe the target runtime environment. */
+    // "jsx": "preserve",                                /* Specify what JSX code is generated. */
+    // "experimentalDecorators": true,                   /* Enable experimental support for legacy experimental decorators. */
+    // "emitDecoratorMetadata": true,                    /* Emit design-type metadata for decorated declarations in source files. */
+    // "jsxFactory": "",                                 /* Specify the JSX factory function used when targeting React JSX emit, e.g. 'React.createElement' or 'h'. */
+    // "jsxFragmentFactory": "",                         /* Specify the JSX Fragment reference used for fragments when targeting React JSX emit e.g. 'React.Fragment' or 'Fragment'. */
+    // "jsxImportSource": "",                            /* Specify module specifier used to import the JSX factory functions when using 'jsx: react-jsx*'. */
+    // "reactNamespace": "",                             /* Specify the object invoked for 'createElement'. This only applies when targeting 'react' JSX emit. */
+    // "noLib": true,                                    /* Disable including any library files, including the default lib.d.ts. */
+    // "useDefineForClassFields": true,                  /* Emit ECMAScript-standard-compliant class fields. */
+    // "moduleDetection": "auto",                        /* Control what method is used to detect module-format JS files. */
+
+    /* Modules */
+    "module": "commonjs",                                /* Specify what module code is generated. */
+    // "rootDir": "./",                                  /* Specify the root folder within your source files. */
+    // "moduleResolution": "node10",                     /* Specify how TypeScript looks up a file from a given module specifier. */
+    // "baseUrl": "./",                                  /* Specify the base directory to resolve non-relative module names. */
+    // "paths": {},                                      /* Specify a set of entries that re-map imports to additional lookup locations. */
+    // "rootDirs": [],                                   /* Allow multiple folders to be treated as one when resolving modules. */
+    // "typeRoots": [],                                  /* Specify multiple folders that act like './node_modules/@types'. */
+    // "types": [],                                      /* Specify type package names to be included without being referenced in a source file. */
+    // "allowUmdGlobalAccess": true,                     /* Allow accessing UMD globals from modules. */
+    // "moduleSuffixes": [],                             /* List of file name suffixes to search when resolving a module. */
+    // "allowImportingTsExtensions": true,               /* Allow imports to include TypeScript file extensions. Requires '--moduleResolution bundler' and either '--noEmit' or '--emitDeclarationOnly' to be set. */
+    // "resolvePackageJsonExports": true,                /* Use the package.json 'exports' field when resolving package imports. */
+    // "resolvePackageJsonImports": true,                /* Use the package.json 'imports' field when resolving imports. */
+    // "customConditions": [],                           /* Conditions to set in addition to the resolver-specific defaults when resolving imports. */
+    "resolveJsonModule": true,                        /* Enable importing .json files. */
+    // "allowArbitraryExtensions": true,                 /* Enable importing files with any extension, provided a declaration file is present. */
+    // "noResolve": true,                                /* Disallow 'import's, 'require's or '<reference>'s from expanding the number of files TypeScript should add to a project. */
+
+    /* JavaScript Support */
+    // "allowJs": true,                                  /* Allow JavaScript files to be a part of your program. Use the 'checkJS' option to get errors from these files. */
+    // "checkJs": true,                                  /* Enable error reporting in type-checked JavaScript files. */
+    // "maxNodeModuleJsDepth": 1,                        /* Specify the maximum folder depth used for checking JavaScript files from 'node_modules'. Only applicable with 'allowJs'. */
+
+    /* Emit */
+    "declaration": true,                              /* Generate .d.ts files from TypeScript and JavaScript files in your project. */
+    // "declarationMap": true,                           /* Create sourcemaps for d.ts files. */
+    // "emitDeclarationOnly": true,                      /* Only output d.ts files and not JavaScript files. */
+    "sourceMap": true,                                /* Create source map files for emitted JavaScript files. */
+    // "inlineSourceMap": true,                          /* Include sourcemap files inside the emitted JavaScript. */
+    // "outFile": "./",                                  /* Specify a file that bundles all outputs into one JavaScript file. If 'declaration' is true, also designates a file that bundles all .d.ts output. */
+    "outDir": "dist",                                   /* Specify an output folder for all emitted files. */
+    // "removeComments": true,                           /* Disable emitting comments. */
+    // "noEmit": true,                                   /* Disable emitting files from a compilation. */
+    // "importHelpers": true,                            /* Allow importing helper functions from tslib once per project, instead of including them per-file. */
+    "downlevelIteration": true,                       /* Emit more compliant, but verbose and less performant JavaScript for iteration. */
+    // "sourceRoot": "",                                 /* Specify the root path for debuggers to find the reference source code. */
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+
+    /* Interop Constraints */
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+    // "isolatedDeclarations": true,                     /* Require sufficient annotation on exports so other tools can trivially generate declaration files. */
+    // "allowSyntheticDefaultImports": true,             /* Allow 'import x from y' when a module doesn't have a default export. */
+    "esModuleInterop": true,                             /* Emit additional JavaScript to ease support for importing CommonJS modules. This enables 'allowSyntheticDefaultImports' for type compatibility. */
+    // "preserveSymlinks": true,                         /* Disable resolving symlinks to their realpath. This correlates to the same flag in node. */
+    "forceConsistentCasingInFileNames": true,            /* Ensure that casing is correct in imports. */
+
+    /* Type Checking */
+    "strict": true,                                      /* Enable all strict type-checking options. */
+    // "noImplicitAny": true,                            /* Enable error reporting for expressions and declarations with an implied 'any' type. */
+    // "strictNullChecks": true,                         /* When type checking, take into account 'null' and 'undefined'. */
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+    // "exactOptionalPropertyTypes": true,               /* Interpret optional property types as written, rather than adding 'undefined'. */
+    // "noImplicitReturns": true,                        /* Enable error reporting for codepaths that do not explicitly return in a function. */
+    // "noFallthroughCasesInSwitch": true,               /* Enable error reporting for fallthrough cases in switch statements. */
+    // "noUncheckedIndexedAccess": true,                 /* Add 'undefined' to a type when accessed using an index. */
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+    // "allowUnusedLabels": true,                        /* Disable error reporting for unused labels. */
+    // "allowUnreachableCode": true,                     /* Disable error reporting for unreachable code. */
+
+    /* Completeness */
+    // "skipDefaultLibCheck": true,                      /* Skip type checking .d.ts files that are included with TypeScript. */
+    "skipLibCheck": true                                 /* Skip type checking all .d.ts files. */
+  },
+  "include": ["src"],
+  "exclude": ["dist"]
+}