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feat: merge default config files #250

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91 changes: 51 additions & 40 deletions src/config.ts
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -396,39 +396,7 @@ function getDefaultConfigPaths(): string[] {
/**
* Load and parse MCP servers configuration
*/
export async function loadConfig(
explicitPath?: string,
): Promise<McpServersConfig> {
let configPath: string | undefined;

// Check explicit path from argument or environment
if (explicitPath) {
configPath = resolve(explicitPath);
} else if (process.env.MCP_CONFIG_PATH) {
configPath = resolve(process.env.MCP_CONFIG_PATH);
}

// If explicit path provided, it must exist
if (configPath) {
if (!existsSync(configPath)) {
throw new Error(formatCliError(configNotFoundError(configPath)));
}
} else {
// Search default paths
const searchPaths = getDefaultConfigPaths();
for (const path of searchPaths) {
if (existsSync(path)) {
configPath = path;
break;
}
}

if (!configPath) {
throw new Error(formatCliError(configSearchError()));
}
}

// Read and parse config
async function parseConfigFile(configPath: string): Promise<McpServersConfig> {
const file = Bun.file(configPath);
const content = await file.text();

Expand All @@ -446,13 +414,6 @@ export async function loadConfig(
throw new Error(formatCliError(configMissingFieldError(configPath)));
}

// Warn if no servers are configured
if (Object.keys(config.mcpServers).length === 0) {
console.error(
'[mcp-cli] Warning: No servers configured in mcpServers. Add server configurations to use MCP tools.',
);
}

// Validate individual server configs
for (const [serverName, serverConfig] of Object.entries(config.mcpServers)) {
if (!serverConfig || typeof serverConfig !== 'object') {
Expand Down Expand Up @@ -496,6 +457,56 @@ export async function loadConfig(
}
}

return config;
}

export async function loadConfig(
explicitPath?: string,
): Promise<McpServersConfig> {
let configPaths: string[] = [];

// Check explicit path from argument or environment
if (explicitPath) {
configPaths = [resolve(explicitPath)];
} else if (process.env.MCP_CONFIG_PATH) {
configPaths = [resolve(process.env.MCP_CONFIG_PATH)];
} else {
// Search default paths and merge all configs that exist.
configPaths = getDefaultConfigPaths().filter((path) => existsSync(path));
}

if (configPaths.length === 0) {
throw new Error(formatCliError(configSearchError()));
}

// Explicit path provided via arg/env must exist.
if (
(explicitPath || process.env.MCP_CONFIG_PATH) &&
!existsSync(configPaths[0])
) {
throw new Error(formatCliError(configNotFoundError(configPaths[0])));
}

let config: McpServersConfig = { mcpServers: {} };

// Merge from lowest priority to highest priority so nearer configs override.
for (const configPath of [...configPaths].reverse()) {
const parsed = await parseConfigFile(configPath);
config = {
mcpServers: {
...config.mcpServers,
...parsed.mcpServers,
},
};
}

// Warn if no servers are configured
if (Object.keys(config.mcpServers).length === 0) {
console.error(
'[mcp-cli] Warning: No servers configured in mcpServers. Add server configurations to use MCP tools.',
);
}

// Substitute environment variables
config = substituteEnvVarsInObject(config);

Expand Down
156 changes: 129 additions & 27 deletions tests/config.test.ts
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -2,16 +2,16 @@
* Unit tests for config module
*/

import { describe, test, expect, beforeEach, afterEach } from 'bun:test';
import { mkdtemp, writeFile, rm } from 'node:fs/promises';
import { tmpdir } from 'node:os';
import { afterEach, beforeEach, describe, expect, test } from 'bun:test';
import { mkdir, mkdtemp, rm, writeFile } from 'node:fs/promises';
import { homedir, tmpdir } from 'node:os';
import { join } from 'node:path';
import {
loadConfig,
getServerConfig,
listServerNames,
isHttpServer,
isStdioServer,
listServerNames,
loadConfig,
} from '../src/config';

describe('config', () => {
Expand All @@ -34,12 +34,14 @@ describe('config', () => {
mcpServers: {
test: { command: 'echo', args: ['hello'] },
},
})
}),
);

const config = await loadConfig(configPath);
expect(config.mcpServers.test).toBeDefined();
expect((config.mcpServers.test as any).command).toBe('echo');
expect(
isStdioServer(config.mcpServers.test) && config.mcpServers.test.command,
).toBe('echo');
});

test('throws on missing config file', async () => {
Expand Down Expand Up @@ -74,14 +76,16 @@ describe('config', () => {
headers: { Authorization: 'Bearer ${TEST_MCP_TOKEN}' },
},
},
})
}),
);

const config = await loadConfig(configPath);
const server = config.mcpServers.test as any;
expect(server.headers.Authorization).toBe('Bearer secret123');
const server = config.mcpServers.test;
expect(isHttpServer(server) && server.headers?.Authorization).toBe(
'Bearer secret123',
);

delete process.env.TEST_MCP_TOKEN;
process.env.TEST_MCP_TOKEN = undefined;
});

test('handles missing env vars gracefully with MCP_STRICT_ENV=false', async () => {
Expand All @@ -98,19 +102,19 @@ describe('config', () => {
env: { TOKEN: '${NONEXISTENT_VAR}' },
},
},
})
}),
);

const config = await loadConfig(configPath);
const server = config.mcpServers.test as any;
expect(server.env.TOKEN).toBe('');
const server = config.mcpServers.test;
expect(isStdioServer(server) && server.env?.TOKEN).toBe('');

delete process.env.MCP_STRICT_ENV;
process.env.MCP_STRICT_ENV = undefined;
});

test('throws error on missing env vars in strict mode (default)', async () => {
// Ensure strict mode is enabled (default)
delete process.env.MCP_STRICT_ENV;
process.env.MCP_STRICT_ENV = undefined;

const configPath = join(tempDir, 'missing_env_strict.json');
await writeFile(
Expand All @@ -122,7 +126,7 @@ describe('config', () => {
env: { TOKEN: '${ANOTHER_NONEXISTENT_VAR}' },
},
},
})
}),
);

await expect(loadConfig(configPath)).rejects.toThrow('MISSING_ENV_VAR');
Expand All @@ -136,10 +140,12 @@ describe('config', () => {
mcpServers: {
badserver: {},
},
})
}),
);

await expect(loadConfig(configPath)).rejects.toThrow('missing required field');
await expect(loadConfig(configPath)).rejects.toThrow(
'missing required field',
);
});

test('throws error on server with both command and url', async () => {
Expand All @@ -153,10 +159,12 @@ describe('config', () => {
url: 'https://example.com',
},
},
})
}),
);

await expect(loadConfig(configPath)).rejects.toThrow('both "command" and "url"');
await expect(loadConfig(configPath)).rejects.toThrow(
'both "command" and "url"',
);
});

test('throws error on null server config', async () => {
Expand All @@ -167,10 +175,104 @@ describe('config', () => {
mcpServers: {
nullserver: null,
},
})
}),
);

await expect(loadConfig(configPath)).rejects.toThrow(
'Invalid server configuration',
);
});

test('merges default config search paths', async () => {
const originalCwd = process.cwd();
const workspaceDir = join(tempDir, 'workspace');
const homeConfigPath = join(homedir(), '.mcp_servers.json');
const backupPath = `${homeConfigPath}.mcp-cli-test-backup`;
await mkdir(workspaceDir, { recursive: true });

let hadExistingHomeConfig = false;
try {
process.chdir(workspaceDir);

if (await Bun.file(homeConfigPath).exists()) {
hadExistingHomeConfig = true;
await writeFile(backupPath, await Bun.file(homeConfigPath).text());
}

await writeFile(
homeConfigPath,
JSON.stringify({
mcpServers: {
personal: { command: 'todoist-mcp' },
},
}),
);
await writeFile(
join(workspaceDir, 'mcp_servers.json'),
JSON.stringify({
mcpServers: {
project: { command: 'playwright-mcp' },
},
}),
);

const config = await loadConfig();
expect(Object.keys(config.mcpServers).sort()).toEqual([
'personal',
'project',
]);
} finally {
process.chdir(originalCwd);
if (hadExistingHomeConfig) {
await writeFile(homeConfigPath, await Bun.file(backupPath).text());
await rm(backupPath, { force: true });
} else {
await rm(homeConfigPath, { force: true });
}
}
});

await expect(loadConfig(configPath)).rejects.toThrow('Invalid server configuration');
test('nearer config overrides same-named server from lower priority config', async () => {
const originalCwd = process.cwd();
const originalHome = process.env.HOME;
const workspaceDir = join(tempDir, 'workspace');
await mkdir(workspaceDir, { recursive: true });
await mkdir(join(tempDir, '.config', 'mcp'), { recursive: true });

try {
process.chdir(workspaceDir);
process.env.HOME = tempDir;

await writeFile(
join(tempDir, '.config', 'mcp', 'mcp_servers.json'),
JSON.stringify({
mcpServers: {
github: { command: 'personal-github-mcp' },
},
}),
);
await writeFile(
join(workspaceDir, 'mcp_servers.json'),
JSON.stringify({
mcpServers: {
github: { command: 'work-github-mcp' },
},
}),
);

const config = await loadConfig();
expect(
isStdioServer(config.mcpServers.github) &&
config.mcpServers.github.command,
).toBe('work-github-mcp');
} finally {
process.chdir(originalCwd);
if (originalHome !== undefined) {
process.env.HOME = originalHome;
} else {
process.env.HOME = undefined;
}
}
});
});

Expand All @@ -184,12 +286,12 @@ describe('config', () => {
server1: { command: 'cmd1' },
server2: { command: 'cmd2' },
},
})
}),
);

const config = await loadConfig(configPath);
const server = getServerConfig(config, 'server1');
expect((server as any).command).toBe('cmd1');
expect(isStdioServer(server) && server.command).toBe('cmd1');
});

test('throws on unknown server', async () => {
Expand All @@ -198,7 +300,7 @@ describe('config', () => {
configPath,
JSON.stringify({
mcpServers: { known: { command: 'cmd' } },
})
}),
);

const config = await loadConfig(configPath);
Expand All @@ -217,7 +319,7 @@ describe('config', () => {
beta: { command: 'b' },
gamma: { url: 'https://example.com' },
},
})
}),
);

const config = await loadConfig(configPath);
Expand Down