Add MCP MCP test harness #2

elasticdotventures · 2025-12-01T12:18:31Z

Summary

add pm2 MCP server implementation exportable start helper
add mocha harness using MCP in-memory transport to validate tools/resources and happy/error flows
wire MCP test into unit.sh

Testing

npx mocha test/mcp/server.mocha.js

Signed-off-by: Brian Horakh <35611074+elasticdotventures@users.noreply.github.com>

Copilot

Pull request overview

This PR adds an MCP (Model Context Protocol) server implementation for PM2, enabling AI tools to interact with PM2 processes through a standardized protocol. It also updates the minimum Node.js version requirement from 16.x to 22.0.0 across all packaging and documentation.

Implements a complete MCP server exposing PM2 operations as tools and resources
Adds comprehensive test harness using in-memory transport for validation
Updates Node.js version requirements across package.json, packagers, and documentation

Reviewed changes

Copilot reviewed 8 out of 10 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
lib/mcp/server.js	New MCP server implementation with PM2 tool/resource handlers
bin/pm2-mcp	New entry point binary for the MCP server
test/mcp/server.mocha.js	Test suite validating MCP server tools and resources
test/unit.sh	Integrates MCP tests into the unit test suite
package.json	Updates Node.js engine requirement to >=22.0.0
package-lock.json	Updates Node.js engine requirement to >=22.0.0
packager/debian/control	Updates Node.js dependency to >=22.0.0
packager/build-deb-rpm.sh	Updates RPM Node.js dependency to >=22.0.0
packager/alpine/pm2/APKBUILD	Updates Alpine Node.js dependency to >=22
README.md	Updates documentation to reflect Node.js 22.x requirement

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Copilot · 2025-12-01T12:22:53Z

lib/mcp/server.js

+ * Exposes the core PM2 controls and state as Model Context Protocol tools/resources.
+ */
+const fs = require('fs');
+const z = require('zod');


The zod package is used but not listed in package.json dependencies. This will cause the MCP server to fail at runtime with a module not found error. Add zod to the dependencies in package.json.

@copilot open a new pull request to apply changes based on this feedback

Copilot · 2025-12-01T12:22:53Z

lib/mcp/server.js

+ */
+const fs = require('fs');
+const z = require('zod');
+const { McpServer, ResourceTemplate } = require('@modelcontextprotocol/sdk/server/mcp.js');


The @modelcontextprotocol/sdk package is used but not listed in package.json dependencies. This will cause imports to fail at runtime. Add @modelcontextprotocol/sdk to the dependencies in package.json.

@copilot open a new pull request to apply changes based on this feedback

Copilot · 2025-12-01T12:22:53Z

test/mcp/server.mocha.js

+const { Client } = require('@modelcontextprotocol/sdk/client');
+const { InMemoryTransport } = require('@modelcontextprotocol/sdk/inMemory.js');


The @modelcontextprotocol/sdk package is used but not listed in package.json dependencies. This will cause imports to fail at runtime. Add @modelcontextprotocol/sdk to the dependencies (or devDependencies for test-only usage).

README.md

Copilot · 2025-12-01T12:22:54Z

test/mcp/server.mocha.js

+        })
+      ]);
+    } finally {
+      clearTimeout(timer);


[nitpick] The clearTimeout(timer) will be called even if timer is undefined (when the Promise.race rejects from the first promise). While this is safe in JavaScript, it would be clearer to initialize timer to null or only clear if defined: if (timer) clearTimeout(timer).

Copilot · 2025-12-01T12:22:54Z

lib/mcp/server.js

+  server.registerTool(
+    'pm2_restart_process',
+    {
+      title: 'Restart a PM2 process',
+      description: 'Restart a process by id, name, or "all".',
+      inputSchema: restartSchema
+    },
+    async ({ process, updateEnv }) => {
+      try {
+        await ensureConnected();
+        await pm2Restart(process, { updateEnv });
+        const processes = (await pm2List()).map(formatProcess);
+        const summary = { action: 'restart', process, updateEnv, processes };
+        return {
+          content: textContent(summary),
+          structuredContent: summary
+        };
+      } catch (err) {
+        return errorResult(err);
+      }
+    }
+  );
+
+  server.registerTool(
+    'pm2_reload_process',
+    {
+      title: 'Reload a PM2 process',
+      description: 'Perform a zero-downtime reload (cluster mode only).',
+      inputSchema: reloadSchema
+    },
+    async ({ process, updateEnv }) => {
+      try {
+        await ensureConnected();
+        await pm2Reload(process, { updateEnv });
+        const processes = (await pm2List()).map(formatProcess);
+        const summary = { action: 'reload', process, updateEnv, processes };
+        return {
+          content: textContent(summary),
+          structuredContent: summary
+        };
+      } catch (err) {
+        return errorResult(err);
+      }
+    }
+  );
+
+  server.registerTool(
+    'pm2_stop_process',
+    {
+      title: 'Stop a PM2 process',
+      description: 'Stop a process by id, name, or "all".',
+      inputSchema: stopSchema
+    },
+    async ({ process }) => {
+      try {
+        await ensureConnected();
+        await pm2Stop(process);
+        const processes = (await pm2List()).map(formatProcess);
+        const summary = { action: 'stop', process, processes };
+        return {
+          content: textContent(summary),
+          structuredContent: summary
+        };
+      } catch (err) {
+        return errorResult(err);
+      }
+    }
+  );
+
+  server.registerTool(
+    'pm2_delete_process',
+    {
+      title: 'Delete a PM2 process',
+      description: 'Delete a process by id, name, or "all".',
+      inputSchema: deleteSchema
+    },
+    async ({ process }) => {
+      try {
+        await ensureConnected();
+        await pm2Delete(process);
+        const processes = (await pm2List()).map(formatProcess);
+        const summary = { action: 'delete', process, processes };
+        return {
+          content: textContent(summary),
+          structuredContent: summary
+        };
+      } catch (err) {
+        return errorResult(err);
+      }
+    }
+  );
+
+  server.registerTool(
+    'pm2_flush_logs',
+    {
+      title: 'Flush PM2 logs',
+      description: 'Flush log files for a process id, name, or "all".',
+      inputSchema: flushSchema
+    },
+    async ({ process }) => {
+      try {
+        await ensureConnected();
+        await pm2Flush(process);
+        return {
+          content: textContent({ action: 'flush', process }),
+          structuredContent: { action: 'flush', process }
+        };
+      } catch (err) {
+        return errorResult(err);
+      }
+    }
+  );
+
+  server.registerTool(
+    'pm2_reload_logs',
+    {
+      title: 'Reload PM2 logs',
+      description: 'Rotate and reopen log files (pm2 reloadLogs).'
+    },
+    async () => {
+      try {
+        await ensureConnected();
+        await pm2ReloadLogs();
+        return {
+          content: textContent({ action: 'reloadLogs' }),
+          structuredContent: { action: 'reloadLogs' }
+        };
+      } catch (err) {
+        return errorResult(err);
+      }
+    }
+  );
+
+  server.registerTool(
+    'pm2_dump',
+    {
+      title: 'Dump PM2 process list',
+      description: 'Persist the current PM2 process list to the dump file.'
+    },
+    async () => {
+      try {
+        await ensureConnected();
+        await pm2Dump();
+        return {
+          content: textContent({ action: 'dump' }),
+          structuredContent: { action: 'dump' }
+        };
+      } catch (err) {
+        return errorResult(err);
+      }
+    }
+  );
+
+  server.registerTool(
+    'pm2_tail_logs',
+    {
+      title: 'Tail PM2 logs',
+      description: 'Read the last N lines from a process log file.',
+      inputSchema: logsSchema
+    },
+    async ({ process, type, lines }) => {
+      try {
+        await ensureConnected();
+        const description = await pm2Describe(process);
+        if (!description || description.length === 0) {
+          throw new Error(`No process found for "${process}"`);
+        }
+        const env = description[0].pm2_env || {};
+        const logPath =
+          type === 'combined'
+            ? env.pm_log_path || env.pm_out_log_path || env.pm_err_log_path
+            : type === 'out'
+              ? env.pm_out_log_path
+              : env.pm_err_log_path;
+
+        if (!logPath) throw new Error('No log path found for this process');
+        const data = await tailFile(logPath, lines);
+        const payload = { process, type, logPath, lines: data };
+        return {
+          content: textContent(`Last ${lines} lines from ${logPath}:\n${data.join('\n')}`),
+          structuredContent: payload
+        };
+      } catch (err) {
+        return errorResult(err);
+      }
+    }
+  );
+
+  server.registerTool(
+    'pm2_kill_daemon',
+    {
+      title: 'Kill PM2 daemon',
+      description: 'Stops the PM2 daemon and all managed processes.'
+    },
+    async () => {
+      try {
+        await ensureConnected();
+        await pm2KillDaemon();
+        isConnected = false;
+        return {
+          content: textContent({ action: 'killDaemon' }),
+          structuredContent: { action: 'killDaemon' }
+        };
+      } catch (err) {
+        return errorResult(err);
+      }
+    }
+  );


Several tools registered in the MCP server lack test coverage: pm2_restart_process, pm2_reload_process, pm2_flush_logs, pm2_reload_logs, and pm2_dump. Consider adding test cases for these tools to ensure they work correctly through the MCP interface.

@copilot open a new pull request to apply changes based on this feedback

Copilot · 2025-12-01T12:33:17Z

@elasticdotventures I've opened a new pull request, #3, to work on those changes. Once the pull request is ready, I'll request review from you.

…ush_logs, pm2_reload_logs, and pm2_dump tools Co-authored-by: elasticdotventures <35611074+elasticdotventures@users.noreply.github.com>

[WIP] Address feedback on 'Add MCP MCP test harness' PR

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com> Signed-off-by: Brian Horakh <35611074+elasticdotventures@users.noreply.github.com>

Copilot · 2025-12-01T12:39:37Z

@elasticdotventures I've opened a new pull request, #4, to work on those changes. Once the pull request is ready, I'll request review from you.

Copilot · 2025-12-01T12:39:55Z

@elasticdotventures I've opened a new pull request, #5, to work on those changes. Once the pull request is ready, I'll request review from you.

[WIP] Update MCP test harness implementation based on feedback

Address feedback on MCP test harness implementation

elasticdotventures and others added 4 commits September 26, 2025 23:36

chore: require Node.js 22+

468a849

chore: sync lockfile after install

3a90692

Merge branch 'master' into chore/node22-min

29b0f21

Signed-off-by: Brian Horakh <35611074+elasticdotventures@users.noreply.github.com>

Add MCP server test harness

7d0c2b9

Copilot AI review requested due to automatic review settings December 1, 2025 12:18

Copilot started reviewing on behalf of elasticdotventures December 1, 2025 12:18 View session

Copilot finished reviewing on behalf of elasticdotventures December 1, 2025 12:21

Copilot AI reviewed Dec 1, 2025

View reviewed changes

elasticdotventures and others added 3 commits December 1, 2025 12:25

Update dependencies locks

02181e9

chore: feature bump

fefa542

Initial plan

a3431f0

Copilot AI mentioned this pull request Dec 1, 2025

Add MCP test coverage for restart, reload, flush, reloadLogs, and dump tools #3

Merged

Copilot AI and others added 4 commits December 1, 2025 12:35

Add test coverage for pm2_restart_process, pm2_reload_process, pm2_fl…

341e310

…ush_logs, pm2_reload_logs, and pm2_dump tools Co-authored-by: elasticdotventures <35611074+elasticdotventures@users.noreply.github.com>

Merge pull request #3 from PromptExecution/copilot/sub-pr-2

2cf602c

[WIP] Address feedback on 'Add MCP MCP test harness' PR

Update README.md

dee69fc

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com> Signed-off-by: Brian Horakh <35611074+elasticdotventures@users.noreply.github.com>

Initial plan

845601f

Copilot AI mentioned this pull request Dec 1, 2025

[WIP] Update MCP test harness implementation based on feedback #4

Merged

3 tasks

Initial plan

2b7d9b4

Copilot AI mentioned this pull request Dec 1, 2025

Address feedback on MCP test harness implementation #5

Merged

elasticdotventures added 2 commits December 1, 2025 23:44

Merge pull request #4 from PromptExecution/copilot/sub-pr-2

a5a0228

[WIP] Update MCP test harness implementation based on feedback

Merge pull request #5 from PromptExecution/copilot/sub-pr-2-again

637ff7e

Address feedback on MCP test harness implementation

elasticdotventures merged commit c51a51c into master Dec 1, 2025
3 of 6 checks passed

		const { Client } = require('@modelcontextprotocol/sdk/client');
		const { InMemoryTransport } = require('@modelcontextprotocol/sdk/inMemory.js');

Add MCP MCP test harness #2

Add MCP MCP test harness #2

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elasticdotventures commented Dec 1, 2025

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