buildmymcpserver/apps/generator/src/worker.ts

import { builds, createDb, eq, mcpServers } from '@bmm/db';
import { GeneratorSpec } from '@bmm/types';
import { Worker } from 'bullmq';
import { Redis } from 'ioredis';
import { config } from './config.js';
import { dockerBuild, prepareBuildContext, staticCheck } from './lib/build.js';
import { generateSpec } from './lib/claude.js';
import {
  allocatePort,
  computePublicUrl,
  deployContainer,
  dockerAvailable,
  stopContainer,
} from './lib/deploy.js';
import { emitDone, emitError, emitLog, emitStatus } from './lib/emit.js';
import { renderServerCode } from './lib/render.js';

const db = createDb();
const connection = new Redis(config.REDIS_URL, { maxRetriesPerRequest: null });
const cacheReader = new Redis(config.REDIS_URL, { maxRetriesPerRequest: null });

interface JobData {
  buildId: string;
  serverId: string;
  orgId: string;
  prompt: string;
  version: number;
  slug: string;
  serverName: string;
  secrets: Record<string, string>;
  previewId?: string;
}

async function loadCachedSpec(previewId: string): Promise<GeneratorSpec | null> {
  const raw = await cacheReader.get(`preview:${previewId}`);
  if (!raw) return null;
  try {
    const parsed = GeneratorSpec.safeParse(JSON.parse(raw));
    return parsed.success ? parsed.data : null;
  } catch {
    return null;
  }
}

async function loadPrebuiltCode(previewId: string): Promise<string | null> {
  return (await cacheReader.get(`prebuilt:${previewId}`)) ?? null;
}

export const worker = new Worker<JobData>(
  'build',
  async (job) => {
    const { buildId, serverId, prompt, version, slug, secrets, previewId } = job.data;
    const log = (level: 'info' | 'warn' | 'error', msg: string) => emitLog(buildId, level, msg);

    // Capture the container currently serving this server (if any) BEFORE the
    // build mutates the row. On an iterate (version > 1) we deploy the new
    // container, then tear this old one down — rolling-deploy, no orphan.
    const [priorState] = await db
      .select({ containerId: mcpServers.containerId })
      .from(mcpServers)
      .where(eq(mcpServers.id, serverId))
      .limit(1);
    const oldContainerId = priorState?.containerId ?? null;

    try {
      await db
        .update(builds)
        .set({ status: 'generating', startedAt: new Date() })
        .where(eq(builds.id, buildId));
      await db
        .update(mcpServers)
        .set({ status: 'generating', updatedAt: new Date() })
        .where(eq(mcpServers.id, serverId));
      await emitStatus(buildId, 'generating');

      let spec: GeneratorSpec | null = null;
      let source: 'claude' | 'glm' | 'mock' | 'cached' = 'mock';

      if (previewId) {
        spec = await loadCachedSpec(previewId);
        if (spec) {
          source = 'cached';
          await log('info', `Re-using preview spec ${previewId} (skipping Claude call)`);
        } else {
          await log('warn', `Preview ${previewId} cache miss — regenerating`);
        }
      }

      if (!spec) {
        await log('info', 'Generating MCP server spec...');
        const result = await generateSpec(prompt);
        spec = result.spec;
        source = result.source;
      }

      await log('info', `Spec ready via ${source} (${spec.tools.length} tool(s))`);

      // Forks supply pre-rendered code via Redis. If present, use it verbatim.
      let generatedCode: string;
      const prebuilt = previewId ? await loadPrebuiltCode(previewId) : null;
      if (prebuilt) {
        await log(
          'info',
          `Using pre-rendered template code (${prebuilt.length} chars) — skipping render`,
        );
        generatedCode = prebuilt;
      } else {
        generatedCode = renderServerCode(spec);
      }
      await db
        .update(builds)
        .set({ generatedSpec: spec, generatedCode })
        .where(eq(builds.id, buildId));

      await db.update(builds).set({ status: 'building' }).where(eq(builds.id, buildId));
      await db
        .update(mcpServers)
        .set({ status: 'building', toolsSchema: spec.tools, updatedAt: new Date() })
        .where(eq(mcpServers.id, serverId));
      await emitStatus(buildId, 'building');
      await log('info', 'Preparing build context...');

      const { contextDir, imageTag } = await prepareBuildContext(
        serverId,
        version,
        slug,
        generatedCode,
        spec,
      );
      await log('info', `Build context at ${contextDir}`);

      await log('info', 'Running static checks...');
      await staticCheck(contextDir);
      await log('info', 'Static checks passed.');

      const hasDocker = await dockerAvailable();
      if (!hasDocker) {
        await log('warn', 'Docker not available — skipping build/deploy. Server marked draft.');
        await db
          .update(builds)
          .set({ status: 'failed', errorMessage: 'docker_unavailable', finishedAt: new Date() })
          .where(eq(builds.id, buildId));
        await db
          .update(mcpServers)
          .set({ status: 'failed', updatedAt: new Date() })
          .where(eq(mcpServers.id, serverId));
        await emitDone(buildId, 'failed', serverId, null);
        return;
      }

      await log('info', `Building Docker image ${imageTag}...`);
      await dockerBuild(contextDir, imageTag, (line) => {
        emitLog(buildId, 'info', line).catch(() => undefined);
      });
      await log('info', 'Image built.');

      await db.update(builds).set({ status: 'deploying' }).where(eq(builds.id, buildId));
      await db
        .update(mcpServers)
        .set({ status: 'deploying', updatedAt: new Date() })
        .where(eq(mcpServers.id, serverId));
      await emitStatus(buildId, 'deploying');

      const port = await allocatePort();
      // The container's PUBLIC_URL must match what end-users (and Claude
      // Desktop's DCR client) actually reach. When MCP_DOMAIN is set we
      // route via https://<MCP_DOMAIN>/<slug>; the hardcoded loopback URL
      // we used to inject caused the runner to advertise an unreachable
      // resource_metadata URL in its WWW-Authenticate header, killing OAuth
      // discovery from any external MCP client.
      const publicUrl = computePublicUrl(slug, port);
      const envVars: Record<string, string> = {
        ...secrets,
        PUBLIC_URL: publicUrl,
        CONTROL_PLANE_URL: config.CONTROL_PLANE_URL,
        OAUTH_ISSUER: `${config.CONTROL_PLANE_PUBLIC_URL}/oauth`,
        PORT: '3000',
        SERVER_ID: serverId,
      };

      const handle = await deployContainer({ serverId, slug, hostPort: port, imageTag, envVars });
      await log(
        'info',
        `Container ${handle.containerId.slice(0, 12)} running at ${handle.publicUrl}`,
      );

      try {
        await db
          .update(builds)
          .set({ status: 'success', finishedAt: new Date() })
          .where(eq(builds.id, buildId));
        await db
          .update(mcpServers)
          .set({
            status: 'live',
            currentVersion: version,
            publicUrl: handle.publicUrl,
            updatedAt: new Date(),
          })
          .where(eq(mcpServers.id, serverId));
      } finally {
        // Rolling deploy: retire the previous container even if the success DB
        // writes above threw — otherwise a DB hiccup after a healthy deploy
        // leaves the old container orphaned, holding its host port. The new
        // container is already live and its id is persisted in deployContainer. (GEN-007)
        if (oldContainerId && oldContainerId !== handle.containerId) {
          const stopped = await stopContainer(oldContainerId);
          await log(
            stopped.ok ? 'info' : 'warn',
            stopped.ok
              ? `Retired previous container ${oldContainerId.slice(0, 12)}`
              : `Could not stop previous container ${oldContainerId.slice(0, 12)}: ${stopped.detail}`,
          );
        }
      }

      await emitStatus(buildId, 'success');
      await emitDone(buildId, 'success', serverId, handle.publicUrl);
    } catch (err) {
      const msg = err instanceof Error ? err.message : String(err);
      console.error('[worker] build failed:', err);
      await db
        .update(builds)
        .set({ status: 'failed', errorMessage: msg, finishedAt: new Date() })
        .where(eq(builds.id, buildId));
      await db
        .update(mcpServers)
        .set({ status: 'failed', updatedAt: new Date() })
        .where(eq(mcpServers.id, serverId));
      await emitError(buildId, msg);
      await emitDone(buildId, 'failed', serverId, null);
    }
  },
  { connection, concurrency: 2 },
);

worker.on('ready', () => console.log('[generator] worker ready'));
worker.on('failed', (job, err) => console.error('[generator] job failed', job?.id, err?.message));
worker.on('error', (err) => console.error('[generator] worker error', err.message));