Imported from waynesutton/convexskills (skills/convex-cron-jobs/SKILL.md) via skills.sh. Install upstream with npx skills add waynesutton/convexskills --skill convex-cron-jobs. Copyright stays with the author.

Convex Cron Jobs

Schedule recurring functions for background tasks, cleanup jobs, data syncing, and automated workflows in Convex applications.

Documentation Sources

Before implementing, do not assume; fetch the latest documentation:

• Primary: https://docs.convex.dev/scheduling/cron-jobs
• Scheduling Overview: https://docs.convex.dev/scheduling
• Scheduled Functions: https://docs.convex.dev/scheduling/scheduled-functions
• For broader context: https://docs.convex.dev/llms.txt

Instructions

Cron Jobs Overview

Convex cron jobs allow you to schedule functions to run at regular intervals or specific times. Key features:

• Run functions on a fixed schedule
• Support for interval-based and cron expression scheduling
• Automatic retries on failure
• Monitoring via the Convex dashboard

Basic Cron Setup

// convex/crons.ts
import { cronJobs } from "convex/server";
import { internal } from "./_generated/api";

const crons = cronJobs();

// Run every hour
crons.interval(
  "cleanup expired sessions",
  { hours: 1 },
  internal.tasks.cleanupExpiredSessions,
  {}
);

// Run every day at midnight UTC
crons.cron(
  "daily report",
  "0 0 * * *",
  internal.reports.generateDailyReport,
  {}
);

export default crons;

Interval-Based Scheduling

Use crons.interval for simple recurring tasks:

// convex/crons.ts
import { cronJobs } from "convex/server";
import { internal } from "./_generated/api";

const crons = cronJobs();

// Every 5 minutes
crons.interval(
  "sync external data",
  { minutes: 5 },
  internal.sync.fetchExternalData,
  {}
);

// Every 2 hours
crons.interval(
  "cleanup temp files",
  { hours: 2 },
  internal.files.cleanupTempFiles,
  {}
);

// Every 30 seconds (minimum interval)
crons.interval(
  "health check",
  { seconds: 30 },
  internal.monitoring.healthCheck,
  {}
);

export default crons;

Cron Expression Scheduling

Use crons.cron for precise scheduling with cron expressions:

// convex/crons.ts
import { cronJobs } from "convex/server";
import { internal } from "./_generated/api";

const crons = cronJobs();

// Every day at 9 AM UTC
crons.cron(
  "morning notifications",
  "0 9 * * *",
  internal.notifications.sendMorningDigest,
  {}
);

// Every Monday at 8 AM UTC
crons.cron(
  "weekly summary",
  "0 8 * * 1",
  internal.reports.generateWeeklySummary,
  {}
);

// First day of every month at midnight
crons.cron(
  "monthly billing",
  "0 0 1 * *",
  internal.billing.processMonthlyBilling,
  {}
);

// Every 15 minutes
crons.cron(
  "frequent sync",
  "*/15 * * * *",
  internal.sync.syncData,
  {}
);

export default crons;

Cron Expression Reference

┌───────────── minute (0-59)
│ ┌───────────── hour (0-23)
│ │ ┌───────────── day of month (1-31)
│ │ │ ┌───────────── month (1-12)
│ │ │ │ ┌───────────── day of week (0-6, Sunday=0)
│ │ │ │ │
* * * * *

Common patterns:

• * * * * * - Every minute
• 0 * * * * - Every hour
• 0 0 * * * - Every day at midnight
• 0 0 * * 0 - Every Sunday at midnight
• 0 0 1 * * - First day of every month
• */5 * * * * - Every 5 minutes
• 0 9-17 * * 1-5 - Every hour from 9 AM to 5 PM, Monday through Friday

Internal Functions for Crons

Cron jobs should call internal functions for security:

// convex/tasks.ts
import { internalMutation, internalQuery } from "./_generated/server";
import { v } from "convex/values";

// Cleanup expired sessions
export const cleanupExpiredSessions = internalMutation({
  args: {},
  returns: v.number(),
  handler: async (ctx) => {
    const oneHourAgo = Date.now() - 60 * 60 * 1000;
    
    const expiredSessions = await ctx.db
      .query("sessions")
      .withIndex("by_lastActive")
      .filter((q) => q.lt(q.field("lastActive"), oneHourAgo))
      .collect();

    for (const session of expiredSessions) {
      await ctx.db.delete(session._id);
    }

    return expiredSessions.length;
  },
});

// Process pending tasks
export const processPendingTasks = internalMutation({
  args: {},
  returns: v.null(),
  handler: async (ctx) => {
    const pendingTasks = await ctx.db
      .query("tasks")
      .withIndex("by_status", (q) => q.eq("status", "pending"))
      .take(100);

    for (const task of pendingTasks) {
      await ctx.db.patch(task._id, {
        status: "processing",
        startedAt: Date.now(),
      });
      
      // Schedule the actual processing
      await ctx.scheduler.runAfter(0, internal.tasks.processTask, {
        taskId: task._id,
      });
    }

    return null;
  },
});

Cron Jobs with Arguments

Pass static arguments to cron jobs:

// convex/crons.ts
import { cronJobs } from "convex/server";
import { internal } from "./_generated/api";

const crons = cronJobs();

// Different cleanup intervals for different types
crons.interval(
  "cleanup temp files",
  { hours: 1 },
  internal.cleanup.cleanupByType,
  { fileType: "temp", maxAge: 3600000 }
);

crons.interval(
  "cleanup cache files",
  { hours: 24 },
  internal.cleanup.cleanupByType,
  { fileType: "cache", maxAge: 86400000 }
);

export default crons;

// convex/cleanup.ts
import { internalMutation } from "./_generated/server";
import { v } from "convex/values";

export const cleanupByType = internalMutation({
  args: {
    fileType: v.string(),
    maxAge: v.number(),
  },
  returns: v.number(),
  handler: async (ctx, args) => {
    const cutoff = Date.now() - args.maxAge;
    
    const oldFiles = await ctx.db
      .query("files")
      .withIndex("by_type_and_created", (q) => 
        q.eq("type", args.fileType).lt("createdAt", cutoff)
      )
      .collect();

    for (const file of oldFiles) {
      await ctx.storage.delete(file.storageId);
      await ctx.db.delete(file._id);
    }

    return oldFiles.length;
  },
});

Monitoring and Logging

Add logging to track cron job execution:

// convex/tasks.ts
import { internalMutation } from "./_generated/server";
import { v } from "convex/values";

export const cleanupWithLogging = internalMutation({
  args: {},
  returns: v.null(),
  handler: async (ctx) => {
    const startTime = Date.now();
    let processedCount = 0;
    let errorCount = 0;

    try {
      const expiredItems = await ctx.db
        .query("items")
        .withIndex("by_expiresAt")
        .filter((q) => q.lt(q.field("expiresAt"), Date.now()))
        .collect();

      for (const item of expiredItems) {
        try {
          await ctx.db.delete(item._id);
          processedCount++;
        } catch (error) {
          errorCount++;
          console.error(`Failed to delete item ${item._id}:`, error);
        }
      }

      // Log job completion
      await ctx.db.insert("cronLogs", {
        jobName: "cleanup",
        startTime,
        endTime: Date.now(),
        duration: Date.now() - startTime,
        processedCount,
        errorCount,
        status: errorCount === 0 ? "success" : "partial",
      });
    } catch (error) {
      // Log job failure
      await ctx.db.insert("cronLogs", {
        jobName: "cleanup",
        startTime,
        endTime: Date.now(),
        duration: Date.now() - startTime,
        processedCount,
        errorCount,
        status: "failed",
        error: String(error),
      });
      throw error;
    }

    return null;
  },
});

Batching for Large Datasets

Handle large datasets in batches to avoid timeouts:

// convex/tasks.ts
import { internalMutation } from "./_generated/server";
import { internal } from "./_generated/api";
import { v } from "convex/values";

const BATCH_SIZE = 100;

export const processBatch = internalMutation({
  args: {
    cursor: v.optional(v.string()),
  },
  returns: v.null(),
  handler: async (ctx, args) => {
    const result = await ctx.db
      .query("items")
      .withIndex("by_status", (q) => q.eq("status", "pending"))
      .paginate({ numItems: BATCH_SIZE, cursor: args.cursor ?? null });

    for (const item of result.page) {
      await ctx.db.patch(item._id, {
        status: "processed",
        processedAt: Date.now(),
      });
    }

    // Schedule next batch if there are more items
    if (!result.isDone) {
      await ctx.scheduler.runAfter(0, internal.tasks.processBatch, {
        cursor: result.continueCursor,
      });
    }

    return null;
  },
});

External API Calls in Crons

Use actions for external API calls:

// convex/sync.ts
"use node";

import { internalAction } from "./_generated/server";
import { internal } from "./_generated/api";
import { v } from "convex/values";

export const syncExternalData = internalAction({
  args: {},
  returns: v.null(),
  handler: async (ctx) => {
    // Fetch from external API
    const response = await fetch("https://api.example.com/data", {
      headers: {
        Authorization: `Bearer ${process.env.API_KEY}`,
      },
    });

    if (!response.ok) {
      throw new Error(`API request failed: ${response.status}`);
    }

    const data = await response.json();

    // Store the data using a mutation
    await ctx.runMutation(internal.sync.storeExternalData, {
      data,
      syncedAt: Date.now(),
    });

    return null;
  },
});

export const storeExternalData = internalMutation({
  args: {
    data: v.any(),
    syncedAt: v.number(),
  },
  returns: v.null(),
  handler: async (ctx, args) => {
    await ctx.db.insert("externalData", {
      data: args.data,
      syncedAt: args.syncedAt,
    });
    return null;
  },
});

// convex/crons.ts
import { cronJobs } from "convex/server";
import { internal } from "./_generated/api";

const crons = cronJobs();

crons.interval(
  "sync external data",
  { minutes: 15 },
  internal.sync.syncExternalData,
  {}
);

export default crons;

Examples

Schema for Cron Job Logging

// convex/schema.ts
import { defineSchema, defineTable } from "convex/server";
import { v } from "convex/values";

export default defineSchema({
  cronLogs: defineTable({
    jobName: v.string(),
    startTime: v.number(),
    endTime: v.number(),
    duration: v.number(),
    processedCount: v.number(),
    errorCount: v.number(),
    status: v.union(
      v.literal("success"),
      v.literal("partial"),
      v.literal("failed")
    ),
    error: v.optional(v.string()),
  })
    .index("by_job", ["jobName"])
    .index("by_status", ["status"])
    .index("by_startTime", ["startTime"]),

  sessions: defineTable({
    userId: v.id("users"),
    token: v.string(),
    lastActive: v.number(),
    expiresAt: v.number(),
  })
    .index("by_user", ["userId"])
    .index("by_lastActive", ["lastActive"])
    .index("by_expiresAt", ["expiresAt"]),

  tasks: defineTable({
    type: v.string(),
    status: v.union(
      v.literal("pending"),
      v.literal("processing"),
      v.literal("completed"),
      v.literal("failed")
    ),
    data: v.any(),
    createdAt: v.number(),
    startedAt: v.optional(v.number()),
    completedAt: v.optional(v.number()),
  })
    .index("by_status", ["status"])
    .index("by_type_and_status", ["type", "status"]),
});

Complete Cron Configuration Example

// convex/crons.ts
import { cronJobs } from "convex/server";
import { internal } from "./_generated/api";

const crons = cronJobs();

// Cleanup jobs
crons.interval(
  "cleanup expired sessions",
  { hours: 1 },
  internal.cleanup.expiredSessions,
  {}
);

crons.interval(
  "cleanup old logs",
  { hours: 24 },
  internal.cleanup.oldLogs,
  { maxAgeDays: 30 }
);

// Sync jobs
crons.interval(
  "sync user data",
  { minutes: 15 },
  internal.sync.userData,
  {}
);

// Report jobs
crons.cron(
  "daily analytics",
  "0 1 * * *",
  internal.reports.dailyAnalytics,
  {}
);

crons.cron(
  "weekly summary",
  "0 9 * * 1",
  internal.reports.weeklySummary,
  {}
);

// Health checks
crons.interval(
  "service health check",
  { minutes: 5 },
  internal.monitoring.healthCheck,
  {}
);

export default crons;

Best Practices

• Never run npx convex deploy unless explicitly instructed
• Never run any git commands unless explicitly instructed
• Only use crons.interval or crons.cron methods, not deprecated helpers
• Always call internal functions from cron jobs for security
• Import internal from _generated/api even for functions in the same file
• Add logging and monitoring for production cron jobs
• Use batching for operations that process large datasets
• Handle errors gracefully to prevent job failures
• Use meaningful job names for dashboard visibility
• Consider timezone when using cron expressions (Convex uses UTC)

Common Pitfalls

1. Using public functions - Cron jobs should call internal functions only
2. Long-running mutations - Break large operations into batches
3. Missing error handling - Unhandled errors will fail the entire job
4. Forgetting timezone - All cron expressions use UTC
5. Using deprecated helpers - Avoid crons.hourly, crons.daily, etc.
6. Not logging execution - Makes debugging production issues difficult

References

• Convex Documentation: https://docs.convex.dev/
• Convex LLMs.txt: https://docs.convex.dev/llms.txt
• Cron Jobs: https://docs.convex.dev/scheduling/cron-jobs
• Scheduling Overview: https://docs.convex.dev/scheduling
• Scheduled Functions: https://docs.convex.dev/scheduling/scheduled-functions