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Use the cron.yaml
file to define scheduled tasks for your application.
To learn more about scheduling tasks, including how to test, deploy, or delete Cron jobs, see Scheduling Tasks with Cron.
Note: Uploading acron.yaml
file via the gcloud CLI below version 322.0.0.
uses a deprecated interface to the service. Starting on 2022-09-20
, attempts to use the upload method can fail with server errors. To resolve this, make sure the Cloud Scheduler API is enabled in your project and your gcloud CLI is updated to at least version 322.0.0.
. Example
The following is an example cron.yaml
file:
cron:
- description: "daily summary job"
url: /tasks/summary
schedule: every 24 hours
- description: "monday morning mailout"
url: /mail/weekly
schedule: every monday 09:00
timezone: Australia/NSW
- description: "new daily summary job"
url: /tasks/summary
schedule: every 24 hours
target: beta
Syntax
The
cron.yaml
file should reside in the root directory of your application alongside
app.yaml
:
cron.yaml
configures scheduled tasks for your Python 2 application.
For more information about the YAML format, see
the YAML website.
Cron job definitions Element Descriptiondescription
Optional. The description is visible in the Google Cloud console and the development server's admin interface. Surround the description value in quotes. retry_parameters
Optional. If a cron job's request handler returns a HTTP status code that is not in the range 200–299 (inclusive) App Engine considers the job to have failed. By default, failed jobs are not retried. You can cause failed jobs to be retried by including a retry-parameters block in your configuration file.
See the Cron retries section for more information.
schedule
Required. Defines the schedule of when the cron job runs, see the syntax below. target
The target
string is prepended to your app's hostname. It is usually the name of a service. The cron job will be routed to the version of the named service that is configured for traffic.
If the service name that is specified for target
is not found, then the Cron request is routed to either the default
service, or to the version of your app that is configured to receive traffic.For more information about routing, see How Requests are Routed.
If you use a dispatch file, your job might be re-routed. For example, given the following cron.yaml
and dispatch.yaml
files, the job will run in service2
, even though its target is service1
:
# cron.yaml cron: - description: "test dispatch vs target" url: /tasks/hello_service2 schedule: every 1 mins target: service1 # dispatch.yaml: dispatch: - url: '*/tasks/hello_service2' service: service2
timezone
The timezone
should be the name of a standard zoneinfo time zone name. If you don't specify a timezone, the schedule will be in UTC (also known as GMT). url
Required. The url
field specifies a URL in your application that will be invoked by the Cron Service. See Securing URLs for Cron for more information. Defining the cron job schedule
Note: Uploading a cron.yaml
file via the gcloud CLI below version 322.0.0.
uses a deprecated interface to the service. Starting on 2022-09-20
, attempts to use the upload method can fail with server errors. To resolve this, make sure the Cloud Scheduler API is enabled in your project and your gcloud CLI is updated to at least version 322.0.0.
.
Cron jobs are scheduled on reoccurring intervals and are specified using a simple English-like format. You can define a schedule so that your job runs multiple times a day, or runs on specific days and months.
Use a sub-daily interval to run a job multiple times a day on a repetitive schedule. You can define either an end-time interval, or a start-time interval:
End-time interval: Defines the time between the "end time" of a job and when the next job starts, where the "end time" is either the time at which the job completes or times out . The Cron service runs jobs in this type of interval throughout the 24 hour day, starting at 00:00
, and waits for the specified duration of time between each job.
Example: For the every 5 minutes
schedule, the job is run daily using a 5-minute interval. If one instance of a job that is running on this schedule complete at 02:01, then the next job waits 5 minute and starts again at 02:06.
Start-time interval: Defines a regular time interval for the Cron service to start each job. Unlike the end-time interval, the start-time interval runs each job independent of when the prior job completes or times-out. You can set a time range within which you want your job to run, or run jobs 24 hours a day, starting at 00:00
.
Because the start time of a job is strict, if an instance of a job runs longer than the defined time interval, then the Cron service can skip a job. An individual start time in the interval can be skipped if the prior job has not completed or times out .
Example: For the every 5 minutes from 10:00 to 14:00
schedule, the first job starts running at 10:00
, and then every 5 minutes thereafter. If that first job runs for 7 minutes, then the 10:05
job is skipped, and therefore, the Cron service does not run another instance of this job until 10:10
.
You can use a custom interval to define a schedule where your job can run once per day on one or more select days, and in one or more select months. Jobs that run on a custom schedule run year-round, only at the specific time on the select days and months.
Example: For the 1,2,3 of month 07:00
schedule, the job runs one time at 07:00
on the first three days of each month.
Important considerations for schedule
:
schedule: every 6 hours mon,wed,fri
.schedule
To specify when your job runs, you must define the schedule
element using the following syntax:
schedule: [TYPE] [INTERVAL_VALUE] [INTERVAL_SCOPE]
Choose an interval type to define your schedule
element:
every
prefix.
Example: schedule: every 12 hours
minutes
or mins
hours
schedule: every 5 minutes
schedule: every 30 mins
every
prefix.
Example: schedule: every 12 hours
minutes
or mins
hours
synchronized
option.
from [HH:MM] to [HH:MM]
clause to define a specific start time and range within which you want to run jobs.
You must specify the time values in the 24 hour format, HH:MM
, where:
HH
are integers from 00
to 23
.MM
are integers from 00
to 59
.synchronized
to specify a 24 hour time range (from 00:00 to 23:59
) that is evenly divided by the [INTERVAL_VALUE] value.
Important: The [INTERVAL_VALUE] must divide 24 into an integer, otherwise the an error occurs. Valid values for [INTERVAL_VALUE] include: 1
, 2
, 3
, 4
, 6
, 8
, 12
, or 24
.
schedule: every 5 minutes from 10:00 to 14:00
schedule: every 1 hours from 08:00 to 16:00
schedule: every 2 hours synchronized
every
prefix to define a repetitive interval, or you can define a specific list of days in a month:
every
prefix.
Examples:
schedule: every day 00:00 schedule: every monday 09:00
1st
or first
2nd
or second
3rd
or third
31st
or thirtyfirst
Example:
schedule: 1st,3rd tuesday schedule: 2nd,third wednesday of month 09:00
1
2
3
31
monday
or mon
tuesday
or tue
wednesday
or wed
thursday
or thu
friday
or fri
saturday
or sat
sunday
or sun
day
to specify all days of the week.Examples:
schedule: 2nd monday,thu schedule: 1,8,15,22 of month 09:00 schedule: 1st mon,wednesday,thu of sep,oct,nov 17:00
of [MONTH]
clause, which specifies a single month in a year, or a comma-separated list of multiple months. You must also define a specific time for when you want the job to run, for example: of [MONTH] [HH:MM]
.
By default, if the of
clause is excluded, the custom interval is run every month.
january
or jan
february
or feb
march
or mar
april
or apr
may
june
or jun
july
or jul
august
or aug
september
or sep
october
or oct
november
or nov
december
or dec
month
to specify all months in the year.HH:MM
, where:
HH
are integers from 00
to 23
.MM
are integers from 00
to 59
.Example:
schedule: 1st monday of sep,oct,nov 09:00 schedule: 1 of jan,april,july,oct 00:00
schedule: every day 00:00
schedule: every monday 09:00
schedule: 2nd wednesday of march 17:00
schedule: 1st,second mon,wed,fri of may 10:00
schedule: 1,8,15,22 of month 09:00
schedule: 1st,third monday of month 04:00
schedule: 1st monday of sep,oct,nov 09:00
schedule: 1 of jan,april,july,oct 00:00
If a cron job's request handler returns a status code that is not in the range 200–299 (inclusive) App Engine considers the job to have failed. By default, failed jobs are not retried. You can cause failed jobs to be retried by including a
block in your configuration file.retry_parameters
Here is a sample cron.yaml file that contains a single cron job configured to retry up to five times (the default) with a starting backoff of 2.5 seconds that doubles each time.
cron:
- description: "retry demo"
url: /retry
schedule: every 10 mins
retry_parameters:
min_backoff_seconds: 2.5
max_doublings: 5
Cron retries syntax
The retry parameters are described in the table below.
Element Descriptionjob_retry_limit
The maximum number of retry attempts for a failed cron job not to exceed 5. If specified with job_age_limit
, App Engine retries the cron job until both limits are reached. When omitted from the parameters, the limit is set to 5 by default. job_age_limit
The time limit for retrying a failed cron job, measured from when the cron job was first run. The value is a number followed by a unit of time, where the unit is s
for seconds, m
for minutes, h
for hours, or d
for days. For example, the value 5d
specifies a limit of five days after the cron job's first execution attempt. If specified with job_retry_limit
, App Engine retries the cron job until both limits are reached. min_backoff_seconds
The minimum number of seconds to wait before retrying a cron job after it fails. max_backoff_seconds
The maximum number of seconds to wait before retrying a cron job after it fails. max_doublings
The maximum number of times that the interval between failed cron job retries will be doubled before the increase becomes constant. The constant is: 2**(max_doublings
- 1) * min_backoff
. Cron requests
Requests from the Cron Service will contain a HTTP header:
X-Appengine-Cron: true
This and other headers are set internally by App Engine. If a client sends these headers, they are removed from the request. The exception being requests from logged in administrators of legacy apps, who are allowed to set the header for testing purposes.
Originating IP addressApp Engine issues Cron requests from the IP address 0.1.0.2
. For Cron jobs created with older gcloud versions (earlier than 326.0.0), Cron requests will come from 0.1.0.1
.
The cron request timeout depends on the scaling type that is configured for your app:
For more information, see How instances are managed.
LimitsFree applications can have up to 20 scheduled tasks. Paid applications can have up to 250 scheduled tasks.
Except as otherwise noted, the content of this page is licensed under the Creative Commons Attribution 4.0 License, and code samples are licensed under the Apache 2.0 License. For details, see the Google Developers Site Policies. Java is a registered trademark of Oracle and/or its affiliates.
Last updated 2025-08-07 UTC.
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Hard to understand","hardToUnderstand","thumb-down"],["Incorrect information or sample code","incorrectInformationOrSampleCode","thumb-down"],["Missing the information/samples I need","missingTheInformationSamplesINeed","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-07 UTC."],[[["The `cron.yaml` file is used to define scheduled tasks for your Python 2 application, allowing for the configuration of recurring jobs with specific URLs and schedules."],["Cron job schedules can be defined using either sub-daily intervals for frequent tasks or custom intervals for tasks that run on specific days and months, but these types can't be mixed."],["When configuring cron job retries, you can specify parameters such as `job_retry_limit`, `job_age_limit`, `min_backoff_seconds`, `max_backoff_seconds`, and `max_doublings` to control how and when failed jobs are retried."],["Cron requests are sent with a unique HTTP header `X-Appengine-Cron: true` and originate from specific IP addresses, and the timeout for these requests varies depending on the application's scaling type, with automatic scaling having a 10-minute limit and basic/manual scaling having a 24-hour limit."],["It is important to be sure that the Cloud Scheduler API is enabled in your project and that your gcloud CLI is at least version `322.0.0` to avoid errors uploading a `cron.yaml` file, and that your application code is idempotent to handle potential duplicate job requests."]]],[]]
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