Scheduled nightly builds delayed more than 15 minutes


Hi everyone. I started to use CircleCI in December, last year but I could not solve what I wanted so I tried other tools like the automated build Docker Hub. It was fine for one of my images but not for an other, so I am here again, since CircleCI has scheduled workflows and pipeline variables so I can have different build process based on whether it was trigged by git push or a cron job. I have spent days to improve my scripts and you can see many failed attempts in the list of the builds, but it finally works and the result is itsziget/httpd24 on Docker Hub.

The unexpectedly long delay and the documentation

So in this post I am not asking for help to build my Docker image, but I noticed that scheduled builds are delayed. The documentations mentions, that

Note: Scheduled workflows may be delayed by up to 15 minutes. This is done to maintain reliability during busy times such as 12:00am UTC. Scheduled workflows should not assume they are started with to-the-minute accuracy.

Although at first I thought the build would not start at all, later I realized it actually ran. I searched for this in the documentation and I found what I quoted above. However, my build was scheduled at 02:00 AM UTC, but it ran about 45 minutes later, which is more than 15 minutes. I can accept it, so no real poblem here, but I don’t know if

  • it is intentional and the documentation was not updated or
  • it should have started the build until 02:15 AM UTC but some unknown conditions affected the scheduling or
  • There are different delays mentioned somewhere in the documentation whcih I could not find yet

How I tried to understand it

I tried to search for “nightly delay”, “sheduled delay”, “nightly”, “scheduled” on the forum, but I could not find the answer so far.

If you go to the project and check the build step, you can see that I logged the event type and the time:

-- [info] -- Event type: cron
-- [info] -- Run cron job
-- [info] -- Current local time: 2022-07-18 02:47:39 UTC
-- [info] -- Current UTC time:   2022-07-18 02:47:39 UTC

About my configuration

The event type is actually a pipeline parameter in the trigger definition. I configured the scheduler from the Web UI not in my config.yml which is this:

On the Web UI I have this configuration:

Repeats on these days: Select All
Start Time: 2:00 UTC
Repeats Per Hour: 1


  • Is this 45 minute delay normal?
  • Is there a documentation mentioning this 45 minute delay which I could not find?
  • Would it be different if I configured the cron job in my config.yml? I know I could test it and maybe I will later.

It may be better to raise a support ticket for this as the team can then pass the question to someone who can answer it. While many circleci staff can be found here, I think many only scan over the question as and when they have some free time as a way to help out, rather than because their jobs have a requirement to get involved with the forums.

It is worth noting that even for ‘free’ users the customer support team have a good track record for replying within the quoted support times and then tracking down/following up with answers.

Thank you for your answer. Since it doesn’t really matter to me if the delay is 15 minutes or 45 minutes, I thought I would ask the community first to find out if it is a well-known behavior. Since you recommend raising a ticket, I guess it isn’t and it should work as it is mentioned in the documentation I found.

It is good to know :slight_smile: Thanks.