You know the scenario, you’re wanting to run jobs either at certain points in a day or throughout the data every N timespans (i.e. every 5 mins). <\/p>\n
Kubernetes has you covered, there’s a specific “kind” of job for this, as you guessed from the title, the CronJob<\/em>.<\/p>\n An example app.<\/strong><\/p>\n Let’s assume you created yourself a job – I’m going to create a simple job that just outputs the date\/time at the scheduled time. I’ve written this in Rust but to be honest it’s simple enough that this could be any language. Here’s the Cargo.toml<\/p>\n The application is just a standard console application named crj (for cronjob or cron rust job, I really didn’t think about it :)).<\/p>\n Here’s the code<\/p>\n See I told you it was simple. <\/p>\n Docker<\/strong><\/p>\n For completeness, here’s the Dockerfile and the steps to get things built, tagged and pushed<\/p>\n Next up we need to build the image using (remember to use the image you created as well as the correct name for your container registry)<\/p>\n then tag it using<\/p>\n Finally we’ll push it to our container registry using<\/p>\n Kubernetes CronJob<\/strong><\/p>\n All pretty standard stuff and to be honest the next bit is simple enough. We need to create a kubernetes yaml file (or helm charts). Here’s my cronjob.yaml<\/p>\n My cronjob has the name scheduled-job<\/em> (I know, not very imaginative). We apply this file to Kubernetes as usual i.e.<\/p>\n Did it work?<\/strong><\/p>\n We’ll ofcourse want to take a look at what happened after this CronJob was set up in Kubernetes. We can simply use the following. You can set the namespace used, such as dev in my case.<\/p>\n you’ll see something like this<\/p>\n In my case the job starts (ACTIVE) and then completes and shuts down. Then 5 minutes later it starts again as expected with this cron schedule.<\/p>\n On the pods side you can run <\/p>\n Now what you’ll see is something like this<\/p>\n Notice that the pod is created and goes into a “Pending” state. Then “ContainerCreating” before “Running” and finally “Completed”, but the next run of the cronjob creates a new pod name. Therefore, if you’re trying to log the pods i.e. kubectl logs scheduled-job-29257380-5w4rg -n dev – then you’ll get something like the below, but you cannot -f (follow) the logs as the next time the job runs it creates a new pod.<\/p>\n You know the scenario, you’re wanting to run jobs either at certain points in a day or throughout the data every N timespans (i.e. every 5 mins). Kubernetes has you covered, there’s a specific “kind” of job for this, as you guessed from the title, the CronJob. An example app. Let’s assume you created yourself […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[314,191],"tags":[],"class_list":["post-11620","post","type-post","status-publish","format-standard","hentry","category-kubernetes","category-rust"],"jetpack_sharing_enabled":true,"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/putridparrot.com\/blog\/wp-json\/wp\/v2\/posts\/11620","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/putridparrot.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/putridparrot.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/putridparrot.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/putridparrot.com\/blog\/wp-json\/wp\/v2\/comments?post=11620"}],"version-history":[{"count":3,"href":"https:\/\/putridparrot.com\/blog\/wp-json\/wp\/v2\/posts\/11620\/revisions"}],"predecessor-version":[{"id":11624,"href":"https:\/\/putridparrot.com\/blog\/wp-json\/wp\/v2\/posts\/11620\/revisions\/11624"}],"wp:attachment":[{"href":"https:\/\/putridparrot.com\/blog\/wp-json\/wp\/v2\/media?parent=11620"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/putridparrot.com\/blog\/wp-json\/wp\/v2\/categories?post=11620"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/putridparrot.com\/blog\/wp-json\/wp\/v2\/tags?post=11620"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}\r\n[package]\r\nname = "crj"\r\nversion = "0.1.0"\r\nedition = "2024"\r\n\r\n[dependencies]\r\nchrono = "0.4"\r\n<\/pre>\n
\r\nuse chrono::Local;\r\n\r\nfn main() {\r\n let now = Local::now();\r\n println!("Current date and time: {}", now);\r\n}\r\n<\/pre>\n\r\nFROM rust:1.89.0-slim AS builder\r\n\r\nWORKDIR \/app\r\nCOPY . .\r\n\r\nRUN cargo build --release\r\n\r\nFROM debian:bookworm-slim\r\n\r\nRUN apt-get update && apt-get install -y ca-certificates && \\\r\n rm -rf \/var\/lib\/apt\/lists\/*\r\n\r\nCOPY --from=builder \/app\/target\/release \/usr\/local\/bin\/crj\r\n\r\nRUN chmod +x \/usr\/local\/bin\/crj\r\n\r\nENTRYPOINT ["\/usr\/local\/bin\/crj\/crj"]\r\n<\/pre>\n
\r\ndocker build -t putridparrot\/crj:1.0.0 .\r\n<\/pre>\n
\r\ndocker tag putridparrot\/crj:1.0.0 putridparrotreg\/putridparrot\/crj:1.0.0\r\n<\/pre>\n
\r\ndocker push putridparrotreg\/putridparrot\/crj:1.0.0\r\n<\/pre>\n
\r\napiVersion: batch\/v1\r\nkind: CronJob\r\nmetadata:\r\n name: scheduled-job\r\n namespace: dev\r\nspec:\r\n schedule: "*\/5 * * * *" # every 5 minutes\r\n jobTemplate:\r\n spec:\r\n template:\r\n spec:\r\n containers:\r\n - name: scheduled-job\r\n image: putridparrotreg\/putridparrot\/crj:1.0.0\r\n restartPolicy: Never\r\n<\/pre>\n
\r\nkubectl apply -f .\\cronjob.yaml\r\n<\/pre>\n
\r\nkubectl get cronjobs --all-namespaces -w\r\n<\/pre>\n
\r\nNAMESPACE NAME SCHEDULE TIMEZONE SUSPEND ACTIVE LAST SCHEDULE AGE\r\ndev scheduled-job *\/5 * * * * <none> False 0 <none> 9s\r\ndev scheduled-job *\/5 * * * * <none> False 1 0s 16s\r\ndev scheduled-job *\/5 * * * * <none> False 0 13s 29s\r\ndev scheduled-job *\/5 * * * * <none> False 1 0s 5m16s\r\n<\/pre>\n
\r\nkubectl get pods -n dev -w\r\n<\/pre>\n
\r\nNAME READY STATUS RESTARTS AGE\r\nscheduled-job-29257380-5w4rg 0\/1 Completed 0 51s\r\nscheduled-job-29257385-qgml2 0\/1 Pending 0 0s\r\nscheduled-job-29257385-qgml2 0\/1 Pending 0 0s\r\nscheduled-job-29257385-qgml2 0\/1 ContainerCreating 0 0s\r\nscheduled-job-29257385-qgml2 1\/1 Running 0 2s\r\nscheduled-job-29257385-qgml2 0\/1 Completed 0 3s\r\nscheduled-job-29257385-qgml2 0\/1 Completed 0 5s\r\nscheduled-job-29257385-qgml2 0\/1 Completed 0 5s\r\nscheduled-job-29257390-2x98r 0\/1 Pending 0 0s\r\nscheduled-job-29257390-2x98r 0\/1 Pending 0 0s\r\nscheduled-job-29257390-2x98r 0\/1 ContainerCreating 0 0s\r\nscheduled-job-29257390-2x98r 1\/1 Running 0 2s\r\n<\/pre>\n
\r\nCurrent date and time: 2025-08-17 15:00:09.294317303 +00:00\r\n<\/pre>\n","protected":false},"excerpt":{"rendered":"