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k8svent

Send Kubernetes pods as JSON to webhook endpoints. k8svent is run from its Docker image in a Kubernetes cluster to send pod state changes to the Atomist Kubernetes webhook endpoint for your Kubernetes cluster integration.

Running

At https://go.atomist.com/, create a Kubernetes cluster integration and following the provided instructions for deploying k8svent to your Kubernetes cluster.

Webhook URLs

When running k8svent, webhook URLs can be specified in several ways:

  • The --url command-line option, which can be specified multiple times.

    $ k8svent --url=https://webhook.atomist.com/atomist/kube/teams/WORKSPACE_ID \
    --url=https://second.com/webhook

  • A comma-delimited list as the value of the K8SVENT_WEBHOOKS environment variable.

    $ K8SVENT_WEBHOOKS=https://webhook.atomist.com/0,https://webhook.atomist.com/1 k8svent

If webhooks are set using the --url command-line option, they override any set by the K8SVENT_WEBHOOKS environment variable. In other words, webhooks provided by the different methods are not additive.

Signing webhook payloads

k8svent can optionally sign the webhook payloads it sends using a secret. The secret can be provided

  • The --secret command-line option.

    $ k8svent --secret=MyS3c43t

  • The value of the K8SVENT_WEBHOOK_SECRET environment variable.

    $ K8SVENT_WEBHOOK_SECRET=MyS3c43t k8svent

A secret provided on the command line takes precedence over one provided via the environment variable. If a secret is provided, it is used to sign the payloads send to all configured webhook endpoints.

Webhook payload

k8svent sends payloads for all pods, which it fetches using the Kubernetes API. It periodically gets all pods and does its best to send only the interesting ones, i.e., ones that have changed or that are under duress. Each pod spec is serialized to JSON and sent to the configured endpoint. The JSON structure is

{
  "pod": {
    ... // k8s.io/api/core/v1.Pod
  }
}

The pod data structure is the same as you would see using kubectl get pod POD -o json.

Updating

When running, k8svent periodically polls Docker Hub for tags and checks the semantic version tags to see if any are newer than the current running version. If the currently running version is a release, it only checks tags that look like release versions. If the currently running version is a prerelease, it checks all semantic version tags for a newer version, which may be a release. If it detects a newer version exists, it exits and lets Kubernetes pull the new image and run it. To stay on the latest release, use the latest tag. To use prerelease versions, use the next tag. To disable updating, use a specific version tag.

Developing

You can download, install, and develop locally using the normal Go build tools.

$ go get github.com/atomist/k8svent

The source code will be under $GOPATH/src/github.com/atomist/k8svent. If $GOPATH/bin is in your PATH, then the k8svent binary will be in your path when the above command completes successfully. Then you can run k8svent locally simply by invoking k8svent from your terminal.

If you make changes to the code, you can run tests using the Go tooling

$ go test ./...

or you can use make

$ make test

To generate, build, test, install, vet, and lint, just run

$ make

Releasing

On each push of new commits to this repository, the Docker image will be built and pushed to Docker Hub. It will be tagged with a prerelease version.

To create a release, push a semantic version tag starting with v, e.g., v1.2.3. The Docker image will be built and tagged with the tag.

Created by Atomist. Need Help? Join our Slack team.