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Triggering and modifying builds

Build triggers

When defining a BuildConfig, you can define triggers to control the circumstances in which the BuildConfig should be run. The following build triggers are available:

  • Webhook

  • Image change

  • Configuration change

Webhook triggers

Webhook triggers allow you to trigger a new build by sending a request to the OpenShift Container Platform API endpoint. You can define these triggers using GitHub, GitLab, Bitbucket, or Generic webhooks.

Currently, OpenShift Container Platform webhooks only support the analogous versions of the push event for each of the Git-based Source Code Management (SCM) systems. All other event types are ignored.

When the push events are processed, the OpenShift Container Platform control plane host confirms if the branch reference inside the event matches the branch reference in the corresponding BuildConfig. If so, it then checks out the exact commit reference noted in the webhook event on the OpenShift Container Platform build. If they do not match, no build is triggered.

oc new-app and oc new-build create GitHub and Generic webhook triggers automatically, but any other needed webhook triggers must be added manually. You can manually add triggers by setting triggers.

For all webhooks, you must define a secret with a key named WebHookSecretKey and the value being the value to be supplied when invoking the webhook. The webhook definition must then reference the secret. The secret ensures the uniqueness of the URL, preventing others from triggering the build. The value of the key is compared to the secret provided during the webhook invocation.

For example here is a GitHub webhook with a reference to a secret named mysecret:

type: "GitHub"
github:
  secretReference:
    name: "mysecret"

The secret is then defined as follows. Note that the value of the secret is base64 encoded as is required for any data field of a Secret object.

- kind: Secret
  apiVersion: v1
  metadata:
    name: mysecret
    creationTimestamp:
  data:
    WebHookSecretKey: c2VjcmV0dmFsdWUx

Using GitHub webhooks

GitHub webhooks handle the call made by GitHub when a repository is updated. When defining the trigger, you must specify a secret, which is part of the URL you supply to GitHub when configuring the webhook.

Example GitHub webhook definition:

type: "GitHub"
github:
  secretReference:
    name: "mysecret"

The secret used in the webhook trigger configuration is not the same as secret field you encounter when configuring webhook in GitHub UI. The former is to make the webhook URL unique and hard to predict, the latter is an optional string field used to create HMAC hex digest of the body, which is sent as an X-Hub-Signature header.

The payload URL is returned as the GitHub Webhook URL by the oc describe command (see Displaying Webhook URLs), and is structured as follows:

Example output
https://<openshift_api_host:port>/apis/build.openshift.io/v1/namespaces/<namespace>/buildconfigs/<name>/webhooks/<secret>/github
Prerequisites

  • Create a BuildConfig from a GitHub repository.

Procedure

  1. To configure a GitHub Webhook:

    1. After creating a BuildConfig from a GitHub repository, run:

      $ oc describe bc/<name-of-your-BuildConfig>

      This generates a webhook GitHub URL that looks like:

      Example output
      <https://api.starter-us-east-1.openshift.com:443/apis/build.openshift.io/v1/namespaces/<namespace>/buildconfigs/<name>/webhooks/<secret>/github

    2. Cut and paste this URL into GitHub, from the GitHub web console.

    3. In your GitHub repository, select Add Webhook from Settings → Webhooks.

    4. Paste the URL output into the Payload URL field.

    5. Change the Content Type from GitHub’s default application/x-www-form-urlencoded to application/json.

    6. Click Add webhook.

      You should see a message from GitHub stating that your webhook was successfully configured.

      Now, when you push a change to your GitHub repository, a new build automatically starts, and upon a successful build a new deployment starts.

      Gogs supports the same webhook payload format as GitHub. Therefore, if you are using a Gogs server, you can define a GitHub webhook trigger on your BuildConfig and trigger it by your Gogs server as well.

  2. Given a file containing a valid JSON payload, such as payload.json, you can manually trigger the webhook with curl:

    $ curl -H "X-GitHub-Event: push" -H "Content-Type: application/json" -k -X POST --data-binary @payload.json https://<openshift_api_host:port>/apis/build.openshift.io/v1/namespaces/<namespace>/buildconfigs/<name>/webhooks/<secret>/github

    The -k argument is only necessary if your API server does not have a properly signed certificate.

Additional resources

Using GitLab webhooks

GitLab webhooks handle the call made by GitLab when a repository is updated. As with the GitHub triggers, you must specify a secret. The following example is a trigger definition YAML within the BuildConfig:

type: "GitLab"
gitlab:
  secretReference:
    name: "mysecret"

The payload URL is returned as the GitLab Webhook URL by the oc describe command, and is structured as follows:

Example output
https://<openshift_api_host:port>/apis/build.openshift.io/v1/namespaces/<namespace>/buildconfigs/<name>/webhooks/<secret>/gitlab
Procedure

  1. To configure a GitLab Webhook:

    1. Describe the BuildConfig to get the webhook URL:

      $ oc describe bc <name>

    2. Copy the webhook URL, replacing <secret> with your secret value.

    3. Follow the GitLab setup instructions to paste the webhook URL into your GitLab repository settings.

  2. Given a file containing a valid JSON payload, such as payload.json, you can manually trigger the webhook with curl:

    $ curl -H "X-GitLab-Event: Push Hook" -H "Content-Type: application/json" -k -X POST --data-binary @payload.json https://<openshift_api_host:port>/apis/build.openshift.io/v1/namespaces/<namespace>/buildconfigs/<name>/webhooks/<secret>/gitlab

    The -k argument is only necessary if your API server does not have a properly signed certificate.

Using Bitbucket webhooks

Bitbucket webhooks handle the call made by Bitbucket when a repository is updated. Similar to the previous triggers, you must specify a secret. The following example is a trigger definition YAML within the BuildConfig:

type: "Bitbucket"
bitbucket:
  secretReference:
    name: "mysecret"

The payload URL is returned as the Bitbucket Webhook URL by the oc describe command, and is structured as follows:

Example output
https://<openshift_api_host:port>/apis/build.openshift.io/v1/namespaces/<namespace>/buildconfigs/<name>/webhooks/<secret>/bitbucket
Procedure

  1. To configure a Bitbucket Webhook:

    1. Describe the 'BuildConfig' to get the webhook URL:

      $ oc describe bc <name>

    2. Copy the webhook URL, replacing <secret> with your secret value.

    3. Follow the Bitbucket setup instructions to paste the webhook URL into your Bitbucket repository settings.

  2. Given a file containing a valid JSON payload, such as payload.json, you can manually trigger the webhook with curl:

    $ curl -H "X-Event-Key: repo:push" -H "Content-Type: application/json" -k -X POST --data-binary @payload.json https://<openshift_api_host:port>/apis/build.openshift.io/v1/namespaces/<namespace>/buildconfigs/<name>/webhooks/<secret>/bitbucket

    The -k argument is only necessary if your API server does not have a properly signed certificate.

Using generic webhooks

Generic webhooks are invoked from any system capable of making a web request. As with the other webhooks, you must specify a secret, which is part of the URL that the caller must use to trigger the build. The secret ensures the uniqueness of the URL, preventing others from triggering the build. The following is an example trigger definition YAML within the BuildConfig:

type: "Generic"
generic:
  secretReference:
    name: "mysecret"
  allowEnv: true (1)
1 Set to true to allow a generic webhook to pass in environment variables.
Procedure

  1. To set up the caller, supply the calling system with the URL of the generic webhook endpoint for your build:

    Example output
    https://<openshift_api_host:port>/apis/build.openshift.io/v1/namespaces/<namespace>/buildconfigs/<name>/webhooks/<secret>/generic

    The caller must invoke the webhook as a POST operation.

  2. To invoke the webhook manually you can use curl:

    $ curl -X POST -k https://<openshift_api_host:port>/apis/build.openshift.io/v1/namespaces/<namespace>/buildconfigs/<name>/webhooks/<secret>/generic

    The HTTP verb must be set to POST. The insecure -k flag is specified to ignore certificate validation. This second flag is not necessary if your cluster has properly signed certificates.

    The endpoint can accept an optional payload with the following format:

    git:
  uri: "<url to git repository>"
  ref: "<optional git reference>"
  commit: "<commit hash identifying a specific git commit>"
  author:
    name: "<author name>"
    email: "<author e-mail>"
  committer:
    name: "<committer name>"
    email: "<committer e-mail>"
  message: "<commit message>"
env: (1)
   - name: "<variable name>"
     value: "<variable value>"
    1 Similar to the BuildConfig environment variables, the environment variables defined here are made available to your build. If these variables collide with the BuildConfig environment variables, these variables take precedence. By default, environment variables passed by webhook are ignored. Set the allowEnv field to true on the webhook definition to enable this behavior.

  3. To pass this payload using curl, define it in a file named payload_file.yaml and run:

    $ curl -H "Content-Type: application/yaml" --data-binary @payload_file.yaml -X POST -k https://<openshift_api_host:port>/apis/build.openshift.io/v1/namespaces/<namespace>/buildconfigs/<name>/webhooks/<secret>/generic

    The arguments are the same as the previous example with the addition of a header and a payload. The -H argument sets the Content-Type header to application/yaml or application/json depending on your payload format. The --data-binary argument is used to send a binary payload with newlines intact with the POST request.

OpenShift Container Platform permits builds to be triggered by the generic webhook even if an invalid request payload is presented, for example, invalid content type, unparsable or invalid content, and so on. This behavior is maintained for backwards compatibility. If an invalid request payload is presented, OpenShift Container Platform returns a warning in JSON format as part of its HTTP 200 OK response.

Displaying webhook URLs

You can use the following command to display webhook URLs associated with a build configuration. If the command does not display any webhook URLs, then no webhook trigger is d