distributor

A distributor can be used to subscribe a Keptn service with the Keptn Control Plane. Both local and remote subscriptions are supported:

• Local (Keptn service runs in the same local Kubernetes cluster as the Keptn Control Plane) It queries event messages from NATS and sends the events to services that have a subscription to the event topic.
• Remote (Keptn service runs in a remote “execution plane”) Subscriptions are implemented using the Keptn Subscription API.

Each service has its own distributor that is configured by environment variables. In most cases, only a subset of these need to be configured. After the application is deployed, its subscription can be changed directly in the Bridge.

Note that some services use cp-connector or go-sdk (which is actually a wrapper for cp-connector) instead of the distributor. This is discussed more in Architecture.

Environment variables

The following environment variables configure the distributor when it runs outside the Keptn cluster:

• KEPTN_API_ENDPOINT - Keptn API Endpoint - needed when the distributor runs outside of the Keptn cluster. default = ""
• KEPTN_API_TOKEN - Keptn API Token - needed when the distributor runs outside of the Keptn cluster. default = ""

The following environment variables configure Keptn to serve as a proxy for the Keptn API:

• API_PROXY_PORT - Port on which the distributor listens for incoming Keptn API requests by its execution plane service. default = 8081.
• API_PROXY_PATH - Path on which the distributor listens for incoming Keptn API requests by its execution plane service. default = /.
• API_PROXY_HTTP_TIMEOUT - Timeout value (in seconds) for the API Proxy’s HTTP Client. default = 30.
• HTTP_POLLING_INTERVAL - Interval (in seconds) in which the distributor checks for new triggered events on the Keptn API. default = 10
• EVENT_FORWARDING_PATH - Path on which the distributor listens for incoming events from its execution plane service. default = /event
• HTTP_SSL_VERIFY - Determines whether the distributor should check the validity of SSL certificates when sending requests to a Keptn API endpoint via HTTPS. default = true

The following environment variables configure the distributor when it runs within the Keptn cluster:

• PUBSUB_URL - The URL of the NATS cluster to which the distributor should connect when the distributor is running within the Keptn cluster. default = nats://keptn-nats

  Note that this environment variable identifies the NATS cluster for the distributor. The NATS URL is also defined using the NATS environment variable, NATS_URL; services that use cp-connector or go-sdk to subscribe to events should use the NATS_URL environment variable to identify the NATS cluster. By default, and in most installations, the PUBSUB_URL and NATS_URL environment variables should have the same value. See Execution Plane Services for architectural details about NATS behavior when Keptn runs on a single cluster and when it is installed in a multi-cluster configuration.

• PUBSUB_TOPIC - Comma separated list of topics (i.e. event types) for which the distributor should listen (see https://github.com/keptn/spec/blob/0.2.4/cloudevents.md for details). This is the initial subscription for the service; it is overridden by subscription information supplied through the Bridge.

  • When running within the Keptn cluster, it is possible to use NATS Subject hierarchies.
  • When running outside of the cluster (polling events via HTTP), wildcards can not be used. In this case, each specific topic must be included in the list.

• PUBSUB_RECIPIENT - Hostname of the execution plane service to which the distributor should forward incoming CloudEvents. default = http://127.0.0.1

• PUBSUB_RECIPIENT_PORT - Port of the execution plane service to which the distributor should forward incoming CloudEvents. default = 8080

• PUBSUB_RECIPIENT_PATH - Path of the execution plane service to which the distributor should forward incoming CloudEvents. default = /

• PUBSUB_GROUP - Used to join a group for receiving messages from the message broker. Note that only one instance of a distributor in a set of distributors having the same PUBSUB_GROUP are able to receive the event. default = ""

The following environment variables filter events:

• PROJECT_FILTER - Filter events for a specific project. default = "", supports a comma-separated list of projects.
• STAGE_FILTER - Filter events for a specific stage. default = "", supports a comma-separated list of stages.
• SERVICE_FILTER - Filter events for a specific service. default = "", supports a comma-separated list of services.

The following

• DISABLE_REGISTRATION - Disables automatic registration of the Keptn integration to the control plane. default = false
• REGISTRATION_INTERVAL - Time duration between trying to re-register to the Keptn control plane. default =10s
• LOCATION - Location on which the distributor is running, e.g. “executionPlane-A”. default = ""
• DISTRIBUTOR_VERSION - The software version of the distributor. default = ""
• VERSION - The version of the Keptn integration. default = ""
• K8S_DEPLOYMENT_NAME - Kubernetes deployment name of the Keptn integration. default = ""
• K8S_POD_NAME - Kubernetes deployment name of the Keptn integration. default = ""
• K8S_NAMESPACE - Kubernetes namespace of the Keptn integration. default = ""
• K8S_NODE_NAME - Kubernetes node name the Keptn integration is running on. default = ""
• OAUTH_CLIENT_ID - OAuth client ID used when performing Oauth Client Credentials Flow. default = ""
• OAUTH_CLIENT_SECRET - OAuth client ID used when performing Oauth Client Credentials Flow. default = ""
• OAUTH_DISCOVERY - Discovery URL called by the distributor to obtain further information for the OAuth Client Credentials Flow, e.g. the token URL. default = ""
• OAUTH_TOKEN_URL - Url to obtain the access token. If set, this will override OAUTH_DISCOVERY meaning, that no discovery will happen. default = ""
• OAUTH_SCOPES - Comma separated list of tokens to be used during the OAuth Client Credentials Flow. =""

All cloud events specified in PUBSUB_TOPIC that match the filters are forwarded to http://{PUBSUB_RECIPIENT}:{PUBSUB_RECIPIENT_PORT}{PUBSUB_RECIPIENT_PATH}, e.g.: http://helm-service:8080.

Usage notes

Configuration examples

The above list of environment variables is pretty long, but in most scenarios only a few of them have to be set. The following examples show how to set the environment variables properly, depending on where the distributor and it’s accompanying execution plane service should run:

Configuring the distributor when running within the Keptn cluster

In this case, usually only the PUBSUB_TOPIC must be defined, e.g.:

PUBSUB_TOPIC: "sh.keptn.event.approval.triggered"

This is not necessary if the distributor is used only as a proxy for the Keptn API and not needed for subscribing to any topic.

This forwards all incoming events of that topic to http://127.0.0.1:8080 which is the URL of the execution plane service running in the same pod as the distributor. If the execution plane service has a different hostname (e.g., when not running in the same pod), a different port, or listens for events on a different path, the env vars PUBSUB_RECIPIENT, PUBSUB_RECIPIENT_PORT and PUBSUB_RECIPIENT_PATH can be set to change this default URL, e.g.:

PUBSUB_RECIPIENT: "http://my-service
PUBSUB_RECIPIENT_PORT: "9000"
PUBSUB_RECIPIENT_PATH: "/event-path

This causes the distributor to forward all incoming events for its subscribed topic to http://my-service:9000/event-path.

The execution plane service can then access the distributor’s Keptn API proxy at http://localhost:8081/, and can forward events by sending them to http://localhost:8081/event. The Keptn API services are then reachable for the execution plane service via the following URLs:

• Mongodb-datastore:

  • http://localhost:8081/mongodb-datastore

• Configuration-service:

  • http://localhost:8081/configuration-service

• Shipyard-controller:

  • http://localhost:8081/controlPlane

If the distributor should listen on a port other than 8081 (e.g. when that port is needed by the execution plane service), a different port can be set using the API_PROXY_PORT environment variable.

Configuring the distributor when running outside of the Keptn cluster

In this case, the Keptn API URL and the API token, as well as a topic have to be defined:

KEPTN_API_ENDPOINT: "https://my-keptn-api:8080/api"
KEPTN_API_TOKEN: "my-keptn-api-token"
PUBSUB_TOPIC: "sh.keptn.event.approval.triggered" # can be left empty if the distributor is only used as a proxy to interact with the Keptn API

If the endpoint specified by KEPTN_API_ENDPOINT does not provide a valid SSL certificate, by default, the distributor denies any requests to that endpoint. This behavior can be changed by setting the variable HTTP_SSL_VERIFY to false.

The remaining parameters, such as PUBSUB_RECIPIENT, PUBSUB_RECIPIENT_PORT and PUBSUB_RECIPIENT_PATH, as well as the API_PROXY_PORT can be configured as described above.

Installation

Distributors are installed automatically as a part of Keptn.

Deploy in your Kubernetes cluster

To deploy the current version of a distributor in your Keptn Kubernetes cluster, use the file deploy/distributor.yaml from this repository and apply it:

kubectl apply -f deploy/service.yaml

Delete in your Kubernetes cluster

To delete a deployed distributor, use the file deploy/distributor.yaml from this repository and delete the Kubernetes resources:

kubectl delete -f deploy/service.yaml

Usage notes

Differences between versions

• In Keptn Release 0.14.x, the NATS dependency is upgraded. Because of this, the NATS cluster name is now keptn-nats rather than keptn-nats-cluster as used in earlier releases. This causes a crashloop for any Keptn service that is not using the 0.14.x distributor. If you cannot update your distributor to 0.14.x, you may be able to run your existing distributor by setting the PUBSUB_URLenvironment variable to nats://keptn-nats. See the Keptn.0.14.1 Release Announcement for details.

See also

• distributor
• Write a Keptn-service