NB this is a pre-beta service. Availability is not 100%. APIs might change. Data could be lost.

Cortex is an API compatible Prometheus implementation, that natively supports multitenancy and horizontal scale-out clustering.

Cortex is a Weaveworks project that forms the monitoring backend of Weave Cloud.

Go to https://cloud.weave.works and sign up. Follow the steps to create a new instance.

Once you have created your instance, note down the 'Service Token' listed underneath 'Probes' in the box on the right of the screen. You will use this token to authenticate your local Prometheus with Weave Cloud.

Install the Cortex agent (an unmodified OSS Prometheus) on your Kubernetes cluster using the following command:

$ kubectl -n kube-system apply -f 'https://cloud.weave.works/k8s/cortex.yaml?t=<token>'

Click Monitor to access the Cortex service in the Weave Cloud UI:

Weave Cloud gives you some example queries that displays general system information. You can of course write your own Prometheus queries.

To learn more about Weave Cortex, consult the follow documents / talks:

• Original design document for Project Frankenstein
• PromCon 2016 Talk: "Project Frankenstein: Multitenant, Scale-Out Prometheus": video, slides
• KubeCon Prometheus Day talk "Weave Cortex: Multi-tenant, horizontally scalable Prometheus as a Service" slides
• Or join us on our Slack channel and ask us directly!

Cortex can be used to monitor virtually any application on any platform, as the local agent is a specially configured unmodified OSS Prometheus binary. You can download Prometheus from its website. You will need v1.2.1 or later.

When you've got Prometheus, you will need to configure it to discover your services and configure it to send its data to Weave Cloud by adding the following top-level stanza to prometheus.yml:

remote_write:
  url: https://cloud.weave.works/api/prom/push
  basic_auth:
    password: <token>

Where <token> is the Service Token you obtained from Weave Cloud.

Once your local Prometheus is running you can enter Prometheus queries into Weave Cloud. Go to https://cloud.weave.works and click Monitor from Weave Cloud header:

To use the Prometheus Service with Grafana, configure your Grafana instance to have a datasource with the following parameters:

• Type: Prometheus
• Url: https://cloud.weave.works/api/prom
• Access: Direct
• Http Auth: Basic Auth
• User: user (this is ignored, but must be non-empty)
• Password: (the same one your retrieval agent uses)

To build & test, install minikube, and run:

eval $(minikube docker-env)
make
kubectl create -f ./k8s

Cortex will sit behind an nginx instance exposed on port 30080. A job is deployed to scrape it itself. Try it:

http://192.168.99.100:30080/api/prom/api/v1/query?query=up

If you have any questions regarding Cortex our hosted Prometheus as a service:

• Invite yourself to the #weave-community slack channel.
• Ask a question on the #weave-community slack channel.
• Join the Weave User Group and get invited to online talks, hands-on training and meetups in your area.
• Send an email to [email protected]
• File an issue.

Your feedback is always welcome!