Add readme for web provider
Also rename sample web provider implemented in Rust to `web-rust`.
This commit is contained in:
Rajasekharan Vengalil
157
providers/web/README.md
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157
providers/web/README.md
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Web provider for Virtual Kubelet
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================================
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Virtual Kubelet providers are written using the Go programming language. While
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Go is a great general purpose programming language, it is however a fact that
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other programming languages exist. The problem that Virtual Kubelet solves is as
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applicable to applications written in those languages as it is for those written
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using Go. This provider aims to serve as a bridge between technology stacks and
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programming languages, as it were, by adapting the Virtual Kubelet provider
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interface using a web endpoint, i.e., this provider is a thin layer that
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forwards all calls that Kubernetes makes to the virtual kubelet to a
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pre-configured HTTP endpoint. This frees the provider's implementor to write
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their code in any programming language and technology stack as they see fit.
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The `providers/web/web-rust` folder contains a sample provider implemented in
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the Rust programming language. Here's a diagram that depicts the interaction
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between Kubernetes, the virtual kubelet web provider and the Rust app.
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+----------------+ +---------------------------+ +------------------------------+
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| | | | HTTP | |
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| Kubernetes | <-----> | Virtual Kubelet: Web | <------> | Provider written in Rust |
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| | | | | |
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+----------------+ +---------------------------+ +------------------------------+
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Provider interface
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------------------
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The web provider uses an environment variable to determine the endpoint to use
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for forwarding requests. The environment variable must be named
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`WEB_ENDPOINT_URL` and must implement the following HTTP API:
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| Path | Verb | Query | Request | Response | Description |
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|-------------------|--------|-----------------------------------------|----------|---------------------------------------------------|---------------------------------------------------------------------------|
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| /createPod | POST | - | Pod JSON | HTTP status code | Create a new pod |
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| /updatePod | PUT | - | Pod JSON | HTTP status code | Update pod spec |
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| /deletePod | DELETE | - | Pod JSON | HTTP status code | Delete an existing pod |
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| /getPod | GET | namespace, name | - | Pod JSON | Given a pod namespace and name, return the pod JSON |
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| /getContainerLogs | GET | namespace, podName, containerName, tail | - | Container logs | Given the namespace, pod name and container name, return `tail` log lines |
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| /getPodStatus | GET | namespace, name | - | Pod status JSON | Given a pod namespace and name, return the pod's status JSON |
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| /getPods | GET | - | - | Array of pod JSON strings | Fetch list of created pods |
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| /capacity | GET | - | - | JSON map containing resource name and values | Fetch resource capacity values |
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| /nodeConditions | GET | - | - | Array of node condition JSON strings | Get list of node conditions (Ready, OutOfDisk etc) |
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| /nodeAddresses | GET | - | - | Array of node address values (type/address pairs) | Fetch a list of addresses for the node status |
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A typical deployment configuration for this setup would be to have the provider
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implementation be deployed as a container in the same pod as the virtual kubelet
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itself (as a "sidecar").
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Take her for a spin
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-------------------
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A sample web provider implementation is included in this repo in order to
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showcase what this enables. The sample has been implemented in
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[Rust](http://rust-lang.org). The easiest way to get this up and running is
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to use the Helm chart available at `providers/web/charts/web-rust`. Open a
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terminal and install the chart like so:
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$ cd providers/web/charts
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$ helm install -n web-provider ./web-rust
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$ kubectl get pods
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NAME READY STATUS RESTARTS AGE
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web-provider-virtual-kubelet-web-6b5b7446f6-279xl 2/2 Running 0 3h
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If you list the nodes in the cluster after this you should see something that
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looks like this:
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$ kubectl get nodes
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NAME STATUS ROLES AGE VERSION
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aks-nodepool1-35187879-0 Ready agent 37d v1.8.2
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aks-nodepool1-35187879-1 Ready agent 37d v1.8.2
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aks-nodepool1-35187879-3 Ready agent 37d v1.8.2
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virtual-kubelet-web Ready agent 3h v1.8.3
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In case the name of the node didn't give it away, the last entry in the output
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above is the virtual kubelet. If you try to list the containers in the pod that
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represents the virtual kubelet you should be able to see the sidecar Rust
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container:
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$ kubectl get pods -o=custom-columns=NAME:.metadata.name,CONTAINERS:.spec.containers[*].name
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NAME CONTAINERS
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web-provider-virtual-kubelet-web-6b5b7446f6-279xl webrust,virtualkubelet
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In the output above, `webrust` is the sidecar container and `virtualkubelet` is
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the broker that forwards requests to `webrust`. You can run a query on the
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`/getPods` HTTP endpoint on the `webrust` container to see a list of the pods
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that it has been asked to create. To do this we first use `kubectl` to setup a
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port forwarding server like so:
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$ kubectl port-forward web-provider-virtual-kubelet-web-6b5b7446f6-279xl 3000:3000
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Now if we run `curl` on the `http://localhost:3000/getPods` URL you should see
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the pod JSON getting dumped to the terminal. I ran my test on a Kubernetes
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cluster deployed on [Azure](https://docs.microsoft.com/en-us/azure/aks/) which
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happens to deploy a daemonset with some, what I imagine are "system" pods to
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every node in the cluster. You can filter the output to see just the pod names
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using the [jq](https://stedolan.github.io/jq/) tool like so:
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$ curl -s http://localhost:3000/getPods | jq '.[] | { name: .metadata.name }'
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{
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"name": "kube-proxy-czz57"
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}
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{
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"name": "kube-svc-redirect-7qlpd"
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}
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You can deploy workloads to the virtual kubelet as you normally do. Here's a
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sample pod spec that uses `nodeSelector` to cause the deployment to be scheduled
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on the virtual kubelet.
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apiVersion: v1
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kind: Pod
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metadata:
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name: vk-pod
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labels:
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foo: bar
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spec:
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containers:
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- name: web1
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image: nginx
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nodeSelector:
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type: virtual-kubelet
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Let's go ahead and deploy the pod and run our `/getPods` query again:
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$ kubectl apply -f ~/tmp/pod1.yaml
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pod "vk-pod" created
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$ curl -s http://localhost:3000/getPods | jq '.[] | { name: .metadata.name }'
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{
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"name": "kube-proxy-czz57"
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}
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{
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"name": "kube-svc-redirect-7qlpd"
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}
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{
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"name": "vk-pod"
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}
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$ kubectl get pods
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NAME READY STATUS RESTARTS AGE
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vk-pod 0/1 Running 0 1m
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web-provider-virtual-kubelet-web-6b5b7446f6-279xl 2/2 Running 6 4h
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As you can tell, a new pod has been scheduled to run on our virtual kubelet
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instance. Deleting pods works as one would expect:
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$ kubectl delete -f ~/tmp/pod1.yaml
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pod "vk-pod" deleted
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$ curl -s http://localhost:3000/getPods | jq '.[] | { name: .metadata.name }'
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{
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"name": "kube-proxy-czz57"
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}
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{
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"name": "kube-svc-redirect-7qlpd"
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}
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@@ -19,7 +19,7 @@ spec:
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release: {{ .Release.Name }}
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spec:
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containers:
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- name: rustwebprovider
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- name: webrust
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image: "{{ .Values.rustwebimage.repository }}:{{ .Values.rustwebimage.tag }}"
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imagePullPolicy: {{ .Values.rustwebimage.pullPolicy }}
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ports:
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@@ -1,5 +1,5 @@
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rustwebimage:
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repository: avranju/rust-web-provider
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repository: avranju/web-rust
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tag: latest
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pullPolicy: Always
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port: 3000
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@@ -1,9 +0,0 @@
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FROM debian:stretch-slim
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WORKDIR /app
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ADD ./rust-web-provider /app/rust-web-provider
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ENV RUST_LOG=info
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EXPOSE 3000
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ENTRYPOINT [ "/app/rust-web-provider" ]
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@@ -558,17 +558,6 @@ dependencies = [
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"url 1.6.0 (registry+https://github.com/rust-lang/crates.io-index)",
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]
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[[package]]
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name = "rust-web-provider"
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version = "0.1.0"
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dependencies = [
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"env_logger 0.4.3 (registry+https://github.com/rust-lang/crates.io-index)",
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"kube_rust 1.0.0 (git+https://github.com/avranju/kube-rust?rev=058de6366d0d75cb60b2d0fd5ba1abd2e7d83fff)",
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"log 0.4.1 (registry+https://github.com/rust-lang/crates.io-index)",
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"time 0.1.38 (registry+https://github.com/rust-lang/crates.io-index)",
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"virtual-kubelet-adapter 0.1.0 (git+https://github.com/avranju/rust-virtual-kubelet-adapter?rev=4250103d31e2864725e47bdd23295e79ee12b6d0)",
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]
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[[package]]
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name = "rustc-serialize"
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version = "0.3.24"
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@@ -852,6 +841,17 @@ name = "void"
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version = "1.0.2"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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[[package]]
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name = "web-rust"
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version = "0.1.0"
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dependencies = [
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"env_logger 0.4.3 (registry+https://github.com/rust-lang/crates.io-index)",
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"kube_rust 1.0.0 (git+https://github.com/avranju/kube-rust?rev=058de6366d0d75cb60b2d0fd5ba1abd2e7d83fff)",
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"log 0.4.1 (registry+https://github.com/rust-lang/crates.io-index)",
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"time 0.1.38 (registry+https://github.com/rust-lang/crates.io-index)",
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"virtual-kubelet-adapter 0.1.0 (git+https://github.com/avranju/rust-virtual-kubelet-adapter?rev=4250103d31e2864725e47bdd23295e79ee12b6d0)",
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]
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[[package]]
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name = "winapi"
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version = "0.2.8"
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@@ -1,5 +1,5 @@
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[package]
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name = "rust-web-provider"
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name = "web-rust"
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version = "0.1.0"
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authors = ["Rajasekharan Vengalil <rajave@microsoft.com>"]
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9
providers/web/web-rust/Dockerfile
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9
providers/web/web-rust/Dockerfile
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FROM debian:stretch-slim
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WORKDIR /app
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ADD ./web-rust /app/web-rust
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ENV RUST_LOG=info
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EXPOSE 3000
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ENTRYPOINT [ "/app/web-rust" ]
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@@ -6,8 +6,8 @@ SCRIPT_NAME=$(basename "$0")
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DIR=$(cd "$(dirname "$0")" && pwd)
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ROOT_FOLDER="$DIR/.."
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PUBLISH_DIR=$ROOT_FOLDER/target/publish
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TARGET_NAME=rust-web-provider
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IMAGE_NAME=rust-web-provider
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TARGET_NAME=web-rust
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IMAGE_NAME=web-rust
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IMAGE_VERSION=latest
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BUILD_RELEASE=true
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SOURCE_RELEASE_DIR=$ROOT_FOLDER/target/release
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@@ -20,7 +20,7 @@ usage()
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echo "Note: You might have to run this as root or sudo."
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echo ""
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echo "options"
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echo " -i, --image-name Image name (default: rust-web-provider)"
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echo " -i, --image-name Image name (default: web-rust)"
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echo " -v, --image-version Docker Image Version (default: latest)"
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echo " -r, --build-release Build release configuration - true|false (default: true)"
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exit 1;
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@@ -74,7 +74,7 @@ impl Provider for UnitProvider {
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info!("Getting pod: {}", name);
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self.pods_map
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.get(name)
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.filter(|pod| {
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.xfilter(|pod| {
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let empty = String::from("");
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let ns = pod.metadata()
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.map(|m| m.namespace())
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@@ -1,9 +1,9 @@
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pub trait Filter<T> {
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fn filter<P: FnOnce(&T) -> bool>(self, predicate: P) -> Self;
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fn xfilter<P: FnOnce(&T) -> bool>(self, predicate: P) -> Self;
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}
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impl<T> Filter<T> for Option<T> {
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fn filter<P: FnOnce(&T) -> bool>(self, predicate: P) -> Self {
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fn xfilter<P: FnOnce(&T) -> bool>(self, predicate: P) -> Self {
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match self {
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Some(x) => {
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if predicate(&x) {
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