Initial release of kubehost

By William Denniss, Van Tu and Cong Liu.

AUTHORS

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+# This is the official list of the Kubehost authors for copyright purposes.
+# This file is distinct from the CONTRIBUTORS files.
+# See the latter for an explanation.
+# Names should be added to this file as:
+# Name or Organization <email address>
+# The email address is not required for organizations.
+
+Google LLC

CONTRIBUTING.md

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+# How to Contribute
+
+We'd love to accept your patches and contributions to this project. There are
+just a few small guidelines you need to follow.
+
+## Contributor License Agreement
+
+Contributions to this project must be accompanied by a Contributor License
+Agreement. You (or your employer) retain the copyright to your contribution;
+this simply gives us permission to use and redistribute your contributions as
+part of the project. Head over to <https://cla.developers.google.com/> to see
+your current agreements on file or to sign a new one.
+
+You generally only need to submit a CLA once, so if you've already submitted one
+(even if it was for a different project), you probably don't need to do it
+again.
+
+## Code reviews
+
+All submissions, including submissions by project members, require review. We
+use GitHub pull requests for this purpose. Consult
+[GitHub Help](https://help.github.com/articles/about-pull-requests/) for more
+information on using pull requests.
+
+## Community Guidelines
+
+This project follows [Google's Open Source Community
+Guidelines](https://opensource.google.com/conduct/).

CONTRIBUTORS

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+# People who have agreed to one of the CLAs and can contribute patches.
+# The AUTHORS file lists the copyright holders; this file
+# lists people.  For example, Google employees are listed here
+# but not in AUTHORS, because Google holds the copyright.
+#
+# https://developers.google.com/open-source/cla/individual
+# https://developers.google.com/open-source/cla/corporate
+#
+# Names should be added to this file as:
+#     Name <email address>
+
+William Denniss <[email protected]>
+Van Tu <[email protected]>
+Cong Liu <[email protected]>
+

LICENSE

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README.md

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+# kubehost
+
+Kubehost helps you expose services directly on nodes of your
+Google Kubernetes Engine (GKE) cluster.
+
+The common way to expose a service and get an external IP is
+`kubectl expose <deployment> --type=LoadBalancer"`, which will expose
+your deployment on a production-grade Google Cloud Load Balancer.
+Sometimes you just want to expose a service on your VM directly, like
+during development where uptime and reliability are not as important.
+That's where Kubehost comes in.
+
+Kubehost uses existing features of GKE to expose your service directly
+onto one of the VMs in your cluster, by creating a Pod that runs on
+the VM's network and forwards traffic to your in-cluster (ClusterIP)
+service, and creating firewall rules to permit external traffic.
+While you could do this manually, Kubehost takes the toil out of
+managing this configuration by automating the necessary actions.
+
+<br>
+
+> ### :warning: For development use only
+> kubehost is NOT designed for production use! Nodes in GKE
+> are designed to be redundant, meaning they can fail.
+> When the node on which your service is exposed via kubehost fails or
+> is upgraded, your service will experience several minutes of downtime.
+> By comparison, if you use a production-grade Google Cloud Load
+> Balancer (and you have enough replicas of your Pod spread over
+> multiple nodes with properly implemented health and readiness checks)
+> then a node can fail with only minimal impact to the availability of
+> your service. At any time you can upgrade to a Google Cloud Load
+> Balancer with the `kubehost upgrade` command.
+
+## Installation
+
+`kubehost` is a bash script. To install, clone this repository and add
+it to your `$PATH`, or copy `kubehost` to your `/usr/local/bin/`.
+
+You may need to set the executable permission, i.e. `chmod +x kubehost`. 
+
+## Configuration
+
+Before using `kubehost`, you need to ensure both `gcloud` and `kubectl`
+are configured with your desired project & cluster.
+
+1. run `gcloud init` to select your account, project and region
+   containing the GKE cluster.
+2. run 
+(get-credentials)[https://cloud.google.com/sdk/gcloud/reference/container/clusters/get-credentials]
+   to configure `kubectl`.
+
+## Exposing a Deployment with kubehost
+
+1. Create your deployment like normal.
+2. Create a ClusterIP service for your deployment (this is the default
+   service type, so no need to specify any type), **on your desired
+   external port**.
+3. Run `kubehost bind ${SERVICE}`, where `${SERVICE}` is the name of
+   the Kubernetes service you created at step 2.
+
+What this does is create some "glue" in the form of a hostPort
+deployment so that your service is bound to port you specified in the
+service on your node's external IP (read "under the hood" for a longer
+technical description). It also opens the necessary GCP firewall rules.
+
+To undo, `kubehost unbind ${SERVICE}`
+
+Complete example:
+
+```bash
+kubectl run hello --image gcr.io/google-samples/hello-app:1.0 --port 8080
+kubectl expose deployment hello --port 80 --target-port 8080 --name hello-service
+kubehost bind hello-service
+```
+
+Cleanup:
+```bash
+kubehost unbind hello-service
+kubectl delete deployment hello
+kubectl delete service hello-service
+```
+
+## Switching between hostPort and a Load Balancer
+
+### Upgrading to a Load Balancer from hostPort
+
+Is your app ready for prime time? Remove the hostPort Pod "glue", and
+convert your Service into one backed by a
+[Google Cloud Load Balancer](https://cloud.google.com/load-balancing/)
+with one simple command:
+
+```bash
+kubehost upgrade ${SERVICE}
+```
+
+Where `${SERVICE}` is the name of your Cluster IP service.
+
+### Downgrading a Load Balancer to hostPort
+
+Did you already expose your service with a Load Balancer and found it's
+more than you needed?  Convert it to an internal ClusterIP service,
+and expose it on a host in one command with:
+
+```bash
+kubehost downgrade ${SERVICE}
+```
+
+Where `${SERVICE}` is the name of your Kubernetes service of type
+LoadBalancer.
+
+## Limitations
+
+* Kubehost currently works with services that have a single port. If you
+  need to expose two ports, create two ClusterIP services.
+* Kubehost is not designed for production usage, see the note above.
+* Kubehost doesn't give you a static IP. The IP address of node may
+  change which will affect your service. You can create a static IP
+  and use the [kubeIP](https://github.com/doitintl/kubeIP) operator to
+  keep it assigned through node maintenance events.
+
+## Under the Hood
+
+What Kubehost is doing when you call `bind` is creating
+a Kubernetes Deployment with a single replica of a Pod that uses
+hostPort to bind onto the host's network interface. The container in
+this Pod forwards traffic to your ClusterIP service.
+
+While you could instead change your deployment to use hostPort directly
+ we think this approach is superior, as:
+
+1. It's closer to the production Kubernetes experience where deployments
+   have a matching service to receive traffic.
+2. It's easier to switch between this and a production setup by
+   changing the Service type to LoadBalancer, and removing the hostPort
+    deployment (and vice-versa) – no need to modify your application
+   deployment.
+3. Your deployment's replica count isn't limited by available ports.