osm install --pre-check command

[michelleN]

to make sure all systems are go before running install command

[asridharan]

@michelleN could you give a sense of the dependencies we are looking at here to verify in the pre-flight check?

[michelleN]

Verification should include:
-- can query the Kubernetes API
-- running the minimum Kubernetes API version
-- control plane namespace does not already exist (we should talk about this one)
-- Can create non-namespaced resources: CRDs, namespaces, ClusterRole, ClusterRoleBinding, MutatingWebhookConfiguration)
-- can create ServiceAccounts, Services, Deployments, ConfigMaps, Secrets
-- can read Secrets
-- has ability to modify IP tables rules

[nojnhuh]

Here's what I've found other service meshes are doing.

linkerd

$ linkerd check --pre
kubernetes-api
--------------
√ can initialize the client
√ can query the Kubernetes API

kubernetes-version
------------------
√ is running the minimum Kubernetes API version
√ is running the minimum kubectl version

pre-kubernetes-setup
--------------------
√ control plane namespace does not already exist
√ can create non-namespaced resources
√ can create ServiceAccounts
√ can create Services
√ can create Deployments
√ can create CronJobs
√ can create ConfigMaps
√ can create Secrets
√ can read Secrets
√ can read extension-apiserver-authentication configmap
√ no clock skew detected

pre-kubernetes-capability
-------------------------
√ has NET_ADMIN capability
√ has NET_RAW capability

linkerd-version
---------------
√ can determine the latest version
√ cli is up-to-date

Status check results are √

Istio

$ istioctl experimental precheck

Checking the cluster to make sure it is ready for Istio installation...

#1. Kubernetes-api
-----------------------
Can initialize the Kubernetes client.
Can query the Kubernetes API Server.

#2. Kubernetes-version
-----------------------
Istio is compatible with Kubernetes: v1.18.2.

#3. Istio-existence
-----------------------
Istio will be installed in the istio-system namespace.

#4. Kubernetes-setup
-----------------------
Can create necessary Kubernetes configurations: Namespace,ClusterRole,ClusterRoleBinding,CustomResourceDefinition,Role,ServiceAccount,Service,Deployments,ConfigMap. 

#5. SideCar-Injector
-----------------------
This Kubernetes cluster supports automatic sidecar injection. To enable automatic sidecar injection see https://istio.io/docs/setup/kubernetes/additional-setup/sidecar-injection/#deploying-an-app

-----------------------
Install Pre-Check passed! The cluster is ready for Istio installation.