Doc for configuration spot instances (oap-project#638)

* Add documentation for configuring spot instances

* Add quick guide as to the cluster key in quick start

* Add instruction to genetate ssh key pair

README.md

@@ -173,6 +173,16 @@ auth:
     ssh_proxy_command: "ncat --proxy-type socks5 --proxy <your_proxy_host>:<your_proxy_port> %h %p"
 ```
 
+The cluster key will be created automatically for AWS and GCP if not specified.
+For Azure, you need to generate an RSA key pair manually (use `ssh-keygen -t rsa -b 4096` to generate a new ssh key pair).
+and configure the public and private key as following,
+
+```
+auth:
+    ssh_private_key: ~/.ssh/my_cluster_rsa_key
+    ssh_public_key: ~/.ssh/my_cluster_rsa_key.pub
+```
+
 Refer to `example/cluster` directory for more cluster configurations examples.
 
 ### 6. Managing clusters

docs/source/GettingStarted/quick-start.md

@@ -163,6 +163,16 @@ auth:
     ssh_proxy_command: "ncat --proxy-type socks5 --proxy <your_proxy_host>:<your_proxy_port> %h %p"
 ```
 
+The cluster key will be created automatically for AWS and GCP if not specified.
+For Azure, you need to generate an RSA key pair manually (use `ssh-keygen -t rsa -b 4096` to generate a new ssh key pair).
+and configure the public and private key as following,
+
+```
+auth:
+    ssh_private_key: ~/.ssh/my_cluster_rsa_key
+    ssh_public_key: ~/.ssh/my_cluster_rsa_key.pub
+```
+
 Refer to `example/cluster` directory for more cluster configurations examples.
 
 ### 6. Managing clusters

docs/source/UserGuide/AdvancedTasks/configuring-spot-instances.md

@@ -0,0 +1,28 @@
+# Configuring Spot Instances
+Cloud providers usually provide user an option to create spot instances.
+Spot Instances are available at a discount compared to On-Demand prices. Cloud provider may terminate a spot instance without notification due to capacity reasons.
+You can use Spot Instances for various stateless, fault-tolerant, or flexible applications such as big data, containerized workloads, CI/CD, web servers, high-performance computing (HPC), and test & development workloads.
+
+By default, CloudTik head node will be created with non-spot instance.
+And prefers spot instances for worker nodes.
+You can override worker node preference on spot instances or non-spot instances.
+
+## Disable spot instance for worker nodes
+If you want to disable spot instance for worker node, you can set prefer_spot_instance to false
+under the provider section. For example,
+
+```buildoutcfg
+
+provider:
+    prefer_spot_instance: false
+```
+
+## Prefer spot instance for worker nodes
+If you want to explicitly prefer spot instance for worker node, you can set prefer_spot_instance to true
+under the provider section. For example,
+
+```buildoutcfg
+
+provider:
+    prefer_spot_instance: true
+```

docs/source/UserGuide/advanced-tasks.rst

@@ -11,3 +11,4 @@ Advanced Tasks
    AdvancedTasks/using-for-on-premise.md
    AdvancedTasks/understanding-cluster-key.md
    AdvancedTasks/switching-client-machine.md
+   AdvancedTasks/configuring-spot-instances.md

docs/source/UserGuide/creating-cluster.md

@@ -120,6 +120,22 @@ under the cloudtik pip installation.
 For more details as to templates, please refer to [Advanced Tasks: Using Templates](./AdvancedTasks/using-templates.md)
 
 
+## Configuring Cluster Key
+If you don't specify cluster key information under auth section of configuration file,
+The cluster key will be created automatically for AWS and GCP.
+For Azure, you need to generate an RSA key pair manually (use `ssh-keygen -t rsa -b 4096` to generate a new ssh key pair).
+and configure the public and private key as following,
+
+```
+auth:
+    ssh_private_key: ~/.ssh/my_cluster_rsa_key
+    ssh_public_key: ~/.ssh/my_cluster_rsa_key.pub
+```
+
+For more details as to cluster key configuration, refer to [Advanced Tasks: Understanding Cluster Key](./AdvancedTasks/understanding-cluster-key.md)
+
+## Starting the cluster
+
 Once the cluster configuration is defined and CloudTik is installed, you can use the following commands to create a cluster with CloudTik
 
 ```