# Kubernetes on Openstack with Terraform Provision a Kubernetes cluster with [Terraform](https://www.terraform.io) on Openstack. ## Status This will install a Kubernetes cluster on an Openstack Cloud. It should work on most modern installs of OpenStack that support the basic services. ## Approach The terraform configuration inspects variables found in [variables.tf](variables.tf) to create resources in your OpenStack cluster. There is a [python script](../terraform.py) that reads the generated`.tfstate` file to generate a dynamic inventory that is consumed by the main ansible script to actually install kubernetes and stand up the cluster. ### Networking The configuration includes creating a private subnet with a router to the external net. It will allocate floating IPs from a pool and assign them to the hosts where that makes sense. You have the option of creating bastion hosts inside the private subnet to access the nodes there. Alternatively, a node with a floating IP can be used as a jump host to nodes without. ### Kubernetes Nodes You can create many different kubernetes topologies by setting the number of different classes of hosts. For each class there are options for allocating floating IP addresses or not. - Master nodes with etcd - Master nodes without etcd - Standalone etcd hosts - Kubernetes worker nodes Note that the Ansible script will report an invalid configuration if you wind up with an even number of etcd instances since that is not a valid configuration. ### GlusterFS The Terraform configuration supports provisioning of an optional GlusterFS shared file system based on a separate set of VMs. To enable this, you need to specify: - the number of Gluster hosts (minimum 2) - Size of the non-ephemeral volumes to be attached to store the GlusterFS bricks - Other properties related to provisioning the hosts Even if you are using Container Linux by CoreOS for your cluster, you will still need the GlusterFS VMs to be based on either Debian or RedHat based images. Container Linux by CoreOS cannot serve GlusterFS, but can connect to it through binaries available on hyperkube v1.4.3_coreos.0 or higher. ## Requirements - [Install Terraform](https://www.terraform.io/intro/getting-started/install.html) - [Install Ansible](http://docs.ansible.com/ansible/latest/intro_installation.html) - you already have a suitable OS image in Glance - you already have a floating IP pool created - you have security groups enabled - you have a pair of keys generated that can be used to secure the new hosts ## Module Architecture The configuration is divided into three modules: - Network - IPs - Compute The main reason for splitting the configuration up in this way is to easily accommodate situations where floating IPs are limited by a quota or if you have any external references to the floating IP (e.g. DNS) that would otherwise have to be updated. You can force your existing IPs by modifying the compute variables in `kubespray.tf` as follows: ``` k8s_master_fips = ["151.101.129.67"] k8s_node_fips = ["151.101.129.68"] ``` ## Terraform Terraform will be used to provision all of the OpenStack resources with base software as appropriate. ### Configuration #### Inventory files Create an inventory directory for your cluster by copying the existing sample and linking the `hosts` script (used to build the inventory based on Terraform state): ```ShellSession $ cp -LRp contrib/terraform/openstack/sample-inventory inventory/$CLUSTER $ ln -s contrib/terraform/openstack/hosts inventory/$CLUSTER/ $ cd inventory/$CLUSTER ``` This will be the base for subsequent Terraform commands. #### OpenStack access and credentials No provider variables are hardcoded inside `variables.tf` because Terraform supports various authentication methods for OpenStack: the older script and environment method (using `openrc`) as well as a newer declarative method, and different OpenStack environments may support Identity API version 2 or 3. These are examples and may vary depending on your OpenStack cloud provider, for an exhaustive list on how to authenticate on OpenStack with Terraform please read the [OpenStack provider documentation](https://www.terraform.io/docs/providers/openstack/). ##### Declarative method (recommended) The recommended authentication method is to describe credentials in a YAML file `clouds.yaml` that can be stored in: * the current directory * `~/.config/openstack` * `/etc/openstack` `clouds.yaml`: ``` clouds: mycloud: auth: auth_url: https://openstack:5000/v3 username: "username" project_name: "projectname" project_id: projectid user_domain_name: "Default" password: "password" region_name: "RegionOne" interface: "public" identity_api_version: 3 ``` If you have multiple clouds defined in your `clouds.yaml` file you can choose the one you want to use with the environment variable `OS_CLOUD`: ``` export OS_CLOUD=mycloud ``` ##### Openrc method (deprecated) When using classic environment variables, Terraform uses default `OS_*` environment variables: With identity v2: ``` source openrc env | grep OS OS_AUTH_URL=https://openstack:5000/v2.0 OS_PROJECT_ID=projectid OS_PROJECT_NAME=projectname OS_USERNAME=username OS_PASSWORD=password OS_REGION_NAME=RegionOne OS_INTERFACE=public OS_IDENTITY_API_VERSION=2 ``` With identity v3 : ``` source openrc env | grep OS OS_AUTH_URL=https://openstack:5000/v3 OS_PROJECT_ID=projectid OS_PROJECT_NAME=username OS_PROJECT_DOMAIN_ID=default OS_USERNAME=username OS_PASSWORD=password OS_REGION_NAME=RegionOne OS_INTERFACE=public OS_IDENTITY_API_VERSION=3 OS_USER_DOMAIN_NAME=Default ``` Terraform does not support a mix of DomainName and DomainID, choose one or the other: ``` * provider.openstack: You must provide exactly one of DomainID or DomainName to authenticate by Username ``` ``` unset OS_USER_DOMAIN_NAME export OS_USER_DOMAIN_ID=default or unset OS_PROJECT_DOMAIN_ID set OS_PROJECT_DOMAIN_NAME=Default ``` #### Cluster variables The construction of the cluster is driven by values found in [variables.tf](variables.tf). For your cluster, edit `inventory/$CLUSTER/cluster.tf`. |Variable | Description | |---------|-------------| |`cluster_name` | All OpenStack resources will use the Terraform variable`cluster_name` (default`example`) in their name to make it easier to track. For example the first compute resource will be named`example-kubernetes-1`. | |`network_name` | The name to be given to the internal network that will be generated | |`dns_nameservers`| An array of DNS name server names to be used by hosts in the internal subnet. | |`floatingip_pool` | Name of the pool from which floating IPs will be allocated | |`external_net` | UUID of the external network that will be routed to | |`flavor_k8s_master`,`flavor_k8s_node`,`flavor_etcd`, `flavor_bastion`,`flavor_gfs_node` | Flavor depends on your openstack installation, you can get available flavor IDs through`nova flavor-list` | |`image`,`image_gfs` | Name of the image to use in provisioning the compute resources. Should already be loaded into glance. | |`ssh_user`,`ssh_user_gfs` | The username to ssh into the image with. This usually depends on the image you have selected | |`public_key_path` | Path on your local workstation to the public key file you wish to use in creating the key pairs | |`number_of_k8s_masters`, `number_of_k8s_masters_no_floating_ip` | Number of nodes that serve as both master and etcd. These can be provisioned with or without floating IP addresses| |`number_of_k8s_masters_no_etcd`, `number_of_k8s_masters_no_floating_ip_no_etcd` | Number of nodes that serve as just master with no etcd. These can be provisioned with or without floating IP addresses | |`number_of_etcd` | Number of pure etcd nodes | |`number_of_k8s_nodes`, `number_of_k8s_nodes_no_floating_ip` | Kubernetes worker nodes. These can be provisioned with or without floating ip addresses. | |`number_of_bastions` | Number of bastion hosts to create. Scripts assume this is really just zero or one | |`number_of_gfs_nodes_no_floating_ip` | Number of gluster servers to provision. | | `gfs_volume_size_in_gb` | Size of the non-ephemeral volumes to be attached to store the GlusterFS bricks | #### Terraform state files In the cluster's inventory folder, the following files might be created (either by Terraform or manually), to prevent you from pushing them accidentally they are in a `.gitignore` file in the `terraform/openstack` directory : * `.terraform` * `.tfvars` * `.tfstate` * `.tfstate.backup` You can still add them manually if you want to. ### Initialization Before Terraform can operate on your cluster you need to install the required plugins. This is accomplished as follows: ```ShellSession $ cd inventory/$CLUSTER $ terraform init contrib/terraform/openstack ``` This should finish fairly quickly telling you Terraform has successfully initialized and loaded necessary modules. ### Provisioning cluster You can apply the Terraform configuration to your cluster with the following command issued from your cluster's inventory directory (`inventory/$CLUSTER`): ```ShellSession $ terraform apply -var-file=cluster.tf ../../contrib/terraform/openstack ``` if you chose to create a bastion host, this script will create `contrib/terraform/openstack/k8s-cluster.yml` with an ssh command for Ansible to be able to access your machines tunneling through the bastion's IP address. If you want to manually handle the ssh tunneling to these machines, please delete or move that file. If you want to use this, just leave it there, as ansible will pick it up automatically. ### Destroying cluster You can destroy your new cluster with the following command issued from the cluster's inventory directory: ```ShellSession $ terraform destroy -var-file=cluster.tf ../../contrib/terraform/openstack ``` ### Debugging You can enable debugging output from Terraform by setting `OS_DEBUG` to 1 and`TF_LOG` to`DEBUG` before running the Terraform command. ### Terraform output Terraform can output values that are useful for configure Neutron/Octavia LBaaS or Cinder persistent volume provisioning as part of your Kubernetes deployment: - `private_subnet_id`: the subnet where your instances are running is used for `openstack_lbaas_subnet_id` - `floating_network_id`: the network_id where the floating IP are provisioned is used for `openstack_lbaas_floating_network_id` ## Ansible ### Node access #### SSH Ensure your local ssh-agent is running and your ssh key has been added. This step is required by the terraform provisioner: ``` $ eval $(ssh-agent -s) $ ssh-add ~/.ssh/id_rsa ``` If you have deployed and destroyed a previous iteration of your cluster, you will need to clear out any stale keys from your SSH "known hosts" file ( `~/.ssh/known_hosts`). #### Bastion host If you are not using a bastion host, but not all of your nodes have floating IPs, create a file `inventory/$CLUSTER/group_vars/no-floating.yml` with the following content. Use one of your nodes with a floating IP (this should have been output at the end of the Terraform step) and the appropriate user for that OS, or if you have another jump host, use that. ``` ansible_ssh_common_args: '-o ProxyCommand="ssh -o StrictHostKeyChecking=no -W %h:%p -q USER@MASTER_IP"' ``` #### Test access Make sure you can connect to the hosts. Note that Container Linux by CoreOS will have a state `FAILED` due to Python not being present. This is okay, because Python will be installed during bootstrapping, so long as the hosts are not `UNREACHABLE`. ``` $ ansible -i inventory/$CLUSTER/hosts -m ping all example-k8s_node-1 | SUCCESS => { "changed": false, "ping": "pong" } example-etcd-1 | SUCCESS => { "changed": false, "ping": "pong" } example-k8s-master-1 | SUCCESS => { "changed": false, "ping": "pong" } ``` If it fails try to connect manually via SSH. It could be something as simple as a stale host key. ### Configure cluster variables Edit `inventory/$CLUSTER/group_vars/all.yml`: - Set variable **bootstrap_os** appropriately for your desired image: ``` # Valid bootstrap options (required): ubuntu, coreos, centos, none bootstrap_os: coreos ``` - **bin_dir**: ``` # Directory where the binaries will be installed # Default: # bin_dir: /usr/local/bin # For Container Linux by CoreOS: bin_dir: /opt/bin ``` - and **cloud_provider**: ``` cloud_provider: openstack ``` Edit `inventory/$CLUSTER/group_vars/k8s-cluster.yml`: - Set variable **kube_network_plugin** to your desired networking plugin. - **flannel** works out-of-the-box - **calico** requires [configuring OpenStack Neutron ports](/docs/openstack.md) to allow service and pod subnets ``` # Choose network plugin (calico, weave or flannel) # Can also be set to 'cloud', which lets the cloud provider setup appropriate routing kube_network_plugin: flannel ``` - Set variable **resolvconf_mode** ``` # Can be docker_dns, host_resolvconf or none # Default: # resolvconf_mode: docker_dns # For Container Linux by CoreOS: resolvconf_mode: host_resolvconf ``` ### Deploy Kubernetes ``` $ ansible-playbook --become -i inventory/$CLUSTER/hosts cluster.yml ``` This will take some time as there are many tasks to run. ## Kubernetes ### Set up kubectl 1. [Install kubectl](https://kubernetes.io/docs/tasks/tools/install-kubectl/) on your workstation 2. Add a route to the internal IP of a master node (if needed): ``` sudo route add [master-internal-ip] gw [router-ip] ``` or ``` sudo route add -net [internal-subnet]/24 gw [router-ip] ``` 3. List Kubernetes certificates & keys: ``` ssh [os-user]@[master-ip] sudo ls /etc/kubernetes/ssl/ ``` 4. Get `admin`'s certificates and keys: ``` ssh [os-user]@[master-ip] sudo cat /etc/kubernetes/ssl/admin-[cluster_name]-k8s-master-1-key.pem > admin-key.pem ssh [os-user]@[master-ip] sudo cat /etc/kubernetes/ssl/admin-[cluster_name]-k8s-master-1.pem > admin.pem ssh [os-user]@[master-ip] sudo cat /etc/kubernetes/ssl/ca.pem > ca.pem ``` 5. Configure kubectl: ```ShellSession $ kubectl config set-cluster default-cluster --server=https://[master-internal-ip]:6443 \ --certificate-authority=ca.pem $ kubectl config set-credentials default-admin \ --certificate-authority=ca.pem \ --client-key=admin-key.pem \ --client-certificate=admin.pem $ kubectl config set-context default-system --cluster=default-cluster --user=default-admin $ kubectl config use-context default-system ``` 7. Check it: ``` kubectl version ``` If you are using floating ip addresses then you may get this error: ``` Unable to connect to the server: x509: certificate is valid for 10.0.0.6, 10.0.0.6, 10.233.0.1, 127.0.0.1, not 132.249.238.25 ``` You can tell kubectl to ignore this condition by adding the `--insecure-skip-tls-verify` option. ## GlusterFS GlusterFS is not deployed by the standard`cluster.yml` playbook, see the [GlusterFS playbook documentation](../../network-storage/glusterfs/README.md) for instructions. Basically you will install Gluster as ```ShellSession $ ansible-playbook --become -i inventory/$CLUSTER/hosts ./contrib/network-storage/glusterfs/glusterfs.yml ``` ## What's next Try out your new Kubernetes cluster with the [Hello Kubernetes service](https://kubernetes.io/docs/tasks/access-application-cluster/service-access-application-cluster/).