mirror of
https://github.com/puppetmaster/typhoon.git
synced 2024-12-27 05:19:34 +01:00
d9c7a9e049
* Original tutorials favored including the platform (e.g. google-cloud) in modules (e.g. google-cloud-yavin). Prefer naming conventions where each module / cluster has a simple name (e.g. yavin) since the platform is usually redundant * Retain the example cluster naming themes per platform
117 lines
4.1 KiB
Markdown
117 lines
4.1 KiB
Markdown
# Concepts
|
|
|
|
Let's cover the concepts you'll need to get started.
|
|
|
|
## Kubernetes
|
|
|
|
[Kubernetes](https://kubernetes.io/) is an open-source cluster system for deploying, scaling, and managing containerized applications across a pool of compute nodes (bare-metal, droplets, instances).
|
|
|
|
#### Nodes
|
|
|
|
All cluster nodes provision themselves from a declarative configuration upfront. Nodes run a `kubelet` service and register themselves with the control plane to join the cluster. All nodes run `kube-proxy` and `calico` or `flannel` pods.
|
|
|
|
#### Controllers
|
|
|
|
Controller nodes are scheduled to run the Kubernetes `apiserver`, `scheduler`, `controller-manager`, `coredns`, and `kube-proxy`. A fully qualified domain name (e.g. cluster_name.domain.com) resolving to a network load balancer or round-robin DNS (depends on platform) is used to refer to the control plane.
|
|
|
|
#### Workers
|
|
|
|
Worker nodes register with the control plane and run application workloads.
|
|
|
|
## Terraform
|
|
|
|
Terraform config files declare *resources* that Terraform should manage. Resources include infrastructure components created through a *provider* API (e.g. Compute instances, DNS records) or local assets like TLS certificates and config files.
|
|
|
|
```tf
|
|
# Declare an instance
|
|
resource "google_compute_instance" "pet" {
|
|
# ...
|
|
}
|
|
```
|
|
|
|
The `terraform` tool parses configs, reconciles the desired state with actual state, and updates resources to reach desired state.
|
|
|
|
```sh
|
|
$ terraform plan
|
|
Plan: 4 to add, 0 to change, 0 to destroy.
|
|
$ terraform apply
|
|
Apply complete! Resources: 4 added, 0 changed, 0 destroyed.
|
|
```
|
|
|
|
With Typhoon, you'll be able to manage clusters with Terraform.
|
|
|
|
### Modules
|
|
|
|
Terraform [modules](https://www.terraform.io/docs/modules/usage.html) allow a collection of resources to be configured and managed together. Typhoon provides a Kubernetes cluster Terraform *module* for each [supported](/#modules) platform and operating system.
|
|
|
|
Clusters are declared in Terraform by referencing the module.
|
|
|
|
```tf
|
|
module "yavin" {
|
|
source = "git::https://github.com/poseidon/typhoon//google-cloud/container-linux/kubernetes"
|
|
cluster_name = "yavin"
|
|
...
|
|
}
|
|
```
|
|
|
|
### Versioning
|
|
|
|
Modules are updated regularly, set the version to a [release tag](https://github.com/poseidon/typhoon/releases) or [commit](https://github.com/poseidon/typhoon/commits/master) hash.
|
|
|
|
```tf
|
|
...
|
|
source = "git:https://github.com/poseidon/typhoon//google-cloud/container-linux/kubernetes?ref=hash"
|
|
```
|
|
|
|
Module versioning ensures `terraform get --update` only fetches the desired version, so plan and apply don't change cluster resources, unless the version is altered.
|
|
|
|
### Organize
|
|
|
|
Maintain Terraform configs for "live" infrastructure in a versioned repository. Seek to organize configs to reflect resources that should be managed together in a `terraform apply` invocation.
|
|
|
|
You may choose to organize resources all together, by team, by project, or some other scheme. Here's an example that manages clusters together:
|
|
|
|
```sh
|
|
.git/
|
|
infra/
|
|
└── terraform
|
|
└── clusters
|
|
├── aws-tempest.tf
|
|
├── azure-ramius.tf
|
|
├── bare-metal-mercury.tf
|
|
├── google-cloud-yavin.tf
|
|
├── digital-ocean-nemo.tf
|
|
├── providers.tf
|
|
├── terraform.tfvars
|
|
└── remote-backend.tf
|
|
```
|
|
|
|
By convention, `providers.tf` registers provider APIs, `terraform.tfvars` stores shared values, and state is written to a remote backend.
|
|
|
|
### State
|
|
|
|
Terraform syncs its state with provider APIs to plan changes to reconcile to the desired state. By default, Terraform writes state data (including secrets!) to a `terraform.tfstate` file. **At a minimum**, add a `.gitignore` file (or equivalent) to prevent state from being committed to your infrastructure repository.
|
|
|
|
```
|
|
# .gitignore
|
|
*.tfstate
|
|
*.tfstate.backup
|
|
.terraform/
|
|
```
|
|
|
|
### Remote Backend
|
|
|
|
Later, you may wish to checkout Terraform [remote backends](https://www.terraform.io/intro/getting-started/remote.html) which store state in a remote bucket like Google Storage or S3.
|
|
|
|
```
|
|
terraform {
|
|
backend "gcs" {
|
|
credentials = "/path/to/credentials.json"
|
|
project = "project-id"
|
|
bucket = "bucket-id"
|
|
path = "metal.tfstate"
|
|
}
|
|
}
|
|
```
|
|
|