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cndi_config

metadata

The cndi_config.yaml file is the core of your CNDI project. It is a YAML file that contains all the information about your project, including the the infrastructure resources you need, the applications you want to deploy, and the Kubernetes cluster_manifests which configure your cluster.

This one file is the key to understanding CNDI, it's pretty simple, lets step through it.

This first block of config shows CNDI's metadata fields at the top.

We select a provider first, this time we are using aws, and then we select the distribution, in this instance AWS' proprietary Kubernetes engine eks. Generally most CNDI projects are Kubernetes clusters, though there can be some exceptions if the goal is to deploy some other type of infrastructure.

infrastructure

CNDI will use the provider and distribution to determine which Stack to deploy, including a group of 3 Kubernetes cluster nodes with a provided instance_type of t3.medium which specifies the hardware spec of the nodes.

project_name: my-postgres-project
cndi_version: v2
provider: aws
distribution: eks
infrastructure:
  cndi:
    nodes:
      - name: postgres-nodes
        count: 3
        instance_type: t3.medium

By running this configuration, CNDI will deploy a Kubernetes cluster with 3 nodes on EKS including some platform features, but on it's own won't do very much!

applications

The next step is to configure the applications you want to deploy. In the block below we are defining a new Application called cnpg which is a Cloud Native PostgreSQL cluster.

Applications in CNDI are provided by Helm Charts, and generally you can find their source by lookng at the index.yaml file available at the repoURL provided.

For example, if we take the repoURL from the block below and append /index.yaml to it, we can visit that file and find the element of the entries object where the key is our chart (cloudnative-pg), and the version field matches our targetRevision (0.18.0).

https://cloudnative-pg.github.io/charts/index.yaml

project_name: my-postgres-project
cndi_version: v2
provider: aws
distribution: eks
infrastructure: {...}
applications:
  cnpg:
    targetRevision: 0.18.0
    destinationNamespace: cnpg-system
    repoURL: "https://cloudnative-pg.github.io/charts"
    chart: cloudnative-pg
    values: {}

Now we're getting somewhere! This block will deploy the cloudnative-pg operator, which will now be on the lookout for a new Kubernetes manifest which requests a new PostgreSQL cluster.

This is called the "Operator Pattern". Rather than configure a database directly in the values section of the cnpg Application, we will create a cluster 'manifest' to configure it instead.

cluster_manifests

This next block of config shows the cluster_manifests section of cndi_config.yaml. It includes all of the configuration for our cluster, sometimes built-in Kubernetes-native resources and other times Custom Resources.

The 3 shown below are a Namespace, a Secret (with some CNDI magic), and the "Custom Resource" cloudnative-pg's Cluster, which the cloudnative-pg operator will watch for.

project_name: my-postgres-project
cndi_version: v2
provider: aws
distribution: eks
infrastructure: {...}
applications: {...}
cluster_manifests: 
  # keys are arbitrary and used as file names
  # eg. ./cndi/cluster_manifests/pg-namespace.yaml
  pg-namespace: # a simple Kubernetes manifest which enables the grouping of resources
    apiVersion: v1
    kind: Namespace
    metadata:
      name: cnpg

  pg-cluster: 
    apiVersion: postgresql.cnpg.io/v1
    kind: "Cluster" # the kind of custom resource that the cloudnative-pg operator will watch for
    metadata:
      name: "my-postgres-cluster"
      namespace: "cnpg"
    spec:
      replicas: 1
      storageSize: 10Gi
  
  cnpg-cluster-superuser-auth-secret: 
    # a Kubernetes Secret resource, which will hold PostgreSQL superuser credentials
    apiVersion: v1
    kind: Secret
    metadata:
      name: cnpg-cluster-superuser-auth-secret
      namespace: cnpg
    type: kubernetes.io/basic-auth
    stringData:
      # below is a CNDI 'macro' which securely encrypts these values from '.env'
      username: $cndi_on_ow.seal_secret_from_env_var(POSTGRESQL_CLUSTER_SUPERUSER)
      password: $cndi_on_ow.seal_secret_from_env_var(POSTGRESQL_PASSWORD)

tl;dr

We recommend understanding broadly how elements of your cndi_config.yaml fit in to your project, and then diving into the specifics of each element as you need to change them.

Templates are meant to provide optimal configuration in the general case right out-of-the-box, when you need to customize things you can dig deeper.