cndi

Start with a Template for a popular service and CNDI will help you deploy it on your own infrastructure, just as easily as you can sign up for a Platform as a Service.

Once your cluster is set up, manage the infrastructure and applications with ease using GitOps and Infrastructure as Code.

installation 🥁

To install CNDI we just need to download the binary and add it to our PATH. This can be done using the script below:

curl -fsSL https://raw.githubusercontent.com/polyseam/cndi/main/install.sh | sh

If you'd prefer to use Windows we have a one-liner for that too described in this short guide.

In either case once the script has finished running, the cndi binary and dependencies are installed to ~/.cndi/bin.

usage

CNDI is a tool with which to deploy GitOps enabled Kubernetes application clusters on any platform as quickly and easily as possible. The best way to understand this process is to look at it as a lifecycle.

lifecycle: init 🌱

The first step in the lifecycle is to initialize the CNDI project. Because CNDI's mechanics are based on the GitOps workflow, we should initialize a Git repository before we do anything else. The best way to do this as a GitHub user is to use the gh cli.

gh repo create cndi-example --private --clone && cd cndi-example

Now that we have a Git repository, we can initialize a new CNDI project.

We can do this in 2 different ways, either by using the interactive CLI, or by writing or forking a "cndi-config" file you got from someone else, named cndi-config.yaml or cndi-config.jsonc.

interactive mode

The best way to get started if you are new to CNDI is to use the interactive cli, so let's look at that first.

# once cndi is in your "PATH" you can run it from anywhere
cndi init --interactive

This will start an interactive cli that will ask you a series of questions, the first is to select a Template. Templates are a CNDI concept, and they can be thought of as a "blueprint" for a data stack. Once you select a Template, CNDI will ask you some general questions about your project and some template-specific questions. Then it will write out a few files inside your project repo.

non-interactive mode

The other way to initialize a CNDI project is to use a CNDI Template file. This is done by calling cndi init --template <template_location>. When specifying a Template location you can choose to use Templates the CNDI team have built that are found in this repo at src/templates. To do this you pass in a Template "name". For example if you wanted to run the Airflow Template on EC2 you would run:

For example if you wanted to run the Airflow Template on EC2 you would run:

cndi init --template ec2/airflow

Alternatively, you can also specify a Template URL. A Template URL resolves to a CNDI Template file, this means that you are not limited to only Templates the CNDI team has put together, you can point to any arbitrary template file that follows the Template Schema.

These Template URLs can be file:// URLs which have an absolute path to the file locally, or typical remote or https:// URLs over the net.

# file:// URLs must be absolute paths
cndi init --template file:///absolute/path/to/template.yaml
# or
cndi init --template https://example.com/path/to/template.yaml

---

Whether you've chosen to use interactive mode or not, CNDI has generated a few files and folders for us based on our cndi-config.yaml file. If you want to learn about what CNDI is really creating, this is the best file to look at.

We break down all of these generated files later in this document in the outputs section.

The next step for our one-time project setup is to make sure that we have all the required envrionment variables for our project. Some of these values are required for every deployment. For example, you always need to have GIT_USERNAME, GIT_PASSWORD and GIT_REPO.

Some are only required for certain "deployment targets" like AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY which are only needed for aws deployments. Lastly, some are only required for certain Templates, for example all airflow templates require GIT_SYNC_PASSWORD for accessing repos that hold Airflow DAGs.

These environment variables are saved to the .env file that CNDI has generated for us. If you didn't use interactive mode you may have some placeholders in that file to overwrite, and they should be easy to spot. CNDI should also tell you if it is missing expected values.

When all of the values have been set, we want to use the gh cli again, this time to push our secret environment variables to GitHub.

# cndi requires version 2.23.0 or later of the GitHub CLI
gh secret set -f .env

Now we are ready for the next phase of the lifecycle!

---

lifecycle: push 🚀

Now that we have initialized our project, CNDI has given us files that describe our infrastructure resources and files that describe what to run on that infrastructure. CNDI has also created a GitHub Action for us which is responsible for calling cndi run. The run command provided in the cndi binary is responsible for calling terraform apply to deploy our infrastructure.

After cndi run has exited successfully you should be able to see new resources spinning up in the deployment target you selected. When the nodes come online in that destination, they will join together to form a Kubernetes cluster.

As the nodes join the cluster automatically, they are going to begin sharing workloads. Some workloads come bundled, we will call these CNDI platform services. There are a couple such services, one is sealed-secrets, and another is ArgoCD. Sealed Secrets enables storing Kubernetes Secrets within git securely, and ArgoCD is a GitOps tool which monitors a repo for Kubernetes manifests, and applies them.

When ArgoCD comes online, it will begin reading files from the cndi/cluster_manifests directory in the GitHub repo we have been pushing to. Ultimately cndi run is only used within GitHub for infrastructure, and ArgoCD is solely responsible for what to run on the cluster.

Your cluster will be online in no time!

---

lifecycle: overwrite ♻️

The next phase of the lifecycle is about making changes to your cluster. These changes can be cluster_manifests oriented, if you are making changes to the software running on your infrastructure, or they can be infrastructure oriented if you are horizontally or vertically scaling your cluster.

In either case, the approach is the same. Open your cndi-config.yaml file in your editor and make changes to your applications, cluster_manifests, or infrastructure then run:

# shorthand for cndi overwrite
cndi ow

Upon execution of the command you should see that some of the files cndi generated for us before have been modified or supplemented with new files. So far no changes have been made to our cluster. Just like before we need to push the changes up for them to take effect. This is what GitOps is all about, we don't login to our servers to make changes, we simply modify our config, and git push!

With these 3 phases you have everything you need to deploy a data infrastructure cluster using CNDI and evolve it over time!

---

lifecycle: destroy 🗑️

When it comes down time to teardown your cluster, there is only one step, just call:

cndi destroy # in your project repo, and we will take care of the rest!

This will delete all of the infrastructure resources that CNDI created for you, and from there you can choose either to delete the repo or keep it around for later.

---

Walkthroughs 🥾

We've got a few walkthroughs you can follow if you'd like, one for each deployment target. The walkthroughs demonstrate how to deploy a production grade Airflow cluster using CNDI's airflow Template.

• ec2/airflow
• eks/airflow
• gcp/airflow
• gke/airflow
• azure/airflow
• aks/airflow
• dev/airflow

If you are interested in using CNDI, these walkthroughs will be entirely transferrable to other applications beyond Airflow.

---

configuration 📝

Let's run through the 3 parts of a cndi-config.yaml file. This one file is the key to understanding CNDI, and it's really pretty simple.

infrastructure.cndi 🏗️

The infrastructure section is used to define the infrastructure that will power our cluster. The infrastructure section is broken out into 2 distinct categories. The first category is cndi, and it refers to infrastructure abstractions our team has invented that CNDI exposes for you.

Currently CNDI exposes only one abstraction, the nodes interface, and it's a wrapper that simplifies deploying Kubernetes cluster nodes. The CNDI nodes interface wraps the compute resources from every deployment target we support.

All nodes entries are nearly identical, the most substantial difference is the kind field which is used to specify the deployment target. These node resources and their supporting infrastructure are ultimately provisioned by Terraform, but we've abstracted a lot of complexity through this interface.

Declaring a node is simple, we give it a name, we give it some specs, and we add it to the array!

# you could use JSON instead, but YAML is preferred
infrastructure:
  cndi:
    nodes:
      - name: gcp-alpha
        kind: gcp
        role: leader # node responsible for instantiating the cluster
        machine_type: n2-standard-16
      - name: gcp-beta # node runs the control plane by default
        kind: gcp
      - name: gcp-charlie
        kind: gcp
      - name: gcp-delta
        kind: gcp
        role: worker # node does not run the control plane

Currently we have support for dev, AWS's ec2 and eks, azure and gcp clusters. More deployment targets are on the way!

Just like every other component in CNDI, nodes can be updated in our cndi-config.jsonc and we can call cndi ow and push the changes to our git remote to modify the cluster accordingly.

infrastructure.terraform 🧱

The second category within infrastructure is terraform. This is where you can define any Terraform resources you want to be provisioned alongside your cluster.

infrastructure:
  cndi: {}
  terraform:
    resource:
      aws_s3_bucket:
        my-bucket:
          acl: public-read
          bucket: s3-website-test.hashicorp.com
          cors_rule:
            - allowed_headers:
                - "*"
              allowed_methods:
                - PUT
                - POST
              allowed_origins:
                - https://s3-website-test.hashicorp.com
              expose_headers:
                - ETag
              max_age_seconds: 3000

💡 You can also use this section to override any of the default Terraform objects that CNDI deploys.

Generally, you should be able to customize CNDI resources through the cndi section instead.

But, if you do need to patch a Terraform resource CNDI has created for you, you simply need to match the resource name we have used, and specify the fields you want to update.

infrastructure:
  cndi: {}
  terraform:
    resource:
      aws_vpc:
        cndi_aws_vpc:
          cidr_block: 10.0.0.0/24

applications 💽

The next thing we need to configure is the applications that will actually run on the cluster. With CNDIv1 we focused on making it a breeze to deploy Apache Airflow in Kubernetes.

Lets see how we accomplish this here in this new and improved CNDI:

infrastructure: {}
applications:
  airflow:
    targetRevision: 1.7.0 # version of Helm chart to use
    destinationNamespace: airflow # kubernetes namespace in which to install application
    repoURL: https://airflow.apache.org
    chart: airflow
    # where you configure your Helm chart values.yaml
    values:
      dags:
        gitSync:
          enabled: true
          repo: https://github.com/polyseam/demo-dag-bag
          branch: main
          wait: 70
          subPath: dags
      # These options are required by Airflow in this context
      createUserJob:
        useHelmHooks: false
      migrateDatabaseJob:
        useHelmHooks: false

This is built on top of ArgoCD's Application CRDs and Helm Charts. If you have a Helm Chart, CNDI can deploy it!

cluster_manifests 📑

The third aspect of a cndi-config file is the cluster_manifests object. Any objects here will be used as Kubernetes Manifests and they'll be applied to your cluster through ArgoCD. This gives you full access to all the Kubernetes systems and APIs.

infrastructure: {}
applications: {}
cluster_manifests: # inside the "cluster_manifests" object you can put all of your custom Kubernetes manifests
  ingress:
    apiVersion: networking.k8s.io/v1
    kind: Ingress
    metadata:
      name: minimal-ingress
      annotations:
        nginx.ingress.kubernetes.io/rewrite-target: "/"
    spec: {}

If you are new to Kubernetes and are unsure what any of that meant, don't sweat it. CNDI is designed to help with that knowledge gap with templates, and you'll learn along the way too!

Pro tip! 🤫

If you want to add a new Kubernetes Secret to use inside of your Kubernetes cluster via GitOps, we make this possible by encrypting your secrets with sealed-secrets so they can live in your repo securely and be picked up by ArgoCD automatically. To add a secret to your cluster add the value to your .env file and then add a cluster_manifest entry like the one below. After that just call cndi ow to seal your secret.

The example below results in sealing the environment variables "GIT_USERNAME" and "GIT_PASSWORD", into the destination secret key names "GIT_SYNC_USERNAME" and "GIT_SYNC_PASSWORD" respectively.

infrastructure: {}
applications: {}
cluster_manifests:
  airflow-git-credentials-secret:
    apiVersion: v1
    kind: Secret
    metadata:
      name: airflow-git-credentials
      namespace: airflow
    stringData:
      GIT_SYNC_USERNAME: "$.cndi.secrets.seal(GIT_USERNAME)"
      GIT_SYNC_PASSWORD: "$.cndi.secrets.seal(GIT_PASSWORD)"

---

outputs 📂

When cndi init is called there are a few files that it produces:

1. a cndi-config.yaml - autogenerated in interactive mode only, described in the configuration section above

2. a .github/workflows folder, with a GitHub Action inside. The workflow is mostly just wrapping the cndi run command in the CNDI binary executable. As such, if you have a different CI system, you can execute the cndi run command on the binary there instead.

3. a cndi/terraform folder, containing the infrastructure resources cndi has generated for terraform, which cndi will apply automatically every time cndi run is executed.

4. a cndi/cluster_manifests folder, containing Kubernetes manifests that will be installed on your new cluster when it is up and running. This includes manifests like Ingress from the cluster_manifests section of your cndi-config.jsonc.

5. a cndi/cluster_manifests/applications folder, which contains a folder for each application defined in the applications section of your cndi-config.yaml, and a generated ArgoCD Application CRD inside that contains our expertly chosen defaults for that App, and the spefic parameters you've specified yourself in the applications section of your cndi-config.yaml.

6. a .env file which contains all of your environment variables that CNDI relies on, these values must be environment variables that are defined and valid when cndi run is executed.

7. a .gitginore file to ensure secret values never get published as source files to your repo

8. a ./README.md file that explains how you can use and modify these files yourself for the lifetime of the cluster

up and running

logging into ArgoCD 🔐

ArgoCD's Web UI is a useful tool for visualizing and debugging your cluster resources. Some of our templates setup Ingress for ArgoCD automatically, if you don't have an Ingress you can still access it by following our port-forwarding doc. Once you can see the login screen for ArgoCD you can login with the username admin and the password we set for you in your .env file under the key ARGOCD_ADMIN_PASSWORD.

dns 🌐

Setting up DNS for your cluster is a critical step if your cluster will be served online. The solution depends on your "deployment target". We have a doc coming soon walking through setting up DNS for AWS and GCP coming soon, but in short you just need to point DNS to the load balancer we provisioned for you. In AWS this means using a CNAME record, or an A record for a cluster running on GCP or Azure.

---

building cndi (contributor guide) 🛠️

If you are hoping to contribute to this project and want to learn the ropes, you are in the right place. Let's start with setting up your environment:

setup 🦕

The first step as you might expect is to clone this repo. Take note of where you clone to, it will matter later when we setup some convenience aliases.

1. Clone Repo:

git clone https://github.com/polyseam/cndi

2. Install Deno:

Next let's install deno, though it can be installed with a package manager, I would recommend that you install it without one. Once Deno is installed, make sure you add it to your PATH.

3. Setup cndi Alias: Let's setup an alias that allows us to use the deno source code as if it were the regular CLI, without colliding with the released cndi binary

# make sure the path below is correct, pointing to the main.ts file in the repo
alias cndi-next="deno run -A ~/dev/polyseam/cndi/main.ts"

We're continuously improving CNDI, but if you have an issue, checkout frequently-asked-questions to get unblocked quickly.

If you have any other issues or questions please message Matt or Tamika in the Polyseam Discord Chat.