Podinate Pod¶

The Podinate Pod is the most commonly used resource provided by Podinate. It is a single container running in the cluster.

Create a Pod¶

This is the most basic Pod. It runs an nginx web server which will listen for requests.

pod.pcl

pod "web-server" {
    image = "nginx"
}

Environment Variables¶

Environment variables can be set in the Pod by adding an environment block.

environment_variable.pcl

pod "web-server" {
    image = "nginx"
    environment "SERVER_NAME" {
        value = "example.com"
    }
}

Services¶

Pods that run services should have a service block to take advantage of Kubernetes service discovery and optional ingress.

service.pcl

pod "web-server" {
    image = "nginx"
    environment "SERVER_NAME" {
        value = "example.com"
    }

    service "www" {
        port = 80
        protocol = "http"

        // Adding protocol = http and a domain_name will set up ingress on this service
        domain_name = "example.com"
    }
}

Volumes¶

A volume is a separate persistent storage space, dedicated to the Pod.

Let's say we want this nginx to have a space to use for a persistent cache.

volume.pcl

pod "web-server" {
    image = "nginx"
    volume "cache" {
        path = "/cache"
    }
}

Shared Volumes¶

A Shared Volume is also a persistent storage space, but it can be shared among many pods. An app can use it to store persistent data that may need to be used by multiple Pods.

shared_volume.pcl

shared_volume "files" { // Create shared volume
    size = 2
}
pod "web-server" {
    image = "nginx"
    volume "cache" {
        path = "/cache"
    }
    shared_volume { // Attach the shared volume to the Pod
        volume_id = "files"
        path = "/var/www/html"
    }
}

Spec¶

This is the complete spec of a Pod Block:

pod_full.pcl

pod "ubuntu" {
    project_id = "ubuntu"
    name = "My Ubuntu Pod"
    image = "ubuntu"
    tag = "22.04"
    command = [ "/bin/bash", "-c", "--" ]
    arguments = [ "while true; do echo 'Hello from Podinate!'; sleep 2; done;" ]
}

Item	Required	Default	Explanation
name	`false`	`-`	The name of the pod only for reference and not required.
project_id	`true`	`-`	The Project this Pod is inside of.
image	`true`	`-`	The image to run where the image is a valid container image file that Kubernetes can understand.
tag	`false`	latest	The tag of the image you want to run.
command	`false`	The RUNPOINT of the container image	The command to run inside the container on startup. If not specified the container image will run the command that it is configured to.
arguments	`false`	`-`	Arguments to pass to the command if command is not specified the arguments will be passed to the container image's configured command. This is how many container images are designed to be used.

Volume Spec¶

Pods can have one or more volume blocks giving them their own distinct storage block.

pod "volume-pod" {
    project_id = "ubuntu"
    image = "ubuntu"
    volume "storage" {
        // The path in the Pod to mount the volume
        // Required
        path = "/var/www/html" 

        // Size limit of the Volume in GB 
        size = 20 

        // The Kubernetes storage class to use for the device
        // To see available storage classes run "podinate kubectl get storageclasses"
        class = "ssd"
    }
}

Roadmap¶

For alpha, you can create a single long-runnning Pod running a single container. Podinate plans to expand this to allow you to run a group of identical containers soon.

Podinate plans to support three types of container:

pod "service" {
    // type = "service" // Default, optional
}
pod "job" {
    // A pod that runs once and exits once done
    type = "job"
}
pod "cronjob" {
    // A pod that is run at a set interval
    type = "cron"
    schedule = "*/5 * * *"
}

Kubernetes¶

A Podinate Pod maps to a Kubernetes Stateful Set