From 0 to Kubernetes – Building an app portal

One more time…

Let’s tie it all together now, ok?

On one end of the chain is a web page in a bog-standard apache, and on the other end is TK4 running in a container.

To describe how I built this I’ll have to start on the TK4 side of things. We want to do the deployment of TK4 with an ansible playbook now, so we take all the different pieces of our deployment yaml file, and wrap them into ansible tasks for the k8s module. The only iffy part is to get the indentation right…

Hello, COBOL, my old friend…
I’ve come to talk with you again…
Because a vision softly creeping…
Left its seeds while I was sleeping…
And the vision that was planted in my brain
Still remains
Within the sounds
of YAML

Anyway, here’s the playbook:

---
- name: deploy turnkey4 in a kubernetes container
  hosts: all
  become: false

  tasks:

  - name: create a namespace
    k8s:
      api_key: '{{ eregion_home_k8s_token }}'
      host: '{{ eregion_home_k8s_host }}'
      verify_ssl: false
      state: present
      definition:
        apiVersion: v1
        kind: Namespace
        metadata:
          name: tk4

  - name: create a deployment
    k8s:
      api_key: '{{ eregion_home_k8s_token }}'
      host: '{{ eregion_home_k8s_host }}'
      verify_ssl: false
      state: present
      definition:
        apiVersion: apps/v1
        kind: Deployment
        metadata:
          name: tk4-app
          namespace: tk4
        spec:
          replicas: 1
          selector:
            matchLabels:
              app: tk4-app
          template:
            metadata:
              labels:
                app: tk4-app
            spec:
              containers:
                - name: tk4-app
                  image: rattydave/docker-ubuntu-hercules-mvs:latest
                  resources:
                    limits:
                      cpu: "0.25"
                      memory: "256Mi"
                  env:
                    - name: NUMCPU
                      value: "1"
                    - name: MAXCPU
                      value: "1"
                  ports:
                    - containerPort: 3270
                    - containerPort: 8038

  - name: create a service
    k8s:
      api_key: '{{ eregion_home_k8s_token }}'
      host: '{{ eregion_home_k8s_host }}'
      verify_ssl: false
      state: present
      definition:
        apiVersion: v1
        kind: Service
        metadata:
          name: tk4-svc
          namespace: tk4
          labels:
            app: tk4-app
        spec:
          ports:
            - port: 8038
              targetport: 8038
              name: tk4-web
              protocol: TCP
            - port: 3270
              targetport: 3270
              name: tk4-telnet
              protocol: TCP
          selector:
            app: tk4-app

  - name: create a traefik ingress route for port 8038
    k8s:
      api_key: '{{ eregion_home_k8s_token }}'
      host: '{{ eregion_home_k8s_host }}'
      verify_ssl: false
      state: present
      definition:
        apiVersion: traefik.containo.us/v1alpha1
        kind: IngressRoute
        metadata:
          name: ingressroutetls
          namespace: tk4
        spec:
          entryPoints:
            - websecure
          routes:
          - match: Host(`tk4.apps.eregion.home`)
            kind: Rule
            services:
            - name: tk4-svc
              port: 8038
          tls: {}

  - name: create a traefik ingress route for TCP port 3270
    k8s:
      api_key: '{{ eregion_home_k8s_token }}'
      host: '{{ eregion_home_k8s_host }}'
      verify_ssl: false
      state: present
      definition:
        apiVersion: traefik.containo.us/v1alpha1
        kind: IngressRouteTCP
        metadata:
          name: ingressroutetcp3270
          namespace: tk4
        spec:
          entryPoints:
            - x3270
          routes:
          - match: HostSNI(`*`)
            services:
            - name: tk4-svc
              port: 3270

Once this works I create a job template with it on my AWX, together with a user account which can’t do anything other than run jobs. Obviously that job needs to target a host that has the python3-openshift module with all dependencies installed, and the host you use for it needs to have the ansible variables for api_key and host set as host vars in AWX.

Then, a php script that launches that job through the REST api of awx (Don’t forget the PHP tags at the start and end of this file – I had to strip them out so wordpress wouldn’t choke on them):

if ($_SERVER["HTTP_HOST"]!="akari.my.lan")
{
        return null;
}

//url
$url = 'https://awx.apps.my.lan/api/v2/job_templates/41/launch/';

//Credentials
$client_id  = "***";
$client_pass= "***";

//HTTP options
$opts = array(
        'http' =>
                array(
                        'method'    => 'POST',
                        'header'    => array ('Content-type: application/json', 'Authorization: Basic '.base64_encode("$client_id:$client_pass")),
                ),
        'ssl' =>
                array(
                        'verify_peer' => false
                )
);

//Do request
$context = stream_context_create($opts);
$json = file_get_contents($url, false, $context);

$result = json_decode($json, true);
if(json_last_error() != JSON_ERROR_NONE){
    return null;
}
Header('Location: '.$_SERVER["HTTP_REFERER"]);

To find the launch url for any given job template you browse to /api/v2/ on your awx, and look for it – or you can grab the job ID by using your AWX “the normal way” and look at the links in the UI.

To scale down my TK4 when I’m not using it I use a version of the same playbook that sets the number of desired replicas to 0, together with a version of my php script that calls that job instead.

Now all I need to find is a web-based 3270 terminal.

On a not completely unrelated note, the start page of my internal web server here looks like this:

Yep, I don’t have anything better to do.

I think one long term project is going to be something about game servers in containers – counterstrike, etc etc – and then plug them into that startpage via AWX in just the same way as my “mainframe on demand”.

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