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Config objects

Ankaios supports the definition of configurations separated from workloads using them. This allows users to update configurations independent of workloads, which is helpful when maintaining a large number of workloads. You can define templates in the handlebars templating syntax which are expanded with the referenced configuration objects. The following workload configuration fields currently support template expansion:

  • agent
  • runtimeConfig
  • the subfields data and binaryData within the files field

For a basic example of separating configurations from workloads, see here. For detailed information about using the files field, see here.

Indentation for multi-line configuration

When using the default handlebars template syntax ({{config_variable}}), the line indentation of the current context is not considered. To ensure the validity of certain layouts that rely on the indentation level of multi-line configuration, utilize the following custom indent control structure, highlighted below:

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apiVersion: v0.1
workloads:
  frontend:
    agent: agent_A
    runtime: podman-kube
    configs:
      nginx_conf: nginx_config
    runtimeConfig: |
      manifest: |
        apiVersion: v1
        kind: ConfigMap
        metadata:
          name: nginx-config
        data:
          nginx.conf: |
            {{> indent content=nginx_conf}}
        ---
        apiVersion: v1
        kind: Pod
        metadata:
          name: nginx-pod
        spec:
          restartPolicy: Never
          containers:
          - name: nginx-container
            image: docker.io/nginx:latest
            ports:
            - containerPort: 80
              hostPort: 8080
            volumeMounts:
            - name: nginx-config-volume
              mountPath: /etc/nginx/nginx.conf
              subPath: nginx.conf
          volumes:
          - name: nginx-config-volume
            configMap:
              name: nginx-config
configs:
  nginx_config: |
    worker_processes  1;

    events {
        worker_connections  1024;
    }

    http {
        server {
            listen 80;
            server_name custom_nginx;

            location /custom {
                default_type text/plain;
                return 200 "The mounted custom nginx.conf is being used!\n";
            }
        }
    }

With the default template syntax ({{nginx_conf}}) instead, the expanded state will result in an invalid YAML:

...
    runtimeConfig: |
      manifest: |
        apiVersion: v1
        kind: ConfigMap
        metadata:
          name: nginx-config
        data:
          nginx.conf: |
            worker_processes  1;

events {
    worker_connections  1024;
}

http {
    server {
...

By using the indent control structure, the line indentation of the current context will be considered which results in an error-free YAML file.

...
    runtimeConfig: |
      manifest: |
        apiVersion: v1
        kind: ConfigMap
        metadata:
          name: nginx-config
        data:
          nginx.conf: |
            worker_processes  1;

            events {
                worker_connections  1024;
            }

            http {
                server {
...