#Template Configuration

Reference for the most commonly used template spec fields. Pass the spec as the spec field when creating or updating a template.

Spec Example#

yaml
spec:
    displayName: "Python 3.12 Data Science"
    description: "Python with numpy, pandas, and jupyter pre-installed"
    tags:
        - python
        - data-science

    mainContainer:
        image: registry.sandbox0-system.svc.cluster.local:5000/my-ds-env:v2.0
        resources:
            cpu: "2"
            memory: 4Gi
        env:
            - name: PYTHONPATH
              value: /workspace

    envVars:
        LOG_LEVEL: info
        TZ: UTC

    pool:
        minIdle: 3
        maxIdle: 10

    network:
        mode: block-all
        egress:
            trafficRules:
                - name: allow-python-package-indexes
                  action: allow
                  domains:
                      - "*.pypi.org"
                      - "*.anaconda.org"
                  ports:
                      - port: 443
                        protocol: tcp
        credentialBindings:
            - ref: gh-token
              sourceRef: github-source
              projection:
                  type: http_headers
                  httpHeaders:
                      headers:
                          - name: Authorization
                            valueTemplate: "Bearer {{token}}"

`mainContainer`#

The main sandbox container configuration.

Field	Type	Default	Description
`image`	string	—	Container image reference. Use a public image (e.g., `python:3.12-slim`) or the `Template image reference` returned by `s0 template image push` for private images.
`resources.cpu`	string	—	CPU limit for the sandbox (e.g., `"1"`, `"2"`, `"500m"`).
`resources.memory`	string	—	Memory limit for the sandbox (e.g., `"2Gi"`, `"512Mi"`).
`env`	array	`[]`	Per-container environment variables. Each entry has `name` and `value`.

ℹ

mainContainer.image, mainContainer.resources.cpu, and mainContainer.resources.memory are strictly validated by the API when creating or updating templates.

`envVars`#

Global environment variables shared across all containers (main container and sidecars).

yaml
envVars:
    LOG_LEVEL: info
    TZ: UTC
    APP_ENV: production

envVars are set at the template level and apply to every sandbox created from this template. Users can override or extend them at sandbox creation time via the env_vars field in the sandbox config.

`pool`#

Warm pool configuration. See Warm Pool for a detailed guide.

Field	Type	Default	Description
`minIdle`	integer	—	Minimum idle pods to pre-warm. Required (`>= 0`).
`maxIdle`	integer	—	Maximum idle pods allowed. Required (`>= minIdle`).

Additional Template Fields#

The template spec also includes:

Field	Type	Description
`lifecycle`	object	Template lifecycle defaults such as `defaultTTL`, `maxTTL`, `idleTimeout`, and `preStop`.
`public`	boolean	Template visibility flag.
`allowedTeams`	string[]	Optional team allowlist.

`network`#

Template-level default network policy. Templates now use the same public SandboxNetworkPolicy shape as claim-time and runtime sandbox network configuration.

Field	Type	Default	Description
`mode`	string	—	Required when `network` is set. Allowed values: `allow-all`, `block-all`. This is the fallback for unmatched traffic.
`egress.trafficRules`	array	—	Ordered allow/deny rules. First matching rule wins. Recommended for new policies.
`network.credentialBindings`	array	—	Credential bindings scoped under the same `network` object. Use this for outbound auth setup.
`egress.credentialRules`	array	—	Destination-scoped auth injection rules that reference `network.credentialBindings[*].ref`.
`egress.allowed` / `egress.denied`	array	—	Legacy compatibility fields. Prefer `trafficRules` instead.

See Network for traffic behavior and Credential for bindings and egress auth.

`displayName` `description` `tags`#

Metadata fields for human-readable identification. Not used by the runtime.

Field	Type	Description
`displayName`	string	Short human-readable name shown in UI and `s0 template list`.
`description`	string	Longer description of the template's purpose.
`tags`	string[]	Labels for filtering and organization.

Privileged Fields#

The following fields require a system-level token. They are not available to regular team API keys and are intended for platform operators configuring multi-tenant or advanced deployments.

Field	Description
`sidecars`	Additional containers running alongside the main container in the sandbox pod. Uses the standard Kubernetes container spec.
`pod.nodeSelector`	Pin sandbox pods to nodes matching specific labels.
`pod.affinity`	Node and pod affinity/anti-affinity rules.
`pod.tolerations`	Allow pods to be scheduled on tainted nodes.
`pod.serviceAccountName`	Kubernetes service account for sandbox pods.
`mainContainer.securityContext`	Container security context: `runAsUser`, `runAsGroup`, `capabilities.drop`. Capability `add` is not permitted.
`mainContainer.imagePullPolicy`	Pull policy override for the main container image. Only system administrators/system tokens can set this field.
`runtimeClassName`	Kubernetes runtime class (e.g., `gvisor` for gVisor isolation).
`clusterId`	Pin the template to a specific cluster in a multi-cluster deployment.

ℹ

Attempting to set privileged fields without a system identity returns 403 Forbidden. Contact your platform administrator if you need access to these fields.

Next Steps#

Volume

Persistent storage for your Sandboxes

Template

Template API workflows and end-to-end examples

Images & Registry

Configure container images and registry credentials