Conditions & Assertions

Conditions and assertions let you control which steps execute and guard against unexpected state.

Conditions

A condition on a step determines whether the step runs. If the condition evaluates to false, the step is skipped and the workflow continues to the next step.

  - type: functionBlock
    label: backup_config
    functionBlock: "fb.examples.neops.io/configBackup:1.0.0"
    runOn: device
    condition:
      type: jmes
      jmes: "{{ check_reachability.result.success == true }}"
      description: "Only back up reachable devices"
    parameters:
      backup_type: "running"

Structure

condition:
  type: jmes
  jmes: "{{ <expression> }}"
  description: "Human-readable explanation"   # optional

The jmes field is a JMESPath expression that must evaluate to a truthy value. The type is always jmes.

Common Patterns

Skip unreachable devices:

condition:
  type: jmes
  jmes: "{{ ping.result.success == true }}"

Only configure access ports:

condition:
  type: jmes
  jmes: "{{ context.interface.facts.port_type == 'access' }}"

Skip devices that already have the config:

condition:
  type: jmes
  jmes: "{{ contains(context.device.facts.applied_configs, 'nac') == false }}"

Run only on Cisco devices:

condition:
  type: jmes
  jmes: "{{ context.device.platform.shortName == 'ios' }}"

Assertions

Assertions are guardrails. If any assertion evaluates to false, the step fails (instead of being silently skipped). Use assertions to enforce preconditions.

assert:
  - type: jmes
    jmes: "{{ check_neighbors.result.success == true }}"
    description: "Device must have CDP neighbors before configuring interfaces"
  - type: jmes
    jmes: "{{ length(context.interfaces) > `0` }}"
    description: "Device must have at least one interface"

Condition vs Assertion

Behavior	Condition (condition)	Assertion (assert)
False →	Step is skipped (workflow continues)	Step fails (triggers error handling)
Use for	Optional steps, platform-specific steps	Safety checks, preconditions
Typical	"Only do this if..."	"This must be true before..."

Combine them

You can use both on the same step. The condition is evaluated first. If the condition is false, the step is skipped entirely and assertions are not checked. If the condition is true, assertions are evaluated before the step executes.

Continue on Error

Not Yet Enforced

continueOnError is defined in the workflow schema and can be set on steps, but the execution engine does not yet evaluate it. A failed step will always stop the workflow regardless of this setting. This feature is planned for a future release.

By default, a failed step stops the entire workflow. When implemented, setting continueOnError: true will let the workflow proceed even if this step fails:

  - type: functionBlock
    label: check_reachability
    functionBlock: "fb.examples.neops.io/ping:1.0.0"
    runOn: device
    parameters:
      host: "{{ context.device.ip }}"
    continueOnError: true

This will be useful for non-critical steps like reachability checks where you want to attempt an operation but not block the rest of the workflow if a few devices are unreachable.

Info

When implemented, continueOnError will not change the transaction classification. If a non-pure step executes and fails, the workflow may still end up as FAILED_UNSAFE even if execution continues past that step.