Atmos Hooks

Use this skill for lifecycle hooks that run before or after component operations, or for generation hooks declared in a scaffold template.

Hooks can run scanners, policy checks, store writes, Git actions, custom commands, or other toolchain-aware automation around Terraform, Helm, Kubernetes, and other component commands.

Related Skills

Need	Load
Store output hooks	atmos-stores
Shared step fields and `kind: step` payloads	atmos-steps
Git hooks and GitOps repositories	atmos-git
Tool installation for hook commands	atmos-toolchain
CI summaries and Atmos Pro upload	atmos-ci and atmos-pro

Hook Shape

Hooks are configured in stack manifests at global, component-type, or component scope.

hooks:
  store-vpc-outputs:
    events:
      - after.terraform.apply
    kind: store
    name: prod/ssm
    outputs:
      vpc_id: .vpc_id

components:
  terraform:
    vpc:
      hooks:
        scan-plan:
          events:
            - after.terraform.plan
          kind: trivy

Modern dotted event names such as after.terraform.plan are preferred. Legacy hyphenated event names may appear in older stacks; modernize them when editing nearby config.

Lifecycle Events

Use before/after events for component operations, for example:

before.terraform.init, after.terraform.init
before.terraform.plan, after.terraform.plan
before.terraform.apply, after.terraform.apply
before.terraform.deploy, after.terraform.deploy
before.terraform.test, after.terraform.test
before.terraform.output, after.terraform.output — fires for atmos terraform output, useful for backfilling a store from already-deployed infrastructure without an apply
before.terraform.refresh, after.terraform.refresh

Kubernetes provides before/after events for render, diff/plan, apply/deploy, delete, and validate. Native Helm provides template, diff, apply/deploy, and delete; Helmfile provides template, diff, apply/sync/deploy, and destroy. Use the canonical dotted events and remember that command aliases normalize to their execution event (deploy to apply, Kubernetes plan to diff, and Helmfile sync to apply).

Scaffold templates use the separate before.scaffold.generate and after.scaffold.generate events. They reuse the condition vocabulary but can run only kind: step and kind: steps; do not configure stack-only kinds in spec.hooks.

Multi-component DAG runs (e.g. --affected, --query, or workflows that fan out across several components) also fire aggregate events once for the whole run, in addition to the per-component events fired for each individual component: after.terraform.plan.aggregate, after.terraform.apply.aggregate, and after.terraform.destroy.aggregate. Use a per-component event for component-specific behavior (scans, store writes) and an aggregate event for run-level summaries or notifications that should fire only once.

Conditional Execution with `when`

Hooks share the same when: condition engine as workflow steps: predicate keywords (ci, local, always, never, success, failure) or a CEL expression built from runtime facts such as stack and component. For example, restrict a hook to CI runs against the prod stack:

hooks:
  prod-ci-scan:
    events:
      - after.terraform.plan
    kind: trivy
    when: stack == "prod" && ci

See atmos-workflows for the full when:/CEL syntax reference.

Hook Kinds

Stack lifecycle hooks support command, store, git, infracost, trivy, checkov, kics, and the step bridge. The legacy ci.* hook kinds still parse but are deprecated no-ops; use the current CI provider bindings instead. Use a named kind when Atmos has one; use command for a project-specific binary. The legacy command: discriminator and hyphenated events remain compatibility input only; author new configuration with kind: and dotted events.

Hooks can use dependencies.tools so required scanners or CLIs are installed and placed on PATH for the hook execution context.

When the hook declares the required binary in dependencies.tools, do not add a separate atmos toolchain install step. Atmos resolves, installs, and injects the tool before the hook fires.

Step-Backed Hook Kinds

Hooks can also delegate to the same step-type registry that workflows, custom commands, and cast recordings use, instead of one of the named kinds above:

kind: step runs one registered step type. Set the step type with the hook's type: field and configure it with with:, exactly like a workflow step.
kind: steps runs an ordered list of registered step types, provided as a YAML list under with:.

Both run strictly in order -- there is no concurrent execution within a step-backed hook.

The hook envelope owns events, when, env, retry, and on_failure; with: is decoded and validated as the step's own configuration. kind: step supplies the one step type through the hook's type:; kind: steps supplies type-bearing objects in its ordered with: list.

hooks:
  check-prereqs:
    events:
      - before.terraform.plan
    kind: step
    type: require
    with:
      tools:
        - kubectl
        - helm

  bring-up-and-plan:
    events:
      - before.terraform.plan
    kind: steps
    with:
      - type: emulator
        command: up
      - type: atmos
        command: terraform plan vpc

Use kind: step/kind: steps when you need a registered step type (container, emulator, require, atmos, shell, and other types workflows support) inside a hook; use the older named kinds (trivy, checkov, kics, infracost) when Atmos already ships a purpose-built scanner integration for the job.

Operational Guidance

Use hooks for repeatable lifecycle behavior, not one-off local scripts.
Scope hooks as narrowly as possible: component hooks for component-specific behavior, shared mixins/defaults for organization-wide checks.
Use --skip-hooks to bypass all hooks for a diagnostic run, or --skip-hooks=name1,name2 to skip specific hooks by name. This flag is registered on the terraform command only today; there is no helmfile or packer equivalent yet.
Treat hook output as part of CI evidence. When Atmos Pro is connected and the hook kind supports upload, prefer structured upload; otherwise rely on local/CI summaries.
Keep destructive hooks opt-in and visible in stack config.

SKILL.md