# OCL Syntax Reference for Process Templates

## Grammar Rules

OCL (Octopus Configuration Language) follows a strict format. The EBNF grammar is defined at https://github.com/OctopusDeploy/Ocl.

### Core Rules

- **Name, `=`, and value** must be on the same line
- **Block name, labels, and `{`** must be on the same line
- **Closing `}`** must be on its own line (except empty blocks like `value "default" {}`)
- **Strings** use double quotes, cannot contain unescaped `"`
- **Multi-line strings** use heredoc: `<<-EOT` / `EOT`
- **Arrays** use `["item1", "item2"]`
- **Dictionaries** use `{ key = "value" }` (one entry per line inside braces)

### Name Restrictions

Template and step names can only contain: letters, numbers, periods, commas, dashes, underscores, hashes.

**Invalid:** `Run Security Scan (SAST/SCA)` — parentheses and slashes not allowed
**Valid:** `Run Security Scan - SAST and SCA`

## Process Template File Structure

```hcl
name = "Template Display Name"
description = "What this template does"

# Parameters (consumed by projects, referenced in steps)
parameter "param_name" {
    display_settings = {
        Octopus.ControlType = "SingleLineText"
    }
    help_text = "Description for UI"
    label = "Display Label"
    value "default_value" {}    # Optional default
}

# Worker pool parameter (REQUIRED — every template needs this)
parameter "worker_pool" {
    display_settings = {
        Octopus.ControlType = "WorkerPool"
    }
    help_text = "Worker pool for server-side steps"
    label = "Worker Pool"
}

# Steps (executed in order)
step "step-slug" {
    name = "Step Display Name"
    start_trigger = "StartAfterPrevious"  # or "StartWithPrevious"

    action {
        action_type = "Octopus.Script"
        properties = {
            Octopus.Action.RunOnServer = "true"
            Octopus.Action.Script.ScriptSource = "Inline"
            Octopus.Action.Script.Syntax = "PowerShell"
            Octopus.Action.Script.ScriptBody = <<-EOT
Write-Host "Hello from #{Octopus.Project.Name}"
EOT
            OctopusUseBundledTooling = "False"
        }
        worker_pool_variable = "worker_pool"
    }
}
```

## Parameter Types

| Type | `Octopus.ControlType` | Can Default | Notes |
|------|----------------------|-------------|-------|
| Single-line text | `SingleLineText` | Yes | Most common for string values |
| Multi-line text | `MultiLineText` | Yes | For scripts, YAML, JSON |
| Sensitive | `Sensitive` | Yes | Encrypted in DB |
| Checkbox | `Checkbox` | Yes | Boolean |
| Dropdown | `Select` | Yes | Predefined options |
| Target Tags | `TargetTags` | No | For Kubernetes/deployment targets |
| Worker Pool | `WorkerPool` | No | **Required on every template** |
| Package | (package) | No | Container image references |
| Environments | (environments) | No | |
| Channels | (channels) | No | |

### Default Values

```hcl
# String default
parameter "cloud_target" {
    display_settings = { Octopus.ControlType = "SingleLineText" }
    help_text = "Cloud provider"
    label = "Cloud Target"
    value "gcp" {}              # Default value in empty block
}

# No default (must be set by consuming project)
parameter "target_tags" {
    display_settings = { Octopus.ControlType = "TargetTags" }
    help_text = "K8s target tags"
    label = "Target Tags"
}
```

## Step Structure

### Inline Script Step (most common in process templates)

```hcl
step "step-slug" {
    name = "Display Name"
    start_trigger = "StartAfterPrevious"

    action {
        action_type = "Octopus.Script"
        properties = {
            Octopus.Action.RunOnServer = "true"
            Octopus.Action.Script.ScriptSource = "Inline"
            Octopus.Action.Script.Syntax = "PowerShell"    # or "Bash"
            Octopus.Action.Script.ScriptBody = <<-EOT
# PowerShell script here
$project = $OctopusParameters['Octopus.Project.Name']
Write-Host "Deploying $project"
EOT
            OctopusUseBundledTooling = "False"
        }
        worker_pool_variable = "worker_pool"
    }
}
```

### Deployment Target Step (runs on targets, not server)

```hcl
step "deploy-step" {
    name = "Deploy to K8s"
    start_trigger = "StartAfterPrevious"
    properties = {
        Octopus.Action.TargetRoles = "#{target_tags}"   # References parameter
    }

    action {
        action_type = "Octopus.Script"
        properties = {
            Octopus.Action.RunOnServer = "false"         # Runs on target
            Octopus.Action.Script.ScriptSource = "Inline"
            Octopus.Action.Script.Syntax = "PowerShell"
            Octopus.Action.Script.ScriptBody = <<-EOT
Write-Host "Deploying to target"
EOT
            OctopusUseBundledTooling = "False"
        }
        worker_pool_variable = "worker_pool"
    }
}
```

### Kubernetes Raw YAML Step

```hcl
step "k8s-deploy" {
    name = "Apply Kubernetes YAML"
    properties = {
        Octopus.Action.TargetRoles = "#{target_tags}"
    }

    action {
        action_type = "Octopus.KubernetesDeployRawYaml"
        properties = {
            Octopus.Action.GitRepository.FilePathFilters = "#{{yaml_path}}"
            Octopus.Action.GitRepository.Source = "External"
            Octopus.Action.Kubernetes.DeploymentTimeout = "180"
            Octopus.Action.Kubernetes.ResourceStatusCheck = "True"
            Octopus.Action.Kubernetes.ServerSideApply.Enabled = "True"
            Octopus.Action.Kubernetes.ServerSideApply.ForceConflicts = "True"
            Octopus.Action.KubernetesContainers.Namespace = "#{namespace}"
            Octopus.Action.Script.ScriptSource = "GitRepository"
        }
        worker_pool_variable = "worker_pool"

        git_dependencies {
            default_branch = "main"
            file_path_filters = ["#{yaml_path}"]
            git_credential_type = "Anonymous"
            repository_uri = "#{repo_url}"
        }
    }
}
```

## Referencing Variables

### Octopus System Variables

Use `$OctopusParameters['Variable.Name']` in PowerShell scripts:

```powershell
$project = $OctopusParameters['Octopus.Project.Name']
$release = $OctopusParameters['Octopus.Release.Number']
$env     = $OctopusParameters['Octopus.Environment.Name']
$channel = $OctopusParameters['Octopus.Release.Channel.Name']
```

### Template Parameters

In OCL properties (outside scripts): `#{parameter_name}`
In PowerShell scripts: `$OctopusParameters['parameter_name']`

```hcl
# In OCL properties
Octopus.Action.TargetRoles = "#{target_tags}"

# In script body
$cloudTarget = $OctopusParameters['cloud_target']
```

**Double-bracing escape:** In some OCL properties, use `#{{param}}` to escape Octopus variable substitution:

```hcl
Octopus.Action.GitRepository.FilePathFilters = "#{{yaml_path}}"
```

### Output Variables

Set output variables from scripts for use in later steps:

```powershell
Write-Host "##octopus[setVariable name='CoveragePercent' value='87']"
```

Read in subsequent steps:
```powershell
$coverage = $OctopusParameters['Octopus.Action[run-unit-tests].Output.CoveragePercent']
```

## Channel Scoping

Scope steps to specific channels (for dual-image patterns):

```hcl
action {
    action_type = "Octopus.Script"
    channels = ["non-prod"]          # Only runs in this channel
    properties = { ... }
}
```

## Environment Scoping

```hcl
action {
    environments = ["production"]              # Only in prod
    excluded_environments = ["development"]    # Not in dev
}
```

## Step Properties Reference

| Property | Type | Values | Default |
|---|---|---|---|
| `step.condition` | enum | `Success`, `Failure`, `Always`, `Variable` | `Success` |
| `step.start_trigger` | enum | `StartAfterPrevious`, `StartWithPrevious` | `StartAfterPrevious` |
| `step.package_requirement` | enum | `LetOctopusDecide`, `BeforePackageAcquisition`, `AfterPackageAcquisition` | `LetOctopusDecide` |
| `action.channels` | string[] | channel slugs | all |
| `action.environments` | string[] | environment slugs | all |
| `action.excluded_environments` | string[] | environment slugs | none |
| `action.is_disabled` | bool | | `False` |
| `action.is_required` | bool | | `False` |
| `action.notes` | string | step description | |
| `action.worker_pool` | string | worker pool slug | |
| `action.worker_pool_variable` | string | variable name | |

## References

- [OCL Format Specification](https://octopus.com/docs/projects/version-control/ocl-file-format)
- [Config as Code Reference](https://octopus.com/docs/projects/version-control/config-as-code-reference)
- [OCL Grammar (EBNF)](https://github.com/OctopusDeploy/Ocl)