# Common nodes
<a name="common-nodes"></a>

Define nodes for the NSD and VNFD.
+ [AWS.HookDefinition.Bash](node-hook-bash.md)

# AWS.HookDefinition.Bash
<a name="node-hook-bash"></a>

Defines an AWS HookDefinition in `bash`.

## Syntax
<a name="hookdefinition-syntax"></a>

```
tosca.nodes.AWS.HookDefinition.Bash:
  properties:
    implementation: String
    environment\$1variables: List
    execution\$1role: String
```

## Properties
<a name="_properties"></a>

 `implementation`    
The relative path to the hook definition. The format must be: `./hooks/script_name.sh`  
Required: Yes  
Type: String

 `environment_variables`    
The environment variables for the hook bash script. Use the following format: `envName=envValue` with the following regex patterns:  
+ For values without references: `^[a-zA-Z0-9]+[a-zA-Z0-9\-\_]*[a-zA-Z0-9]+=[a-zA-Z0-9]+[a-zA-Z0-9\-\_]*[a-zA-Z0-9]+$`
+ For static references: `^[a-zA-Z0-9]+[a-zA-Z0-9\-\_]*[a-zA-Z0-9]+=\$\{[a-zA-Z0-9]+\.(properties|capabilities|requirements)(\.([a-zA-Z0-9\-_]+))+\}$`
+ For dynamic references: `^[a-zA-Z0-9]+[a-zA-Z0-9\-\_]*[a-zA-Z0-9]+=\$\{[a-zA-Z0-9]+\.(name|id|arn)\}$`
Ensure that the `envName=envValue` value meets the following criteria:  
+ Do not use spaces.
+ Start **envName** with a letter (A-Z or a-z) or number (0-9).
+ Do not start the environment variable name with the following AWS TNB reserved keywords (case insensitive):
  + CODEBUILD
  + TNB
  + HOME
  + AWS
+ You can use any number of letters (A-Z or a-z), numbers (0-9), and special characters `-` and `_` for **envName** and **envValue**.
+ Each environment variable (each **envName**=**envValue**) must be less than 128 characters.
Example: `A123-45xYz=Example_789`  
Required: No  
Type: List

 `execution_role`    
The role for hook execution.  
Required: Yes  
Type: String

## Example
<a name="hookdefinition-example"></a>

```
SampleHookScript:
  type: tosca.nodes.AWS.HookDefinition.Bash
  properties:
    implementation: "./hooks/myhook.sh"
    environment_variables:
      - "variable01=value01"
      - "variable02=value02"
    execution_role: "arn:aws:iam::${AWS::TNB::AccountId}:role/SampleHookPermission"
```