Built-in hooks
You can use hooks to execute actions at specific stages of stack deploy and undeploy operations. Takomo has two built-in hooks, and you can also implement your own.
In a stack configuration, you choose which type of hook to use by providing value to the
type
property. You also need to give a name for each hook. In addition to these two mandatory properties, each hook type may have its own set of additional properties.The command hook executes the specified shell command.
Here are the properties of the Command hook:
Key | Required | Type | Description |
type | yes | string | Type of the hook, this must be cmd. |
name | yes | string | Name of the hook. |
command | yes | string | Shell command to execute. |
cwd | no | string | Path to the working directory from where the shell command is executed. Relative to the current project directory. |
exposeStackCredentials | no | boolean | Make the current stack's AWS credentials available for the shell command. Defaults to false. |
exposeStackRegion | no | boolean | Make the current stack's region available for the shell command. Defaults to false. |
capture | no | string | Controls how to capture the output of the executed shell command. By default, all output is captured. To capture only the last line, set this to last-line. |
The following environment variables are available in the shell command:
Name | Description |
TKM_COMMAND_STAGE | The current stack operation stage. |
TKM_COMMAND_OPERATION | The current stack operation. |
TKM_COMMAND_STATUS | The current stack operation status, not present in before stage |
AWS_ACCESS_KEY_ID | If exposeStackCredentials is true, this will hold the access key id of credentials of the current stack. |
AWS_SECRET_ACCESS_KEY | If exposeStackCredentials is true, this will hold the secret access key of credentials of the current stack. |
AWS_SESSION_TOKEN | If exposeStackCredentials is true, this will hold the session token of credentials of the current stack. |
AWS_SECURITY_TOKEN | If exposeStackCredentials is true, this will hold the session token of credentials of the current stack. |
AWS_DEFAULT_REGION | If exposeStackRegion is true, this will hold the region of the current stack. |
TKM_HOOK_{hook-name} | Values returned from previous hooks are exposed in environment variables where the {hook-name} placeholder is replaced with the hook's name. Hooks whose name has unsafe characters not compatible with a pattern /^[a-zA-Z_]+[a-zA-Z0-9_]*$/ are not exposed and a warning is logged instead. |
Any output the hook prints to the stdout is captured and exposed to other hooks.
A command hook that runs a simple shell command:
- name: my-hook
type: cmd
command: echo 'hello world'
A command hook that exposes the current stack's AWS credentials to the shell command:
- name: my-another-hook
type: cmd
exposeStackCredentials: true
command: aws sts get-caller-identity
The checksum hook calculates a checksum from a specified directory. The checksum is calculated recursively, i.e. all files and directories under the specified directory are included in the checksum.
Here are the properties of the Checksum hook:
Key | Required | Type | Description |
type | yes | string | Type of the hook, this must be checksum |
name | yes | string | Name of the hook |
dir | yes | string | Path to the directory from where the checksum should be calculated. The path can be absolute or relative to the project directory. |
encoding | no | string | Encoding used to encode the calculated checksum. Supported values are base64 (default) and hex. |
Calculate a checksum from a directory lambda/scripts located in the project directory.
- name: my-checksum
type: checksum
dir: lambda/scripts
The same as above but using the hex encoding.
- name: my-hex-checksum
type: checksum
dir: lambda/scripts
encoding: hex
Last modified 1yr ago