> For the complete documentation index, see [llms.txt](https://docs.graviti.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.graviti.com/guide/tensorbay/action/yaml-syntax-description.md).

# YAML Syntax Description

## Related Concepts

Job is the basic unit of the Action workflow. A [DAG](https://en.wikipedia.org/wiki/Directed_acyclic_graph) is generated by defining multiple jobs and setting the dependencies of the jobs. The TensorBay workflow engine can automate tasks by executing DAGs. Set the following YAML file as an example.

![](/files/-MhX2C_dhXqrINAy7JAy)

1.  \[tasks]: Define all the jobs under this workflow.
2.  \[tasks.hello-world]: Defines a task, with the name "hello-world".
3.  \[tasks.hello-world.container]: This job is executed under the docker container.
4. \[tasks.hello-world.container.image]: The image used by the docker container is alpine:latest.
5.  \[tasks.hello-world.container.command]: The command executed in the docker container is 991\`called echo.
6. \[tasks.hello-world.container.args]: The argument to echo is "hello world".

## Runtime Environment of Job

Job supports the following three runtime environments. Each job has only one runtime environment.

**1. Container**

In this environment you can use a specified image to generate a container and execute it.The job content will be defined by the image.

![](/files/-MhllnSpT7CfaGvCjdAe)

**2. Script**

In this environment, a specified script wil be excuted in the docker container.

![](/files/-MhX2Uj-DskoLHQtzko-)

 **3. Git**

In this environment, a git repo code will be executed inside the docker container.

![](/files/-MhX2b-Y2H7sKEfGk9lh)

## Job Dependencies

**Dependencies**

Jobs can define their dependencies by keywords.

![](/files/-MhX2qkVdKXdzefuhTCb)

**Flowchart**

A diamond-shaped DAG. Task A executes first, then task B and task C conduct simultaneously. Task D only starts to run when task B and task C are finished.

![](/files/-MhX2vkUwqy72p9F0gsX)

## Parameters Setting of Job 

### Attributes of Parameters

#### **Name**

The name of a parameter, which is used to refer to the parameter in the code of a workflow.

#### **Type**

The type of a parameter. The following three types of parameters are supported in Actions now.

* String: string
* Number: number, including integers and floating-point numbers
* Boolean: boolean value, true/false

#### **Default**

The default value of a parameter. If the default value is not specified at the beginning, the system will automatically use a preset default value.

### Definition of Parameters

Support to view and set the detailed parameters on the parameter details page.

![](/files/-MhXdWRR0XZtgNIR3DAS)

### Parameters Setting

**Manual Parameters Setting**: If a workflow is started manually, then its values can be set via the TensorBay console.

**Automatic Parameters Setting**: If a workflow is started automatically, then the system will use default values.

![](/files/-MhXc6lmzyPLqBiv29T3)

### How to Quote Parameters

You can quote a parameter in workflow with its name.

![](/files/-MhX9HFBmnXa4F3Pb7ew)

{% hint style="info" %}

1. The parameter to be quoted must be within {{}}.
2. The parameter name must start with **workflow\.parameters**.
3. The parameter name must be the same as **the preset one**.
   {% endhint %}

### Environment Settings of Jobs

**Environment** defines the environment variables of the **container**, which can be quoted in the same way as the environment variables of the normal **docker container**.