AWS SAM CLI configuration file

The AWS Serverless Application Model Command Line Interface (AWS SAM CLI) supports a project-level configuration file that you can use to configure AWS SAM CLI command parameter values.

For documentation on creating and using configuration files, see Configuring the AWS SAM CLI.

Default configuration file settings

AWS SAM uses the following default configuration file settings:

• Name – samconfig.

• Location – At the root of your project. This is the same location as your template.yaml file.

• Format – TOML. To learn more, see TOML in the TOML documentation.

The following is an example project structure that includes the default configuration file name and location:

sam-app
├── README.md
├── __init__.py
├── events
├── hello_world
├── samconfig.toml
├── template.yaml
└── tests

The following is an example samconfig.toml file:

...
version = 0.1

[default]
[default.global]
[default.global.parameters]
stack_name = "sam-app"

[default.build.parameters]
cached = true
parallel = true

[default.deploy.parameters]
capabilities = "CAPABILITY_IAM"
confirm_changeset = true
resolve_s3 = true

[default.sync.parameters]
watch = true

[default.local_start_api.parameters]
warm_containers = "EAGER"

[prod]
[prod.sync]
[prod.sync.parameters]
watch = false

Supported configuration file formats

TOML and [YAML|YML] formats are supported. See the following basic syntax:

TOML

version = 0.1
[environment]
[environment.command]
[environment.command.parameters]
option = parameter value

YAML

version: 0.1
environment:
  command:
    parameters:
      option: parameter value

Specify a configuration file

By default, the AWS SAM CLI looks for a configuration file in the following order:

1. Custom configuration file – If you use the --config-file option to specify a file name and location, the AWS SAM CLI looks for this file first.

2. Default samconfig.toml file – This is the default configuration file name and format, located at the root of your project. If you don’t specify a custom configuration file, the AWS SAM CLI looks for this file next.

3. samconfig.[yaml|yml] file – If the samconfig.toml does not exist at the root of your project, the AWS SAM CLI looks for this file.

The following is an example of specifying a custom configuration file using the --config-file option:

$ sam deploy --config-file myconfig.yaml

Configuration file basics

Environment

An environment is a named identifier that contains a unique set of configuration settings. You can have multiple environments in a single AWS SAM application.

The default environment name is default.

Use the AWS SAM CLI --config-env option to specify the environment to use.

Command

The command is the AWS SAM CLI command to specify parameter values for.

To specify parameter values for all commands, use the global identifier.

When referencing an AWS SAM CLI command, replace spaces ( ) and hyphens (–) with underscores (_). See the following examples:

• build

• local_invoke

• local_start_api

Parameters

Parameters are specified as key-value pairs.

• The key is the AWS SAM CLI command option name.

• The value is the value to specify.

When specifying keys, use the long-form command option name and replace hyphens (–) with underscores (_). The following are examples:

• region

• stack_name

• template_file

Parameter value rules

TOML

• Boolean values can be true or false. For example, confirm_changeset = true.

• For string values, use quotation marks (""). For example, region = "us-west-2".

• For list values, use quotation marks ("") and separate each value using a space ( ). For example: capabilities = "CAPABILITY_IAM CAPABILITY_NAMED_IAM".

• For values that contain a list of key-value pairs, the pairs are space-delimited ( ) and the value of each pair is surrounded by encoded quotation marks (\" \"). For example, tags = "project=\"my-application\" stage=\"production\"".

• For parameter values that can be specified multiple times, the value is an array of arguments. For example: image_repositories = ["my-function-1=image-repo-1", "my-function-2=image-repo-2"].

YAML

• Boolean values can be true or false. For example, confirm_changeset: true.

• For entries that contain a single string value, quotation marks ("") are optional. For example, region: us-west-2. This includes entries that contain multiple key-value pairs that are provided as a single string. The following is an example:

  $ sam deploy --tags "foo=bar hello=world"

  default:
    deploy:
      parameters:
        tags: foo=bar hello=world

• For entries that contain a list of values, or entries that can be used multiple times in a single command, specify them as a list of strings.

  The following is an example:

  $ sam remote invoke --parameter "InvocationType=Event" --parameter "LogType=None"

  default:
    remote_invoke:
      parameter:
      - InvocationType=Event
      - LogType=None

Configuration precedence

When configuring values, the following precedence takes place:

• Parameter values that you provide at the command line take precedence over corresponding values in the configuration file and Parameters section of the template file.

• If the --parameter-overrides option is used at the command line or in your configuration file with the parameter_overrides key, its values take precedence over values in the Parameters section of the template file.

• In your configuration file, entries provided for a specific command take precedence over global entries. In the following example, the sam deploy command will use the stack name my-app-stack.

  TOML

  [default.global.parameters]
  stack_name = "common-stack"
  
  [default.deploy.parameters]
  stack_name = "my-app-stack"

  YAML

  default:
    global:
      parameters:
        stack_name: common-stack
    deploy:
      parameters:
        stack_name: my-app-stack

Creating and modifying configuration files

Creating configuration files

When you create an application using sam init, a default samconfig.toml file is created. You can also manually create your configuration file.

Modifying configuration files

You can manually modify your configuration files. Also, during any AWS SAM CLI interactive flow, configured values will be displayed in brackets ([ ]). If you modify these values, the AWS SAM CLI will update your configuration file.

The following is an example interactive flow using the sam deploy --guided command:

$ sam deploy --guided

Configuring SAM deploy
======================

    Looking for config file [samconfig.toml] :  Found
    Reading default arguments  :  Success

    Setting default arguments for 'sam deploy'
    =========================================
    Stack Name [sam-app]: ENTER
    AWS Region [us-west-2]: ENTER
    #Shows you resources changes to be deployed and require a 'Y' to initiate deploy
    Confirm changes before deploy [Y/n]: n
    #SAM needs permission to be able to create roles to connect to the resources in your template
    Allow SAM CLI IAM role creation [Y/n]: ENTER
    #Preserves the state of previously provisioned resources when an operation fails
    Disable rollback [y/N]: ENTER
    HelloWorldFunction may not have authorization defined, Is this okay? [y/N]: y
    Save arguments to configuration file [Y/n]: ENTER
    SAM configuration file [samconfig.toml]: ENTER
    SAM configuration environment [default]: ENTER

When modifying your configuration file, the AWS SAM CLI handles global values as follows:

• If the parameter value exists in the global section of your configuration file, the AWS SAM CLI doesn’t write the value to the specific command section.

• If the parameter value exists in both the global and specific command sections, the AWS SAM CLI deletes the specific entry in favor of the global value.