Test all the CloudFormation things! (with TaskCat)
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What is taskcat?

taskcat is a tool that tests AWS CloudFormation templates. It deploys your AWS CloudFormation template in multiple AWS Regions and generates a report with a pass/fail grade for each region. You can specify the regions and number of Availability Zones you want to include in the test, and pass in parameter values from your AWS CloudFormation template. taskcat is implemented as a Python class that you import, instantiate, and run.

TestCat was developed by the AWS QuickStart team to test AWS CloudFormation templates that automatically deploy workloads on AWS. We’re pleased to make the tool available to all developers who want to validate their custom AWS CloudFormation templates across AWS Regions


Feature Request Report Bugs Frequently Asked Questions

Installing taskcat

taskcat can be install using docker or pip

Installing via docker

Docker Required

curl -s https://raw.githubusercontent.com/aws-quickstart/taskcat/master/installer/docker-installer.sh | sh

Note: (If you do not have root privileges taskcat will install in the current directory)

Python Requirements:

Python pipPyPI - Python Version

Installing via pip3

pip3 install taskcat

Installing via pip3 --user

(for those who want to install taskcat into their homedir)

pip3 install taskcat --user

Note: (the user install dir is platform specific)

For Example: (On Mac: ~/Library/Python/3.x/bin/taskcat)

For Example: (On Linux: ~/.local/bin)

Warning: Be sure to add the python bin dir to your $PATH

Running taskcat

Note: If you have AWS credentials sourced (or default boto profile is available)

taskcat -c sample-taskcat-project/ci/config.yml

If you need to pass ACCESS and SECRET keys

taskcat -c sample-taskcat-project/ci/config.yml -A YOUR_ACCESS_KEY -S YOUR_SECRET_KEY

If you want to use a different account or profile

taskcat -c sample-taskcat-project/ci/config.yml -P boto-profile-name

Files you’ll need

  • taskcat.yml - This file contains the test cases

  • JSON input - This file contains the inputs that you want to pass to AWS CloudFormation template that is being tested

  • Step 1: Building your configuration file

  • Step 2: Building your JSON input file.

Step 1: Creating a taskcat.yml

Open the taskcat.yml file with and editor and update the filenames to match your need.

example here: taskcat.yml

Example of taskcat.yml

  owner: owner@company.com
  qsname: sample-cloudformation-project <- Must match the root directory of project (usually the name of git repo)
  #s3bucket: projectx-templates <- (Optional) Only needed if you want to use a specific bucket
    - us-east-1
    - us-east-2
    - us-west-1
    - us-west-2
  # The following test will test in both us-west-1 and us-east-1 using sample-cloudformation-input.json as inputs
      - us-west-1
      - us-east-1
    template_file: sample-cloudformation-project-novpc.template
    parameter_input: sample-cloudformation-input-novpc.json
  # The following test will test in both all 4 region defined in the global region section using sample-cloudformation-input.json as inputs
    parameter_input: sample-cloudformation-input-withvpc.json
    template_file: sample-cloudformation-project-withvpc.template

Example of project directory structure

├── LICENSE.txt
├── README.md
├── ci
│   ├── taskcat.yml <- This the config file that will hold all the test definitions
│   ├──  sample-cloudformation-input-novpc.json <-  This file contain input that will pass in during stack creation [vpc version] (See auto parms for more info)
│   └──  sample-cloudformation-input-withvpc.json <-  This file contain input that will pass in during stack creation [no-vpc version](See auto parms for more info)
├── scripts
│   └── userdata.sh <- If you have userdata scripts you can load then in the scripts directory
├── submodules  <- If you have git submodules you can load them in the submodules directory
│   └── quickstart-aws-vpc
│       └── templates
│           └── aws-vpc.template
└── templates
    ├── sample-cloudformation-project-novpc.template
    └── sample-cloudformation-project-withvpc.template <- Second version on template that will create a vpc with the workload

Step 2: Building a json input file

The example below shows an input file for a stack that requires seven parameters KeyPairName,InstanceType, AvailablityZones, RandomString, RandomNumbers, GenerateUUID and Password

Note: you can auto generate values at runtime using taskcat runtime injection (see example below).

The following json will evaluate


    "ParameterKey": "KeyPairName",
    "ParameterValue": "mykey"
}, {
    "ParameterKey": "InstanceType",
    "ParameterValue": "t2.small"
}, {
    "ParameterKey": "AvailablityZones",
    "ParameterValue": "$[taskcat_genaz_2]"
}, {
    "ParameterKey": "RandomString",
    "ParameterValue": "$[taskcat_random-string]"
}, {
    "ParameterKey": "RandomNumbers",
    "ParameterValue": "$[taskcat_random-numbers]"
}, {
    "ParameterKey": "GenerateUUID",
    "ParameterValue": "$[taskcat_genuuid]"
}, {
    "ParameterKey": "Password",
    "ParameterValue": "$[taskcat_genpass_8A]"
}, {
    "ParameterKey": "PasswordConfirm",
    "ParameterValue": "$[taskcat_getval_Password]"


    "ParameterKey": "KeyPair",
    "ParameterValue": "mykey"
}, {
    "ParameterKey": "InstanceType",
    "ParameterValue": "t2.small"
} {
    "ParameterKey": "AvailablityZones",
    "ParameterValue": "us-east-1a, us-east1b"
}, {
    "ParameterKey": "RandomString",
    "ParameterValue": "yysuawpwubvotiqgwjcu"
}, {
    "ParameterKey": "RandomNumbers",
    "ParameterValue": "56188163597280820763"
}, {
    "ParameterKey": "GenerateUUID",
    "ParameterValue": "1c2e3483-2c99-45bb-801d-8af68a3b907b"
}, {
    "ParameterKey": "Password",
    "ParameterValue": "tI8zN3iX8"
}, {
    "ParameterKey": "PasswordConfirm",
    "ParameterValue": "tI8zN3iX8"

More information on taskcat runtime injection


Value that matches the following pattern will be replaced:

  • All runtime injection parameters must start with $[
  • Parameters must end with ]

To generate a random 8 character alpha-numeric password for testing use $[taskcat_genpass_8] as the value in the json input file

  • The number (8) in the injection string tells taskcat you want a password that character long.
  • Changing the 8 to 12 would result in a 12 character string

(Optionally - you can specify the type of password by adding A or S)

  • A alpha-numeric passwords
  • S passwords with special characters

Example: $[taskcat_genpass_8A]

Generates: tI8zN3iX8

Example: $[taskcat_genpass_8S]

Generates: mA5@cB5!

(Availability Zones)

Value that matches the following pattern will be replaced

  • Parameters must start with $[
  • Parameters must end with ]
  • genaz in invoked when taskcat_genaz_X is found
  • A number of AZ's will be selected from the region the stack is attempting to launch

Example: $[taskcat_genaz_2]

Generates: us-east-1a, us-east-2b

(if the region is us-east-1)

(Auto generated s3 bucket )

Example: $[taskcat_autobucket]

Generates: evaluates to auto generated bucket name (taskcat-tag-sample-taskcat-project-5fba6597)

(Generate UUID String)

Example: $[taskcat_genuuid]

Generates: 1c2e3483-2c99-45bb-801d-8af68a3b907b

(Generate Random Values)


Example: $[taskcat_random-string]

Generates: yysuawpwubvotiqgwjcu


Example: $[taskcat_random-numbers]

Generates: 56188163597280820763

(Retrieve previously generated value based on parameter name)

UseCase: Need to confirm a dynamically generated password

"ParameterKey": "MyAppPassword"

"ParameterValue": "$[taskcat_genpass_8A]"

Generates: pI8zN4iX8

"ParameterKey": "ConfirmMyAppPassword"

"ParameterValue": "$[taskcat_getval_MyAppPassword]"

Generates: pI8zN4iX8

More info here

Local Parameter Overrides.

In certain situations it may be desirable to introduce local Parameter Override values. taskcat supports this via two files.

The first is located .aws directory within the home-directory of the running user.


The second applies per-project and is located the 'ci' directory.


Parameters defined in either file will supersede parameters within the normal parameter files. The override includes are read in the following order.

  • Home Directory (~/.aws/taskcat_global_override.json)
  • Project Directory (ci/taskcat_project_override.json)

Note: Keys defined in the Project override with supersede the same keys defined in the global override. More info here

Packaging lambda functions

taskcat can automatically zip lambda function source found in functions/source/* folders. folders are zipped up and placed in functions/packages/FunctionName/lambda.zip. To enable this functionality you will need to enable it in your taskcat.yaml file by adding package-lambda: true to the global section:

  package-lambda: true

Additionally, taskcat can be set to package zips and then exit without taking any other actions. This can be done by setting the -b or --lambda-build-only flag.


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