What is Iacer?

Iacer is a tool that tests Terraform and ROS(Resource Orchestration Service) templates. It deploys your template in multiple Alibaba Cloud Regions and generates a report for each region via a simple configuration file.

Installation

pip install iacer

Requirements

Python 3.7+

The iacer is run on requires access to an Alibaba Cloud account, this can be done by any of the following mechanisms:

1. AliyunCli default configuration file (~/.aliyun/config.json)
2. Environment variables (ALIBABA_CLOUD_ACCESS_KEY_ID and ALIBABA_CLOUD_ACCESS_KEY_SECRET)
3. The ini configuration file defined by the environment variable ALIBABA_CLOUD_CREDENTIALS_FILE
4. Alibaba Cloud SDK Credentials default configuration file (~/.alibabacloud/credentials.ini or ~/.aliyun/credentials.ini)

Usage

iacer adopts a similar cli command structure to git with a iacer command subcommand --flag style. The cli is also designed to be the simplest if run from the root of a project. Let's have a look at equivalent command to run a test:

cd into the project root and type test run

cd ./demo
iacer test run

or run it from anywhere by providing the path to the project root

iacer test run --project-path ./demo

Cli Command

The cli is self documenting by using --help or -h, the most common command is iacer test

iacer test -h
usage: iacer [args] test [args] [subcommand] [args] 

Performs functional tests on IaC templates.

options:
  -h, --help  show this help message and exit

subcommands:
  clean - Manually clean up the stacks which were created by Iacer
  list - List stacks which were created by Iacer for all regions
  params - Generate pseudo parameters
  run - tests whether IaC templates are able to successfully launch

iacer test run -h
usage: iacer [args] <command> [args] run [args] 

tests whether IaC templates are able to successfully launch

options:
  -h, --help            show this help message and exit
  -t TEMPLATE, --template TEMPLATE
                        path to a template
  -c CONFIG_FILE, --config-file CONFIG_FILE
                        path to a config file
  -o OUTPUT_DIRECTORY, --output-directory OUTPUT_DIRECTORY
                        path to an output directory
  -r REGIONS, --regions REGIONS
                        comma separated list of regions to test in
  --test-names TEST_NAMES
                        comma separated list of tests to run
  --no-delete           don't delete stacks after test is complete
  --project-path PROJECT_PATH
                        root path of the project relative to config file,
                        template file and output file
  --keep-failed         do not delete failed stacks
  --dont-wait-for-delete
                        exits immediately after calling delete stack
  -g, --generate-parameters
                        generate pseudo parameters

Configuration files

There are 2 config files which can be used to set behaviors.

1. Global config file, located in ~/.iacer.yml
2. Project config file, located in <PROJECT_ROOT>/.iacer.yml

Each configuration file supports three-tier configuration, which includes general, project and tests, and tests is required.

general configuration item

• auth Aliyun authentication section.

{
  "name": "default", 
  "location": "~/.aliyun/config.json"
}

• oss_config Oss bucket configuration, include BucketName, BucketRegion and etc.

{
  "bucket_name": "",
  "bucket_region": "",
  "object_prefix": "",
  "callback_params": {
    "callback_url": "",
    "callback_host": "",
    "callback_body": "",
    "callback_body_type": "",
    "callback_var_params": ""
  }
}

• parameters Parameter key-values to pass to template.

{
  "vpc_id": "",
  "vsw_id": ""
}

project configuration item

• name Project Name
• regions List of aliyun regions.
• parameters Parameter key-values to pass to template.
• tags Tags
• role_name Role name
• template_config Template config

{
  "template_location": "myTemplate/",
  "template_url": "oss://xxx",
  "template_body": "",
  "template_id": "",
  "template_version": ""
}

tests configuration item

• name Project Name
• regions List of aliyun regions.
• parameters Parameter key-values to pass to template.
• tags Tags
• role_name Role name
• template_config Template config

{
  "template_location": "myTemplate/",
  "template_url": "oss://xxx",
  "template_body": "",
  "template_id": "",
  "template_version": ""
}

Precedence

Except the parameters section, more specific config with the same key takes precedence.

The rationale behind having parameters function this way is so that values can be overridden at a system level outside a project, that is likely committed to source control. parameters that define account specific things like VPC details, Key Pairs, or secrets like API keys can be defined per host outside of source control.

For example, consider this global config in ~/.iacer.yml

general:
  oss_config: 
    bucket_name: global-bucket
  parameters:
    KeyPair: my-global-ecs-key-pair

and this project config

project:
  name: my-project
  regions:
    - cn-hangzhou
  oss_config:
    bucket_name: project-bucket
tests:
  default:
    template_config:
      template_url: "oss://xxx"
    regions:
      - cn-beijing
    parameters:
      KeyPair: my-test-ecs-key-pair

Would result in this effective test configuration:

tests:
  default:
    template_config:
      template_url: "oss://xxx"
    regions:
      - cn-beijing
    oss_config:
      bucket_name: project-bucket
    parameters:
      KeyPair: my-test-ecs-key-pair

Notice that bucket_name and regions took the most specific value and KeyPair the most general.

Pseudo Parameters

You can automatically get the available parameters through the $[iacer-auto] pseudo-parameter if the parameter is the following 2 cases

1. The resource attribute corresponding to the parameter supports the ROS GetTemplateParameterConstraints interface.
2. Parameters whose name itself has a specific meaning. For example, VpcId means the id of virtual private cloud and $[iacer-auto] will automatically obtain a vpcId randomly in the current region of the current account. Currently supported are as follows:
   1. Satisfying the regularity r"(\w*)vpc(_|)id(_|)(\d*)" will automatically and randomly obtain the VpcId in the current region.
   2. Satisfying the regularity r"(\w*)v(_|)switch(_|)id(_|)(\d*)" will automatically and randomly obtain the VswitchId in the current region. If there is a parameter whose name satisfies the regularity r"(\w*)zone(_|)id(_|)(\d*)", it will query the VswitchId of the corresponding availability zone
   3. Satisfying the regularity r"(\w*)security(_|)group(_id|id)(_|)(\d*)" will automatically and randomly obtain the SecurityGroupId in the current region.
   4. Satisfying the regularity r"(\w*)name(_|)(\d*)" will automatically generate a random string starting with iacer-.
   5. Satisfying the regularity r"(\w*)password(_|)(\d*)" will automatically generate a password.
   6. Satisfying the regularity r"(\w*)uuid(_|)(\d*)" will automatically generate an uuid.