declapract

Scalable software best practices. Declare, plan, and apply software practices across code bases.

Table of Contents

• Table of Contents
• Purpose
• Usage
• Commands
• Philosophy
• Declarations
• Contribution

Purpose

Scaling software best practices across an organization is difficult - but when done right, is a super power!

declapract provides a declarative, scalable, and maintainable way to define, enforce, and evolve software best practices to unlock:

• systematic knowledge synthesis
  • practices are declaratively defined with code and explained with readmes
  • so that
    • future travelers can read exactly why a practice was deemed "best" or "bad"
    • future travelers can collaborate on, debate, improve, and manage software practices like code (e.g., with pull requests, issues, etc)
• automatic knowledge transfer
  • developers in your org are alerted any time they don't follow a best practice - or use a bad practice!
  • so that
    • knowledge is not siloed to people that have learned through tribal knowledge already what practices are best or bad
    • knowledge can be transferred automatically as part of the automated software development lifecycle (e.g., as part of your cicd-pipeline, exposed in pull-requests)
• effortless code base monitoring
  • determine for any code base whether and which software practices it is not adhering to with one command
  • so that
    • you can automatically block code changes that introduce bad practices / don't follow best practices
    • you can easily get check each code base in your organization to get an overview of technical debt
• scalable technical debt elimination
  • automatically fix code bases, upgrading them to your best practices and removing bad practices
  • so that
    • you can scale keeping your code bases up to date
    • your developers can get back to adding business value instead of upgrading old project

Software practices are an infrastructure of their own. Its time we manage them like it.

Usage

There are a few cases for using declapract. We'll go over each.

Case 1: Create a new code base from declared best practices

Similar to git clone, but leveraging explicitly declared best practices to create an entirely new project instead.

Example:

npx declapract clone --declarations=npm:module-with-your-declarations --use-case=your-use-case

Case 2: Add best practice management to a code base

Sets up a code base to follow a set of declared best practices.

install

npm install --save-dev declapract

configure

touch ./declapract.use.yml;
echo "
declarations: npm:module-with-your-practices
useCase: your-use-case
variables:
  variableName: 'variableValue' # the variables required by the  practices
  ...
" >> ./declapract.use.yml;

Case 3: Declare best practices

First, you'll need to create a new repository that will house your declared practices. The best way to do this is to clone our best practices for declaring best practices 😄

npx declapract --declarations=ssh:github.com/uladkasach/best-practices-declarations --use-case=declare

Next, you'll need to declare your practices, use-cases, and examples. See the docs on declarations to learn how to do this.

Commands

• declapract apply
• declapract compile
• declapract help [COMMAND]
• declapract plan
• declapract validate

declapract apply

apply fixes to all files which have failed to adhere to any of the project's declared practices and have an automatic fix available.

USAGE
  $ declapract apply

OPTIONS
  -c, --config=config      (required) [default: declapract.use.yml] path to the declapract usage config yml
  -f, --file=file          the file path of a specific file you want to scope checking for
  -h, --help               show CLI help
  -p, --practice=practice  the name of a specific practice you want to scope checking for

See code: dist/contract/commands/apply.ts

declapract compile

compile the declared declarations so that they can be packaged and distributed by npm safely

USAGE
  $ declapract compile

OPTIONS
  -d, --distributionDirectory=distributionDirectory  (required) [default: dist] the distribution directory to which we
                                                     will compile the declarations

  -h, --help                                         show CLI help

  -s, --sourceDirectory=sourceDirectory              (required) [default: src] the source directory which contains the
                                                     declarations to compile

See code: dist/contract/commands/compile.ts

declapract help [COMMAND]

display help for declapract

USAGE
  $ declapract help [COMMAND]

ARGUMENTS
  COMMAND  command to show help for

OPTIONS
  --all  see all commands in CLI

See code: @oclif/plugin-help

declapract plan

plan and display what actions need to be taken in order to make a software project adhere to its declared practices.

USAGE
  $ declapract plan

OPTIONS
  -c, --config=config      (required) [default: declapract.use.yml] path to the declapract usage config yml
  -f, --file=file          the file path of a specific file you want to scope checking for
  -h, --help               show CLI help
  -p, --practice=practice  the name of a specific practice you want to scope checking for

See code: dist/contract/commands/plan.ts

declapract validate

validate the declared practices, use cases, and examples; checks that these declarations are usable and don't contain declaration errors

USAGE
  $ declapract validate

OPTIONS
  -c, --config=config  (required) [default: declapract.declare.yml] path to the declapract declarations config yml
  -h, --help           show CLI help

See code: dist/contract/commands/validate.ts

Philosophy

declarative > imperative

define what you want/dont-want to see, not how to check it

why? maintainability! declarative code is much easier to read, write, and collaborate on

note:

• although declapract still lets you imperatively define custom check functions, you should be writing your checks declaratively in most cases.
• if you find a common use case that you can't write declaratively, open up an issue so we can get it supported!

automatic fixes for everything

files failing checks should have a fix that can be automatically applied

why? speed, quality, and happiness: computers are much better at, faster at, and happier to do repetitive tasks than humans

note:

• declapract automatically defines fixes for you on as many FileCheckTypes as possible, but you may still need to explicitly define the fix in some cases yourself
• if you find a common use case that you have to write custom fixes for, open up an issue so we can get it supported!

Declarations

declapract enables you to define your best-practices and bad-practices by showing examples of what you want/dont-want files to be like in the projects you're checking.

For example, a file structure such as this:

- src/
  - practices/
    - terraform/
      - best-practice/
        - .terraform-version
        - terraform/
          - modules/
            - main.tf.declapract.ts
            - sqs.tf.declapract.ts
          - environments/
            - prod/
              - main.tf
              - main.tf.declapract.ts
            - dev
              - main.tf
              - main.tf.declapract.ts
      - bad-practices/
        - tfvars/
          - terraform/
            - **/
              - *.tfvars.declapract.ts

tells us that we have one best-practice and one bad-practice defined.

The best-practice directory declares an example of what a project following the best practice looks like, with some declapract metadata files that allow us to customize what to check for.

The best-practice, in this example, checks several files. For example:

• .terraform-version has its expected contents declared
  • which means that projects using this practice will need
    • a file with path .terraform-version to exist (it is required, by default)
    • the file the match the exact file contents declared here (the check type is FileCheckType.EXACT, when file contents are declared, by default)
• terraform/modules/main.tf has a metadata file declared for it, terraform/modules/main.tf.declapract.tf
  • this could mean multiple things, as the metadata file gives you lots of customization over what to check
  • for example:
    • there may be a custom check defined
    • the file may just need to be checked for existence
  • see more details about the file-check-metadata file below
• terraform/environments/prod/main.tf has both: a file declaring expected contents and a metadata file
  • the fact that the user declared expected contents means that they likely want to use them in the check
  • the presence of the metadata file could mean many things
    • the user may have just wanted to define a custom fix function
    • the user may have wanted to check that the file contains the declared contents, instead of the default exact equals check
    • the user may have also wanted to specify that the existence of this file is optional
  • we'd have to read the contents of the file-check-metadata file to find out for sure, but these are the options above

The bad-practice directory, on the other hand, declares an example of what not to do; i.e., what a project that followed this bad practice would look like. It too includes declapract metadata files in order to customize what to check for, for each file.

The bad-practice bad-practices/tfvars, in this example, can check many files even though it only declares one checks:

• terraform/**/*.tfvars is the glob pattern for the files to check declared by this bad-practice
  • this means that the check defined here will apply to all files that match the terraform/**/*.tfvars glob pattern, if any

Practices

Practices are coding patterns that you either want to require in projects - or forbid in projects. Practices are defined in a declarative way by defining the files that are relevant to the practice and how to check them. Practices are defined through the example of a best-practice or one or more bad-practices (or both).

The name of a practice is defined by the name of the directory its declarations live in. For example, a directory named practices/terraform/ would house the terraform practice.

Practices can have up to one best-practice and any number of bad-practices declared. These, too, are identified by directory structure. For example, practices/terraform/best-practice will house the best-practice declaration for terraform - and practices/terraform/bad-practices/tfvars would house a bad-practice declaration.

Both best-practice and bad-practice declarations are defined in the same way, by declaring an example of a project that should be matched against. In other words, you'll define the files you want to check by defining them just like you would in a real project - and you'll define how to check them by declaring their contents, metadata, or a custom check function.

File Check Declaration Examples

FileCheckType.EQUALS

The most straight forward file check type is the "exact contents" file check. Its used to check that a file's contents exactly equal the contents you declare.

To define one of these, simply declare the contents of the file you want to check.

For example:

• declare practices/terraform/best-practice/.terraform-version as:

  0.14.11
  

• to check that:
  • a file named .terraform-version is defined at path <root>/.terraform-version and that
  • its contents exactly equal what is declared in that file: 0.14.11.

FileCheckType.CONTAINS

Another common file check type is the "contains contents" file check. Its used to check that a file's contents contain the contents you declare.

To define one of these, declare the contents that you want to see contained in the file matching the file path - and then additionally define a file-check-metadata file for that file's path and use it to specify that the check type should be CONTAINS.

For example:

• declare practices/git/best-practice/.gitignore as

  dist
  node_modules
  coverage
  .serverless
  .env
  .terraform
  .terraform.lock
  

• and declare practices/git/best-practice/.gitignore.declapract.ts as

  import { FileCheckType } from 'declapract';
  
  export const check = FileCheckType.CONTAINS;

• to check that:
  • a file named .gitignore is defined at path <root>/.gitignore
  • its contents contain what is declared in practices/git/best-practice/.gitignore

@declapract{variable}s in declaration files

Declapract supports referencing project variables in declaration files.

For example:

• declare the variables for your project in your declapract.use.yml config

  variables:
    serviceName: 'svc-awesomeness'
    organizationName: 'all-the-things-corp'

• and declare a file check that references these variables, practices/npm/best-practice/README.md

  # @declapract{variable.serviceName}
  
  this is the repo for `@declapract{variable.serviceName}` of org `@declapract{variable.organizationName}`
  
  this readme contains all of the relevant details needed to be known about @declapract{variable.serviceName}

• to check that:

  • a file named README.md is defined at path <root>/README.md and that
  • it contains the contents of:

    # svc-awesomeness
    
    this is the repo for `svc-awesomeness` of org `all-the-things-corp`
    
    this readme contains all of the relevant details that are needed to be known about svc-awesomeness

FileCheckType.CONTAINS on a .json file

A more specific case of the "contains check" is when it applies to a JSON file. Declapract defaults to using a special contains check function which checks that each key-value pair of the found json object and the declared json objects match, instead of doing a simple "contains substring" check like normal.

For example:

• declare practices/prettier/best-practice/package.json as

  {
    "name": "@declapract{variable.serviceName}",
    "devDependencies": {
      "prettier": "@declapract{check.minVersion('2.0.0')}"
    },
    "scripts": {
      "format": "prettier --write 'src/**/*.ts'"
    }
  }

• and declare practices/prettier/best-practice/package.json as

  import { FileCheckType } from 'declapract';
  
  export const check = FileCheckType.CONTAINS;

• to check that:
  • a file named package.json is defined at path <root>/package.json
  • that it contains a json object
  • that the json object has a key name defined as the serviceName declared in your project's variables
    • note that this part employs the use of a declapract variable
  • that the json object has key scripts.format defined as "prettier --write 'src/**/*.ts'
  • that the json object has key devDependencies.prettier defined as a version which is greater than or equal to 2.0.0
    • note that this part employs the use of a declapract check expression

FileCheckType.EXISTS

Another common file check type is the "exists" file check. As you'd expect, its used to check whether a file exists.

To define one of these, simply define a file-check-metadata file for that file's path and specify that the check type should be EXISTS.

For example, for defining a best practice:

• declare practices/npm/best-practice/package-lock.json.declapract.ts as:

  import { FileCheckType } from 'declapract';
  
  export const check = FileCheckType.EXISTS;

• to check that:
  • a file with path practices/npm/best-practice/package-lock.json exists

For example, for defining a bad practice:

• declare practices/directory-structure/bad-practices/models-dir/src/models/**/*.ts.declapract.ts as:

  import { FileCheckType } from 'declapract';
  
  export const check = FileCheckType.EXISTS;

• to check that:
  • no files match the path <root>/src/models/**/*.ts
  • note that in this example we specified a bad-practice, which is why declapract will make sure that files which match the EXISTS check for this path do not exist.

FileCheckType.CUSTOM

When the above checks don't meet your needs, you are able to declare a custom check for files that match a file path.

To define one of these, simply define a file-check-metadata file for that file's path and specify a custom check function.

Throw an error if the file does not pass the check - or return nothing if it does.

For example:

• declare practices/npm/best-practice/package.json.declapract.ts

  import { FileCheckFunction, FileCheckContext } from 'declapract';
  
  export const check: FileCheckFunction = (contents: string | null, context: FileCheckContext) => {
    // anything way you want to check
  }

To Do

todo: update the readme to better document how to define FileCheckDeclarations and PracticeDeclarations

• fixes
• more clear examples
• best practice -vs- bad practices
• syntax on defining custom check functions
• etc

Contribution

Team work makes the dream work! Please create a ticket for any features you think are missing and, if willing and able, draft a PR for the feature :)