philiprehberger-env_diff

Compare environment variables across environments and report differences

Requirements

• Ruby >= 3.1

Installation

Add to your Gemfile:

gem "philiprehberger-env_diff"

Or install directly:

gem install philiprehberger-env_diff

Usage

require "philiprehberger/env_diff"

# Compare two hashes
source = { "DATABASE_URL" => "postgres://localhost/dev", "SECRET" => "abc", "OLD_KEY" => "remove_me" }
target = { "DATABASE_URL" => "postgres://prod-host/app", "SECRET" => "abc", "NEW_KEY" => "added" }

diff = Philiprehberger::EnvDiff.compare(source, target)

diff.added     # => ["NEW_KEY"]
diff.removed   # => ["OLD_KEY"]
diff.changed   # => { "DATABASE_URL" => { source: "postgres://localhost/dev", target: "postgres://prod-host/app" } }
diff.unchanged # => ["SECRET"]
diff.changed?  # => true
puts diff.summary
# + NEW_KEY
# - OLD_KEY
# ~ DATABASE_URL: "postgres://localhost/dev" -> "postgres://prod-host/app"

Masked summary

Hide sensitive values in the summary output using exact strings or regex patterns:

puts diff.summary(mask: ["SECRET", /PASSWORD|TOKEN/])
# + NEW_KEY
# - OLD_KEY
# ~ SECRET: *** -> ***

Structured output

diff.to_h
# => { added: { "NEW_KEY" => "added" }, removed: { "OLD_KEY" => "remove_me" },
#      changed: { "DATABASE_URL" => { source: "postgres://localhost/dev", target: "postgres://prod-host/app" } },
#      unchanged: { "SECRET" => "abc" } }

diff.to_json  # => JSON string of the structured hash

Filter by pattern

db_diff = diff.filter(pattern: /^DATABASE/)
db_diff.changed.keys  # => ["DATABASE_URL"]

Stats

diff.stats
# => { added: 1, removed: 1, changed: 1, unchanged: 1, total: 4 }

Validation

Check that all required keys exist in a target hash or .env file:

target = { 'DATABASE_URL' => 'postgres://localhost', 'PORT' => '3000' }
result = Philiprehberger::EnvDiff.validate(target, required: %w[DATABASE_URL SECRET PORT])
result[:valid]   # => false
result[:missing] # => ["SECRET"]

# Also works with .env file paths
result = Philiprehberger::EnvDiff.validate(".env.production", required: %w[DATABASE_URL SECRET])

Case-Insensitive Comparison

Normalize keys to uppercase before comparing by passing case_sensitive: false:

diff = Philiprehberger::EnvDiff.compare(
  { "db_host" => "localhost" },
  { "DB_HOST" => "localhost" },
  case_sensitive: false
)
diff.changed? # => false
diff.unchanged # => ["DB_HOST"]

Export Formats

Format a diff result as a Markdown or HTML table:

diff = Philiprehberger::EnvDiff.compare(source, target)

puts Philiprehberger::EnvDiff.to_markdown(diff)
# | Key | Status | Source | Target |
# | --- | ------ | ------ | ------ |
# | NEW_KEY | added | | added |
# | OLD_KEY | removed | remove_me | |
# | DATABASE_URL | changed | postgres://localhost/dev | postgres://prod-host/app |
# | SECRET | unchanged | abc | abc |

puts Philiprehberger::EnvDiff.to_html(diff)
# <table>
#   <tr><th>Key</th><th>Status</th><th>Source</th><th>Target</th></tr>
#   <tr><td>NEW_KEY</td><td>added</td><td></td><td>added</td></tr>
#   ...
# </table>

Compare against system ENV

diff = Philiprehberger::EnvDiff.from_system({ "APP_ENV" => "production" })
diff = Philiprehberger::EnvDiff.from_system(".env.production")

Compare .env files

diff = Philiprehberger::EnvDiff.from_env_file(".env.development", ".env.production")
puts diff.summary

Parse .env files

vars = Philiprehberger::EnvDiff::Parser.parse(<<~ENV)
  # Database config
  DATABASE_URL=postgres://localhost/dev
  export SECRET_KEY="my-secret"
  APP_NAME='my-app'
ENV
# => { "DATABASE_URL" => "postgres://localhost/dev", "SECRET_KEY" => "my-secret", "APP_NAME" => "my-app" }

API

Method / Class	Description
EnvDiff.compare(source, target, case_sensitive: true)	Compare two hashes and return a Diff
EnvDiff.from_hash(hash_a, hash_b, case_sensitive: true)	Alias for compare
EnvDiff.from_env_file(path_a, path_b, case_sensitive: true)	Parse two .env files and compare them
EnvDiff.from_system(target, case_sensitive: true)	Compare current ENV against a target hash or .env file path
EnvDiff.validate(target, required:)	Check that all required keys exist in target; returns { valid:, missing: }
EnvDiff.to_markdown(diff)	Format a diff result as a Markdown table string
EnvDiff.to_html(diff)	Format a diff result as an HTML table string
Diff#added	Array of keys in target but not source
Diff#removed	Array of keys in source but not target
Diff#changed	Hash of keys with different values
Diff#unchanged	Array of keys with identical values
Diff#changed?	true if any differences exist
Diff#summary(mask: [])	Human-readable multiline diff string with optional value masking
Diff#to_h	Structured hash with :added, :removed, :changed, :unchanged
Diff#to_json	JSON serialization of the structured hash
Diff#filter(pattern:)	New Diff containing only keys matching the regex pattern
Diff#stats	Hash of counts: :added, :removed, :changed, :unchanged, :total
Parser.parse(content)	Parse .env string into a hash
Parser.parse_file(path:)	Read and parse a .env file

Development

bundle install
bundle exec rspec
bundle exec rubocop

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License

MIT