ktlint

ktlint documentation

Version in MegaLinter: 1.0.1
Visit Official Web Site
See Index of problems detected by ktlint

Configuration in MegaLinter

Enable ktlint by adding KOTLIN_KTLINT in ENABLE_LINTERS variable
Disable ktlint by adding KOTLIN_KTLINT in DISABLE_LINTERS variable

Enable autofixes by adding KOTLIN_KTLINT in APPLY_FIXES variable

Variable	Description	Default value
KOTLIN_KTLINT_ARGUMENTS	User custom arguments to add in linter CLI call Ex: `-s --foo "bar"`
KOTLIN_KTLINT_COMMAND_REMOVE_ARGUMENTS	User custom arguments to remove from command line before calling the linter Ex: `-s --foo "bar"`
KOTLIN_KTLINT_FILTER_REGEX_INCLUDE	Custom regex including filter Ex: `(src\\|lib)`	Include every file
KOTLIN_KTLINT_FILTER_REGEX_EXCLUDE	Custom regex excluding filter Ex: `(test\\|examples)`	Exclude no file
KOTLIN_KTLINT_CLI_LINT_MODE	Override default CLI lint mode - `file`: Calls the linter for each file - `project`: Call the linter from the root of the project	`file`
KOTLIN_KTLINT_FILE_EXTENSIONS	Allowed file extensions. `"*"` matches any extension, `""` matches empty extension. Empty list excludes all files Ex: `[".py", ""]`	`[".kt", ".kts"]`
KOTLIN_KTLINT_FILE_NAMES_REGEX	File name regex filters. Regular expression list for filtering files by their base names using regex full match. Empty list includes all files Ex: `["Dockerfile(-.+)?", "Jenkinsfile"]`	Include every file
KOTLIN_KTLINT_PRE_COMMANDS	List of bash commands to run before the linter	None
KOTLIN_KTLINT_POST_COMMANDS	List of bash commands to run after the linter	None
KOTLIN_KTLINT_UNSECURED_ENV_VARIABLES	List of env variables explicitly not filtered before calling KOTLIN_KTLINT and its pre/post commands	None
KOTLIN_KTLINT_DISABLE_ERRORS	Run linter but consider errors as warnings	`false`
KOTLIN_KTLINT_DISABLE_ERRORS_IF_LESS_THAN	Maximum number of errors allowed	`0`
KOTLIN_KTLINT_CLI_EXECUTABLE	Override CLI executable	`['ktlint']`

IDE Integration

Use ktlint in your favorite IDE to catch errors before MegaLinter !

	IDE	Extension Name	Install
	Emacs	flycheck-kotlin	Visit Web Site
	vim	ale	Visit Web Site

MegaLinter Flavours

This linter is available in the following flavours

Flavor	Description	Embedded linters
all	Default MegaLinter Flavor	121
c_cpp	Optimized for pure C/C++ projects	55
cupcake	MegaLinter for the most commonly used languages	85
documentation	MegaLinter for documentation projects	51
dotnet	Optimized for C, C++, C# or VB based projects	64
dotnetweb	Optimized for C, C++, C# or VB based projects with JS/TS	73
go	Optimized for GO based projects	53
java	Optimized for JAVA based projects	55
javascript	Optimized for JAVASCRIPT or TYPESCRIPT based projects	60
php	Optimized for PHP based projects	54
python	Optimized for PYTHON based projects	62
ruby	Optimized for RUBY based projects	51
rust	Optimized for RUST based projects	51
salesforce	Optimized for Salesforce based projects	55
swift	Optimized for SWIFT based projects	51
terraform	Optimized for TERRAFORM based projects	55

Behind the scenes

How are identified applicable files

File extensions: .kt, .kts

How the linting is performed

ktlint is called one time by identified file (file CLI lint mode)

Example calls

ktlint myfile.kt

ktlint --format myfile.kt

Help content


An anti-bikeshedding Kotlin linter with built-in formatter.
(https://github.com/pinterest/ktlint).

Usage:
  ktlint <flags> [patterns]
  java -jar ktlint.jar <flags> [patterns]

Examples:
  # Check the style of all Kotlin files (ending with '.kt' or '.kts') inside
the current dir (recursively).
  #
  # Hidden folders will be skipped.
  ktlint

  # Check only certain locations starting from the current directory.
  #
  # Prepend ! to negate the pattern, KtLint uses .gitignore pattern style
syntax.
  # Globs are applied starting from the last one.
  #
  # Hidden folders will be skipped.
  # Check all '.kt' files in 'src/' directory, but ignore files ending with
'Test.kt':
  ktlint "src/**/*.kt" "!src/**/*Test.kt"
  # Check all '.kt' files in 'src/' directory, but ignore 'generated' directory
and its subdirectories:
  ktlint "src/**/*.kt" "!src/**/generated/**"

  # Auto-correct style violations.
  ktlint -F "src/**/*.kt"

  # Using custom reporter jar and overriding report location
  ktlint --reporter=csv,artifact=/path/to/reporter/csv.jar,
output=my-custom-report.csv
Flags:

      --code-style=<codeStyle>
                        Defines the code style (ktlint_official, intellij_idea
                          or android_studio) to be used for formatting the
                          code. This option is deprecated, and will be removed
                          in Ktlint 1.1. The code style has to be defined as '.
                          editorconfig' property 'ktlint_code_style'.
      --color           Make output colorful
      --color-name=<colorName>
                        Customize the output color
      --disabled_rules=<disabledRules>
                        Comma-separated list of rules to globally disable. This
                          option is deprecated, and will be removed in Ktlint
                          1.1. The disabled rules have to be defined as '.
                          editorconfig' properties. See https://pinterest.
                          github.io/ktlint/1.0.0
                          /faq/#how-do-i-enable-or-disable-a-rule
  -F, --format          Fix deviations from the code style when possible
      --limit=<limit>   Maximum number of errors to show (default: show all)
      --relative        Print files relative to the working directory (e.g.
                          dir/file.kt instead of /home/user/project/dir/file.kt)
      --reporter=<reporterConfigurations>
                        A reporter to use (built-in: plain (default), plain?
                          group_by_file, plain-summary, json, sarif,
                          checkstyle, html). To use a third-party reporter
                          specify a path to a JAR file on the filesystem via ',
                          artifact=' option. To override reporter output, use ',
                          output=' option.
  -R, --ruleset=<rulesetJarPaths>
                        A path to a JAR file containing additional ruleset(s)
      --stdin           Read file from stdin
      --patterns-from-stdin[=<stdinDelimiter>]
                        Read additional patterns to check/format from stdin.
                          Patterns are delimited by the given argument.
                          (default is newline) If the argument is an empty
                          string, the NUL byte is used.
      --editorconfig=<editorConfigPath>
                        Path to the default '.editorconfig'. A property value
                          from this file is used only when no '.editorconfig'
                          file on the path to the source file specifies that
                          property. Note: up until ktlint 0.46 the property
                          value in this file used to override values found in '.
                          editorconfig' files on the path to the source file.
      --experimental    Enable experimental rules. This option is deprecated,
                          and will be removed in Ktlint 1.1. The experimental
                          flag has to be set as '.editorconfig' property
                          'ktlint_experimental'. See https://pinterest.github.
                          io/ktlint/1.0.0
                          /faq/#how-do-i-enable-or-disable-a-rule-set
      --baseline=<baselinePath>
                        Defines a baseline file to check against
  -l, --log-level=<minLogLevel>
                        Defines the minimum log level (trace, debug, info,
                          warn, error) or none to suppress all logging
  -h, --help            Show this help message and exit.
  -V, --version         Print version information and exit.
Commands:
  installGitPreCommitHook  Install git hook to automatically check files for
                             style violations on commit
  installGitPrePushHook    Install git hook to automatically check files for
                             style violations before push
  generateEditorConfig     Generate kotlin style section for '.editorconfig'
                             file.

Installation on mega-linter Docker image

Dockerfile commands :

# Parent descriptor install
ENV JAVA_HOME=/usr/lib/jvm/java-17-openjdk
ENV PATH="$JAVA_HOME/bin:${PATH}"
# Linter install
RUN curl --retry 5 --retry-delay 5 -sSLO https://github.com/pinterest/ktlint/releases/latest/download/ktlint && \
    chmod a+x ktlint && \
    mv "ktlint" /usr/bin/