tflint

tflint documentation

• Version in MegaLinter: 0.33.1
• Visit Official Web Site
• See How to configure tflint rules
  • If custom .tflint.hcl config file is not found, .tflint.hcl will be used
• See How to disable tflint rules in files
• See Index of problems detected by tflint

Configuration in MegaLinter

• Enable tflint by adding TERRAFORM_TFLINT in ENABLE_LINTERS variable
• Disable tflint by adding TERRAFORM_TFLINT in DISABLE_LINTERS variable

Variable	Description	Default value
TERRAFORM_TFLINT_ARGUMENTS	User custom arguments to add in linter CLI call Ex: -s --foo "bar"
TERRAFORM_TFLINT_FILTER_REGEX_INCLUDE	Custom regex including filter Ex: (src\|lib)	Include every file
TERRAFORM_TFLINT_FILTER_REGEX_EXCLUDE	Custom regex excluding filter Ex: (test\|examples)	Exclude no file
TERRAFORM_TFLINT_CLI_LINT_MODE	Override default CLI lint mode - file: Calls the linter for each file - list_of_files: Call the linter with the list of files as argument - project: Call the linter from the root of the project	{linter.cli_lint_mode}
TERRAFORM_TFLINT_FILE_EXTENSIONS	Allowed file extensions. "*" matches any extension, "" matches empty extension. Empty list excludes all files Ex: [".py", ""]	[".tf"]
TERRAFORM_TFLINT_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
TERRAFORM_TFLINT_PRE_COMMANDS	List of bash commands to run before the linter	[{"command": "tflint --init", "cwd": "workspace"}]
TERRAFORM_TFLINT_POST_COMMANDS	List of bash commands to run after the linter	None
TERRAFORM_TFLINT_CONFIG_FILE	tflint configuration file name Use LINTER_DEFAULT to let the linter find it	.tflint.hcl
TERRAFORM_TFLINT_RULES_PATH	Path where to find linter configuration file	Workspace folder, then MegaLinter default rules
TERRAFORM_TFLINT_DISABLE_ERRORS	Run linter but consider errors as warnings	false
TERRAFORM_TFLINT_DISABLE_ERRORS_IF_LESS_THAN	Maximum number of errors allowed	0

MegaLinter Flavours

This linter is available in the following flavours

	Flavor	Description	Embedded linters	Info
	all	Default MegaLinter Flavor	95
	terraform	Optimized for TERRAFORM based projects	46

Behind the scenes

How are identified applicable files

• File extensions: .tf

How the linting is performed

• tflint is called one time by identified file

Example calls

tflint myfile.tf

tflint -c .tflint.hcl myfile.tf

Help content

Usage:
  tflint [OPTIONS] [FILE or DIR...]

Application Options:
  -v, --version                                                 Print TFLint
                                                                version
      --init                                                    Install plugins
      --langserver                                              Start language
                                                                server
  -f, --format=[default|json|checkstyle|junit|compact|sarif]    Output format
                                                                (default:
                                                                default)
  -c, --config=FILE                                             Config file
                                                                name (default:
                                                                .tflint.hcl)
      --ignore-module=SOURCE                                    Ignore module
                                                                sources
      --enable-rule=RULE_NAME                                   Enable rules
                                                                from the
                                                                command line
      --disable-rule=RULE_NAME                                  Disable rules
                                                                from the
                                                                command line
      --only=RULE_NAME                                          Enable only
                                                                this rule,
                                                                disabling all
                                                                other defaults.
                                                                Can be
                                                                specified
                                                                multiple times
      --enable-plugin=PLUGIN_NAME                               Enable plugins
                                                                from the
                                                                command line
      --var-file=FILE                                           Terraform
                                                                variable file
                                                                name
      --var='foo=bar'                                           Set a Terraform
                                                                variable
      --module                                                  Inspect modules
      --force                                                   Return zero
                                                                exit status
                                                                even if issues
                                                                found
      --no-color                                                Disable
                                                                colorized output
      --loglevel=[trace|debug|info|warn|error]                  Change the
                                                                loglevel

Help Options:
  -h, --help                                                    Show this help
                                                                message

Installation on mega-linter Docker image

• Dockerfile commands :

FROM ghcr.io/terraform-linters/tflint:latest as tflint
COPY --from=tflint /usr/local/bin/tflint /usr/bin/

Example success log

Results of tflint linter (version 0.21.0)
See documentation on https://megalinter.github.io/descriptors/terraform_tflint/
-----------------------------------------------

[SUCCESS] .automation/test/terraform/good/terraform_good_1.tf

Example error log

Results of tflint linter (version 0.21.0)
See documentation on https://megalinter.github.io/descriptors/terraform_tflint/
-----------------------------------------------

[ERROR] .automation/test/terraform/bad/terraform_bad_1.tf
    Failed to load configurations. 1 error(s) occurred:

    Error: Invalid expression

      on .automation/test/terraform/bad/terraform_bad_1.tf line 3, in resource "aws_instance" "bad":
       3:   instance_type =            # invalid type!
       4: }

    Expected the start of an expression, but found an invalid expression token.