tflint

tflint documentation

• Version in Mega-Linter: 0.33.0
• 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 Mega-Linter

• 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 Mega-Linter 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

Mega-Linter Flavours

This linter is available in the following flavours

	Flavor	Description	Embedded linters	Info
	all	Default Mega-Linter Flavor	94
	terraform	Optimized for TERRAFORM based projects	45

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.