tflint

tflint documentation

Version in Mega-Linter: 0.32.1
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 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	93
	terraform	Optimized for TERRAFORM based projects	44

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]    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://nvuillam.github.io/mega-linter/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://nvuillam.github.io/mega-linter/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.