fix: Support valid Terragrunt tfr:/// format in autodiscovery #7357
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Fixes parsing of Terragrunt module sources using the tfr:/// (triple slash) format, which is the valid Terragrunt syntax for default registry. The current implementation fails on tfr:/// because it constructs baseUrl with a leading slash (/terraform-aws-modules/eks/aws) which ParseModuleSource rejects. URL format: protocol://hostname/path - tfr:///namespace/name/target → Host="", Path="/namespace/name/target" - tfr://registry.io/namespace/name/target → Host="registry.io", Path="/namespace/name/target" - tfr://namespace/name/target → Host="namespace", Path="/name/target" The 2-slash format (tfr://terraform-aws-modules/...) works in Updatecli's parser by accident but FAILS in actual Terragrunt with "lookup terraform-aws-modules: no such host" because it treats the namespace as a hostname. This fix strips the leading slash and correctly handles all valid formats.
Update all test files and test expectations to use the valid tfr:/// (triple slash) format instead of the invalid tfr:// (two slash) format. Changes: - testdata/*.hcl: Updated module sources to tfr:/// - main_test.go: Updated expected manifest outputs - matching_rule_test.go: Updated test cases and assertions - matching_rule.go: Updated documentation example
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The matching rule code strips 'tfr://' from patterns, leaving an extra slash when the pattern is 'tfr:///'. This causes invalid wildcard URLs like 'tfr:////updatecliswildcard'. Add TrimPrefix to remove the leading slash after stripping the protocol, ensuring correct token counting for wildcard expansion. Also update utils_test.go expectations to use tfr:/// format.
Contributor
Author
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Hi @olblak how does that look to you? |
andreyreshetnikov-zh
approved these changes
Dec 31, 2025
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Thanks @eugenestarchenko for the pull request. |
Member
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Thanks for the pull request, it looks great to me especially with the test I'll merge it once done |
olblak
previously approved these changes
Jan 1, 2026
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Author
done |
olblak
approved these changes
Jan 1, 2026
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Problem
Terragrunt's valid
tfr:///(triple slash) format fails in autodiscovery with:Root Cause
Both the parser and matching rule code strip
tfr://from URLs, but this leaves a leading slash when the format istfr:///:Example:
tfr:///terraform-aws-modules/eks/awstfr://:/terraform-aws-modules/eks/awsIn matching rules with wildcards:
tfr:///(match all registry modules)tfr://:/remainstfr:////updatecliswildcard/updatecliswildcard/updatecliswildcardWhy not use 2 slash format?
The test suite uses
tfr://terraform-aws-modules/...(2 slashes), which works in Updatecli but fails in actual Terragrunt:Per URL spec
protocol://hostname/path, the 2-slash format treatsterraform-aws-modulesas a hostname, causing DNS lookup failures.Valid Terragrunt formats:
tfr:///terraform-aws-modules/eks/aws(3 slashes = empty hostname → defaults to registry.terraform.io)tfr://registry.terraform.io/terraform-aws-modules/eks/aws(explicit registry)Invalid in Terragrunt:
tfr://terraform-aws-modules/eks/aws(2 slashes = namespace treated as hostname)See https://terragrunt.gruntwork.io/docs/reference/hcl/blocks/#terraform
Result
All valid Terragrunt formats now work:
Testing
Verified with real Terragrunt module: