Terraform Provider Semvers

Implements a data-source semvers_list to make semver sorting easy in TF, and provider functions (TF >= 1.8 is required):

• data.semvers_list: sorts a list of semver strings
• provider::semvers::compare: compares two semver strings
• provider::semvers::constrained: checks whether semver is within constrains
• provider::semvers::equals: checks two semver strings for equality
• provider::semvers::pick: filters a list of semver strings by constraint
• provider::semvers::sort: sorts a list of semver strings, returns sorted one

See the Terraform Registry provider page.

Provider configuration

provider "semvers" {
  ignore_invalid_tags = false # default; set true to skip invalid semver strings in list inputs
}

When ignore_invalid_tags is true, invalid semver strings in list inputs are skipped instead of returning an error. This applies to semvers_list, sort, and pick. Skipped tags are logged at INFO when TF_LOG is enabled:

TF_LOG=INFO terraform plan

Example — pick the latest matching dev tag from a mixed image tag list:

provider "semvers" {
  ignore_invalid_tags = true
}

reverse(provider::semvers::pick(
  ["develop-latest", "1.2.3-dev.1", "1.2.3-dev.2", "0.1.0"],
  "~> 1.2.3-dev",
))[0]
# => "1.2.3-dev.2"

Single-version functions (compare, equals, constrained) are unchanged and still return an error when a version string is invalid.

Provider aliases and provider functions

Provider functions are called as provider::semvers::<function>(...). In Terraform, that syntax always uses the default (non-aliased) provider configuration. There is no way to select an aliased provider for a function call — aliases only apply to resources and data sources via the provider meta-argument:

provider "semvers" {
  ignore_invalid_tags = false # default
}

provider "semvers" {
  alias               = "lenient"
  ignore_invalid_tags = true
}

# Uses semvers.lenient — alias selection works
data "semvers_list" "example" {
  provider = semvers.lenient
  list     = ["1.0.0", "develop-latest"]
}

# Always uses the default semvers provider — alias is ignored
provider::semvers::pick(["1.0.0", "develop-latest"], ">= 1.0")

If you need different provider settings (such as ignore_invalid_tags) in the same module under Terraform, use a data source with provider = semvers.<alias>, or split the work into child modules with different default providers passed via providers.

OpenTofu (1.7+) supports alias-aware provider functions:

provider::semvers::lenient::pick(["1.0.0", "develop-latest"], ">= 1.0")

Development

# install dev version of the provider
go install

# test dev version of the provider
(cd ./test; terraform plan)

# run acceptance testing
TF_ACC=1 go test -v ./...

# check and fix formatting
go fmt ./...

# update go modules
go get -u

# generate docs
go generate ./...