Allow to specify range specification instead of fixed version

That allows to install for example the latest bug-fix version of
terraform 1.12.* even if 1.13 is already installed.

README.md

@@ -136,19 +136,29 @@ steps:
 
 ## Inputs
 
-The following inputs are supported.
+The action supports the following inputs:
 
-- `cli_config_credentials_hostname` - (optional) The hostname of a Terraform Cloud/Enterprise instance to place within the credentials block of the Terraform CLI configuration file. Defaults to `app.terraform.io`.
+- `cli_config_credentials_hostname` - (optional) The hostname of a Terraform Cloud/Enterprise instance to 
+   place within the credentials block of the Terraform CLI configuration file. Defaults to `app.terraform.io`.
 
-- `cli_config_credentials_token` - (optional) The API token for a Terraform Cloud/Enterprise instance to place within the credentials block of the Terraform CLI configuration file.
+- `cli_config_credentials_token` - (optional) The API token for a Terraform Cloud/Enterprise instance to
+   place within the credentials block of the Terraform CLI configuration file.
 
-- `terraform_version` - (optional) The version of Terraform CLI to install. A value of `latest` will install the latest version of Terraform CLI. Defaults to `latest`.
+- `terraform_version` - (optional) The version of Terraform CLI to install. Instead of a full version string,
+   you can also specify a constraint string (see [Semver Ranges](https://www.npmjs.com/package/semver#ranges)
+   for available range specifications). Examples are: `<1.13.0`, `~1.12`, `1.12.x` (all three installing
+   the latest available 1.12 version). The special value of `latest` installs the latest version of
+   Terraform CLI. Defaults to `latest`.
+
+- `terraform_wrapper` - (optional) Whether to install a wrapper to wrap subsequent calls of 
+   the `terraform` binary and expose its STDOUT, STDERR, and exit code as outputs
+   named `stdout`, `stderr`, and `exitcode` respectively. Defaults to `true`.
 
-- `terraform_wrapper` - (optional) Whether or not to install a wrapper to wrap subsequent calls of the `terraform` binary and expose its STDOUT, STDERR, and exit code as outputs named `stdout`, `stderr`, and `exitcode` respectively. Defaults to `true`.
 
 ## Outputs
 
-This action does not configure any outputs directly. However, when the `terraform_wrapper` input is set to `true`, the following outputs will be available for subsequent steps that call the `terraform` binary.
+This action does not configure any outputs directly. However, when you set the `terraform_wrapper` input
+to `true`, the following outputs is available for subsequent steps that call the `terraform` binary.
 
 - `stdout` - The STDOUT stream of the call to the `terraform` binary.
 

action.yml

@@ -1,6 +1,6 @@
 name: 'HashiCorp - Setup Terraform'
 description: 'Sets up Terraform CLI in your GitHub Actions workflow.'
-author: 'HashiCorp, Inc.'
+author: 'HashiCorp, Inc. (original)'
 inputs:
   cli_config_credentials_hostname:
     description: 'The hostname of a Terraform Cloud/Enterprise instance to place within the credentials block of the Terraform CLI configuration file. Defaults to `app.terraform.io`.'
@@ -10,7 +10,7 @@ inputs:
     description: 'The API token for a Terraform Cloud/Enterprise instance to place within the credentials block of the Terraform CLI configuration file.'
     required: false
   terraform_version:
-    description: 'The version of Terraform CLI to install. A value of `latest` will install the latest version of Terraform CLI. Defaults to `latest`.'
+    description: 'The version of Terraform CLI to install. Instead of full version string you can also specify constraint string starting with "<" (for example `<1.13.0`) to install the latest version satisfying the constraint. A value of `latest` will install the latest version of Terraform CLI. Defaults to `latest`.'
     default: 'latest'
     required: false
   terraform_wrapper:

dist/index.js

@@ -2068,14 +2068,23 @@ function findLatest (allVersions) {
 // Find specific version given list of all available
 function findSpecific (allVersions, version) {
   core.debug(`Parsing version list for version ${version}`);
+  return allVersions.versions[version];
+}
 
-  const versionObj = allVersions.versions[version];
-
-  if (!versionObj) {
-    throw new Error(`Could not find Terraform version ${version} in version list`);
+// Find specific version given list of all available
+function findLatestMatchingSpecification (allVersions, version) {
+  core.debug(`Parsing version list for latest matching specification ${version}`);
+  const versionList = [];
+  for (const _version in allVersions.versions) {
+    versionList.push(_version);
+  }
+  const bestMatchVersion = semver.maxSatisfying(versionList, version);
+  if (!bestMatchVersion) {
+    throw new Error(`Could not find Terraform version matching ${version} in version list`);
   }
+  core.info(`Latest version satisfying ${version} is ${bestMatchVersion}`);
 
-  return versionObj;
+  return allVersions.versions[bestMatchVersion];
 }
 
 async function downloadMetadata () {
@@ -2215,30 +2224,37 @@ async function run () {
     // Download metadata about all versions of Terraform CLI
     const versionMetadata = await downloadMetadata();
 
+    const specificMatch = findSpecific(versionMetadata, version);
     // Find latest or a specific version like 0.1.0
-    const versionObj = version.toLowerCase() === 'latest' ? findLatest(versionMetadata) : findSpecific(versionMetadata, version);
+    const versionObj = version.toLowerCase() === 'latest'
+      ? findLatest(versionMetadata) : specificMatch || findLatestMatchingSpecification(versionMetadata, version);
 
-    // Get the build available for this runner's OS and a 64 bit architecture
-    const buildObj = getBuild(versionObj, osPlat, osArch);
+    if (versionObj) {
+      // Get the build available for this runner's OS and a 64 bit architecture
+      const buildObj = getBuild(versionObj, osPlat, osArch);
 
-    // Download requested version
-    const pathToCLI = await downloadCLI(buildObj.url);
+      // Download requested version
+      const pathToCLI = await downloadCLI(buildObj.url);
 
-    // Install our wrapper
-    if (wrapper) {
-      await installWrapper(pathToCLI);
-    }
+      // Install our wrapper
+      if (wrapper) {
+        await installWrapper(pathToCLI);
+      }
 
-    // Add to path
-    core.addPath(pathToCLI);
+      // Add to path
+      core.addPath(pathToCLI);
 
-    // Add credentials to file if they are provided
-    if (credentialsHostname && credentialsToken) {
-      await addCredentials(credentialsHostname, credentialsToken, osPlat);
+      // Add credentials to file if they are provided
+      if (credentialsHostname && credentialsToken) {
+        await addCredentials(credentialsHostname, credentialsToken, osPlat);
+      }
+      return versionObj;
+    } else {
+      core.setFailed(`Could not find Terraform version ${version} in version list`);
     }
   } catch (error) {
     core.error(error);
-    throw new Error(error);
+    throw error;
   }
 }
 

lib/setup-terraform.js

@@ -33,14 +33,23 @@ function findLatest (allVersions) {
 // Find specific version given list of all available
 function findSpecific (allVersions, version) {
   core.debug(`Parsing version list for version ${version}`);
+  return allVersions.versions[version];
+}
 
-  const versionObj = allVersions.versions[version];
-
-  if (!versionObj) {
-    throw new Error(`Could not find Terraform version ${version} in version list`);
+// Find specific version given list of all available
+function findLatestMatchingSpecification (allVersions, version) {
+  core.debug(`Parsing version list for latest matching specification ${version}`);
+  const versionList = [];
+  for (const _version in allVersions.versions) {
+    versionList.push(_version);
   }
+  const bestMatchVersion = semver.maxSatisfying(versionList, version);
+  if (!bestMatchVersion) {
+    throw new Error(`Could not find Terraform version matching ${version} in version list`);
+  }
+  core.info(`Latest version satisfying ${version} is ${bestMatchVersion}`);
 
-  return versionObj;
+  return allVersions.versions[bestMatchVersion];
 }
 
 async function downloadMetadata () {
@@ -180,30 +189,37 @@ async function run () {
     // Download metadata about all versions of Terraform CLI
     const versionMetadata = await downloadMetadata();
 
+    const specificMatch = findSpecific(versionMetadata, version);
     // Find latest or a specific version like 0.1.0
-    const versionObj = version.toLowerCase() === 'latest' ? findLatest(versionMetadata) : findSpecific(versionMetadata, version);
-
-    // Get the build available for this runner's OS and a 64 bit architecture
-    const buildObj = getBuild(versionObj, osPlat, osArch);
-
-    // Download requested version
-    const pathToCLI = await downloadCLI(buildObj.url);
-
-    // Install our wrapper
-    if (wrapper) {
-      await installWrapper(pathToCLI);
-    }
-
-    // Add to path
-    core.addPath(pathToCLI);
-
-    // Add credentials to file if they are provided
-    if (credentialsHostname && credentialsToken) {
-      await addCredentials(credentialsHostname, credentialsToken, osPlat);
+    const versionObj = version.toLowerCase() === 'latest'
+      ? findLatest(versionMetadata) : specificMatch || findLatestMatchingSpecification(versionMetadata, version);
+
+    if (versionObj) {
+      // Get the build available for this runner's OS and a 64 bit architecture
+      const buildObj = getBuild(versionObj, osPlat, osArch);
+
+      // Download requested version
+      const pathToCLI = await downloadCLI(buildObj.url);
+
+      // Install our wrapper
+      if (wrapper) {
+        await installWrapper(pathToCLI);
+      }
+
+      // Add to path
+      core.addPath(pathToCLI);
+
+      // Add credentials to file if they are provided
+      if (credentialsHostname && credentialsToken) {
+        await addCredentials(credentialsHostname, credentialsToken, osPlat);
+      }
+      return versionObj;
+    } else {
+      core.setFailed(`Could not find Terraform version ${version} in version list`);
     }
   } catch (error) {
     core.error(error);
-    throw new Error(error);
+    throw error;
   }
 }