Document pre-release behavior (#73)

* Add user agent reporting to terraform download
* Upgrade js-releases dependency

README.md

@@ -147,8 +147,8 @@ The action supports the following inputs:
 - `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: `<0.14.0`, `~0.13.0`, `0.13.x` (all three installing
-   the latest available 0.13 version). Prerelease versions are always ignored. The special value of `latest`
-   installs the latest version of Terraform CLI. Defaults to `latest`.
+   the latest available 0.13 version). Prerelease versions can be specified and a range will stay within the
+   given tag such as `beta` or `rc`. If no version is given, it will default 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

dist/index.js

@@ -2347,7 +2347,7 @@ async function run () {
     const osArch = os.arch();
 
     core.debug(`Finding releases for Terraform version ${version}`);
-    const release = await releases.getRelease('terraform', version);
+    const release = await releases.getRelease('terraform', version, 'GitHub Action: Setup Terraform');
     const platform = mapOS(osPlatform);
     const arch = mapArch(osArch);
     core.debug(`Getting build for Terraform version ${release.version}: ${platform} ${arch}`);
@@ -52497,27 +52497,30 @@ class Release {
     }
 }
 exports.Release = Release;
-function getRelease(product, version, userAgent) {
+function getRelease(product, version, userAgent, includePrerelease) {
     return __awaiter(this, void 0, void 0, function* () {
-        const validVersion = semver.validRange(version); // "latest" will return invalid but that's ok because we'll select it by default
+        const validVersion = semver.validRange(version, { includePrerelease, loose: true }); // "latest" will return invalid but that's ok because we'll select it by default
         const indexUrl = `${releasesUrl}/${product}/index.json`;
         const headers = userAgent ? { 'User-Agent': userAgent } : null;
         const body = yield utils_1.httpsRequest(indexUrl, { headers });
         const response = JSON.parse(body);
         let release;
-        if (!validVersion) { // pick the latest release
-            version = Object.keys(response.versions).sort(semver.rcompare)[0];
+        if (!validVersion) { // pick the latest release (prereleases will be skipped for safety, set an explicit version instead)
+            const releaseVersions = Object.keys(response.versions).filter(v => !semver.prerelease(v));
+            version = releaseVersions.sort((a, b) => semver.rcompare(a, b))[0];
             release = new Release(response.versions[version]);
         }
         else {
-            release = matchVersion(response.versions, validVersion);
+            release = matchVersion(response.versions, validVersion, includePrerelease);
         }
         return release;
     });
 }
 exports.getRelease = getRelease;
-function matchVersion(versions, range) {
-    const version = semver.maxSatisfying(Object.keys(versions), range);
+function matchVersion(versions, range, includePrerelease) {
+    // If a prerelease version range is given, it will match in that series (0.14-rc0, 0.14-rc1)
+    // https://www.npmjs.com/package/semver#prerelease-tags
+    const version = semver.maxSatisfying(Object.keys(versions), range, { includePrerelease });
     if (version) {
         return new Release(versions[version]);
     }

lib/setup-terraform.js

@@ -117,7 +117,7 @@ async function run () {
     const osArch = os.arch();
 
     core.debug(`Finding releases for Terraform version ${version}`);
-    const release = await releases.getRelease('terraform', version);
+    const release = await releases.getRelease('terraform', version, 'GitHub Action: Setup Terraform');
     const platform = mapOS(osPlatform);
     const arch = mapArch(osArch);
     core.debug(`Getting build for Terraform version ${release.version}: ${platform} ${arch}`);

package.json

@@ -18,7 +18,7 @@
     "@actions/github": "^4.0.0",
     "@actions/io": "^1.0.2",
     "@actions/tool-cache": "^1.6.1",
-    "@hashicorp/js-releases": "^1.1.0"
+    "@hashicorp/js-releases": "^1.2.0"
   },
   "devDependencies": {
     "@zeit/ncc": "0.22.1",