chore: encode npm disttag in version resolution (aws#12627)

This version is used by check-api-compatibility.sh instead of relying on
the environment variables.

----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

release.json

@@ -1,4 +1,5 @@
 {
   "majorVersion": 1,
-  "releaseType": "stable"
+  "releaseType": "stable",
+  "distTag": "latest"
 }

scripts/check-api-compatibility.sh

@@ -57,22 +57,12 @@ if ! ${SKIP_DOWNLOAD:-false}; then
 
     echo "Determining baseline version..." >&2
     version=$(node -p 'require("./scripts/resolve-version.js").version')
+    disttag=$(node -p 'require("./scripts/resolve-version.js").npmDistTag')
     echo "  Current version is $version." >&2
 
     if ! package_exists_on_npm aws-cdk $version; then
-      echo "  Version $version does not exist in npm. Falling back to env vars." >&2
-      # occurs within a release PR where the version is bumped but is not yet published to npm.
-      major_version=$(echo $version | cut -d '.' -f 1)
-      if [ "$major_version" == "1" ]; then
-        echo "  Setting version to $NPM_DISTTAG_V1" >&2
-        version=$NPM_DISTTAG_V1
-      elif [ "$major_version" == "2" ]; then
-        echo "  Setting version to $NPM_DISTTAG_V2" >&2
-        version=$NPM_DISTTAG_V2
-      else
-        echo "Unknown major version $major_version. Failing..." >&2
-        exit 1
-      fi
+      echo "  Version $version does not exist in npm. Falling back to resolved dist tag '$disttag'" >&2
+      version=$disttag
     fi
 
     echo "Using version '$version' as the baseline..."

scripts/resolve-version-lib.js

@@ -17,6 +17,7 @@ function resolveVersion(rootdir) {
   const releaseConfig = require(releaseFile);
   const majorVersion = releaseConfig.majorVersion;
   const releaseType = releaseConfig.releaseType;
+  const distTag = releaseConfig.distTag;
   if (!majorVersion) { throw new Error(`"majorVersion"" must be defined in ${releaseFile}`); }
   if (!releaseType) { throw new Error(`"releaseType" must be defined in ${releaseFile}`); }
   if (typeof(majorVersion) !== 'number') { throw new Error(`majorVersion=${majorVersion} must be a number`); }
@@ -69,6 +70,7 @@ function resolveVersion(rootdir) {
     changelogFile: changelogFile,
     prerelease: releaseType !== 'stable' ? releaseType : undefined,
     marker: '0.0.0',
+    ...(distTag ? { npmDistTag: distTag } : {}),
   };
 }
 

scripts/script-tests/resolve-version.test.js

@@ -80,6 +80,23 @@ happy({
   }
 });
 
+happy({
+  name: 'dist tag is correctly shown',
+  inputs: { 
+    'release.json': { majorVersion: 2, releaseType: 'alpha', distTag: 'v2-preview' },
+    'version.v2.json': { version: '2.0.0-alpha.5' }
+  },
+  expected: {
+    changelogFile: 'CHANGELOG.v2.md',
+    marker: '0.0.0',
+    prerelease: 'alpha',
+    version: '2.0.0-alpha.5',
+    versionFile: 'version.v2.json',
+    npmDistTag: 'v2-preview',
+  }
+});
+
+
 failure({
   name: 'invalid release type',
   inputs: { 'release.json': { majorVersion: 2, releaseType: 'build' } },