Fetch CLI verisons from Homebrew where applicable. (#3290)

If the CLI seems to have been installed using Homebrew, do not consult
the service for the latest version. Instead, consult the Homebrew JSON
API.

Fixes #3230.

CHANGELOG.md

@@ -8,23 +8,34 @@ CHANGELOG
   using defaults calculated by the provider.
   [#3245](https://github.com/pulumi/pulumi/pull/3245)
 
+- Fetch version information from the Homebrew JSON API for CLIs installed using `brew`.
+  [#3290](https://github.com/pulumi/pulumi/pull/3290)
+
 ## 1.2.0 (2019-09-26)
 
 - Support emitting high-level execution trace data to a file and add a debug-only command to view trace data.
   [#3238](https://github.com/pulumi/pulumi/pull/3238)
+
 - Fix parsing of GitLab urls with subgroups.
   [#3239](https://github.com/pulumi/pulumi/pull/3239)
+
 - `pulumi refresh` can now be scoped to refresh a subset of resources by adding a `--target urn` or
   `-t urn` argument.  Multiple resources can be specified using `-t urn1 -t urn2`.
+
 - `pulumi destroy` can now be scoped to delete a single resource (and its dependents) by adding a
   `--target urn` or `-t urn` argument.  Multiple resources can be specified using `-t urn1 -t urn2`.
+
 - `pulumi update` can now be scoped to update a single resource by adding a `--target urn` or `-t urn`
   argument.  Multiple resources can be specified using `-t urn1 -t urn2`.
+
 - Avoid re-encrypting secret values on each checkpoint write. These changes should improve update times for stacks
   that contain secret values.
   [#3183](https://github.com/pulumi/pulumi/pull/3183)
+
 - Add Codefresh CI detection.
+
 - Add `-c` (config array) flag to the `preview` command.
+
 - Adds the ability to provide transformations to modify the properties and resource options that
   will be used for any child resource of a component or stack.
   [#3174](https://github.com/pulumi/pulumi/pull/3174)
@@ -33,17 +44,23 @@ CHANGELOG
 
 - Fix a bug that caused the Python runtime to ignore unhandled exceptions and erroneously report that a Pulumi program executed successfully.
   [#3170](https://github.com/pulumi/pulumi/pull/3170)
+
 - Read operations are no longer considered changes for the purposes of `--expect-no-changes`.
   [#3197](https://github.com/pulumi/pulumi/pull/3197)
+
 - Increase the MaxCallRecvMsgSize for interacting with the gRPC server.
   [#3201](https://github.com/pulumi/pulumi/pull/3201)
+
 - Do not ask for a passphrase in non-interactive sessions (fix [#2758](https://github.com/pulumi/pulumi/issues/2758)).
   [#3204](https://github.com/pulumi/pulumi/pull/3204)
+
 - Support combining the filestate backend (local or remote storage) with the cloud-backed secrets providers (KMS, etc.).
   [#3198](https://github.com/pulumi/pulumi/pull/3198)
+
 - Moved `@pulumi/pulumi` to target `es2016` instead of `es6`.  As `@pulumi/pulumi` programs run
   inside Nodejs, this should not change anything externally as Nodejs already provides es2016
   support. Internally, this makes more APIs available for `@pulumi/pulumi` to use in its implementation.
+
 - Fix the --stack option of the `pulumi new` command.
   ([#3131](https://github.com/pulumi/pulumi/pull/3131) fixes [#2880](https://github.com/pulumi/pulumi/issues/2880))
 

cmd/pulumi.go

@@ -19,6 +19,8 @@ import (
 	"bytes"
 	"encoding/json"
 	"fmt"
+	"net/http"
+	"net/url"
 	"os"
 	"os/exec"
 	"os/user"
@@ -41,6 +43,7 @@ import (
 	"github.com/pulumi/pulumi/pkg/diag/colors"
 	"github.com/pulumi/pulumi/pkg/util/cmdutil"
 	"github.com/pulumi/pulumi/pkg/util/contract"
+	"github.com/pulumi/pulumi/pkg/util/httputil"
 	"github.com/pulumi/pulumi/pkg/util/logging"
 	"github.com/pulumi/pulumi/pkg/version"
 	"github.com/pulumi/pulumi/pkg/workspace"
@@ -232,6 +235,15 @@ func getCLIVersionInfo() (semver.Version, semver.Version, error) {
 		return semver.Version{}, semver.Version{}, err
 	}
 
+	brewLatest, isBrew, err := getLatestBrewFormulaVersion()
+	if err != nil {
+		return semver.Version{}, semver.Version{}, err
+	}
+	if isBrew {
+		// When consulting Homebrew for version info, we just use the latest version as the oldest allowed.
+		latest, oldest = brewLatest, brewLatest
+	}
+
 	err = cacheVersionInfo(latest, oldest)
 	if err != nil {
 		logging.V(3).Infof("failed to cache version info: %s", err)
@@ -401,6 +413,49 @@ func isBrewInstall(exe string) (bool, error) {
 	return exePath == brewPrefixExePath, nil
 }
 
+func getLatestBrewFormulaVersion() (semver.Version, bool, error) {
+	exe, err := os.Executable()
+	if err != nil {
+		return semver.Version{}, false, err
+	}
+
+	isBrew, err := isBrewInstall(exe)
+	if err != nil {
+		return semver.Version{}, false, err
+	}
+	if !isBrew {
+		return semver.Version{}, false, nil
+	}
+
+	url, err := url.Parse("https://formulae.brew.sh/api/formula/pulumi.json")
+	contract.AssertNoError(err)
+
+	resp, err := httputil.DoWithRetry(&http.Request{
+		Method: http.MethodGet,
+		URL:    url,
+	}, http.DefaultClient)
+	if err != nil {
+		return semver.Version{}, false, err
+	}
+	defer contract.IgnoreClose(resp.Body)
+
+	type versions struct {
+		Stable string `json:"stable"`
+	}
+	var formula struct {
+		Versions versions `json:"versions"`
+	}
+	if err := json.NewDecoder(resp.Body).Decode(&formula); err != nil {
+		return semver.Version{}, false, err
+	}
+
+	stable, err := semver.ParseTolerant(formula.Versions.Stable)
+	if err != nil {
+		return semver.Version{}, false, err
+	}
+	return stable, true, nil
+}
+
 func isDevVersion(s semver.Version) bool {
 	if len(s.Pre) == 0 {
 		return false