fix: Add dependency check for pulumi providers. (#650)

cloud/common/deploy/provider/dependencies.go

@@ -0,0 +1,64 @@
+// Copyright 2021 Nitric Technologies Pty Ltd.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package provider
+
+import (
+	"fmt"
+	"os/exec"
+)
+
+type DependencyCheck func() error
+
+func checkPulumiAvailable() error {
+	_, err := exec.LookPath("pulumi")
+	if err != nil {
+		return fmt.Errorf("pulumi is required to use this provider, please install pulumi and try again")
+	}
+
+	return nil
+}
+
+func checkDockerAvailable() error {
+	cmd := exec.Command("docker", "info")
+	err := cmd.Run()
+	if err != nil {
+		return fmt.Errorf("docker is required to use this provider, please install docker and try again")
+	}
+
+	return nil
+}
+
+func checkDependencies(checks ...DependencyCheck) error {
+	errs := []error{}
+
+	for _, check := range checks {
+		err := check()
+		if err != nil {
+			errs = append(errs, err)
+		}
+	}
+
+	if len(errs) > 0 {
+		errMsg := "The following dependencies are missing:"
+		for _, e := range errs {
+			errMsg += fmt.Sprintf("\n - %s", e.Error())
+		}
+
+		// combine the errors in a list
+		return fmt.Errorf(errMsg)
+	}
+
+	return nil
+}

cloud/common/deploy/provider/pulumi.go

@@ -31,6 +31,8 @@ import (
 	"github.com/pulumi/pulumi/sdk/v3/go/auto/optup"
 	"github.com/pulumi/pulumi/sdk/v3/go/pulumi"
 	"google.golang.org/grpc"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
 )
 
 type PulumiProviderServer struct {
@@ -196,6 +198,11 @@ func parsePulumiError(err error) error {
 
 // Up - automatically called by the Nitric CLI via the `up` command
 func (s *PulumiProviderServer) Up(req *deploymentspb.DeploymentUpRequest, stream deploymentspb.Deployment_UpServer) error {
+	// Verify if dependencies are available
+	if err := checkDependencies(checkPulumiAvailable, checkDockerAvailable); err != nil {
+		return status.Error(codes.FailedPrecondition, err.Error())
+	}
+
 	projectName, stackName, err := stackAndProjectFromAttributes(req.Attributes.AsMap())
 	if err != nil {
 		return err
@@ -284,6 +291,11 @@ func (s *PulumiProviderServer) Up(req *deploymentspb.DeploymentUpRequest, stream
 
 // Down - automatically called by the Nitric CLI via the `down` command
 func (s *PulumiProviderServer) Down(req *deploymentspb.DeploymentDownRequest, stream deploymentspb.Deployment_DownServer) error {
+	// Verify if dependencies are available
+	if err := checkDependencies(checkPulumiAvailable, checkDockerAvailable); err != nil {
+		return status.Error(codes.FailedPrecondition, err.Error())
+	}
+
 	projectName, stackName, err := stackAndProjectFromAttributes(req.Attributes.AsMap())
 	if err != nil {
 		return err