Add ready command for gateway and functions

This new command will block until either the gateway or a
given function is ready and is for use in CI and scripts.

Signed-off-by: Alex Ellis (OpenFaaS Ltd) <alexellis2@gmail.com>

commands/ready.go

@@ -0,0 +1,134 @@
+// Copyright (c) Alex Ellis 2017. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+package commands
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+	"net/url"
+	"os"
+	"time"
+
+	"github.com/openfaas/faas-cli/proxy"
+	"github.com/openfaas/faas-cli/stack"
+	"github.com/spf13/cobra"
+)
+
+func init() {
+	// Setup flags that are used by multiple commands (variables defined in faas.go)
+	readyCmd.Flags().StringVarP(&gateway, "gateway", "g", defaultGateway, "Gateway URL starting with http(s)://")
+
+	readyCmd.Flags().BoolVar(&tlsInsecure, "tls-no-verify", false, "Disable TLS validation")
+
+	readyCmd.Flags().Int("attempts", 60, "Number of attempts to check the gateway")
+	readyCmd.Flags().Duration("interval", time.Second*1, "Interval between attempts in seconds")
+
+	faasCmd.AddCommand(readyCmd)
+}
+
+var readyCmd = &cobra.Command{
+	Use:   `ready [--gateway GATEWAY_URL] [--tls-no-verify] [FUNCTION_NAME]`,
+	Short: "Block until the gateway or a function is ready for use",
+	Example: `  # Block until the gateway is ready
+  faas-cli ready --gateway https://127.0.0.1:8080
+
+  # Block until the env function is ready
+  faas-cli store deploy env && \
+  faas-cli ready env`,
+	RunE: runReadyCmd,
+}
+
+func runReadyCmd(cmd *cobra.Command, args []string) error {
+	interval, err := cmd.Flags().GetDuration("interval")
+	if err != nil {
+		return err
+	}
+
+	attempts, err := cmd.Flags().GetInt("attempts")
+	if err != nil {
+		return err
+	}
+
+	var services stack.Services
+	var gatewayAddress string
+	var yamlGateway string
+	if len(yamlFile) > 0 {
+		parsedServices, err := stack.ParseYAMLFile(yamlFile, regex, filter, envsubst)
+		if err != nil {
+			return err
+		}
+
+		if parsedServices != nil {
+			services = *parsedServices
+			yamlGateway = services.Provider.GatewayURL
+		}
+	}
+	gatewayAddress = getGatewayURL(gateway, defaultGateway, yamlGateway, os.Getenv(openFaaSURLEnvironment))
+	transport := GetDefaultCLITransport(tlsInsecure, &commandTimeout)
+
+	if len(args) == 0 {
+
+		c := &http.Client{
+			Transport: transport,
+		}
+
+		u, err := url.Parse(gatewayAddress)
+		if err != nil {
+			return err
+		}
+
+		u.Path = "/healthz"
+
+		for i := 0; i < attempts; i++ {
+			fmt.Printf("[%d/%d] Waiting for gateway\n", i+1, attempts)
+			req, err := http.NewRequest(http.MethodGet, u.String(), nil)
+			if err != nil {
+				return err
+			}
+
+			res, err := c.Do(req)
+			if err != nil {
+				fmt.Printf("[%d/%d] Error reaching OpenFaaS gateway: %s\n", i+1, attempts, err.Error())
+			} else if res.StatusCode == http.StatusOK {
+				fmt.Printf("OpenFaaS gateway is ready\n")
+				break
+			}
+
+			time.Sleep(interval)
+		}
+	} else {
+		functionName := args[0]
+
+		cliAuth, err := proxy.NewCLIAuth(token, gatewayAddress)
+		if err != nil {
+			return err
+		}
+
+		cliClient, err := proxy.NewClient(cliAuth, gatewayAddress, transport, &commandTimeout)
+		if err != nil {
+			return err
+		}
+
+		ctx := context.Background()
+
+		for i := 0; i < attempts; i++ {
+			fmt.Printf("[%d/%d] Waiting for function %s\n", i+1, attempts, functionName)
+
+			function, err := cliClient.GetFunctionInfo(ctx, functionName, functionNamespace)
+			if err != nil {
+				return err
+			}
+
+			if function.AvailableReplicas > 0 {
+				fmt.Printf("Function %s is ready\n", functionName)
+				break
+			}
+			time.Sleep(interval)
+		}
+
+	}
+
+	return nil
+}