Add --if-not-exists option to podman network create

cmd/podman/networks/create.go

@@ -48,6 +48,9 @@ func networkCreateFlags(cmd *cobra.Command) {
 	flags.IPVar(&networkCreateOptions.Gateway, gatewayFlagName, nil, "IPv4 or IPv6 gateway for the subnet")
 	_ = cmd.RegisterFlagCompletionFunc(gatewayFlagName, completion.AutocompleteNone)
 
+	if !registry.IsRemote() {
+		flags.BoolVar(&networkCreateOptions.IfNotExists, "if-not-exists", false, "do not error if the network name already exists")
+	}
 	flags.BoolVar(&networkCreateOptions.Internal, "internal", false, "restrict external access from this network")
 
 	ipRangeFlagName := "ip-range"

docs/source/markdown/podman-network-create.1.md

@@ -39,6 +39,12 @@ The `vlan` option assign VLAN tag and enables vlan\_filtering. Defaults to none.
 Define a gateway for the subnet. If you want to provide a gateway address, you must also provide a
 *subnet* option.
 
+#### **--if-not-exists**
+
+Do not error if a network with the given name already exists. Instead do nothing.
+
+This option is not supported on the remote client.
+
 #### **--internal**
 
 Restrict external access of this network

libpod/network/create.go

@@ -10,6 +10,7 @@ import (
 
 	"github.com/containernetworking/cni/pkg/version"
 	"github.com/containers/common/pkg/config"
+	"github.com/containers/podman/v2/libpod/define"
 	"github.com/containers/podman/v2/pkg/domain/entities"
 	"github.com/containers/podman/v2/pkg/rootless"
 	"github.com/containers/podman/v2/pkg/util"
@@ -33,7 +34,8 @@ func Create(name string, options entities.NetworkCreateOptions, runtimeConfig *c
 	} else {
 		fileName, err = createBridge(name, options, runtimeConfig)
 	}
-	if err != nil {
+	// do not error if IfNotExists is true and the error cause is ErrNetworkExists
+	if err != nil && !(options.IfNotExists && errors.Cause(err) == define.ErrNetworkExists) {
 		return nil, err
 	}
 	return &entities.NetworkCreateReport{Filename: fileName}, nil
@@ -207,7 +209,8 @@ func createBridge(name string, options entities.NetworkCreateOptions, runtimeCon
 			return "", err
 		}
 		if util.StringInSlice(name, netNames) {
-			return "", errors.Errorf("the network name %s is already used", name)
+			path := filepath.Join(GetCNIConfDir(runtimeConfig), fmt.Sprintf("%s.conflist", name))
+			return path, errors.Wrapf(define.ErrNetworkExists, "the network name %s is already used", name)
 		}
 	} else {
 		// If no name is given, we give the name of the bridge device
@@ -261,7 +264,8 @@ func createMacVLAN(name string, options entities.NetworkCreateOptions, runtimeCo
 			return "", err
 		}
 		if util.StringInSlice(name, netNames) {
-			return "", errors.Errorf("the network name %s is already used", name)
+			path := filepath.Join(GetCNIConfDir(runtimeConfig), fmt.Sprintf("%s.conflist", name))
+			return path, errors.Wrapf(define.ErrNetworkExists, "the network name %s is already used", name)
 		}
 	} else {
 		name, err = GetFreeDeviceName(runtimeConfig)

pkg/domain/entities/network.go

@@ -52,12 +52,14 @@ type NetworkCreateOptions struct {
 	DisableDNS bool
 	Driver     string
 	Gateway    net.IP
-	Internal   bool
-	Labels     map[string]string
-	MacVLAN    string
-	Range      net.IPNet
-	Subnet     net.IPNet
-	IPv6       bool
+	// Do not error if the network name is already used.
+	IfNotExists bool
+	Internal    bool
+	Labels      map[string]string
+	MacVLAN     string
+	Range       net.IPNet
+	Subnet      net.IPNet
+	IPv6        bool
 	// Mapping of driver options and values.
 	Options map[string]string
 }

test/e2e/network_create_test.go

@@ -10,6 +10,7 @@ import (
 	cniversion "github.com/containernetworking/cni/pkg/version"
 	"github.com/containers/podman/v2/libpod/network"
 	. "github.com/containers/podman/v2/test/utils"
+	"github.com/containers/storage/pkg/stringid"
 	. "github.com/onsi/ginkgo"
 	. "github.com/onsi/gomega"
 	"github.com/pkg/errors"
@@ -365,4 +366,19 @@ var _ = Describe("Podman network create", func() {
 		Expect(nc).To(ExitWithError())
 	})
 
+	It("podman network create with if not exists", func() {
+		SkipIfRemote("--if-not-exists is not supported on remote")
+		net := stringid.GenerateNonCryptoID()
+		nc := podmanTest.Podman([]string{"network", "create", "--if-not-exists", net})
+		nc.WaitWithDefaultTimeout()
+		defer podmanTest.removeCNINetwork(net)
+		Expect(nc.ExitCode()).To(BeZero())
+		Expect(nc.OutputToString()).To(ContainSubstring(net))
+
+		nc = podmanTest.Podman([]string{"network", "create", "--if-not-exists", net})
+		nc.WaitWithDefaultTimeout()
+		Expect(nc.ExitCode()).To(BeZero())
+		Expect(nc.OutputToString()).To(ContainSubstring(net))
+	})
+
 })