Remote OpenStack instances using Gophercloud Library (using Nova Networking)
2020-03-16T22:46:24Z
Introduction:
Following program uses gophercloudlibrary to spin instances in OpenStack environment.
Requirments:
An already running OpenStack environment. You can get a free playground for OpenStack to play with at http://trystack.org/. At minimum you need following information.
Auth URL : It may look like this http://10.0.2.15:5000/v2.0
UserName : This is a user in OpenStack. default: admin
Password : This is an API password. API password can be different from user password.
Tenant : This is more like a project/Account or Organization. A tenant can have multiple users associated with it.. default: admin
Region : Default region is set to RegionOne.In trystack.org this information can be found at https://x86.trystack.org/dashboard/project/access_and_security/ and click on Download OpenStack RC file. Contents of RC file will have all the required information.
Following is the source code.
package main
import (
"crypto/rand"
"errors"
"flag"
"fmt"
"github.com/rackspace/gophercloud"
"github.com/rackspace/gophercloud/openstack"
"github.com/rackspace/gophercloud/openstack/compute/v2/extensions/floatingip"
"github.com/rackspace/gophercloud/openstack/compute/v2/flavors"
"github.com/rackspace/gophercloud/openstack/compute/v2/images"
"github.com/rackspace/gophercloud/openstack/compute/v2/servers"
"github.com/rackspace/gophercloud/openstack/networking/v2/networks"
"os"
"strconv"
"time"
)
func checkErrorAndExit(err error) {
if err != nil {
fmt.Printf("Error: %v\n", err.Error())
os.Exit(3)
}
}
func checkErrorAndContinue(err error) {
if err != nil {
fmt.Printf("Error: %v\n", err.Error())
}
}
func generateRandomString() string {
b := make([]byte, 8)
_, err := rand.Read(b)
checkErrorAndExit(err)
name := fmt.Sprintf("%X", b[0:4])
return name
}
func getFreeFloatingIP(client *gophercloud.ServiceClient) (*string, error) {
pager := floatingip.List(client)
singlePage, err := pager.AllPages()
checkErrorAndExit(err)
floatingIPList, err := floatingip.ExtractFloatingIPs(singlePage)
checkErrorAndExit(err)
for _, floatingIP := range floatingIPList {
// Check ip floatingIP is assigned to any Instance.
if len(floatingIP.InstanceID) > 0 {
//Do nothing
} else {
return &floatingIP.IP, nil
}
}
return nil, errors.New("ERROR: Free FloatingIP not available.")
}
func assignFloatingIP(client *gophercloud.ServiceClient, id string, ip string) {
fmt.Printf("Attaching floating IP with first VM. It can take a few seconds.\n")
opts := floatingip.AssociateOpts{ServerID: id, FloatingIP: ip}
for {
server, err := servers.Get(client, id).Extract()
checkErrorAndExit(err)
if server.Status == "ACTIVE" {
result := floatingip.AssociateInstance(client, opts)
if result.Err != nil {
fmt.Println(result.Err)
} else {
fmt.Println("Floating IP assigned successfully.")
}
os.Exit(0)
}
time.Sleep(1000 * time.Millisecond)
//fmt.Println(details.Status)
}
}
func main() {
user := flag.String("user", "admin", "OS Username")
pass := flag.String("password", "xxxx", "Password")
authUrl := flag.String("authurl", "http://10.0.2.15:5000/v2.0", "AUTH URL")
tenant := flag.String("tenant", "admin", "Tenant Name")
region := flag.String("region", "RegionOne", "Region for VM")
defaultRun := flag.Bool("runwithdefaultvalues", false, "Use this flag to use default values")
image := flag.String("image", "cirros", "Image to be used")
flavor := flag.String("flavor", "m1.tiny", "Size of VM")
network := flag.String("network", "private", "Network for VM")
securityGroup := flag.String("securitygroup", "default", "Security Group for VM")
hostNamePrefix := flag.String("hostnameprefix", generateRandomString(), "Hostname Prefix. default: randomly generated.")
total := flag.String("total", "5", "Total number of instances")
flag.Parse()
os.Setenv("OS_USERNAME", *user)
os.Setenv("OS_PASSWORD", *pass)
os.Setenv("OS_AUTH_URL", *authUrl)
os.Setenv("OS_TENANT_NAME", *tenant)
os.Setenv("OS_REGION_NAME", *region)
if flag.NFlag() == 0 {
flag.PrintDefaults()
os.Exit(1)
} else if *defaultRun == true {
fmt.Println("Creating VMs: ")
} else {
fmt.Println("Creating VMs: ")
}
authOpts, err := openstack.AuthOptionsFromEnv()
checkErrorAndExit(err)
provider, err := openstack.AuthenticatedClient(authOpts)
checkErrorAndExit(err)
otherOpts := gophercloud.EndpointOpts{Region: *region}
client, err := openstack.NewComputeV2(provider, otherOpts)
imageID, err := images.IDFromName(client, *image)
checkErrorAndExit(err)
flavorID, err := flavors.IDFromName(client, *flavor)
checkErrorAndExit(err)
netClient, err := openstack.NewNetworkV2(provider, gophercloud.EndpointOpts{Name: "neutron", Region: *region})
checkErrorAndExit(err)
networkID, err := networks.IDFromName(netClient, *network)
checkErrorAndExit(err)
/* This code is not needed.
securityGroupID, err := getSecurityGroupID(client, *securityGroup)
checkErrorAndExit(err)
fmt.Println(*securityGroupID)
*/
network1 := servers.Network{UUID: networkID, FixedIP: "", Port: ""}
allNetworks := []servers.Network{network1}
noOfInstances, err := strconv.Atoi(*total)
checkErrorAndExit(err)
for i := 1; i <= noOfInstances; i++ {
vmName := *hostNamePrefix + strconv.Itoa(i)
serverCreateOpts := servers.CreateOpts{Name: vmName,
FlavorRef: flavorID,
ImageRef: imageID,
Networks: allNetworks,
UserData: []byte{},
SecurityGroups: []string{*securityGroup}}
_, err := servers.Create(client, serverCreateOpts).Extract()
checkErrorAndContinue(err)
fmt.Printf("%s VM creation request sent successfully.\n Details: { flavor=%s, image=%s, network=%s, sec_group=%s }\n", vmName, *flavor, *image, *network, *securityGroup)
fmt.Println("===================================")
}
vmID, err := servers.IDFromName(client, *hostNamePrefix+strconv.Itoa(1))
checkErrorAndExit(err)
fmt.Printf("Obtaining free floating IP: ")
floatingIP, err := getFreeFloatingIP(client)
checkErrorAndExit(err)
fmt.Printf("%s found.\n", *floatingIP)
assignFloatingIP(client, vmID, *floatingIP)
}Create a file launchOpenStackInstances.go and populate it with above contents. Use following steps on Linux and MacOS to compile/build it.
- Make sure GO Lang compiler is installed.
- Place go source code in a directory. (most likely home directory)
mkdir MYGO
export GOPATH=$HOME/MYGO
go get github.com/rackspace/gophercloud
go build launchOpenStackInstances.go- An executable with name launchOpenStackInstances will be there.
Example Run:
# ./launchOpenStackInstances -authurl=http://10.0.2.15:5000/v2.0 -image=cirros -user=admin -password=xxxxx -tenant=admin -flavor=m1.tiny -region=RegionOne -total=3
Creating VMs:
B081CB981 VM creation request sent successfully.
Details: { flavor=m1.tiny, image=cirros, network=private, sec_group=default }
===================================
B081CB982 VM creation request sent successfully.
Details: { flavor=m1.tiny, image=cirros, network=private, sec_group=default }
===================================
B081CB983 VM creation request sent successfully.
Details: { flavor=m1.tiny, image=cirros, network=private, sec_group=default }
===================================
Assigning Floating IP to first instance. Can take a few seconds.
done.Observation 1: This program is using Nova Networking.
Observation 2: Take a look at function assignFloatingIP. There is an infinite loop in this function. This is required as floatingIP can be assigned only when VM is in ACTIVEstate. However this trick can be avoided when Neutron networking is used.