Snippet of Pulumi-Go code that attempts to write out an inventory file with the IP addresses of the instances it launches

main.go

		// Create a file handle for the inventory file
		f, err := os.Create("hosts")
		if err != nil {
			log.Printf("error creating file: %s", err.Error())
		}

		// Launch an EC2 instance to serve as bastion host
		bastion, err := ec2.NewInstance(ctx, "bastion", &ec2.InstanceArgs{
			Ami:                      pulumi.String(amiID.Id),
			InstanceType:             pulumi.String("t2.small"),
			AssociatePublicIpAddress: pulumi.Bool(true),
			KeyName:                  pulumi.String("aws_vmw_rsa"),
			SubnetId:                 pulumi.String(subnets.Ids[0]),
			VpcSecurityGroupIds:      pulumi.StringArray{bastionSecGrp.ID()},
			Tags: pulumi.StringMap{
				"Name": pulumi.String("ans-int-bastion"),
			},
		})
		if err != nil {
			log.Printf("error launching bastion instance: %s", err.Error())
		}
		ctx.Export("bastionInstanceId", bastion.ID())
		ctx.Export("bastionPublicIpAddress", bastion.PublicIp)
		ctx.Export("bastionPrivateIpAddress", bastion.PrivateIp)
		// Write IP address to inventory file
		fmt.Fprintln(f, bastion.PrivateIp)
		if err != nil {
			log.Printf("error writing to file: %s", err.Error())
		}

		// Launch a private EC2 instance in each subnet/AZ
		nodeIds := make([]pulumi.StringInput, numSubnets)
		for idx := 0; idx < numSubnets; idx++ {
			instance, err := ec2.NewInstance(ctx, fmt.Sprintf("node-%d", idx), &ec2.InstanceArgs{
				Ami:                      pulumi.String(amiID.Id),
				InstanceType:             pulumi.String("t2.large"),
				AssociatePublicIpAddress: pulumi.Bool(false),
				KeyName:                  pulumi.String("aws_vmw_rsa"),
				SubnetId:                 pulumi.String(subnets.Ids[idx]),
				VpcSecurityGroupIds:      pulumi.StringArray{nodeSecGrp.ID()},
				Tags: pulumi.StringMap{
					"Name": pulumi.String(fmt.Sprintf("ans-int-%d", idx)),
				},
			})
			if err != nil {
				log.Printf("error launching instance: %s", err.Error())
			}
			// Export some information
			nodeIds[idx] = instance.ID()
			ctx.Export(fmt.Sprintf("node%dPublicIpAddress", idx), instance.PublicIp)
			ctx.Export(fmt.Sprintf("node%dPrivateIpAddress", idx), instance.PrivateIp)
			// Write IP address to inventory file
			fmt.Fprintln(f, instance.PrivateIp.ApplyString(func(s string) string {
				var res string
				res = s
				return res
			}))
			if err != nil {
				log.Printf("error writing to file: %s", err.Error())
			}
		}
		ctx.Export("nodeIdArray", pulumi.StringArray(nodeIds))

		// Close the file handle on the inventory file
		err = f.Close()
		if err != nil {
			log.Printf("error closing file: %s", err.Error())
		}