This chapter covers one of the services that always exists in almost all OpenStack installations. Have a look at Figure For example, metadata are size, type, owner, etc. As you can see in Figure , external services never touches glance-registry directly.
As you can also see in Figure , Glance itself does not store images by themselves. Glance uses plug-ins for particular storage, which can be your local file system, Swift object storage, Ceph storage, NFS Network File System , or other back ends. Metadata of images are stored in the Glance database, usually as a MariaDB instance.
Glance supports many disk formats. Table describes some of them. If the glance-api finds the requested image, the service will return the URL where the image is located. Then you need to look through the main configuration files for the glance-api and glance-registry. But sometimes you need to have a clear look at what is in the configs. You can use RegEx magic to remove all comments and make the configs shorter. It can really make your life easier.
As discussed earlier, Glance uses the database for storing metadata. In both config files, you can find something like this: [database] The next important thing you will need is the authentication parameters for Keystone. Each has its own port number— and , respectively. Also as you can see, in the config files the user name for Glance, service tenant, and password are in clear text.
It is very important to keep the right permissions for all config files because many of them contain the password in clear text. Most major Linux distributions already have prepared images for OpenStack.
Table shows several examples. The password is cubswin:. To get information about the image, you can use the command openstack image show followed by the ID of the image or name. In this case, the ID is eedbdda-9bc4- db and the name is cirros Only the image name, format, and file are mandatory.
It is possible to edit or add some part of metadata from this point. Figure shows this page. In old versions of OpenStack, you can use only the glance command.
This command will probably become obsolete in the future. For searching particular options and command descriptions, add —h to the end of your subcommand. For example: Table Table shows how some commands work. Once you have your image set up, you can download it. The utilities glance and openstack have the --debug option, if you want to see what is behind the CLI.
In this case Glance will choose a particular back end depending on the free space and priority. You can do that with the old- fashioned command keystone or with the new openstack command. All communications are happening through http. In real life it can also be done through the https protocol.
URLs for admin interface, public interface, and internal interface can also be different. Keep in mind that glance-registry is listening on port , but you will not expose the registry for external services. Where are the images stored when using the local file system by default? Which two main daemons does Glance consist of choose two? How can the storage volume be limited in Glance per user?
Figure shown the objects in the OpenStack Networking. The network consists of subnets, and each subnet is a logical subdivision of an IP network. A subnet can be private or public.
Virtual machines can get access to an external world through the public subnet. If a virtual machine is connected only to the private subnet, then only other virtual machines from this particular network can access it. Only a user with an admin role can create a public network.
A router can have one gateway and many connected subnets. It is possible to change a Security Group at runtime. It is a connection between the subnet and vNIC or virtual router.
Neutron is usually spread across three of them. API service usually exists at the control node. Open vSwitch and client-side Neutron agents are usually started at the Hypervisor or Compute node. And all server-side components of the OpenStack Networking service work on Networks nodes, which can be gateways to an external network. Also neutron-dhcp-agent starts proxies for the metadata server. Agent acts as a proxy to nova-api for retrieving metadata. Neutron also uses Open vSwitch. Its configuration will be discussed in the next section of this chapter.
Table lists what type of node Compute, Network, or Control services are started and the location of their configs. Open vSwitch is not a part of OpenStack project. It can operate in distributed configurations with a central controller.
This module is an engine of traffic processing. Most likely you will not need to manage Open vSwitch at the exam time, but commands can be useful.
This bridge acts as a virtual switch where all virtual network cards from all virtual machines are connected. OVS Neutron agent automatically creates the integration bridge. In our example, physical interface eth1 is connected to this bridge.
As you can see in our particular example, it connects the node with the IP address In our example, a GRE tunnel was used. For that you can use the neutron command and sometimes nova. Both commands have built-in help.
After changes, you will need to restart Neutron service. The next step is to create a subnet for this network. You will then see an opened window as shown in Figure By clicking Next, you will then go to the Subnet tab.
Net creating dialog in Horizon Now it is possible to check the work that has already been done. Actually the only action where you need an admin role is when you name the network as external. An example of the router properties is shown in Figure It is shown in Figure Network Topology tab in Horizon At this point you have only one missing part.
Your instances within the one tenant network can connect to each other. But none of the instances can reach out to an external network. You need to add a floating IP from ext-net to the virtual machine. You will need this ID soon. Next, you should determine which port you will associate the IP with. An example of information provided at this tab is shown in Figure They are implemented with iptables rules in the reference configuration. An example of the information provided on this tab is shown in Figure Here is an example: [quota] Number of networks allowed per tenant.
A negative value means unlimited. DbQuotaDriver Keep in track in the database of current resourcequota usage. Part of the networks quotas edit page is shown in Figure Its configuration files were shown at the beginning of this chapter. Neutron API service is bound to port Open vSwitch agent centos7 :- True neutron-openvswitch-agent L3 agent centos7 nova :- True neutron-l3-agent 7c..
Metering agent centos7 :- True neutron-metering-agent DHCP agent centos7 nova :- True neutron-dhcp-agent 9b.. What service provides routing and Network Address Translation? How can you check the status of running Neutron agents? Name the Neutron API service config. How can you correctly add a new rule to an existing Security Group?
Where is the Neutron API log file situated? Its main goal is to manage basic virtual machines functions like creating, starting, stopping, and so on. As with other services, Nova uses a message broker and database. It takes requests for starting instances from the queue and selects a compute node for running a virtual machine on it.
The selection of Hypervisor is based on its weight and filters. Filters can include an amount of memory, a requested availability zone, a set of group hosts, among others. The rules apply each time the instance is started or when migrating to another Hypervisor.
It helps with horizontal scalability. This daemon usually runs only on compute nodes. It is designed to manage pools of computer resources and can work with widely available virtualization technologies.
The former acts as the VNC-proxy and the latter is responsible for authorization. Figures and illustrate the process of starting an instance. Instance provision workflow—Part II In this example two hosts are used: compute host, which acts as the Hypervisor when nova-compute service is running, and controller node, with all its management services. The workflow of the starting instance is: 1.
The client in this particular example the client is Horizon web client, but it can be nova CLI command asks keystone-api for authentication and generates the access token. If authentication succeeds, the client sends a request for a running instance to nova-api. It is similar to the nova boot command. Nova service validates the token and receives headers with roles and permissions from keystone-api. Nova checks the database for conflicts with existing names of objects and creates a new entry for this instance in its database.
Nova-api sends the RPC for a scheduling instance to nova-scheduler service. Nova-scheduler service picks up the request from the message queue. Nova-scheduler service finds an appropriate compute host through the database via filters and weights. Then scheduler sends the RPC call to nova-compute service to launch the virtual machine. Nova-compute service picks up the request from the message queue. Nova-compute service asks nova-conductor to fetch information about the instance, for example: host ID, flavor, etc.
Nova-conductor service picks up the request from the message queue. Nova-conductor service gets information about an instance from the database.
Nova-compute takes the instance information from the queue. At this moment the compute host knows what image will be used to start the instance. Nova- compute asks the glance-api service for a particular image URL. Glance-api validates the token and returns the metadata of the image including the URL.
Nova-compute service passes a token to neutron-api and asks it to configure the network for the instance. Neutron validates the token and configures the network. Nova-compute interacts with cinder-api to attach the volume to the instance. Nova-compute generates data for Hypervisor and executes the request via libvirt.
Table shows the main configuration options available from config. It is also known as an instance type. Immediately after installation of OpenStack cloud, you will have several predefined flavors. You can also add new flavors and delete existing ones. SSH Secure Shell allows you to authenticate users by using the private-public keypair. You should generate two linked cryptographic keys: public and private.
The public key can be given to anyone. Your private key should be kept in a secure place—it is only yours. An instance with running the OpenSSH server that has your public key can issue a challenge that can only be answered by the system holding your private key.
As a result, it can be authenticated through the presence of your key. This allows you to access a virtual machine in a way that does not require passwords. It is your responsibility to keep the private key secured. In that case you should remove the public key from your cloud and generate a new keypair.
If somebody stole a private key, they can get access to your instances. You will learn in the next section how to run an instance and how to insert a public key to it. The instance source can be an image, snapshot, or block storage volume. At boot time you can also specify optional parameters like keypair, security group, user data files, and volume for persistent storage. You also specified the security group named apress-sgroup and the keypair apresskey1. The example is shown in Figure Example of console of running instance in browser If you prefer to work with instances in GUI, you can use the Horizon web interface.
The example of the launch dialog is shown in Figure There are not enough hosts available. Flavor m1. What You Will Study Perceive the parts that make up the cloud. Learn to troubleshoot all the primary OpenStack companies. Perceive the place to seek out info for future work with OpenStack. Download e-Book Pdf. Discover how to implement and operate in an Agile manner at every level of your enterprise and at every point from idea to delivery.
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