Get metadata process details-5 minutes a day to play OpenStack (167)

Tag:open   stack    tutorial    

Next, start neutron router instance   C1   > Finally got the metadata, from the following     Startup log:

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C1 considers the metadata service address to be 169.254.169.254and the port is 80. We tried to visit metadata in C1 .

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can actually get metadata. But we know that Nova-api-metadata is running on the control node, IP is not 169.254.169.254 , how is this implemented? Let's analyze the process below.

from  C1   's routing table to access  169.254.169.254   's request will go  17.17.17.1 .

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17.17.17.1   is actually  test_router   in  test_net the interface IP on the  . This route is automatically added to instance by OpenStack, which forwards metadata requests to neutron router.

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ip netnsis the command that manages the Linux network namespace, if you are unfamiliar with namespace, refer to the relevant chapters in the previous tutorials.

test_routerThe received c1 request is forwarded to Port 9697 via the iptable rule.

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What is Port 9697 for? This is the Neutron-ns-metadata-proxy listening port.

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Here we can get back to the idea:

2. The instance is metadata by a predefined 169.254.169.254 request.
   
   

4. The request is forwarded to the neutron router.
   
   

6. Router forwarded the request to Neutron-ns-metadata-proxy.
   
   

8. The following is simple: Neutron-ns-metadata-proxy will request to send neutron-metadata-agent through the UNIX domain socket, which is then sent to nova-api-metadata through the management network.

OpenStack creates and manages Neutron-ns-metadata-proxy by default through L3-agent. But not all environments have l3-agent, such as scenes that use physical router directly. Then you need to let dhcp-agent to manage Neutron-ns-metadata-proxy.

In the next section we analyze how Dhcp-agent handles metadata requests.

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Get metadata process details-5 minutes a day to play OpenStack (167)