Skip to content

HTTPS clone URL

Subversion checkout URL

You can clone with
or
.
Download ZIP
Fetching contributors…

Cannot retrieve contributors at this time

293 lines (213 sloc) 23.731 kB

pyrax – Python Bindings for OpenStack and the Rackspace Cloud


Getting Started With pyrax

pyrax is the Python language binding for OpenStack and the Rackspace Cloud. By installing pyrax, you have the ability to build on any OpenStack cloud using standard Python objects and code.

Prerequisites

You need Python 2.7.x to run pyrax. It may work with earlier versions, but this has not been tested. There are plans to port it to run in both 2.x and 3.x, but that work has not yet been started. But no matter what version you run, if you encounter a problem with pyrax, please report it on https://github.com/rackspace/pyrax/issues.

The documentation assumes that you are experienced with programming in Python, and have a basic understanding of cloud computing concepts. If you would like to brush up on cloud computing, you should visit the Rackspace Knowledge Center.

Installing pyrax

You install pyrax like any other third-party Python module. Just run:

pip install pyrax

You need to do this as root/administrator (that is, using sudo), unless you are installing into a virtualenv. pip pulls in all of the other modules and client libraries that pyrax needs.

You can also install directly from GitHub (where the pyrax source code is hosted). To do that, run:

pip install git+git://github.com/rackspace/pyrax.git

The difference is that using the GitHub installation method installs the current trunk version, which has the latest changes, but may also be less stable.

To upgrade your installation in the future, re-run the same command, but this time add the --upgrade option to make sure that pyrax and any dependecies are updated to the newest available version.

Set up Authentication

You need to submit your username and password in order to authenticate. If you are using the Rackspace Public Cloud, that would be your account username and API key. If you are using another OpenStack cloud, you also need to include your tenant ID, which you should be able to get from your provider.

Please note that all versions of pyrax beginning with 1.4.0 require that you define what type of authentication system you are working with. Previous versions only worked with Rackspace authentication, so this was not an issue. To do this, you have three options, listed below. In all cases the examples use keystone as the identity_type, but if you're using the Rackspace Cloud, change this to rackspace.

  1. Configuration File: make sure that the line identity_type = keystone is in your configuration file.
  2. Environment Variable - If you don't have a configuration file, pyrax checks for the environment variable CLOUD_ID_TYPE. Set this by executing export CLOUD_ID_TYPE=keystone in a bash shell, or by setting it in the System section of the Control Panel in Windows.
  3. Set in Code - if you can't do either of the above, change the import statement to add pyrax.set_setting("identity_type", "keystone") immediately after the import pyrax statement.

Authenticating

You can authenticate in any one of three ways:

  • explicitly pass your credentials to pyrax
  • create a file containing those credentials and pass that file path to pyrax
  • add them to your operating system's keychain

The credential file is a standard configuration file, with the following format:

[keystone]
username = my_username
password = top_secret
tenant_id = 01234567890abcdef

For the Rackspace Public Cloud, the credential file should look like this:

[rackspace_cloud]
username = my_username
api_key = 01234567890abcdef

To use the keychain method, you need to add your password or API key to your operating system's keychain in the pyrax namespace. Doing a pip install pyrax installs the Python module keyring, which provides ready access to this feature. To configure your keychain credentials, run the following in Python:

import keyring
keyring.set_password("pyrax", "my_username",
        "my_password")

To authenticate, run the following code using one of these authentication methods; which method you choose depends on your preference for passing credentials.

import pyrax

# Using direct method
pyrax.set_credentials("my_username", "01234567890abcdef")

# Using credentials file
pyrax.set_credential_file("/path/to/credential/file")

# Using keychain
pyrax.keyring_auth("my_username")
# Using keychain with username set in configuration file
pyrax.keyring_auth()

Note that the keyring_auth() command allows you to specify a particular username. This is especially useful if you need to connect to multiple cloud accounts in a particular environment. If you only have a single account, you can specify the username for your account in the config file (explained below), and pyrax uses that by default.

If you are using pyrax in conjunction with other software, you may already have authenticated using that other program. In that case, you can call the auth_with_token(), supplying the token along with either your tenant name or tenant ID. For Rackspace authentication, both of these values are your account number.

# Using an existing token
pyrax.auth_with_token(my_token, tenant_name="0728829")

If you use this method to authenticate in pyrax, be aware that you are responsible for ensuring that the token is valid. That means that if the token expires while your application is running, you need to catch that error, re-authenticate, and then call auth_with_token() again with the new token.

Once you have authenticated, you now have access to Cloud Servers, Cloud Files, Cloud Block Storage, Cloud Databases, Cloud Load Balancers, Cloud DNS, and Cloud Networks using the following references:

pyrax.cloudservers
pyrax.cloudfiles
pyrax.cloud_blockstorage
pyrax.cloud_databases
pyrax.cloud_loadbalancers
pyrax.cloud_dns
pyrax.cloud_networks

You don't have to authenticate to each service separately; pyrax handles that for you. And since it can be cumbersome to type those names throughout your code, these aliases are commonly set at the beginning of scripts:

cs = pyrax.cloudservers
cf = pyrax.cloudfiles
cbs = pyrax.cloud_blockstorage
cdb = pyrax.cloud_databases
clb = pyrax.cloud_loadbalancers
dns = pyrax.cloud_dns
cnw = pyrax.cloud_networks

These abbreviated aliases are used throughout much of the documentation and sample code for pyrax.

Auth Token Expiration

When you authenticate the cloud identity service returns a token, which is simply a random set of characters that identifies you as an authenticated user. This token is valid for a set period of time; the exact length of the valid period varies across cloud providers.

Every request needs to have the authentication information included in the headers of the API calls; pyrax handles this automatically for you. In addition, pyrax catches the error when a token is no longer valid, and attempts to re-authenticate in the background. As long as your original credentials are still valid, this happens transparently to your application. This enables you to write a long-running application without worrying about handling token expiration in your own code.

Please note that if you used auth_with_token() to authenticate originally, pyrax does not have your credentials, and so cannot automatically re-authenticate you. In this case, your code must handle the authentication failure when the token expires, and re-authenticate using whatever process you used to get your initial token. Once you've done that, you need to call auth_with_token() again to add the new token to pyrax.

Pyrax Configuration

You can control how pyrax behaves through the configuration file. It should be named ~/.pyrax.cfg. Like the credential file, ~/.pyrax.cfg is a standard configuration file. Alternatively, you may set these values using environment variables in the OS. Note that the configuration file values take precendence over any environment variables. Environment variables also do not support multiple configurations.

NOTE: At the very least, you must set the identity_type setting so that can use the correct identity class. Prior versions only worked with Rackspace identity, but that is no longer the case. If you don't want to use a configuration file or an environment variable, you can do this in code:

pyrax.set_setting("identity_type", "keystone")

or

pyrax.set_setting("identity_type", "rackspace")

Configuration Environments

Pyrax supports multiple configurations, which are referred to as environments. An environment is a separate OpenStack deployment with which you want to interact. A common situation is when you have a private cloud for some of your work, but also have a public cloud account for the rest. Each of these clouds require different authentication endpoints, and may require different settings for other things such as region, identity type, etc.

Each environment is a separate section in the configuration file, and the section name is used as the name of the environment. You can name your environments whatever makes sense to you, but there are two special names: 'default' and 'settings'. If a section is named 'default', it is used by pyrax unless you explicitly set a different environment. Also, for backwards compatibility with versions of pyrax before 1.4, a section named 'settings' is interpreted as the default. Those versions only supported a single environment in the configuration file, and used 'settings' as the section name. NOTE: if you do not have a section named either 'default' or 'settings', then the first section listed is used as the default environment.

Changing Environments

If you have multiple environments, you need to set the desired environment before you authenticate and connect to the services. If you want the default environment, you don't need to do anything. But if you want to connect to a different provider, you should run the following:

import pyrax
pyrax.set_environment("desired_environment")

Note that changing the environment requires that you authenticate against the new environment, and create new connections to the various services. In other words, if you had already authenticated so that a service such as pyrax.cloudservers referenced the compute service on that cloud, changing the environment to point to a different cloud discards the previous identity and service connections, so that now pyrax.cloudservers is None. Once you authenticate in the new environment, pyrax.cloudservers references the compute service on the cloud for the new environment.

Available Configuration Settings

Setting Affects Default Notes Env. Variable
identity_type The system used for authentication. -none- This should be "rackspace" (for the Rackspace Public Cloud) or "keystone" (for all Keystone-based auth systems). Any other system needs a class defined to handle that auth system, and its script added to the pyrax/identity directory. The entry for such custom classes should be in the format of 'module_name.ClassName'. CLOUD_ID_TYPE
auth_endpoint The URI of the authentication service -none- Not required for the Rackspace Public Cloud, where it can be determined from the region. For everything else it is required. CLOUD_AUTH_ENDPOINT
keyring_username User name used when fetching password from keyring. -none- Without setting this, you need to supply the username every time you use keyring_auth(). CLOUD_KEYRING_USER
region Regional datacenter to connect to; either 'DFW', 'ORD', or 'LON' for Rackspace; typically 'RegionOne' in Keystone. DFW This must be specified for all non-Rackspace environments. CLOUD_REGION
tenant_id The tenant ID used for authentication. -none- Not used in the Rackspace Public Cloud. CLOUD_TENANT_ID
tenant_name The tenant name used for authentication. -none- Not used in the Rackspace Public Cloud. CLOUD_TENANT_NAME
encoding The encoding to use when working with non-ASCII values. Unless you have a specific need, the default should work fine. utf-8 CLOUD_ENCODING
custom_user_agent Customizes the User-agent string sent to the server. -none- CLOUD_USER_AGENT
debug When True, causes all HTTP requests and responses to be output to the console to aid in debugging. False Previous versions called this setting 'http_debug'. CLOUD_DEBUG
verify_ssl Set this to False to bypass SSL certificate verification. True CLOUD_VERIFY_SSL

Here is a sample:

[private]
identity_type = keystone
region = RegionOne
custom_user_agent =
debug = True
auth_endpoint = http://192.168.0.1:5000/v2.0/
tenant_name = demo
tenant_id = abc123456
keyring_username = demo

[public]
identity_type = rackspace
keyring_username = joeracker
region = ORD
custom_user_agent = CrazyApp/2.0
debug = False
verify_ssl = False

The above configuration file defines two environments: private and public. Since there is no 'default' or 'settings' section, the 'private' environment is the default, since it is listed first.

When using the 'private' environment, pyrax uses Keystone authentication with the tenant name of 'demo', the tenant ID of 'abc123456', and the password stored in the keyring for user 'demo'. It also emits debugging messages for all HTTP requests and responses, and each request contains the standard User-agent header of 'pyrax/1.4.x'.

If the environment is then changed to 'public', pyrax switches to Rackspace authentication against the ORD region, using the username 'joeracker'. It no longer emits debug messages, does not perform SSL certificate verification, and all requests have the custom User-agent header of 'CrazyApp/2.0 pyrax/1.4.x'.

Accessing Environment Information

Pyrax offers several methods for querying and modifying envrionments and their settings. To start, you can determine the current environment by calling pyrax.get_environment(). You can also get a list of all defined envrionments by calling pyrax.list_environments(). And as mentioned above, you can switch the current envrionment by calling pyrax.set_environment(new_env_name).

To get the value of a setting, call pyrax.get_setting(key). Normally you do not need to change settings in the middle of a session, but just in case you do, you can use the pyrax.set_setting(key, val) method. Both of these methods work on the current environment by default. You can get/set settings in other environments with those calls by passing in the envrionment name as the optional env parameter to those methods.

Debugging HTTP requests

Sometimes when developing an application, the results received from the server are not what were expected. In those cases, it is helpful to be able to see the requests being sent to the API server, along with the responses received from the server. For those situations, there is the pyrax http_debug setting. There are two ways to enable this behavior globally. First, if you want to track all HTTP activity, you can change the debug entry in the configuration file mentioned above to 'True'. This causes all API calls and responses to be printed out to the terminal screen. Alternatively, you can call pyrax.set_http_debug(True) to turn on debug output, and pyrax.set_http_debug(False) to turn it off. This enables you to fine-tune the logging behavior for only the portion of your application that is of concern. Finally, if you only wish to debug HTTP requests for a single service, you can set the http_log_debug attribute of that service to True. For example, if you wanted to only see the HTTP traffic for the block storage service, you would call pyrax.cloud_blockstorage.http_log_debug = True.

Working with Rackspace's Multiple Regions

Rackspace divides its cloud infrastructure into "regions", and some interactions are only possible if the entities share a region. For example, if you wish to access a Cloud Database from a Cloud Server, that is only possible if the two are in the same region. Furthermore, if you connect to a region and call pyrax.cloudservers.list(), you only get a list of servers in that region. To get a list of all your servers, you have to query each region separately. This is simple to do in pyrax.

As of this writing, Rackspace has two cloud regions in the US: "DFW" and "ORD". It also has one UK region: "LON", which has separate login credentials. To get a list of all your US servers, you can do the following

cs_dfw = pyrax.connect_to_cloudservers(region="DFW")
cs_ord = pyrax.connect_to_cloudservers(region="ORD")
dfw_servers = cs_dfw.servers.list()
ord_servers = cs_ord.servers.list()
all_servers = dfw_servers + ord_servers

The important point to keep in mind when dealing with multiple regions is that all of pyrax's connect_to_* methods take a region parameter, and return a region-specific object. If you do not explicitly include a region, the default region you defined in your config file is used. If you did not define a default region, pyrax defaults to the "DFW" region.

The Identity Class

pyrax has an Identity class that is used to handle authentication and cache credentials. You can access it in your code using the reference pyrax.identity. Once authenticated, it stores your credentials and authentication token information. In most cases you do not need to interact with this object directly; pyrax uses it to handle authentication tasks for you. But it is available in case you need more fine-grained control of the authentication process, such as querying endpoints in different regions, or getting a list of user roles.

You can check its authenticated attribute to determine if authentication was successful; if so, its token and expires attributes contain the returned authentication information, and its services attribute contains a dict with all the service endpoint information. Here is an example of the contents of services after authentication (with identifying information obscured):

{u'access':
        {u'serviceCatalog': [
            {u'endpoints': [{u'publicURL': u'https://ord.loadbalancers.api.rackspacecloud.com/v1.0/000000',
                              u'region': u'ORD',
                              u'tenantId': u'000000'},
                             {u'publicURL': u'https://dfw.loadbalancers.api.rackspacecloud.com/v1.0/000000',
                              u'region': u'DFW',
                              u'tenantId': u'000000'}],
              u'name': u'cloudLoadBalancers',
              u'type': u'rax:load-balancer'},
             {u'endpoints': [{u'internalURL': u'https://snet-storage101.dfw1.clouddrive.com/v1/MossoCloudFS_ffffffff-ffff-ffff-ffff-ffffffffffff',
                              u'publicURL': u'https://storage101.dfw1.clouddrive.com/v1/MossoCloudFS_ffffffff-ffff-ffff-ffff-ffffffffffff',
                              u'region': u'DFW',
                              u'tenantId': u'MossoCloudFS_ffffffff-ffff-ffff-ffff-ffffffffffff'},
                             {u'internalURL': u'https://snet-storage101.ord1.clouddrive.com/v1/MossoCloudFS_ffffffff-ffff-ffff-ffff-ffffffffffff',
                              u'publicURL': u'https://storage101.ord1.clouddrive.com/v1/MossoCloudFS_ffffffff-ffff-ffff-ffff-ffffffffffff',
                              u'region': u'ORD',
                              u'tenantId': u'MossoCloudFS_ffffffff-ffff-ffff-ffff-ffffffffffff'}],
              u'name': u'cloudFiles',
              u'type': u'object-store'},
             {u'endpoints': [{u'publicURL': u'https://dfw.servers.api.rackspacecloud.com/v2/000000',
                              u'region': u'DFW',
                              u'tenantId': u'000000',
                              u'versionId': u'2',
                              u'versionInfo': u'https://dfw.servers.api.rackspacecloud.com/v2',
                              u'versionList': u'https://dfw.servers.api.rackspacecloud.com/'},
                             {u'publicURL': u'https://ord.servers.api.rackspacecloud.com/v2/000000',
                              u'region': u'ORD',
                              u'tenantId': u'000000',
                              u'versionId': u'2',
                              u'versionInfo': u'https://ord.servers.api.rackspacecloud.com/v2',
                              u'versionList': u'https://ord.servers.api.rackspacecloud.com/'}],
              u'name': u'cloudServersOpenStack',
              u'type': u'compute'},
             {u'endpoints': [{u'publicURL': u'https://dns.api.rackspacecloud.com/v1.0/000000',
                              u'tenantId': u'000000'}],
              u'name': u'cloudDNS',
              u'type': u'rax:dns'},
             {u'endpoints': [{u'publicURL': u'https://dfw.databases.api.rackspacecloud.com/v1.0/000000',
                              u'region': u'DFW',
                              u'tenantId': u'000000'},
                             {u'publicURL': u'https://ord.databases.api.rackspacecloud.com/v1.0/000000',
                              u'region': u'ORD',
                              u'tenantId': u'000000'}],
              u'name': u'cloudDatabases',
              u'type': u'rax:database'},
             {u'endpoints': [{u'publicURL': u'https://servers.api.rackspacecloud.com/v1.0/000000',
                              u'tenantId': u'000000',
                              u'versionId': u'1.0',
                              u'versionInfo': u'https://servers.api.rackspacecloud.com/v1.0',
                              u'versionList': u'https://servers.api.rackspacecloud.com/'}],
              u'name': u'cloudServers',
              u'type': u'compute'},
             {u'endpoints': [{u'publicURL': u'https://cdn1.clouddrive.com/v1/MossoCloudFS_ffffffff-ffff-ffff-ffff-ffffffffffff',
                              u'region': u'DFW',
                              u'tenantId': u'MossoCloudFS_ffffffff-ffff-ffff-ffff-ffffffffffff'},
                             {u'publicURL': u'https://cdn2.clouddrive.com/v1/MossoCloudFS_ffffffff-ffff-ffff-ffff-ffffffffffff',
                              u'region': u'ORD',
                              u'tenantId': u'MossoCloudFS_ffffffff-ffff-ffff-ffff-ffffffffffff'}],
              u'name': u'cloudFilesCDN',
              u'type': u'rax:object-cdn'},
             {u'endpoints': [{u'publicURL': u'https://monitoring.api.rackspacecloud.com/v1.0/000000',
                              u'tenantId': u'000000'}],
              u'name': u'cloudMonitoring',
              u'type': u'rax:monitor'}],
u'token': {u'expires': u'2222-02-22T22:22:22.000-02:00',
    u'id': u'xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx',
    u'tenant': {u'id': u'000000', u'name': u'000000'}},
u'user': {u'RAX-AUTH:defaultRegion': u'',
   u'id': u'123456',
   u'name': u'someuser',
   u'roles': [{u'description': u'User Admin Role.',
               u'id': u'3',
               u'name': u'identity:user-admin'}]}}}
Jump to Line
Something went wrong with that request. Please try again.