swift-middleware.md

swift-middleware.md

Installing Custom Middleware

Sometimes, middleware needs to be added or configured differently than the assumptions made in the swift-private-cloud cookbook.

Fortunately, there are provisions for modifying to configurations to achieve different goals.

As an example, let's install Swift's "Static Web" middleware, as described in the OpenStack Object Storage manual.

According to this documentation, the proxy server configuration must be changed to include the following sections:

[DEFAULT]
...

[pipeline:main]
pipeline = healthcheck cache tempauth staticweb proxy-server

...

[filter:staticweb]
use = egg:swift#staticweb
# Seconds to cache container x-container-meta-web-* header values.
# cache_timeout = 300
# You can override the default log routing for this filter here:
# set log_name = staticweb
# set log_facility = LOG_LOCAL0
# set log_level = INFO
# set access_log_name = staticweb
# set access_log_facility = LOG_LOCAL0
# set access_log_level = INFO
# set log_headers = False

In general, only two things need to be done. A middleware stanza must be added for staticweb, and it must be added to the application pipeline. Simple enough.

Swift Config Files

In prior cookbooks, configuration files were only able to be templated to the degree that the chef templates were wired to allow it. With the new swift cookbooks, however, all values in all the major config files are able to be customized.

The config files themselves are stored as a big json blob in chef itself. These json blobs are serialized into the config files on each run.

For example, a section of the account server config file might look like this:

[DEFAULT]
backlog = 4096
bind_ip = 0.0.0.0
bind_port = 6002
workers = 6

[filter:healthcheck]
use = egg:swift#healthcheck

[app:account-server]
use = egg:swift#account

[pipeline:main]
pipeline = healthcheck account-server

The json blob that corresponds to this config snippet is at node['swift-private-cloud']['account']['config'], and looks like this:

{
  "DEFAULT": {
    "backlog": 4096,
    "bind_ip": "0.0.0.0",
	 "bind_port": 6002,
	 "workers": 6
  },
  "filter:healthcheck": {
    "use": "egg:swift#healthcheck"
  },
  "pipeline:main": {
    "pipeline": "healthcheck account-server"
  }
}

The configuration doesn't have to be specified as a json blob, however. Individual settings can be overridden in the environment with an attribute like this:

"override_attributes": {
  "swift-private-cloud": {
    "account": {
      "config": {
        "DEFAULT": {
          "workers": 12
        }
      }
    }
  }
  ... other config values omitted ...
}

Which will leave the default configuration intact, with the exception of the single override on default workers.

In a like manner, the following configuration files can be overriden at the following environment locations:

Config File	Attribute Location
/etc/swift/object-server.conf	node['swift-private-cloud']['object']['config']
/etc/swift/container-server.conf	node['swift-private-cloud']['container']['config']
/etc/swift/account-server.conf	node['swift-private-cloud']['account']['config']
/etc/swift/proxy-server.conf	node['swift-private-cloud']['proxy']['config']
/etc/swift/object-expirer.conf	node['swift-private-cloud']['object-expirer']['config']

Adding Static Web Middleware

So, given the configuration information above, the task of adding the staticweb middleware becomes a problem of defining the config file overrides necessary to cause the correct config to be dropped on the proxy servers.

Since this is a modification to proxy-server.conf, we must modify the json blob in node['swift-private-cloud']['proxy']['config']. We need to add a section called "filter:staticweb" with the key/value pair ("use" "egg:swift#staticweb").

This can be accomplished with an override attribute in the environment:

"override_attributes": {
  "swift-private-cloud": {
    "proxy": {
      "config": {
        "filter:staticweb": {
          "use": "egg:swift#staticweb"
        }
      }
    }
  }
}

In addition, the pipeline must be changed to add the staticweb middleware. The documentation is a little bit off, as what we really want to do is add the staticweb middleware into the existing proxy pipeline. Changing the pipeline to what is documented in the OpenStack docs would result in losing a number of important pipeline middleware. Looking at the default config values for the proxy server, we can see that the default pipeline (node['swift-private-cloud']['proxy']['config']['pipeline:main']['pipeline']) is "catch_errors proxy-logging healthcheck cache ratelimit authtoken keystoneauth proxy-logging proxy-server".

We'll just add the staticweb module right before proxy-server, as it was in the documentation:

"override_attributes": {
  "swift-private-cloud": {
    "proxy": {
      "config": {
        "pipeline:main": {
          "pipeline": "catch_errors proxy-logging healthcheck cache ratelimit authtoken keystoneauth proxy-logging staticweb proxy-server"
        }
      }
    }
  }
}

The combined environment might look something like this:

"override_attributes": {
  "swift-private-cloud": {
    "proxy": {
      "config": {
        "filter:staticweb": {
          "use": "egg:swift#staticweb"
        },
        "pipeline:main": {
          "pipeline": "catch_errors proxy-logging healthcheck cache ratelimit authtoken keystoneauth proxy-logging staticweb proxy-server"
        }
      }
    }
  }
}

Try It

1. Edit the environment to add the environment suggested above
2. Run chef-client on the proxy
3. Observe that the config file has been changed (/etc/swift/proxy-server.conf)
4. Make a web site:
5. ssh into the proxy server (as root?)
6. source .openrc
7. echo "<html><h1>Hi</h1></html>" > index.html
8. swift upload web index.html
9. swift post -r '.r:*' web
10. swift post -m 'web-index:index.html' web
11. view at http://<proxy-ip>:8080/v1/<account>/web (account looks like AUTH_<hex digits>, and can be found with swift stat)

Summary

Customizing your swifts. YOU CAN DO IT!