Windows Azure：如何将配置设置公开为环境变量？

Question

I tried adding this to my ServiceDefinition.csdef file:

<WorkerRole ...><Runtime><Environment>
    <Variable name="AZURE_STORAGE_ACCOUNT">
      <RoleInstanceValue xpath="/RoleEnvironment/CurrentInstance/ConfigurationSettings/ConfigurationSetting[@name='AZURE_STORAGE_ACCOUNT']/@value" />
    </Variable>
</Environment></Runtime></WorkerRole>

And I set the configuration setting in my ServiceConfiguration.Cloud.cscfg file:

<Role name="WorkerRole">
  <ConfigurationSettings>
    <Setting name="AZURE_STORAGE_ACCOUNT" value="<secret stuff>" />
  </ConfigurationSettings>
</Role>

But I got the following error when I run cspack :

CloudServices091 : The '/RoleEnvironment/CurrentInstance/Configur
ationSettings/ConfigurationSetting[@name='AZURE_STORAGE_ACCOUNT']/@value' is an
invalid xpath expression.

Answer 1

Are you missing the declaration of that setting? I don't see the appropriate element in your .csdef , something like <ConfigurationSettings><Setting name="AZURE_STORAGE_ACCOUNT"/></ConfigurationSettings> . You need one of those in your .csdef , and then you still want the one in your .cscfg that includes the value.

If you're using Visual Studio, it should edit both files for you if you use its property view. (Just double click the role and then click around to get to config settings and add a new one.)

Answer 2

The configuration seems to be correct. It would be better if you can make sure you're using the latest SDK. The xPath feature is available in Windows Azure SDK 1.5 and later.

Best Regards,

Ming Xu.

Answer 3

I have tried out different options mentioned at blogs, like including the setting in both .cscfg and .csdef. But, it doesn't seem to work. Also, other Xpath queries like

      <RoleInstanceValue xpath="/RoleEnvironment/CurrentInstance/@id"/>

work correctly.

Finally, I figured out that the variable name used was different:

In cscfg I had :

<Setting name="WFFEPeriodicRestartTime" value="168:00:00" />

in csdef I had :

  <ConfigurationSettings>
      <Setting name="PeriodicRestartTime" />
   </ConfigurationSettings>

.... ....

 <Variable name="PeriodicRestartTime">
            <RoleInstanceValue xpath="/RoleEnvironment/CurrentInstance/ConfigurationSettings/ConfigurationSetting[@name='WFFEPeriodicRestartTime']/@value" />
  </Variable>

---

Changed csdef to :

<ConfigurationSettings>
      <Setting name="WFFEPeriodicRestartTime" />
   </ConfigurationSettings>

.... ....

 <Variable name="WFFEPeriodicRestartTime">
            <RoleInstanceValue xpath="/RoleEnvironment/CurrentInstance/ConfigurationSettings/ConfigurationSetting[@name='WFFEPeriodicRestartTime']/@value" />
          </Variable>

---

It seems to work correctly now

Answer 4

Ran into the same issue here as I was trying to read config values via the example provided here: https://docs.microsoft.com/en-us/azure/cloud-services/cloud-services-role-config-xpath#config-setting - lost quite a few brain cells in the process!

The trick is, this doesnt mean that you read config values from your web.config (which is how I mis read it), but from the Settings in the cscfg file.

With cloud services you have 1 csdef file that applies to all your cloud service convigurations, but then a cscfg for each environment. In my scenario I have cscfg's for DEV, QA, Prod, and I needed to set a different variable depending on the environment.

So for the OP's question, when you try to perform the "RoleEnvironment/CurrentInstance/ConfigurationSettings.." statement and get the invalid xpath value, its essentially saying "hey I cant find this value"

How to make the magic happen:

Your csdef file needs the following:

<ConfigurationSettings>
    <Setting name="AZURE_STORAGE_ACCOUNT" />
</ConfigurationSettings>

Your cscfg then needs:

<ConfigurationSettings>
      <Setting name="AZURE_STORAGE_ACCOUNT" value="Some Secret Value" />
</ConfigurationSettings>

For my purposes I was trying to use this value in a startup.cmd file, so I was able to add the following to my csdef startup task

<Startup>
  <Task commandLine="Startup.cmd" executionContext="elevated" taskType="simple">
    <Environment>
      <Variable name="AZURE_STORAGE_ACCOUNT">
        <RoleInstanceValue xpath="/RoleEnvironment/CurrentInstance/ConfigurationSettings/ConfigurationSetting[@name='AZURE_STORAGE_ACCOUNT']/@value" />
      </Variable>
    </Environment>
  </Task>
</Startup>

Then in my startup.cmd you can just reference the value as %%AZURE_STORAGE_ACCOUNT%%