Ambiguity occurs when constructing configuration object after a refresh()

[prafed]

Version: azure+app-configuration-provider@2.4.0

We have the following structure in Azure App Configuration:

apiCarts_markets: { "allCountryUrls": {"gb": {...}, "dk": {...}, ...}
apiCarts_markets.markets.dk: { ... }
apiCarts_markets.markets.gb: { ... }
apiCarts_markets.markets.fi: { ... }
....

When we load our function app we perform an initialise and load the settings like so:

settings = await load(APP_CONFIG_ENDPOINT, credential, {
      refreshOptions: {
        enabled: true,
        refreshIntervalInMs: APP_CONFIG_REFRESH_INTERVAL_MS,
      },
      keyVaultOptions: {
        credential,
        parallelSecretResolutionEnabled: true,
        secretRefreshIntervalInMs: APP_CONFIG_SECRET_REFRESH_INTERVAL_MS,
        clientOptions: {
          userAgentOptions: {
            userAgentPrefix: `service/${getServiceName()}`,
          },
        },
      },
      clientOptions: {
        userAgentOptions: {
          userAgentPrefix: `service/${getServiceName()}`,
        },
      },
      selectors: [
        {
          keyFilter: `apiCarts_*`,
        },
      ],
      trimKeyPrefixes: ["apiCarts_"],
    })

settingsObject = settings.constructConfigurationObject({
  separator: '.',
})

settingsObject correctly reads and resolves our App Configuration.

We then preserve this settings object in another module and call settingsObject.refresh() every minute

We have also setup a refresh callback: (Which should only be called when APP_CONFIG_REFRESH_INTERVAL_MS elapses and there are actual changes in the AppConfig)

And call constructConfigurationObject on the same settings object
(This is just pseudocode for demonstration purposes, ignore variable scoping issues etc..)

settingsObject.onRefresh(() => {
    newSettingsObject = settingsObject.constructConfigurationObject({
      separator: '.',
    })
}

We are seeing this error come up only when we call constructConfigurationObject() after a ssettingsObject.refresh()
Initial load of constructConfigurationObject() works fine.

InvalidOperationError: Ambiguity occurs when constructing configuration object from key 'markets.markets.dk', value '[object Object]'. The key should not be part of another key.
at Rk.constructConfigurationObject (/node_modules/.pnpm/@azure+app-configuration-provider@2.4.0/node_modules/@azure/app-configuration-provider/src/appConfigurationImpl.ts:334:23)

[zhiyuanliang-ms]

Hey, @prafed

Sorry for the inconvenience. Could you provide more information to help me reproduce the error?

const connectionString = "xxxx"

import { promisify } from "node:util";
const sleepInMs = promisify(setTimeout);

import { load } from "@azure/app-configuration-provider";
const appConfig = await load(connectionString, {
	selectors: [
        {
          keyFilter: `apiCarts_*`,
        },
  	],
  	trimKeyPrefixes: ["apiCarts_"],
  	refreshOptions: {
        enabled: true,
        refreshIntervalInMs: 2_000
    }
})


let settingsObject = appConfig.constructConfigurationObject({
  separator: '.',
})
appConfig.onRefresh(() => {
	settingsObject = appConfig.constructConfigurationObject({
	  separator: '.',
	})
})

console.log(settingsObject)
while (true) {
    console.log("refreshing...");
    appConfig.refresh();
    await sleepInMs(3000); 

    console.log(settingsObject)
}

I used the above code to reproduce the error.

In my app config store, there are three kvs:
All three kvs have content type: application/json
"apiCarts_markets" with value:

{
	"gb": {
		"url": "https://api.example.com/gb-updated"
	},
	"dk": {
		"url": "https://api.example.com/dk"
	}
}

"apiCarts_markets.markets.dk" with value:

{
	"currency": "DKK"
}

"apiCarts_markets.markets.gb" with value:

{
	"currency": "GBP"
}

I tried to modify the url and the currency. I also tried to add a new kv: "apiCarts_markets.markets.us".

But I didn't the get the error you got.

Could you share more information about how you update your kv in your App Config store?

[jimmythomson]

Hi @zhiyuanliang-ms - for reference, we can see the error when there are no data changes. So presumably it'll pull down the same config again. We'll try and get you some more detail, but wanted to at least give you that specific detail asap.

Thanks.

[jimmythomson]

I think that you can effectively replicate the error by calling constructConfigurationObject twice:

let settingsObject = appConfig.constructConfigurationObject({
  separator: '.',
})

settingsObject = appConfig.constructConfigurationObject({
  separator: '.',
})

I appreciate that you wouldn't ordinarily expect two calls like this, but should that cause an error?

[zhiyuanliang-ms]

Hey, @jimmythomson

I reproduced the issue. And this is a bug. I've identified the root cause: when constructConfigurationObject() builds the hierarchical object, it assigns parsed JSON values by reference rather than by copy. If another key shares the same prefix (e.g., "markets" and "markets.markets.dk"), the method inadvertently modifies the original stored value during the first call, which causes the second call to fail with an ambiguity error.

Fixed in #288

[jimmythomson]

Thanks very much for the quick turnaround @zhiyuanliang-ms - we'll update the package version once released and test it out.

[prafed]

Thanks for this! Any news on when this will be released?

[zhiyuanliang-ms]

Hey, @prafed
We planed a release this week.

[linglingye001]

Hi @prafed , the fix has been released in v2.4.1.