Zipdeploy for function app deploys wrong function app?

[razzemans]

We have two Azure functions, let's call them A and B, that we deploy using Azure Devops. Looking at the deployment logs, first the right package is deployed followed by a deploy where the contents of Function App A are deployed to Function app B. How this happens is a mystery.

The strange things is, looking at the logs and what is inside Kudu, they don't match up. For example, the latest deploy log, which deploys the incorrect version, will say this:

[
  {
    "log_time": "2021-09-17T10:57:17.3180234Z",
    "id": "",
    "message": "Command: \"D:\\home\\site\\deployments\\tools\\deploy.cmd\"",
    "type": 0,
    "details_url": null
  },
  {
    "log_time": "2021-09-17T10:57:18.5999063Z",
    "id": "",
    "message": "Handling Basic Web Site deployment.",
    "type": 0,
    "details_url": null
  },
  {
    "log_time": "2021-09-17T10:57:24.8723981Z",
    "id": "",
    "message": "Creating app_offline.htm",
    "type": 0,
    "details_url": null
  },
  {
    "log_time": "2021-09-17T10:57:24.9036384Z",
    "id": "",
    "message": "KuduSync.NET from: 'D:\\local\\Temp\\zipdeploy\\extracted' to: 'D:\\home\\site\\wwwroot'",
    "type": 0,
    "details_url": null
  },
  {
    "log_time": "2021-09-17T10:57:25.0941627Z",
    "id": "",
    "message": "Deleting file: 'OurCompany.Api.B.dll'",
    "type": 0,
    "details_url": null
  },
    "log_time": "2021-09-17T10:57:25.1557977Z",
    "id": "",
    "message": "Copying file: 'extensions.json'",
    "type": 0,
    "details_url": null
  },
  {
    "log_time": "2021-09-17T10:57:25.1718472Z",
    "id": "",
    "message": "Copying file: 'OurCompany.Api.A.dll'",
    "type": 0,
    "details_url": null
  },
  {
    "log_time": "2021-09-17T10:57:27.4441118Z",
    "id": "",
    "message": "Deleting app_offline.htm",
    "type": 0,
    "details_url": null
  },
  {
    "log_time": "2021-09-17T10:57:27.5223301Z",
    "id": "",
    "message": "Finished successfully.",
    "type": 0,
    "details_url": null
  }
]

But when I go to Kudu on the server of the OurCompany.Api.B function app and I look at the actual contents in D:\\local\\Temp\\zipdeploy\\extracted I see no OurCompany.Api.A.dll at all - only OurCompany.Api.B.dll. Note that the timestamp of the files in the extracted folder predate the second deployment, so they are from the first and CORRECT deploy.

If I look at the contents inside D:\\home\\site\\wwwroot I DO see the incorrect OurCompany.Api.A.dll but where this is coming from I have no idea.

So... how can the deploy logs mention the copying of incorrect dll files while they are not in the folder on the server, and never were there because the timestamps don't add up? We've been working on this issue for days now without succes.

[suwatch]

See if both function apps happen to use the same Azure Files Share.

[razzemans]

Appreciate the reply. They were hosted on the same App Service Plan so that is the case I assume. I actually hosted them on separate app service plans after my initial post and the issue has gone away. So what is happening here? Can we not host more than one Azure function on the same App Service plan? Or only when using zip deploys?

[suwatch]

App Service Plan (same or different) should not matter. Each App Service will have its own file system - one deployment should not affect the other. Often times - users setup Azure Files for each App Services; however, many point to the same file share overriding the content.

[razzemans]

I can only say that after migrating to a different App Service Plan the issue went away 100%. I'm fairly sure it is not an issue with our deployment pipeline since the logs / kudu clearly show that somehow files are overwritten. We did not setup Azure File Share for these function apps.
I'm happy that the issue resolved using a different App Service Plan, but on the other hand something clearly goes wrong here which might affect other users in the future.

[jvano]

Hi

If the problem persists and is related to running it on Azure App Service, please open a support incident in Azure:
https://learn.microsoft.com/en-us/azure/azure-portal/supportability/how-to-create-azure-support-request

This way we can better track and assist you on this case

Thanks,

Joaquin Vano
Azure App Service