Where can I find docker container logs for Azure App Service

Question

I do have a Docker container running a .net core 2 app.

The logging is configured using this code in Program.cs

public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
    WebHost.CreateDefaultBuilder(args)
        .ConfigureLogging((hostingContext, logging) =>
        {
            logging.AddConfiguration(hostingContext.Configuration.GetSection("Logging"));
            logging.AddConsole();
            logging.AddDebug();
        })
        .UseStartup<Startup>();

and the appsettings.json file

{
  "Logging": {
    "LogLevel": {
      "Default": "Information"
    }
  },
}

Logging seems to be Ok, when running Kestrel directly, I can see the logs in the terminal. Same thing, when containerized: the command docker logs shows what I want.

Troubles arise in production, when run in as a container in Azure Web App. I cannot find any consistent docker logs.

I made attempts to visit the Log file via FTP or via the url https://[mysite].scm.azurewebsites.net/api/logs/docker the log files are almost empty for example, https://[mysite].scm.azurewebsites.net/api/vfs/LogFiles/2018_09_09_RD0003FF74F63E_docker.log , only container starting lines are present

Also I do have the same lines in the usual portal interface.

The question is: do docker logs are automatically output in docker.log files in Azure Web App? Is there something that I am missing?

Answer 1

Firstly you need to enable container logs

[App Service] -> Monitoring -> App Service logs

Then you can see container logs in [App Service] -> Monitoring -> Log stream

UPD

Also you can find logs in KUDU

Then "Current Docker Logs"

Answer 2

I've been cursing this for a good while, and eventually found something that works for me.

First I enabled filesystem logging as per @dima_horror's answer.

Next I ran a command-line az webapp log tail --name myApp --resource-group myRg

That now seems to give me useful output (it gave me nothing prior to enabling filesystem logging).

Answer 3

Have you checked the logs in container settings? I followed this guide to deploy a container to Azure web app.

Answer 4

To add to the answers, if you're having trouble with deploying the image in your App Service and need logs for that specifically, you can get the docker logs for the provisioning phase of your container under Deployment Center, eg:

Answer 5

I have the same exact issue, the App Service container logs is generic and vague. This is not the same logs that Docker shows us whenever we run a container.

17/02/2020 08:59:25.186 INFO - Site: tutorial-api - Start container succeeded. Container: f8bfa7e27680c0e9551c6157f9d1c8a73c9a3e739b4f15de8586ce52809798d3 17/02/2020 08:59:30.675 INFO - Site: tutorial-api - Application Logging (Filesystem): On 17/02/2020 08:59:44.106 INFO - Site: tutorial-api - Waiting for container to be ready 17/02/2020 08:59:49.116 INFO - Site: tutorial-api - Container has exited 17/02/2020 08:59:49.117 ERROR - Site: tutorial-api - Container could not be started 17/02/2020 08:59:49.120 INFO - Site: tutorial-api - Purging after container failed to start 17/02/2020 08:59:49.120 ERROR - Site: tutorial-api - Unable to start container. Error message: Container could not be started: tutorial-api_20

"Unable to start container, container couldn't be started"

Wow! Azure just told me every 60 seconds a minute has passed.

I understand that this is production environment, but you got to give us something!

Out of frustration, I decided to run same image in a Azure Container Instance resource, there it shows you the same detailed logs that Docker provides (see screenshot below)

Now that's what I'm talking about!

Using the error logs in Azure Container Instance, I found out that my App Service couldn't access the Sql Server resource (even though they are within the same resource group). I simply enabled the Sql Server resource to be accessed within the same resource group