dotnet app in Docker container not seeing environment variables - docker

Question

I have a working dotnet application that I can run locally, as well, the same code runs in an azure web app. I have been able to containerize it. However, when I run it in the container it fails to read the environment variable:
Code to get/check environment variable in the controller:
public ReportController(ILogger<ReportController> logger, IConfiguration iconfig)
{
_logger = logger;
_config = iconfig;
_storageConnString = Environment.GetEnvironmentVariable("AzureWebJobsStorage");
_containerName = Environment.GetEnvironmentVariable("ReportContainer");
string CredentialConnectionString = Environment.GetEnvironmentVariable("CredentialConnectionString");
if(CredentialConnectionString == null)
{
throw new Exception("Credential connection string is null");
}
}
code in start up:
public static void Main(string[] args)
{
CreateHostBuilder(args).Build().Run();
}
public static IHostBuilder CreateHostBuilder(string[] args) =>
Host.CreateDefaultBuilder(args)
.ConfigureWebHostDefaults(webBuilder =>
{
webBuilder.UseStartup<Startup>();
})
.ConfigureAppConfiguration((hostingContext, config) =>
{
config.AddEnvironmentVariables();
});
```
my docker compose that is setting the variables:
services:
myreports:
image: myreports
build:
context: .
dockerfile: myreports/Dockerfile
ports: [5000:5000]
environment:
- "APPSETTINGS_AzureWebJobsStorage = DefaultEndpointsProtocol=https;AccountName=mystorage;AccountKey=xxxx+xx/xx==;EndpointSuffix=core.windows.net"
- "APPSETTINGS_HarmonyConnectionString = Data Source=mydb.database.windows.net;AttachDbFilename=;Initial Catalog=Harmony;Integrated Security=False;Persist Security Info=False;User ID=sqlreporter;Password=mypass"
- "APPSETTINGS_CredentialConnectionString = Data Source=mydb.database.windows.net;AttachDbFilename=;Initial Catalog=Credential;Integrated Security=False;Persist Security Info=False;User ID=sqlreporter;Password=mypass"
- "CredentialConnectionString = Data Source=mydb.database.windows.net;AttachDbFilename=;Initial Catalog=Credential;Integrated Security=False;Persist Security Info=False;User ID=sqlreporter;Password=mypass"
- "APPSETTINGS_ReportContainer = taxdocuments"
As you can see I'm attempting both the APPSETTINGS_ prefix and not
but when I hit the port in the app the container returns:
myreports-1 | System.Exception: Credential connection string is null
the code works fine the in the app service getting the variables

Answer 1

You don't need to add APPSETTINGS_ in front of the variable names. What's causing the issue is the spaces around the equals sign in your docker-compose file. The quotes are not needed, so I'd remove them.
This should work
services:
myreports:
image: myreports
build:
context: .
dockerfile: myreports/Dockerfile
ports: [5000:5000]
environment:
- AzureWebJobsStorage=DefaultEndpointsProtocol=https;AccountName=mystorage;AccountKey=xxxx+xx/xx==;EndpointSuffix=core.windows.net
- HarmonyConnectionString=Data Source=mydb.database.windows.net;AttachDbFilename=;Initial Catalog=Harmony;Integrated Security=False;Persist Security Info=False;User ID=sqlreporter;Password=mypass
- CredentialConnectionString=Data Source=mydb.database.windows.net;AttachDbFilename=;Initial Catalog=Credential;Integrated Security=False;Persist Security Info=False;User ID=sqlreporter;Password=mypass
- ReportContainer=taxdocuments