.NET and SQL Server container with EF Core and K8s

Question

.NET and SQL Server container with EF Core and K8s

My goal is to deploy a blazor web application using ASP.NET as the frontend and a SQL Server (on Linux) as the backend. The problem is utilizing the EF Core code because of my embedded connection string:

var connectionString = "Server=localhost,1433;Database=HelmDevDb;uid=sa;pwd=27u6DG;MultipleActiveResultSets=true;";

The problem is that within the Blazor application it either has to have EF Core commented out (working) or I have to leave uncommented and guess the connection string and

docker build -t schneeple/myapp:v3 -f Dockerfile ..

command. and then update the helm script with:

helm uninstall myapp
helm install myapp myapp
kubectl get pods

and then see the status which usually tends to make the myapp-deployment app break.

➜ kubectl get pods --watch
NAME                                 READY   STATUS      RESTARTS   AGE
myapp-deployment-5cdcd7d4bc-nrl72    0/1     Completed   1          36s
myapp-mssql-linux-784b846c6c-666s5   1/1     Running     0          36s

When I view the k8s logs of the myapp-deployment-5cdcd7d4bc-nrl72 pod it gives the following error:

➜ kubectl logs myapp-deployment-5cdcd7d4bc-nrl72
[23:30:36 INF] Starting up
[23:30:36 WRN] Storing keys in a directory '/root/.aspnet/DataProtection-Keys' that may not be persisted outside of the container. Protected data will be unavailable when container is destroyed.
[23:30:36 INF] User profile is available. Using '/root/.aspnet/DataProtection-Keys' as key repository; keys will not be encrypted at rest.
[23:30:36 INF] Creating key {bc4aa022-61fe-4fe4-b215-572c8337869d} with creation date 2020-06-30 23:30:36Z, activation date 2020-06-30 23:30:36Z, and expiration date 2020-09-28 23:30:36Z.
[23:30:36 WRN] No XML encryptor configured. Key {bc4aa022-61fe-4fe4-b215-572c8337869d} may be persisted to storage in unencrypted form.
[23:30:36 INF] Writing data to file '/root/.aspnet/DataProtection-Keys/key-bc4aa022-61fe-4fe4-b215-572c8337869d.xml'.
[23:30:37 INF] Entity Framework Core 3.1.4 initialized 'AppDbContext' using provider 'Microsoft.EntityFrameworkCore.SqlServer' with options: None
[23:30:52 FTL] Application startup exception
Microsoft.Data.SqlClient.SqlException (0x80131904): A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: TCP Provider, error: 40 - Could not open a connection to SQL Server)
   at Microsoft.Data.SqlClient.SqlInternalConnectionTds..ctor(DbConnectionPoolIdentity identity, SqlConnectionString connectionOptions, SqlCredential credential, Object providerInfo, String newPassword, SecureString newSecurePassword, Boolean redirectedUserInstance, SqlConnectionString userConnectionOptions, SessionData reconnectSessionData, Boolean applyTransientFaultHandling, String accessToken, DbConnectionPool pool, SqlAuthenticationProviderManager sqlAuthProviderManager)
   at Microsoft.Data.SqlClient.SqlConnectionFactory.CreateConnection(DbConnectionOptions options, DbConnectionPoolKey poolKey, Object poolGroupProviderInfo, DbConnectionPool pool, DbConnection owningConnection, DbConnectionOptions userOptions)
   at Microsoft.Data.ProviderBase.DbConnectionFactory.CreatePooledConnection(DbConnectionPool pool, DbConnection owningObject, DbConnectionOptions options, DbConnectionPoolKey poolKey, DbConnectionOptions userOptions)
   at Microsoft.Data.ProviderBase.DbConnectionPool.CreateObject(DbConnection owningObject, DbConnectionOptions userOptions, DbConnectionInternal oldConnection)
   at Microsoft.Data.ProviderBase.DbConnectionPool.UserCreateRequest(DbConnection owningObject, DbConnectionOptions userOptions, DbConnectionInternal oldConnection)
   at Microsoft.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, UInt32 waitForMultipleObjectsTimeout, Boolean allowCreate, Boolean onlyOneCheckConnection, DbConnectionOptions userOptions, DbConnectionInternal& connection)
   at Microsoft.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal& connection)
   at Microsoft.Data.ProviderBase.DbConnectionFactory.TryGetConnection(DbConnection owningConnection, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal oldConnection, DbConnectionInternal& connection)
   at Microsoft.Data.ProviderBase.DbConnectionInternal.TryOpenConnectionInternal(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)
   at Microsoft.Data.ProviderBase.DbConnectionClosed.TryOpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)
   at Microsoft.Data.SqlClient.SqlConnection.TryOpen(TaskCompletionSource`1 retry)
   at Microsoft.Data.SqlClient.SqlConnection.Open()
   at Microsoft.EntityFrameworkCore.Storage.RelationalConnection.OpenDbConnection(Boolean errorsExpected)
   at Microsoft.EntityFrameworkCore.Storage.RelationalConnection.Open(Boolean errorsExpected)
   at Microsoft.EntityFrameworkCore.SqlServer.Storage.Internal.SqlServerDatabaseCreator.<>c__DisplayClass18_0.<Exists>b__0(DateTime giveUp)
   at Microsoft.EntityFrameworkCore.ExecutionStrategyExtensions.<>c__DisplayClass12_0`2.<Execute>b__0(DbContext c, TState s)
   at Microsoft.EntityFrameworkCore.SqlServer.Storage.Internal.SqlServerExecutionStrategy.Execute[TState,TResult](TState state, Func`3 operation, Func`3 verifySucceeded)
   at Microsoft.EntityFrameworkCore.ExecutionStrategyExtensions.Execute[TState,TResult](IExecutionStrategy strategy, TState state, Func`2 operation, Func`2 verifySucceeded)
   at Microsoft.EntityFrameworkCore.ExecutionStrategyExtensions.Execute[TState,TResult](IExecutionStrategy strategy, TState state, Func`2 operation)
   at Microsoft.EntityFrameworkCore.SqlServer.Storage.Internal.SqlServerDatabaseCreator.Exists(Boolean retryOnNotExists)
   at Microsoft.EntityFrameworkCore.SqlServer.Storage.Internal.SqlServerDatabaseCreator.Exists()
   at Microsoft.EntityFrameworkCore.Migrations.HistoryRepository.Exists()
   at Microsoft.EntityFrameworkCore.Migrations.Internal.Migrator.Migrate(String targetMigration)
   at Microsoft.EntityFrameworkCore.RelationalDatabaseFacadeExtensions.Migrate(DatabaseFacade databaseFacade)
   at AuSight.Startup.Configure(IApplicationBuilder app, IWebHostEnvironment env, AppDbContext data) in /src/AuSight/Startup.cs:line 105
   at System.RuntimeMethodHandle.InvokeMethod(Object target, Object[] arguments, Signature sig, Boolean constructor, Boolean wrapExceptions)
   at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
   at Microsoft.AspNetCore.Hosting.ConfigureBuilder.Invoke(Object instance, IApplicationBuilder builder)
   at Microsoft.AspNetCore.Hosting.ConfigureBuilder.<>c__DisplayClass4_0.<Build>b__0(IApplicationBuilder builder)
   at Microsoft.AspNetCore.Hosting.GenericWebHostBuilder.<>c__DisplayClass13_0.<UseStartup>b__2(IApplicationBuilder app)
   at Microsoft.ApplicationInsights.AspNetCore.ApplicationInsightsStartupFilter.<>c__DisplayClass2_0.<Configure>b__0(IApplicationBuilder app)
   at Microsoft.AspNetCore.Mvc.Filters.MiddlewareFilterBuilderStartupFilter.<>c__DisplayClass0_0.<Configure>g__MiddlewareFilterBuilder|0(IApplicationBuilder builder)
   at Microsoft.AspNetCore.HostFilteringStartupFilter.<>c__DisplayClass0_0.<Configure>b__0(IApplicationBuilder app)
   at Microsoft.AspNetCore.Hosting.GenericWebHostService.StartAsync(CancellationToken cancellationToken)
ClientConnectionId:00000000-0000-0000-0000-000000000000
[23:30:52 FTL] Application start-up failed
Microsoft.Data.SqlClient.SqlException (0x80131904): A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: TCP Provider, error: 40 - Could not open a connection to SQL Server)
   at Microsoft.Data.SqlClient.SqlInternalConnectionTds..ctor(DbConnectionPoolIdentity identity, SqlConnectionString connectionOptions, SqlCredential credential, Object providerInfo, String newPassword, SecureString newSecurePassword, Boolean redirectedUserInstance, SqlConnectionString userConnectionOptions, SessionData reconnectSessionData, Boolean applyTransientFaultHandling, String accessToken, DbConnectionPool pool, SqlAuthenticationProviderManager sqlAuthProviderManager)
   at Microsoft.Data.SqlClient.SqlConnectionFactory.CreateConnection(DbConnectionOptions options, DbConnectionPoolKey poolKey, Object poolGroupProviderInfo, DbConnectionPool pool, DbConnection owningConnection, DbConnectionOptions userOptions)
   at Microsoft.Data.ProviderBase.DbConnectionFactory.CreatePooledConnection(DbConnectionPool pool, DbConnection owningObject, DbConnectionOptions options, DbConnectionPoolKey poolKey, DbConnectionOptions userOptions)
   at Microsoft.Data.ProviderBase.DbConnectionPool.CreateObject(DbConnection owningObject, DbConnectionOptions userOptions, DbConnectionInternal oldConnection)
   at Microsoft.Data.ProviderBase.DbConnectionPool.UserCreateRequest(DbConnection owningObject, DbConnectionOptions userOptions, DbConnectionInternal oldConnection)
   at Microsoft.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, UInt32 waitForMultipleObjectsTimeout, Boolean allowCreate, Boolean onlyOneCheckConnection, DbConnectionOptions userOptions, DbConnectionInternal& connection)
   at Microsoft.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal& connection)
   at Microsoft.Data.ProviderBase.DbConnectionFactory.TryGetConnection(DbConnection owningConnection, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal oldConnection, DbConnectionInternal& connection)
   at Microsoft.Data.ProviderBase.DbConnectionInternal.TryOpenConnectionInternal(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)
   at Microsoft.Data.ProviderBase.DbConnectionClosed.TryOpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)
   at Microsoft.Data.SqlClient.SqlConnection.TryOpen(TaskCompletionSource`1 retry)
   at Microsoft.Data.SqlClient.SqlConnection.Open()
   at Microsoft.EntityFrameworkCore.Storage.RelationalConnection.OpenDbConnection(Boolean errorsExpected)
   at Microsoft.EntityFrameworkCore.Storage.RelationalConnection.Open(Boolean errorsExpected)
   at Microsoft.EntityFrameworkCore.SqlServer.Storage.Internal.SqlServerDatabaseCreator.<>c__DisplayClass18_0.<Exists>b__0(DateTime giveUp)
   at Microsoft.EntityFrameworkCore.ExecutionStrategyExtensions.<>c__DisplayClass12_0`2.<Execute>b__0(DbContext c, TState s)
   at Microsoft.EntityFrameworkCore.SqlServer.Storage.Internal.SqlServerExecutionStrategy.Execute[TState,TResult](TState state, Func`3 operation, Func`3 verifySucceeded)
   at Microsoft.EntityFrameworkCore.ExecutionStrategyExtensions.Execute[TState,TResult](IExecutionStrategy strategy, TState state, Func`2 operation, Func`2 verifySucceeded)
   at Microsoft.EntityFrameworkCore.ExecutionStrategyExtensions.Execute[TState,TResult](IExecutionStrategy strategy, TState state, Func`2 operation)
   at Microsoft.EntityFrameworkCore.SqlServer.Storage.Internal.SqlServerDatabaseCreator.Exists(Boolean retryOnNotExists)
   at Microsoft.EntityFrameworkCore.SqlServer.Storage.Internal.SqlServerDatabaseCreator.Exists()
   at Microsoft.EntityFrameworkCore.Migrations.HistoryRepository.Exists()
   at Microsoft.EntityFrameworkCore.Migrations.Internal.Migrator.Migrate(String targetMigration)
   at Microsoft.EntityFrameworkCore.RelationalDatabaseFacadeExtensions.Migrate(DatabaseFacade databaseFacade)
   at AuSight.Startup.Configure(IApplicationBuilder app, IWebHostEnvironment env, AppDbContext data) in /src/AuSight/Startup.cs:line 105
   at System.RuntimeMethodHandle.InvokeMethod(Object target, Object[] arguments, Signature sig, Boolean constructor, Boolean wrapExceptions)
   at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
   at Microsoft.AspNetCore.Hosting.ConfigureBuilder.Invoke(Object instance, IApplicationBuilder builder)
   at Microsoft.AspNetCore.Hosting.ConfigureBuilder.<>c__DisplayClass4_0.<Build>b__0(IApplicationBuilder builder)
   at Microsoft.AspNetCore.Hosting.GenericWebHostBuilder.<>c__DisplayClass13_0.<UseStartup>b__2(IApplicationBuilder app)
   at Microsoft.ApplicationInsights.AspNetCore.ApplicationInsightsStartupFilter.<>c__DisplayClass2_0.<Configure>b__0(IApplicationBuilder app)
   at Microsoft.AspNetCore.Mvc.Filters.MiddlewareFilterBuilderStartupFilter.<>c__DisplayClass0_0.<Configure>g__MiddlewareFilterBuilder|0(IApplicationBuilder builder)
   at Microsoft.AspNetCore.HostFilteringStartupFilter.<>c__DisplayClass0_0.<Configure>b__0(IApplicationBuilder app)
   at Microsoft.AspNetCore.Hosting.GenericWebHostService.StartAsync(CancellationToken cancellationToken)
   at Microsoft.Extensions.Hosting.Internal.Host.StartAsync(CancellationToken cancellationToken)
   at Microsoft.Extensions.Hosting.HostingAbstractionsHostExtensions.RunAsync(IHost host, CancellationToken token)
   at Microsoft.Extensions.Hosting.HostingAbstractionsHostExtensions.RunAsync(IHost host, CancellationToken token)
   at Microsoft.Extensions.Hosting.HostingAbstractionsHostExtensions.Run(IHost host)
   at AuSight.Program.Main(String[] args) in /src/AuSight/Program.cs:line 29
ClientConnectionId:00000000-0000-0000-0000-000000000000

I believe I have my mssql-linux helm dependency setup correctly and has a targetPort=1433;port=1433 for the backend service which have the appropriate selectors.

service.yaml

apiVersion: v1
kind: Service
metadata:
  name: RELEASE-NAME-mssql-linux
  labels:
    app: mssql-linux
    chart: mssql-linux-0.11.2
    release: RELEASE-NAME
    heritage: Helm
    tier: backend
spec:
  type: ClusterIP
  ports:
  - name: mssql
    port: 1433
    targetPort: mssql
    protocol: TCP
  selector:
    app: mssql-linux
    release: RELEASE-NAME

With part of the deployment.yaml

# Source: vault/charts/mssql-linux/templates/deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: RELEASE-NAME-mssql-linux
  labels:
    app: mssql-linux
    chart: mssql-linux-0.11.2
    release: RELEASE-NAME
    heritage: Helm
    tier: backend
spec:
  replicas: 
  selector:
    matchLabels:
      app: mssql-linux
      release: RELEASE-NAME
  template:
    metadata:
      labels:
        app: mssql-linux
        release: RELEASE-NAME
    spec:
      containers:
        - name: mssql-linux
          image: "microsoft/mssql-server-linux:2017-CU5"
          imagePullPolicy: IfNotPresent
          env:
            - name: ACCEPT_EULA
              value: "Y"
            - name: MSSQL_PID
              value: "Enterprise"
            - name: SA_PASSWORD
              valueFrom:
               secretKeyRef:
                 name: RELEASE-NAME-mssql-linux-secret
                 key: sapassword
            - name: MSSQL_DATA_DIR
              value: /mssql-data/data
            - name: MSSQL_LOG_DIR
              value: /mssql-translog/translog
            - name: MSSQL_TCP_PORT
              value: "1433"
            - name: MSSQL_BACKUP_DIR
              value: "/mssql-backup/backup"
            - name: MSSQL_COLLATION
              value: "SQL_Latin1_General_CP1_CI_AS"
            - name: MSSQL_LCID
              value: "1033"

Is there something I am missing to have myapp-deployment pod be able to find the correct port/IP inside the mssql-linux pod?

docker

kubernetes

blazor

kubernetes-helm

ef-core-3.1

asked on Stack Overflow Jun 30, 2020 by

Colton Neary • edited Jul 1, 2020 by

marc_s

2 Answers

I guess what here is missing is the Readiness Probe for the DB. Your App does not wait for the DB to be running and fails...

answered on Stack Overflow Jun 30, 2020 by

Armando Ballaci

Your connection string is wrong (Server=localhost,1433) it should be :

Server=mssql-linux;Database=HelmDevDb;uid=sa;pwd=27u6DG;MultipleActiveResultSets=true;

You should use the pod name to access to your SqlServer instance. More, if you want to specifie a port use : not ,

answered on Stack Overflow Jul 1, 2020 by

agua from mars

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