HttpContext.Request.Body is disposed when accessing via ApplicationInsights ITelemetryInitializer - azure-application-insights

Question

I'm trying to log POST, PUT, PATCH json bodies to app insights using ITelemetryInitializer. Every time a post comes in though it seems that my body stream is already disposed of some how. I'm assuming there is something in the request pipeline that I'm not registering/doing properly.
public class RequestBodyLogger : ITelemetryInitializer
{
readonly IHttpContextAccessor httpContextAccessor;
public RequestBodyLogger(IHttpContextAccessor httpContextAccessor)
{
this.httpContextAccessor = httpContextAccessor;
}
public void Initialize(ITelemetry telemetry)
{
try
{
if (telemetry is RequestTelemetry requestTelemetry)
{
if ((httpContextAccessor.HttpContext.Request.Method == HttpMethods.Post ||
httpContextAccessor.HttpContext.Request.Method == HttpMethods.Put ||
httpContextAccessor.HttpContext.Request.Method == HttpMethods.Patch) &&
httpContextAccessor.HttpContext.Request.Body.CanRead)
{
const string jsonBody = "JsonBody";
if (requestTelemetry.Properties.ContainsKey(jsonBody))
{
return;
}
//Allows re-usage of the stream
httpContextAccessor.HttpContext.Request.EnableRewind();
var stream = new StreamReader(httpContextAccessor.HttpContext.Request.Body);
var body = stream.ReadToEnd(); <<Blows here object disposed (stream)
//Reset the stream so data is not lost
httpContextAccessor.HttpContext.Request.Body.Position = 0;
requestTelemetry.Properties.Add(jsonBody, body);
}
}
}
catch (Exception e)
{
}
}
}
Configure services method...
public void ConfigureServices(IServiceCollection services)
{
if (_env.IsDevelopment())
{
services.AddSwaggerGen(c =>
{
c.SwaggerDoc(Constants.ApiVersion, new Info { Title = Constants.ApiName, Version = Constants.ApiVersion });
c.AddSecurityDefinition("Bearer", new ApiKeyScheme { In = "header", Description = "Please enter Bearer Token", Name = "Authorization", Type = "apiKey" });
c.AddSecurityRequirement(new Dictionary<string, IEnumerable<string>> { { "Bearer", Enumerable.Empty<string>() } });
c.IncludeXmlComments($"{AppDomain.CurrentDomain.BaseDirectory}\\TradeJournal.Api.xml");
});
}
services.AddAuthentication(options =>
{
options.DefaultChallengeScheme = JwtBearerDefaults.AuthenticationScheme;
options.DefaultAuthenticateScheme = JwtBearerDefaults.AuthenticationScheme;
})
.AddJwtBearer(options =>
{
options.Authority = Configuration["IdentityAuthority"];
options.TokenValidationParameters = new Microsoft.IdentityModel.Tokens.TokenValidationParameters
{
IssuerSigningKeyResolver = (s, securityToken, identifier, parameters) =>
{
var json = new WebClient().DownloadString(parameters.ValidIssuer + "/.well-known/jwks.json");
var keys = JsonConvert.DeserializeObject<JsonWebKeySet>(json).Keys;
return (IEnumerable<SecurityKey>)keys;
},
ValidIssuer = Configuration["IdentityAuthority"],
ValidateIssuerSigningKey = true,
ValidateIssuer = true,
ValidateLifetime = true,
ValidateAudience = false
};
});
services
.AddCors(c =>
{
c.AddPolicy("AllowOrigin", options => options.AllowAnyOrigin().AllowAnyHeader().AllowAnyMethod().AllowCredentials());
});
services.AddMvc(opts =>
{
opts.Filters.Add(typeof(ModelStateValidationFilter));
}).SetCompatibilityVersion(CompatibilityVersion.Version_2_2)
.AddJsonOptions(opt =>
{
opt.SerializerSettings.DateFormatString = "yyyy-MM-ddTHH:mm:ssZ";
});
services.AddSingleton<ITelemetryInitializer, RequestBodyLogger>();
services.AddTransient<ExceptionToHttpResponseMiddleware>();
services.AddTransient<MaintenanceMiddleware>();
services.AddRouting(opts =>
{
opts.LowercaseUrls = true;
opts.LowercaseQueryStrings = true;
});
BootstrapLayers(services);
}
```
Configure method...
public void Configure(IApplicationBuilder app)
{
if (_env.IsDevelopment())
{
app.UseDeveloperExceptionPage();
app.UseSwagger();
// Enable middleware to serve swagger-ui (HTML, JS, CSS, etc.),
// specifying the Swagger JSON endpoint.
app.UseSwaggerUI(c =>
{
c.SwaggerEndpoint($"/swagger/{Constants.ApiVersion}/swagger.json", Constants.ApiName);
});
}
else
{
//The default HSTS value is 30 days.You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
app.UseHsts();
}
app.UseAuthentication();
app.UseCors(options => options.AllowAnyOrigin().AllowAnyMethod().AllowAnyHeader().AllowCredentials());
app.UseMiddleware<ExceptionToHttpResponseMiddleware>();
app.UseMiddleware<MaintenanceMiddleware>();
app.UseHttpsRedirection();
app.UseMvc();
}
**Why is the context disposed by the time AI calls this telemetry initializer?**

Answer 1

This is also discussed in github: https://github.com/microsoft/ApplicationInsights-aspnetcore/issues/940#issuecomment-513297006
Since by the time TelemetryInitializers are run, the request body is disposed, your best bet is to read and populate the body into RequestTelemetry when the body is still available. If its a controller or middleware - then retrieve RequestTelemetry there, add body to it. The following is sample code to be written in controller/middleware where you can retrieve request body.
RequestTelemetry reqTelemetry = httpContext?.Features.Get<RequestTelemetry>();
reqTelemetry.Properties.Add("body","body contents").