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Best way to check if ubuntu service has stopped in c#

I want to get an alert when a service (grafana or influxdb) in an Azure virtual machine (Ubuntu 16.04) has stopped. I'd like to use c# to connect to the VM and check the status of grafana and influxdb services. Can anyone share a code sample that implements this?

Both services provide health endpoints that can be used to check their status from a remote server. There's no need to open a remote shell connection. In fact, it would be impossible to monitor large server farms if one had to SSH to each one.
In the simplest case, and ignoring networking issues, one can simply hit the health endpoints to check the status of both services. A rough implementation could look like this :
public async Task<bool> CheckBoth()
{
var client = new HttpClient
{
Timeout = TimeSpan.FromSeconds(30)
};
const string grafanaHealthUrl = "https://myGrafanaURL/api/health";
const string influxPingUrl = "https://myInfluxURL/ping";
var (grafanaOK, grafanaError) = await CheckAsync(client, grafanaHealthUrl,
HttpStatusCode.OK, "Grafana error");
var (influxOK, influxError) = await CheckAsync(client, influxPingUrl,
HttpStatusCode.NoContent,"InfluxDB error");
if (!influxOK || !grafanaOK)
{
//Do something with the errors
return false;
}
return true;
}
public async Task<(bool ok, string result)> CheckAsync(HttpClient client,
string healthUrl,
HttpStatusCode expected,
string errorMessage)
{
try
{
var status = await client.GetAsync(healthUrl);
if (status.StatusCode != expected)
{
//Failure message, get it and log it
var statusBody = await status.Content.ReadAsStringAsync();
//Possibly log it ....
return (ok: false, result: $"{errorMessage}: {statusBody}");
}
}
catch (TaskCanceledException)
{
return (ok: false, result: $"{errorMessage}: Timeout");
}
return (ok: true, "");
}
Perhaps a better solution would be to use Azure Monitor to ping the health URLs periodically and send an alert if they are down.

Here is something you can use to connect to Azure linux using SSH in c#
using (var client = new SshClient("my-vm.cloudapp.net", 22, "username", "password​"))
{
client.Connect();
Console.WriteLine("it worked!");
client.Disconnect();
Console.ReadLine();
}
Usually SSH server only allow public key auth or other two factor auth.
Change your /etc/ssh/sshd_configuncomment #PasswordAuthentication yes
# Change to no to disable tunnelled clear text passwords
#PasswordAuthentication yes
Later you can poll for installed services.
Also for an alternative solution, you can deploy a rest api in your linux VM to check the status of your service and the call it from C# httpclient for the status.
Hope it helps

UWP AppServiceConnection not getting value

I'm trying to communicate between my host app and service via AppServiceConnection. I'm using the following code in my host app:
using (var connection = new AppServiceConnection())
{
connection.AppServiceName = extension.AppServiceName;
connection.PackageFamilyName = extension.PackageFamilyName;
var connectionStatus = await connection.OpenAsync();
if (connectionStatus == AppServiceConnectionStatus.Success)
{
var response = await connection.SendMessageAsync(requestMessage);
if (response.Status == AppServiceResponseStatus.Success)
returnValue = response.Message as ValueSet;
}
}
And my service code:
private async void OnRequestReceived(AppServiceConnection sender, AppServiceRequestReceivedEventArgs args)
{
var messageDeferral = args.GetDeferral();
var message = args.Request.Message;
var returnData = new ValueSet();
var command = message["Command"] as string;
switch (command)
{
case "ACTION":
var value = await AsyncAction();
returnData = new ValueSet { { "Value", JsonConvert.SerializeObject(value) } };
break;
default:
break;
}
await args.Request.SendResponseAsync(returnData);
messageDeferral.Complete();
}
This works some of the time, but other times the ValueSet (returnValue) is randomly empty when the host receives it. It has Value in it when returned in the service, but when I get the response in the host, nothing.
I've verified that the service is indeed setting the value, adding it to the ValueSet and returning it correctly.
Note that my service is receiving the request, the host is receiving the response and the response status is Success; a failed connection isn't the issue.
Sometimes this happens only once before requests start working again, other times it will happen ten times in a row.
The first working response after a failure always takes significantly longer than normal.
Also, I have no issues in the request from host to service. It's always service to host where the problem shows up.
Has anyone else run into this issue and figured it out?

In the process of creating a sample app I realized what the problem was. I was performing an asynchronous action (albeit a very short one) before my line var messageDeferral = args.GetDeferral();. It appears that this was allowing the background task to be closed before it had responded to the host. Simply moving that line to the beginning of the OnRequestReceived function fixed the problem for me.
So for anyone who runs into a similar issue, get your deferral before you do anything else! Spare yourself the pain I went through.

C# HttpClient Uri value

I'm working on creating a WindowsPhone 8.1 app, and I'm having trouble getting the client to access the database. I created a server-side project that works fine using web api. I'm able to run debugger and add "/api/entityName" to return a list of all the rows in that table or just a single row if I specify an id value. After doing a lot of testing on the client side, I think I've pinpointed my error: the uri value. Can someone tell me what value I should be passing into the uri constructor? Here's the method that I'm using in the client:
public async void GetBars()
{
var uri = new Uri("http://localhost:20672/tables/bars"); //seems like this value is the problem
var httpClient = new HttpClient();
barsListBox.Items.Add("right before try starts");
// Always catch network exceptions for async methods
try
{
barsListBox.Items.Add("try started");
var result = await httpClient.GetStringAsync(uri); //never gets past this line. goes straight to finally
barsListBox.Items.Add("right before linq");
var queryAllBars =
from bar in result
select bar;
barsListBox.Items.Add("linq finished");
foreach (var bar in queryAllBars)
{
barsListBox.Items.Add(bar);
}
}
catch
{
// Details in ex.Message and ex.HResult.
}
finally
{
barsListBox.Items.Add("finally executed");
httpClient.Dispose();
}
}
The database is a SQL Server database being hosted on Azure. I've tried using the URL listed for the database in Azure, my current IP address, just about every combination of using/excluding the port number, etc but nothing seems to work. I don't get any errors, but I also don't get anything displayed in the UI (except for the testing statements I've entered). Try started gets printed, but right before linq doesn't, which is why I believe my problem is coming from the uri value being passed int GetStringAsync. Thanks for the help.

You can Try like this
using (var client = new HttpClient())
{
client.BaseAddress = new Uri("http://Ipaddress/mammo/");
client.DefaultRequestHeaders.Accept.Clear();
client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
HttpResponseMessage response = await client.GetAsync("api/controllername");
if (response.IsSuccessStatusCode)
{
IList<something> data = await response.Content.ReadAsAsync<IList<something>>();
}
}

Thanks to #Midhun's answer and other answers I received, I was able to get the bars to print correctly. I used Midhun's code above with the uri of my hosted database (the azurewebsites.net url) instead of my localhost database. I also changed the IList to a String and wrote a method that picks out the values using IndexOf and Substring as follows:
start = bar.IndexOf("BarID", start) + 7;
int end = bar.IndexOf(",", start);
int id = Convert.ToInt32(bar.Substring(start, (end - start)));
Bars newBar = new Bars(id, name, street, city, state, phone, zip);
Bars.barsList.Add(newBar);
I then created a static list in my Bars model to add the newly created Bars items to.

UploadValuesAsync response time

I am writing test harness to test a HTTP Post. Test case would send 8 http request using UploadValuesAsync in webclient class in 10 seconds interval. It sleeps 10 seconds after every 8 request. I am recording start time and end time of each request. When I compute the average response time. I am getting around 800 ms. But when I run this test case synchronously using UploadValues method in web client I am getting average response time 250 milliseconds. Can you tell me why is difference between these two methods? I was expecting the less response time in Aync but I did not get that.
Here is code that sends 8 requests async
var count = 0;
foreach (var nameValueCollection in requestCollections)
{
count++;
NameValueCollection collection = nameValueCollection;
PostToURL(collection,uri);
if (count % 8 == 0)
{
Thread.Sleep(TimeSpan.FromSeconds(10));
count = 0;
}
}
UPDATED
Here is code that sends 8 requests SYNC
public void PostToURLSync(NameValueCollection collection,Uri uri)
{
var response = new ServiceResponse
{
Response = "Not Started",
Request = string.Join(";", collection.Cast<string>()
.Select(col => String.Concat(col, "=", collection[col])).ToArray()),
ApplicationId = collection["ApplicationId"]
};
try
{
using (var transportType2 = new DerivedWebClient())
{
transportType2.Expect100Continue = false;
transportType2.Timeout = TimeSpan.FromMilliseconds(2000);
response.StartTime = DateTime.Now;
var responeByte = transportType2.UploadValues(uri, "POST", collection);
response.EndTime = DateTime.Now;
response.Response = Encoding.Default.GetString(responeByte);
}
}
catch (Exception exception)
{
Console.WriteLine(exception.ToString());
}
response.ResponseInMs = (int)response.EndTime.Subtract(response.StartTime).TotalMilliseconds;
responses.Add(response);
Console.WriteLine(response.ResponseInMs);
}
Here is the code that post to the HTTP URI
public void PostToURL(NameValueCollection collection,Uri uri)
{
var response = new ServiceResponse
{
Response = "Not Started",
Request = string.Join(";", collection.Cast<string>()
.Select(col => String.Concat(col, "=", collection[col])).ToArray()),
ApplicationId = collection["ApplicationId"]
};
try
{
using (var transportType2 = new DerivedWebClient())
{
transportType2.Expect100Continue = false;
transportType2.Timeout = TimeSpan.FromMilliseconds(2000);
response.StartTime = DateTime.Now;
transportType2.UploadValuesCompleted += new UploadValuesCompletedEventHandler(transportType2_UploadValuesCompleted);
transportType2.UploadValuesAsync(uri, "POST", collection,response);
}
}
catch (Exception exception)
{
Console.WriteLine(exception.ToString());
}
}
Here is the upload completed event
private void transportType2_UploadValuesCompleted(object sender, UploadValuesCompletedEventArgs e)
{
var now = DateTime.Now;
var response = (ServiceResponse)e.UserState;
response.EndTime = now;
response.ResponseInMs = (int) response.EndTime.Subtract(response.StartTime).TotalMilliseconds;
Console.WriteLine(response.ResponseInMs);
if (e.Error != null)
{
response.Response = e.Error.ToString();
}
else
if (e.Result != null && e.Result.Length > 0)
{
string downloadedData = Encoding.Default.GetString(e.Result);
response.Response = downloadedData;
}
//Recording response in Global variable
responses.Add(response);
}

One problem you're probably running into is that .NET, by default, will throttle outgoing HTTP connections to the limit (2 concurrent connections per remote host) that are mandated by the relevant RFC. Assuming 2 concurrent connections and 250ms per request, that means the response time for your first 2 requests will be 250ms, the second 2 will be 500ms, the third 750ms, and the last 1000ms. This would yield a 625ms average response time, which is not far from the 800ms you're seeing.
To remove the throttling, increase ServicePointManager.DefaultConnectionLimit to the maximum number of concurrent connections you want to support, and you should see your average response time go down alot.
A secondary problem may be that the server itself is slower handling multiple concurrent connections than handing one request at a time. Even once you unblock the throttling problem above, I'd expect each of the async requests to, on average, execute somewhat slower than if the server was only executing one request at a time. How much slower depends on how well the server is optimized for concurrent requests.
A final problem may be caused by test methodology. For example, if your test client is simulating a browser session by storing cookies and re-sending cookies with each request, that may run into problems with some servers that will serialize requests from a single user. This is often a simplification for server apps so they won't have to deal with locking cross-requests state like session state. If you're running into this problem, make sure that each WebClient sends different cookies to simulate different users.
I'm not saying that you're running into all three of these problems-- you might be only running into 1 or 2-- but these are the most likley culprits for the problem you're seeing.

As Justin said, I tried ServicePointManager.DefaultConnectionLimit but that did not fix the issue. I could not able reproduce other problems suggested by Justin. I am not sure how to reproduce them in first place.
What I did, I ran the same piece of code in peer machine that runs perfectly response time that I expected. The difference between the two machines is operating systems. Mine is running on Windows Server 2003 and other machine is running on Windows Server 2008.
As it worked on the other machines, I suspect that it might be one of the problem specified by Justin or could be server settings on 2003 or something else. I did not spend much time after that to dig this issue. As this is a test harness that we had low priority on this issue. We left off with no time further.
As I have no glue on what exactly fixed it, I am not accepting any answer other than this. Becuase at very least I know that switching to server 2008 fixed this issue.

Why does Http Web Request and IWebProxy work at weird times

Another question about Web proxy.
Here is my code:
IWebProxy Proxya = System.Net.WebRequest.GetSystemWebProxy();
Proxya.Credentials = CredentialCache.DefaultNetworkCredentials;
HttpWebRequest rqst = (HttpWebRequest)WebRequest.Create(targetServer);
rqst.Proxy = Proxya;
rqst.Timeout = 5000;
try
{
rqst.GetResponse();
}
catch(WebException wex)
{
connectErrMsg = wex.Message;
proxyworks = false;
}
This code hangs the first time it is called for a minute of two. After that on successive calls it works sometimes, but not others. It also never hits the catch block.
Now the weird part. If I add a MessageBox.Show(msg) call in the first section of code before the GetResponse() call this all will work every time without hanging. Here is an example:
try
{
// ========Here is where I make the call and get the response========
System.Windows.Forms.MessageBox.Show("Getting Response");
// ========This makes the whole thing work every time========
rqst.GetResponse();
}
catch(WebException wex)
{
connectErrMsg = wex.Message;
proxyworks = false;
}
I'm baffled about why it is behaving this way. I don't know if the timeout is not working (it's in milliseconds, not seconds, so should timeout after 5 seconds, right?...) or what is going on. The most confusing this is that the message box call makes it all work without hanging.
So any help and suggestions on what is happening is appreciated. These are the kind of bugs that drive me absolutely out of my mind.
EDIT and CORRECTION:
OK, so I've been testing this and the problem is caused when I try to download data from the URI that I am getting a response from. I am testing the connectivity using the GetResponse() method with a WebRequest, but am downloading the data with a WebClient. Here is the code for that:
public void LoadUpdateDataFromNet(string url, IWebProxy wProxy)
{
//Create web client
System.Net.WebClient webClnt = new System.Net.WebClient();
//set the proxy settings
webClnt.Proxy = wProxy;
webClnt.Credentials = wProxy.Credentials;
byte[] tempBytes;
//download the data and put it into a stream for reading
try
{
tempBytes = webClnt.DownloadData(url); // <--HERE IS WHERE IT HANGS
}
catch (WebException wex)
{
MessageBox.Show("NEW ERROR: " + wex.Message);
return;
}
//Code here that uses the downloaded data
}
The WebRequest and WebClient are both accessing the same URL which is a web path to an XML file and the proxy is the same one created in the method at the top of this post. I am testing to see if the created IWebProxy is valid for the specified path and file and then downloading the file.
The first piece of code I put above and this code using the WebClient are in separate classes and are called at different times, yet using a message box in the first bit of code still makes the whole thing run fine, which confuses me. Not sure what all is happening here or why message boxes and running/debugging in Visual Studio makes the program run OK. Suggestions?

So, I figured out the answer to the problem. The timeout for the we request is still 5 sec, but for some reason if it is not closed explicitly it makes consecutive web requests hang. Here is the code now:
IWebProxy Proxya = System.Net.WebRequest.GetSystemWebProxy();
//to get default proxy settings
Proxya.Credentials = CredentialCache.DefaultNetworkCredentials;
Uri targetserver = new Uri(targetAddress);
Uri proxyserver = Proxya.GetProxy(targetserver);
HttpWebRequest rqst = (HttpWebRequest)WebRequest.Create(targetserver);
rqst.Proxy = Proxya;
rqst.Timeout = 5000;
try
{
//Get response to check for valid proxy and then close it
WebResponse wResp = rqst.GetResponse();
//===================================================================
wResp.Close(); //HERE WAS THE PROBLEM. ADDING THIS CALL MAKES IT WORK
//===================================================================
}
catch(WebException wex)
{
connectErrMsg = wex.Message;
proxyworks = false;
}
Still not sure exactly how calling the message box was making everything work, but it doesn't really matter at this point. The whole thing works like a charm.