in src/Agent.Listener/SelfUpdater.cs [223:476]
private async Task DownloadLatestAgent(CancellationToken token)
{
string latestAgentDirectory = Path.Combine(HostContext.GetDirectory(WellKnownDirectory.Work), Constants.Path.UpdateDirectory);
IOUtil.DeleteDirectory(latestAgentDirectory, token);
Directory.CreateDirectory(latestAgentDirectory);
int agentSuffix = 1;
string archiveFile = null;
bool downloadSucceeded = false;
bool validationSucceeded = false;
try
{
// Download the agent, using multiple attempts in order to be resilient against any networking/CDN issues
for (int attempt = 1; attempt <= Constants.AgentDownloadRetryMaxAttempts && !validationSucceeded; attempt++)
{
// Generate an available package name, and do our best effort to clean up stale local zip files
while (true)
{
if (_targetPackage.Platform.StartsWith("win"))
{
archiveFile = Path.Combine(latestAgentDirectory, $"agent{agentSuffix}.zip");
}
else
{
archiveFile = Path.Combine(latestAgentDirectory, $"agent{agentSuffix}.tar.gz");
}
// The package name is generated, check if there is already a file with the same name and path
if (!string.IsNullOrEmpty(archiveFile) && File.Exists(archiveFile))
{
Trace.Verbose("Deleting latest agent package zip '{0}'", archiveFile);
try
{
// Such a file already exists, so try deleting it
IOUtil.DeleteFile(archiveFile);
// The file was successfully deleted, so we can use the generated package name
break;
}
catch (Exception ex)
{
// Couldn't delete the file for whatever reason, so generate another package name
Trace.Warning("Failed to delete agent package zip '{0}'. Exception: {1}", archiveFile, ex);
agentSuffix++;
}
}
else
{
// There is no a file with the same name and path, so we can use the generated package name
break;
}
}
// Allow a 15-minute package download timeout, which is good enough to update the agent from a 1 Mbit/s ADSL connection.
var timeoutSeconds = AgentKnobs.AgentDownloadTimeout.GetValue(_knobContext).AsInt();
Trace.Info($"Attempt {attempt}: save latest agent into {archiveFile}.");
using (var downloadTimeout = new CancellationTokenSource(TimeSpan.FromSeconds(timeoutSeconds)))
using (var downloadCts = CancellationTokenSource.CreateLinkedTokenSource(downloadTimeout.Token, token))
{
try
{
Trace.Info($"Download agent: begin download");
//open zip stream in async mode
using (var handler = HostContext.CreateHttpClientHandler())
using (var httpClient = new HttpClient(handler))
using (var fs = new FileStream(archiveFile, FileMode.Create, FileAccess.Write, FileShare.None, bufferSize: 4096, useAsync: true))
using (var result = await httpClient.GetStreamAsync(_targetPackage.DownloadUrl))
{
//81920 is the default used by System.IO.Stream.CopyTo and is under the large object heap threshold (85k).
await result.CopyToAsync(fs, 81920, downloadCts.Token);
await fs.FlushAsync(downloadCts.Token);
}
Trace.Info($"Download agent: finished download");
downloadSucceeded = true;
validationSucceeded = HashValidation(archiveFile);
}
catch (OperationCanceledException) when (token.IsCancellationRequested)
{
Trace.Info($"Agent download has been canceled.");
throw;
}
catch (SocketException ex)
{
ExceptionsUtil.HandleSocketException(ex, _targetPackage.DownloadUrl, Trace.Warning);
}
catch (Exception ex)
{
if (downloadCts.Token.IsCancellationRequested)
{
Trace.Warning($"Agent download has timed out after {timeoutSeconds} seconds");
}
Trace.Warning($"Failed to get package '{archiveFile}' from '{_targetPackage.DownloadUrl}'. Exception {ex}");
}
}
}
if (!downloadSucceeded)
{
throw new TaskCanceledException($"Agent package '{archiveFile}' failed after {Constants.AgentDownloadRetryMaxAttempts} download attempts.");
}
if (!validationSucceeded)
{
throw new TaskCanceledException(@"Agent package checksum validation failed.
There are possible reasons why this happened:
1) The agent package was compromised.
2) The agent package was not fully downloaded or was corrupted during the download process.
You can skip checksum validation for the agent package by setting the environment variable DISABLE_HASH_VALIDATION=true");
}
// If we got this far, we know that we've successfully downloadeded the agent package
if (archiveFile.EndsWith(".zip", StringComparison.OrdinalIgnoreCase))
{
ZipFile.ExtractToDirectory(archiveFile, latestAgentDirectory);
}
else if (archiveFile.EndsWith(".tar.gz", StringComparison.OrdinalIgnoreCase))
{
string tar = WhichUtil.Which("tar", trace: Trace);
if (string.IsNullOrEmpty(tar))
{
throw new NotSupportedException($"tar -xzf");
}
// tar -xzf
using (var processInvoker = HostContext.CreateService<IProcessInvoker>())
{
processInvoker.OutputDataReceived += new EventHandler<ProcessDataReceivedEventArgs>((sender, args) =>
{
if (!string.IsNullOrEmpty(args.Data))
{
Trace.Info(args.Data);
}
});
processInvoker.ErrorDataReceived += new EventHandler<ProcessDataReceivedEventArgs>((sender, args) =>
{
if (!string.IsNullOrEmpty(args.Data))
{
Trace.Error(args.Data);
}
});
int exitCode = await processInvoker.ExecuteAsync(latestAgentDirectory, tar, $"-xzf \"{archiveFile}\"", null, token);
if (exitCode != 0)
{
throw new NotSupportedException($"Can't use 'tar -xzf' extract archive file: {archiveFile}. return code: {exitCode}.");
}
}
}
else
{
throw new NotSupportedException($"{archiveFile}");
}
Trace.Info($"Finished getting latest agent package at: {latestAgentDirectory}.");
}
finally
{
try
{
// delete .zip file
if (!string.IsNullOrEmpty(archiveFile) && File.Exists(archiveFile))
{
Trace.Verbose("Deleting latest agent package zip: {0}", archiveFile);
IOUtil.DeleteFile(archiveFile);
}
}
catch (Exception ex)
{
//it is not critical if we fail to delete the .zip file
Trace.Warning("Failed to delete agent package zip '{0}'. Exception: {1}", archiveFile, ex);
}
}
if (!String.IsNullOrEmpty(AgentKnobs.DisableAuthenticodeValidation.GetValue(HostContext).AsString()))
{
Trace.Warning("Authenticode validation skipped for downloaded agent package since it is disabled currently by agent settings.");
}
else
{
if (PlatformUtil.RunningOnWindows)
{
var isValid = this.VerifyAgentAuthenticode(latestAgentDirectory);
if (!isValid)
{
throw new Exception("Authenticode validation of agent assemblies failed.");
}
else
{
Trace.Info("Authenticode validation of agent assemblies passed successfully.");
}
}
else
{
Trace.Info("Authenticode validation skipped since it's not supported on non-Windows platforms at the moment.");
}
}
// copy latest agent into agent root folder
// copy bin from _work/_update -> bin.version under root
string binVersionDir = Path.Combine(HostContext.GetDirectory(WellKnownDirectory.Root), $"{Constants.Path.BinDirectory}.{_targetPackage.Version}");
Directory.CreateDirectory(binVersionDir);
Trace.Info($"Copy {Path.Combine(latestAgentDirectory, Constants.Path.BinDirectory)} to {binVersionDir}.");
IOUtil.CopyDirectory(Path.Combine(latestAgentDirectory, Constants.Path.BinDirectory), binVersionDir, token);
// copy externals from _work/_update -> externals.version under root
string externalsVersionDir = Path.Combine(HostContext.GetDirectory(WellKnownDirectory.Root), $"{Constants.Path.ExternalsDirectory}.{_targetPackage.Version}");
Directory.CreateDirectory(externalsVersionDir);
Trace.Info($"Copy {Path.Combine(latestAgentDirectory, Constants.Path.ExternalsDirectory)} to {externalsVersionDir}.");
IOUtil.CopyDirectory(Path.Combine(latestAgentDirectory, Constants.Path.ExternalsDirectory), externalsVersionDir, token);
// copy and replace all .sh/.cmd files
Trace.Info($"Copy any remaining .sh/.cmd files into agent root.");
foreach (FileInfo file in new DirectoryInfo(latestAgentDirectory).GetFiles() ?? new FileInfo[0])
{
// Copy and replace the file.
file.CopyTo(Path.Combine(HostContext.GetDirectory(WellKnownDirectory.Root), file.Name), true);
}
// for windows service back compat with old windows agent, we need make sure the servicehost.exe is still the old name
// if the current bin folder has VsoAgentService.exe, then the new agent bin folder needs VsoAgentService.exe as well
if (PlatformUtil.RunningOnWindows)
{
if (File.Exists(Path.Combine(HostContext.GetDirectory(WellKnownDirectory.Bin), "VsoAgentService.exe")))
{
Trace.Info($"Make a copy of AgentService.exe, name it VsoAgentService.exe");
File.Copy(Path.Combine(binVersionDir, "AgentService.exe"), Path.Combine(binVersionDir, "VsoAgentService.exe"), true);
File.Copy(Path.Combine(binVersionDir, "AgentService.exe.config"), Path.Combine(binVersionDir, "VsoAgentService.exe.config"), true);
Trace.Info($"Make a copy of Agent.Listener.exe, name it VsoAgent.exe");
File.Copy(Path.Combine(binVersionDir, "Agent.Listener.exe"), Path.Combine(binVersionDir, "VsoAgent.exe"), true);
File.Copy(Path.Combine(binVersionDir, "Agent.Listener.dll"), Path.Combine(binVersionDir, "VsoAgent.dll"), true);
// in case of we remove all pdb file from agent package.
if (File.Exists(Path.Combine(binVersionDir, "AgentService.pdb")))
{
File.Copy(Path.Combine(binVersionDir, "AgentService.pdb"), Path.Combine(binVersionDir, "VsoAgentService.pdb"), true);
}
if (File.Exists(Path.Combine(binVersionDir, "Agent.Listener.pdb")))
{
File.Copy(Path.Combine(binVersionDir, "Agent.Listener.pdb"), Path.Combine(binVersionDir, "VsoAgent.pdb"), true);
}
}
}
}