Using Windows system variables in a SSIS Package (Visual Studio) - windows

Question

I've created a Windows system variable called DATA_PATH which references to a path.
I'm trying to use it in a Flat File Connection Manager in Visual Studio like this: %DATA_PATH% or #[DATA_PATH], but it is not working.

Answer 1

Correct, you cannot make up syntax and expect it to work.
There are 4 approaches I can come up with to make use of a Windows environment variable in an SSIS package.
Use command line arguments
Use Configuration
Use a Script Task
Use Execute Process Task
My sample package looks like the following + a Project Parameter named ScalaHome data type of string and initialized to the same "NOT DEFINED"
Parameter/Variable via invocation
At run-time, you can specify the value of variables. For example, when I run this command
dtexec /file ./Order.dtsx /Set \Package.Variables[User::Counter].Properties[Value];3
It will run the Order package and initialize the value of my variable User::Counter to 3.
Extending that pattern, you can run your package and use your environment variable value to set a package value.
dtexec /file ./Order.dtsx /Set \Package.Variables[User::LocalPath].Properties[Value];%DATA_PATH%
If you're using parameters, the command would be something like
dtexec /package Order.dtsx /project ./MyProj.ispac /PAR "$Package::LocalPath";"%DATA_PATH%"
EXCEPT, that won't work because
The Parameter option can only be specified with the ISServer option.
So instead, even though there is a /parameter option, you need to use the /SET route. In this example, I'm going to reference my existing SCALA_HOME environment variable
Before
dtexec /proj C:\Users\bfellows\source\repos\SO_Trash\SO_Trash\bin\Development\SO_Trash.ispac /pack SO_74786096.dtsx /rep eiw
Microsoft (R) SQL Server Execute Package Utility
Version 14.0.3456.2 for 32-bit
Copyright (C) 2017 Microsoft. All rights reserved.
Started: 8:54:58 AM
Info: 2022-12-13 08:52:58.86
Code: 0x00000000
Source: SCR Echo Back SCR Echo Back
Description: $Project::ScalaHome:->NOT DEFINED
End Info
DTExec: The package execution returned DTSER_SUCCESS (0).
Started: 8:52:58 AM
Finished: 8:52:58 AM
Elapsed: 0.422 seconds
After
dtexec /proj C:\Users\bfellows\source\repos\SO_Trash\SO_Trash\bin\Development\SO_Trash.ispac /pack SO_74786096.dtsx /rep eiw /SET \Package.Variables[$Project::ScalaHome];"%SCALA_HOME%"
Microsoft (R) SQL Server Execute Package Utility
Version 14.0.3456.2 for 32-bit
Copyright (C) 2017 Microsoft. All rights reserved.
Started: 8:53:14 AM
Info: 2022-12-13 08:53:15.15
Code: 0x00000000
Source: SCR Echo Back SCR Echo Back
Description: $Project::ScalaHome:->C:\Program Files (x86)\scala
End Info
DTExec: The package execution returned DTSER_SUCCESS (0).
Started: 8:53:14 AM
Finished: 8:53:15 AM
Elapsed: 0.359 seconds
The development experience is a bit fiddly because even though you can specify CmdLineArguments, adding the same /SET \Package.Variables[$Project::ScalaHome];"%SCALA_HOME%" in there had no effect
Configurations
We're gonna go old-school here as this is no longer a favored method for handling configurations with the advent of the SSIS Catalog. But it still exists, it's just harder to access in the Project Deployment Model. Right-click on a package and select Property. Find the Configurations collection and click the ellipses ...
Check the "Enable Package Configurations" box
Click Add...
In the resulting wizard, pick your Configuration Type and find the Environment Variable
In the Next window, you need to set the target property, aka push that value into a local variable. Here I'm using User::ConfigValue and importantly I am expanding the Properties tree and selecting the Value
Give it a name
Ok and Close.
Now when you run it, you'll see 2 information messages. The first that it's trying to use config and the second will be our Script Task spitting out values.
Info: 2022-12-13 09:14:23.72
Code: 0x40016038
Source: SO_74786096
Description: The package is attempting to configure from the environment variable "SCALA_HOME".
End Info
Info: 2022-12-13 09:14:23.84
Code: 0x00000000
Source: SCR Echo Back SCR Echo Back
Description: User::ConfigValue:->C:\Program Files (x86)\scala
End Info
Script Task
Add a read-write variable to the mix.
// Lazy approach and beware the lack of checking
public void Main()
{
var value = System.Environment.GetEnvironmentVariable("SCALA_HOME");
Dts.Variables[0].Value = value;
Dts.TaskResult = (int)ScriptResults.Success;
}
Reference answer for C# and accessing environment variables https://stackoverflow.com/a/185214/181965
Execute Process Task
Pop the value of the environment variable into an SSIS variable. The command I'll use is cmd.exe as the process. Arguments are /C echo %SCALA_HOME% Note that I'm routing the StandardOutput to my variable
Putting it all together
C:\Users\bfellows>dtexec /proj C:\Users\bfellows\source\repos\SO_Trash\SO_Trash\bin\Development\SO_Trash.ispac /pack SO_74786096.dtsx /rep eiw /SET \Package.Variables[$Project::ScalaHome];"%SCALA_HOME%"
Microsoft (R) SQL Server Execute Package Utility
Version 14.0.3456.2 for 32-bit
Copyright (C) 2017 Microsoft. All rights reserved.
Started: 9:25:32 AM
Info: 2022-12-13 09:25:32.27
Code: 0x40016038
Source: SO_74786096
Description: The package is attempting to configure from the environment variable "SCALA_HOME".
End Info
Info: 2022-12-13 09:25:32.48
Code: 0x00000000
Source: SCR Echo Back SCR Echo Back
Description: User::ConfigValue:->C:\Program Files (x86)\scala
End Info
Info: 2022-12-13 09:25:32.48
Code: 0x00000000
Source: SCR Echo Back SCR Echo Back
Description: User::EPTValue:->C:\Program Files (x86)\scala
End Info
Info: 2022-12-13 09:25:32.48
Code: 0x00000000
Source: SCR Echo Back SCR Echo Back
Description: $Project::ScalaHome:->C:\Program Files (x86)\scala
End Info
Info: 2022-12-13 09:25:32.48
Code: 0x00000000
Source: SCR Echo Back SCR Echo Back
Description: User::SCRValue:->C:\Program Files (x86)\scala
End Info
DTExec: The package execution returned DTSER_SUCCESS (0).
Started: 9:25:32 AM
Finished: 9:25:32 AM
Elapsed: 0.469 seconds
Echo back script
My all purpose tester script. Pick the variables you want to have written to the Output window as ReadOnly variables.
using System;
using System.Data;
using Microsoft.SqlServer.Dts.Runtime;
using System.Windows.Forms;
namespace ST_710ef65337734ee281706ce24a9162f1
{
[Microsoft.SqlServer.Dts.Tasks.ScriptTask.SSISScriptTaskEntryPointAttribute]
public partial class ScriptMain : Microsoft.SqlServer.Dts.Tasks.ScriptTask.VSTARTScriptObjectModelBase
{
public void Main()
{
bool fireAgain = false;
foreach (Variable item in Dts.Variables)
{
Dts.Events.FireInformation(0, "SCR Echo Back", string.Format("{0}:->{1}", item.QualifiedName, item.Value), "", 0, ref fireAgain);
}
Dts.TaskResult = (int)ScriptResults.Success;
}
enum ScriptResults
{
Success = Microsoft.SqlServer.Dts.Runtime.DTSExecResult.Success,
Failure = Microsoft.SqlServer.Dts.Runtime.DTSExecResult.Failure
};
}
}
Closing thoughts
The "right" answer is super dependent on you and your organization.
If you were engaging me as a consultant, I'd advise against trying to make use of the environment variable. I'd advise you to create a Project level parameter so that all packages can reference the same value. Then when deployed the SSIS catalog and promoted through the environments, I would use the Configuration section of the SSISDB to set the current value for your data path.
If you choose to go against the advice, the Script Task is the cleanest and most native approach but many organizations have silly commandments of Thou Shalt Not Use Script Task/Component in SSIS packages.
Old blog articles I referenced while assembling this answer
https://billfellows.blogspot.com/2008/09/ssis-configuration-precedence.html
https://billfellows.blogspot.com/2016/04/biml-script-task-test-for-echo.html