Can't use 'script' post action to run 'npm install'

[SteveSandersonMS]

Glad to see the improved postActions support!

I've tried to add this to the ASP.NET Core SPA templates. The postAction for dotnet restore works well, but I've not succeeded in configuring a postAction to run npm install.

With this config:

{
    "description": "Restores NPM packages required by this project.",
    "manualInstructions": [{ "text": "Run 'npm install'" }],
    "actionId": "3A7C4B45-1F5D-4A30-959A-51B88E82B5D2",
    "args": { "executable": "npm", "args": "install" },
    "continueOnError": false
}

... it instantly fails with this error:

Processing post-creation actions...
Template is configured to run the following action:
Description: Restores NPM packages required by this project.
Manual instructions: Run 'npm install'
Actual command: npm install
Do you want to run this action (Y|N)?
y
Running command 'npm install'...
The system cannot find the file specified

... even though running npm install manually in the same command line works fine.

I think this is because, on Windows, npm is installed as a batch file called npm.cmd (not npm.exe).

If I change the config to "args": { "executable": "npm.cmd", args: "install" } (which is obviously not a cross-platform solution), then it gets a little further, but then fails with:

Processing post-creation actions...
Template is configured to run the following action:
Description: Restores NPM packages required by this project.
Manual instructions: Run 'npm install'
Actual command: npm.cmd install
Do you want to run this action (Y|N)?
y
Running command 'npm.cmd install'...
Command failed.
Output from command:
module.js:471
    throw err;
    ^

Error: Cannot find module 'C:\path\to\yourproject\node_modules\npm\bin\npm-cli.js'
    at Function.Module._resolveFilename (module.js:469:15)
    at Function.Module._load (module.js:417:25)
    at Module.runMain (module.js:604:10)
    at run (bootstrap_node.js:390:7)
    at startup (bootstrap_node.js:150:9)
    at bootstrap_node.js:505:3
module.js:471
    throw err;

Again, this doesn't occur when running npm.cmd install manually, so this is a problem to do with how the process is being launched.

As a further test, I tried changing the config to "args": { "executable": "cmd", args: "/c \"npm install\"" } (which again is obviously not a cross-platform solution, but this is just for debugging). In this case it does succeed with running npm install, but it's not practical as a solution because:

• It's not cross-platform
• It completely hides npm's console output, so there's no progress indication. Since npm install can take minutes to complete, seeing the progress output is essential.

Possible solutions

1. Maybe you could fix this by changing this line to set UseShellExecute to true - not sure. If you do this, please make sure the command's console output is passed through and visible to the user.
2. Better solution Have an explicit built-in post action for npm install, considering what a mainstream use case this is. This is better, because then you wouldn't have to throw up the scary permissions prompt. It would feel a lot more streamlined.

Do you think it will be possible to resolve this before preview2 ships? We're planning to have SPA templates in the box in preview 2.

[mlorbetske]

@SteveSandersonMS let's chat about this as soon as possible. For VS, our ability to easily make changes for preview 2 ends tomorrow at 6 pm, for CLI it's on Friday I believe. Is the intention to ship the spa templates with VS or CLI or both?

@phenning @seancpeters

[SteveSandersonMS]

Is the intention to ship the spa templates with VS or CLI or both?

Both, but it's less important to have the npm install postAction in the VS host, because VS natively restores NPM packages anyway. It matters more with the CLI, where NPM packages aren't automatically restored.

let's chat about this as soon as possible.

I'm available via email or Skype.

[mlorbetske]

Ok, all caught up with context. Since there'll be a 2.0 flavor of these templates (and we only plan to include the 2.0 version), then all we have to do is to set up the insertion into CLI & make sure the VS metadata is set correctly. Please work with @phenning to get the VS metadata in place. Once a new package version for the templates carrying the 2.0 bits & VS artifacts, we'll be able to do that insertion.

For the time being, let's just print a message telling the user to run npm install & we'll investigate how we can make the experience better. @seancpeters please work with @SteveSandersonMS to figure out what the optimal experience is here - having an NPM (or NPM install specific post-action) may be a solution, but it'd need to be done very quickly to hit preview 2.

[seancpeters]

@SteveSandersonMS
Without creating a specific npm install post action, if we could come up with a set of process start post action configurations that each correctly run on some platform(s), and collectively cover all targeted platforms, then we could set them up with platform-based conditions on the post actions so that only the appropriate one runs on each platform.

Something like:

"postActions": [
  {
    "condition": "(IsWindows)",
    <windows-specific config here>
  },
  {
    "condition": "(IsMac)",
    <mac specific config here>
  },
  {
    "condition": (!IsWindows && !IsMac)",
    <other config here>
  }
]```

...or however many are needed. 

But if it's deemed best to have an npm install post-action, I can spend some time on it today & tomorrow.

[SteveSandersonMS]

@seancpeters Thanks for looking into it!

Having a set of platform-specific configs would be an OK stopgap measure. I know time is very tight. But is there a reasonable way to do it on Windows at all? The closest I got was the cmd /c "npm install" approach, which is not really viable since it provides no progress feedback on a process that can take minutes. I think it would be better to go back to showing manual instructions only rather than having dotnet new appear to hang. Or is there another way?

If you think you could do an npm install-specific postAction without it being an insane scramble, that would certainly be cleanest, but I'll leave that with you and @mlorbetske to determine how feasible it is.

Finally, if we end up just having to show manual instructions instead of invoking npm install automatically, it's not so bad. People have successfully done that with the existing SPA templates for months now.

[seancpeters]

Regarding the problem of the output not being displayed until the end, I'm currently writing up a change to the script handler post action that reads the command stdout & stderr async, and reports it to the console. If I can get that working, we may be in business.

[SteveSandersonMS]

@seancpeters Does that approach look like it's going to work out?

Also, do you know whether the VS host will honour and execute the script postActions, or is that only a CLI concept?

[seancpeters]

@SteveSandersonMS - I've got it basically working so the script running console output is reported to the console in real-time. But I haven't been able to capture output if the post action runs cmd <whatever>

[seancpeters]

VS can run post actions, but the implementation is host-specific. So there can be cases where the CLI implements certain post actions, and but VS does not, or vice-versa.