Get nx graph data via stdout

[skeate]

• I'd be willing to implement this feature (contributing guide)

Description

Add a mechanism to get project graph data out of nx in a manner useful for scripts.

Motivation

nx graph by itself spins up a web server to serve an interactive graph, which is fine for humans but unusable for scripting. Sometimes it would be nice to programmatically get (for example) a list of the internal projects that a particular project depends on.

Suggested Implementation

A --stdout option (or something similar) for the nx graph command.

Alternate Implementations

There is a workaround, though it's a bit convoluted; nx graph already can output JSON if you give it a --file=<something>.json option (presumably this looks at the extension, since you can also do --file=<something>.html and get an HTML page). Thus, with some tempfile shenanigans, you can get a one-liner that does the same kind of thing, something like

$TMPDIR=$(mktemp -d) nx graph --file=$TMPDIR/graph.json && \
  jq -r ".graph.dependencies" $TMPDIR/graph.json

but that's ugly, and I'm honestly not sure how portable it is (my original attempts used other options of mktemp which aren't actually options in MacOS's version of the program).

Since there's already the mechanism to output JSON, this should be a fairly simple addition. But maybe there is already a way (aside from my hack) and I just couldn't find it in the docs.

[FrozenPandaz]

There is actually a way.

You can pass --file stdout but I think we can definitely add a --print flag which would print the graph to the terminal.

Would you be interested in making a PR?

[skeate]

Hmm. I feel like there's not too much gain with --print over --file stdout; it's just pretty unclear that the latter is an option from the documentation. Maybe this is just an "improve docs" request?

Or do you think it would be worth having a separate --print flag for better discoverability?

Either way, yeah, I can probably make a PR for this.

[FrozenPandaz]

Exactly, --print is more self-explanatory. It will show up in the docs, --help, etc.

We cannot remove --file stdout because it allows for nx build nx --graph stdout.

--file stdout also needs to be documented properly though. That would be a separate change though.

[rlmestre]

I could take this if work hasn't started on it yet. (adding the new flag + docs, docs for --file stdout)

[jhecking]

I was looking for a way to use the generated graph programatically as well and was very happy to find out about the stdout option through this ticket. Especially since it works with nx affected --graph <file> as well. Definitely should be documented better!

However, I am still facing some minor issues with this feature:

1. When trying to pipe the output of nx affected -t build --graph stdout to another command the output seems to be truncated. E.g. nx affected -t build --graph stdout | jq . results in "parse error: Unfinished JSON term at EOF at line 2566, column 4".

❯ nx affected -t build --graph stdout | tail
              "options": {
                "lintFilePatterns": [
                  "apps/borneo-cli/**/*.ts"
                ]
              },
              "configurations": {}
            }
          },
          "tags": [],
          "implicitDepen

On the other hand, when redirecting the stdout output to a file, it seems to be complete – obviously, this defeats the purpose of using --graph stdout in the first place, though.

❯ nx affected -t build --graph stdout > graph.json

❯ tail graph.json
      "smithy:build": [],
      "borneo-workers:bundle-workflows:production": [],
      "borneo-encryption:build": [],
      "borneo-client-internal:build": [
        "smithy:build"
      ],
      "smithy-server-express:build": []
    }
  }
}

2. Depending on other options passed, nx graph --file stdout includes other content in the output on stdout, which makes it hard to process it, e.g.

❯ nx graph --affected --file stdout | head

 >  NX   Affected criteria defaulted to --base=main --head=HEAD

{
  "graph": {
    "nodes": {
      "borneo-client-internal": {
        "name": "borneo-client-internal",
        "type": "lib",
        "data": {

If this text would be printed to stderr instead it would be easy to filter out, e.g. nx graph --file stdout 2>/dev/null. Or, alternatively, maybe there should be a --quiet or --silent option or some such.

[github-actions]

This issue has been automatically marked as stale because it hasn't had any activity for 6 months.
Many things may have changed within this time. The issue may have already been fixed or it may not be relevant anymore.
If at this point, this is still an issue, please respond with updated information.
It will be closed in 21 days if no further activity occurs.
Thanks for being a part of the Nx community! 🙏

[github-actions]

This issue has been closed for more than 30 days. If this issue is still occuring, please open a new issue with more recent context.