[ES|QL] PromQL pretty-printing support by vadimkibana · Pull Request #247399 · elastic/kibana

vadimkibana · 2025-12-23T16:26:12Z

Summary

Partially addresses #243932

Adds ability to transforms a PromQL AST back to text: pretty-print. Supports basic pretty printing where the whole PromQL query is printed on a single line with minimal whitespace.

Checklist

Unit or functional tests were updated or added to match the most common scenarios

vadimkibana · 2025-12-29T09:05:07Z

/ci

elasticmachine · 2025-12-29T09:05:52Z

Pinging @elastic/kibana-esql (Team:ESQL)

sddonne

Nice!
Code looks correct, left some suggestions and some doubts, feel free to decide if they makes sense or not :)

sddonne · 2025-12-29T10:29:00Z

src/platform/packages/shared/kbn-esql-language/src/promql/parser/cst_to_ast_converter.ts


-    return PromQLBuilder.expression.literal.string(ctx.getText(), '', this.getParserFields(ctx));
+    const text = ctx.getText();
+    return PromQLBuilder.expression.literal.string('', text, this.getParserFields(ctx));


What's the reason for the value unquoted to be empty string?

Because PromQLBuilder can construct the AST node from two patterns: (1) parsed from source text; (2) created programmatically without the source text. In the first case the second argument text is passed and the "unquoted" version is figured out by the builder. In the second case, the actual string (the unquoted version) is passed and the pretty-printer later figures out how to quote it, if at all.

sddonne · 2025-12-29T10:52:50Z

...ages/shared/kbn-esql-language/src/promql/pretty_print/__tests__/basic_pretty_printer.test.ts

+    });
+  });
+
+  describe('synthetic AST (Builder-constructed)', () => {


Aren't this set of tests more related to the builder inner workings than the pretty printer?
I understand the usage of the pretty printer here is just to check the builder created the correct query, anyway these ones seems different from the rest of the tests in the file so maybe could be good to move them into another one, with these large files it could become difficult to find the correct place to add a new test.
Could be /builder/builder.test.ts to match the ES|QL scaffolding or /pretty_print/__tests__/print_from_builder.test.ts if you prefer to keep them here.

How do you see it?

My idea was to test also the pretty-printing of queries that are not parsed, but constructed programmatically using the PromqlBuilder. I've put them now into a separate test suite to separate the two AST construction patterns.

sddonne · 2025-12-29T10:59:32Z

src/platform/packages/shared/kbn-esql-language/src/promql/pretty_print/basic_pretty_printer.ts

+      case 'unknown':
+        return '<unknown>';
+      default:
+        return '';


Just for my understanding, why is it better to ignore unsupported expression types and return '' rather than return the raw text?

It is just one way of doing it. The default clause should not ever execute, so what we put there should not matter that much. Could also be the .text field, I don't have a strong opinion.

With printing the raw text there are few issues to be solved:

The raw source text is available only if we parsed the original query. If we constructed it using a builder programmatically, it would not have raw text version. Also, the way the pretty-printer is set up now, it receives only the AST node for printing, it does not receive the source text where to cut the nodes from, we would need to change the API of it to accept source text (and make it optional as programmatically constructed queries don't have the source text).

Some other issues with raw text: the .text field on AST nodes is stripped of hidden channel tokens (whitespace), so we cannot use that. But if we were to use the actual source text an cut out text from it we would have another whitespace issue: this "basic" pretty printer is setup to print everything on one line with a single space as separator, but the original source whitespace could have more than one space and more complex whitespace characters, line newline \n.

Clear, thank you for the explanation 🙏

sddonne · 2025-12-29T11:09:11Z

src/platform/packages/shared/kbn-esql-language/src/promql/pretty_print/basic_pretty_printer.ts

+
+  protected formatOperator(op: string): string {
+    // Set operators (and, or, unless) might need case formatting
+    if (op === 'and' || op === 'or' || op === 'unless') {


We have these defined here , maybe we can define them as

export const promQLOperators = ['and', 'or', 'unless'] as const; export type PromQLSetOperator = (typeof promQLOperators)[number];

To re-use them here.

We could put them in an array, once we need them in an array.

One thing I don't understand, is why would we infer the type from a runtime variable? If (as you mentioned) the type PromQLSetOperator is already defined, we can just use the type:

export const promQLOperators: PromQLSetOperator[] = ['and', 'or', 'unless'];

It's a way of only listing them once,

export const promQLOperators = ['and', 'or', 'unless'] as const; export type PromQLSetOperator = (typeof promQLOperators)[number];

vs

export type PromQLSetOperator = 'and' | 'or' | 'unless'; export const promQLOperators: PromQLSetOperator[] = ['and', 'or', 'unless'];

then you could do
if (promQLOperators.inlcudes(op) {... instead of
if (op === 'and' || op === 'or' || op === 'unless') {

…inter-2

elasticmachine · 2026-01-05T11:58:00Z

💛 Build succeeded, but was flaky

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Commit: 2c461bd

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[job] [logs] FTR Configs #64 / Cloud Security Posture Security Network Page - Graph visualization ECS fields only expanded flyout - entity enrichment for multiple actors and targets

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💛 Build #376904 was flaky 6ff341f

## Summary Partially addresses elastic#243932 Adds ability to transforms a PromQL AST back to text: pretty-print. Supports basic pretty printing where the whole PromQL query is printed on a single line with minimal whitespace. ### Checklist - [x] [Unit or functional tests](https://www.elastic.co/guide/en/kibana/master/development-tests.html) were updated or added to match the most common scenarios

vadimkibana and others added 2 commits December 23, 2025 17:25

add promql pretty printing

92df1a9

Merge branch 'main' into promql-printer-2

6ff341f

vadimkibana changed the title ~~add promql pretty printing~~ [ES|QL] PromQL pretty-printing support Dec 29, 2025

vadimkibana marked this pull request as ready for review December 29, 2025 09:05

vadimkibana requested a review from a team as a code owner December 29, 2025 09:05

vadimkibana added the Team:ESQL ES|QL related features in Kibana t// label Dec 29, 2025

vadimkibana added review backport:skip This PR does not require backporting Feature:ES|QL ES|QL related features in Kibana v9.4.0 release_note:skip Skip the PR/issue when compiling release notes labels Dec 29, 2025

sddonne approved these changes Dec 29, 2025

View reviewed changes

vadimkibana and others added 3 commits January 5, 2026 10:26

Merge branch 'main' into promql-printer-2

52a6724

create separate builder test file

f34b95b

Merge remote-tracking branch 'origin/promql-printer-2' into promql-pr…

2c461bd

…inter-2

vadimkibana enabled auto-merge (squash) January 5, 2026 09:54

vadimkibana merged commit 492c9f0 into elastic:main Jan 5, 2026
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vadimkibana commented Dec 29, 2025

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elasticmachine commented Dec 29, 2025

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elasticmachine commented Jan 5, 2026

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vadimkibana commented Dec 23, 2025 •

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vadimkibana Jan 5, 2026 •

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sddonne Dec 29, 2025 •

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