Display a warning when dune builds via RPC #11833

gridbugs · 2025-05-22T06:27:44Z

When an instance of dune is already running, invoking dune build will still build the target, howwever other command line arguments are silently ignored by dune as the current RPC interface is too limited to express them. This may change over time, but currently it's unusual UX for dune build to behave differently depending on whether or not another instance of dune build is already running. To more accurately set user expectations, print a warning when dune is running with this reduced functionality.

nojb · 2025-05-23T07:17:26Z

test/blackbox-tests/test-cases/watching/watching-eager-concurrent-build-command.t

+  Warning: A running dune (pid: 124305) instance has locked the build
+  directory. If this is not the case, please delete "_build/.lock".
+  The requested targets will still be built however functionality will be
+  reduced and some command line arguments will be ignored.


A couple of questions:

"If this is not the case, please delete ..." is this relevant ? if the build is being forwarded to a running instance, it doesn't make much sense to me to ask the user to delete the lock file.

"functionality will be reduced" what does this refer to?

I suggest tweaking the message and making it a bit less scary:

Warning: your build request is being forwarded to a running Dune instance (pid: 124305). Note that certain command line arguments may be ignored.

Leonidas-from-XIV

I like the idea of warning the user when flags get ignored, but I would suggest that this would only happen if there are flags that will get discarded.

bin/build_cmd.ml

test/blackbox-tests/test-cases/watching/watching-eager-concurrent-build-command.t

gridbugs · 2025-05-26T09:18:15Z

Updated so that it only prints the warning if extra arguments were passed to dune build. This is done by comparing the Builder.t parsed from command-line arguments to the default Builder.t that would be created if no arguments were passed. This has become a fairly big change because I needed to propagate equal functions throughout the code, and I needed to change how Log.File.t is defined so that it can be tested for equality.

I also added Term.eval_no_args for extracting the default value of a type by running its command-line argument parser with no input which is possibly a controversial way of getting a default value, but I think otherwise computing a default value of a Builder.t would require quite a big refactor.

Leonidas-from-XIV

It's a bit sad all these very verbose equal functions need to be added but I understand the idea.

Overall I think it needs a small wording change and an additional test and then it is good to go.

bin/build_cmd.ml

test/blackbox-tests/test-cases/watching/watching-eager-concurrent-build-command.t

test/expect-tests/dune_rpc_e2e/dune_rpc_e2e.ml

The only [out_channel] that was ever passed in was stderr. Removing the [Out_channel] case allows us to more easily test [Log.File.t] for equality. Signed-off-by: Stephen Sherratt <[email protected]>

Signed-off-by: Stephen Sherratt <[email protected]>

When an instance of dune is already running, invoking `dune build` will still build the target, howwever other command line arguments are silently ignored by dune as the current RPC interface is too limited to express them. This may change over time, but currently it's unusual UX for `dune build` to behave differently depending on whether or not another instance of `dune build` is already running. To more accurately set user expectations, print a warning when dune is running with this reduced functionality. Signed-off-by: Stephen Sherratt <[email protected]>

@rgrinberg

CHANGES: ### Fixed - Stop re-running cram tests after promotion when it's not necessary (ocaml/dune#11994, @rgrinberg) - fix: `$ dune subst` should not fail when adding the version field in opam files (ocaml/dune#11801, fixes ocaml/dune#11045, @btjorge) - Kill all processes in the process group after the main process has terminated; in particular this avoids background processes in cram tests to stick around after the test finished (ocaml/dune#11841, fixes ocaml/dune#11820, @Alizter, @Leonidas-from-XIV) ### Added - `(tests)` stanzas now generate aliases with the test name. To run `(test (name a))` you can do `dune build @runtest-a`. (ocaml/dune#11558, grants part of ocaml/dune#10239, @Alizter) - Inline test libraries now produce aliases `runtest-name_of_lib` allowing users to run specific inline tests as `dune build @runtest-name_of_lib`. (ocaml/dune#11109, partially fixes ocaml/dune#10239, @Alizter) - feature: `$ dune subst` use version from `dune-project` when no version control repository has been detected (ocaml/dune#11801, @btjorge) - Allow `dune exec` to run concurrently with another instance of dune in watch mode (ocaml/dune#11840, @gridbugs) - Introduce `%{os}`, `%{os_version}`, `%{os_distribution}`, and `%{os_family}` percent forms. These have the same values as their opam counterparts. (ocaml/dune#11863, @rgrinberg) - Introduce option `(implicit_transitive_deps false-if-hidden-includes-supported)` that is equivalent to `(implicit_transitive_deps false)` when `-H` is supported by the compiler (OCaml >= 5.2) and equivalent to `(implicit_transitive_deps true)` otherwise. (ocaml/dune#11866, fixes ocaml/dune#11212, @nojb) - Add `dune describe location` for printing the path to the executable that would be run (ocaml/dune#11905, @gridbugs) - `dune runtest` can now understand absolute paths as well as run tests in specific build contexts (ocaml/dune#11936, @Alizter). - Added 'empty' alias which contains no targets. (ocaml/dune#11556 ocaml/dune#11952 ocaml/dune#11955 ocaml/dune#11956, grants ocaml/dune#4161, @Alizter and @rgrinberg) - Allow `dune promote` to properly run while a watch mode server is running (ocaml/dune#12010, @ElectreAAS) - Add `--alias` and `--alias-rec` flags as an alternative to the `@@` and `@` syntax in the command line (ocaml/dune#12043, fixes ocaml/dune#5775, @rgrinberg) - Added a `(timeout <float>)` field to the `(cram)` stanza to specify per-test time limits. Tests exceeding the timeout are terminated with an error. (ocaml/dune#12041, @Alizter) ### Changed - Format long lists in s-expressions to fill the line instead of formatting them in a vertical way (ocaml/dune#10892, fixes ocaml/dune#10860, @nojb) - Switch from MD5 to BLAKE3 for digesting targets and rules. BLAKE3 is both more performant and difficult to break than MD5 (ocaml/dune#11735, @rgrinberg, @Alizter) - Print a warning when `dune build` runs over RPC (ocaml/dune#11833, @gridbugs) - Stop emitting empty module group wrapper `.js` file in `melange.emit` (ocaml/dune#11987, fixes ocaml/dune#11986, @anmonteiro)

@rgrinberg

CHANGES: ### Fixed - Stop re-running cram tests after promotion when it's not necessary (ocaml/dune#11994, @rgrinberg) - fix: `$ dune subst` should not fail when adding the version field in opam files (ocaml/dune#11801, fixes ocaml/dune#11045, @btjorge) - Kill all processes in the process group after the main process has terminated; in particular this avoids background processes in cram tests to stick around after the test finished (ocaml/dune#11841, fixes ocaml/dune#11820, @Alizter, @Leonidas-from-XIV) ### Added - `(tests)` stanzas now generate aliases with the test name. To run `(test (name a))` you can do `dune build @runtest-a`. (ocaml/dune#11558, grants part of ocaml/dune#10239, @Alizter) - Inline test libraries now produce aliases `runtest-name_of_lib` allowing users to run specific inline tests as `dune build @runtest-name_of_lib`. (ocaml/dune#11109, partially fixes ocaml/dune#10239, @Alizter) - feature: `$ dune subst` use version from `dune-project` when no version control repository has been detected (ocaml/dune#11801, @btjorge) - Allow `dune exec` to run concurrently with another instance of dune in watch mode (ocaml/dune#11840, @gridbugs) - Introduce `%{os}`, `%{os_version}`, `%{os_distribution}`, and `%{os_family}` percent forms. These have the same values as their opam counterparts. (ocaml/dune#11863, @rgrinberg) - Introduce option `(implicit_transitive_deps false-if-hidden-includes-supported)` that is equivalent to `(implicit_transitive_deps false)` when `-H` is supported by the compiler (OCaml >= 5.2) and equivalent to `(implicit_transitive_deps true)` otherwise. (ocaml/dune#11866, fixes ocaml/dune#11212, @nojb) - Add `dune describe location` for printing the path to the executable that would be run (ocaml/dune#11905, @gridbugs) - `dune runtest` can now understand absolute paths as well as run tests in specific build contexts (ocaml/dune#11936, @Alizter). - Added 'empty' alias which contains no targets. (ocaml/dune#11556 ocaml/dune#11952 ocaml/dune#11955 ocaml/dune#11956, grants ocaml/dune#4161, @Alizter and @rgrinberg) - Allow `dune promote` to properly run while a watch mode server is running (ocaml/dune#12010, @ElectreAAS) - Add `--alias` and `--alias-rec` flags as an alternative to the `@@` and `@` syntax in the command line (ocaml/dune#12043, fixes ocaml/dune#5775, @rgrinberg) - Added a `(timeout <float>)` field to the `(cram)` stanza to specify per-test time limits. Tests exceeding the timeout are terminated with an error. (ocaml/dune#12041, @Alizter) ### Changed - Format long lists in s-expressions to fill the line instead of formatting them in a vertical way (ocaml/dune#10892, fixes ocaml/dune#10860, @nojb) - Switch from MD5 to BLAKE3 for digesting targets and rules. BLAKE3 is both more performant and difficult to break than MD5 (ocaml/dune#11735, @rgrinberg, @Alizter) - Print a warning when `dune build` runs over RPC (ocaml/dune#11833, @gridbugs) - Stop emitting empty module group wrapper `.js` file in `melange.emit` (ocaml/dune#11987, fixes ocaml/dune#11986, @anmonteiro)

@rgrinberg

CHANGES: ### Fixed - Stop re-running cram tests after promotion when it's not necessary (ocaml/dune#11994, @rgrinberg) - fix: `$ dune subst` should not fail when adding the version field in opam files (ocaml/dune#11801, fixes ocaml/dune#11045, @btjorge) - Kill all processes in the process group after the main process has terminated; in particular this avoids background processes in cram tests to stick around after the test finished (ocaml/dune#11841, fixes ocaml/dune#11820, @Alizter, @Leonidas-from-XIV) ### Added - `(tests)` stanzas now generate aliases with the test name. To run `(test (name a))` you can do `dune build @runtest-a`. (ocaml/dune#11558, grants part of ocaml/dune#10239, @Alizter) - Inline test libraries now produce aliases `runtest-name_of_lib` allowing users to run specific inline tests as `dune build @runtest-name_of_lib`. (ocaml/dune#11109, partially fixes ocaml/dune#10239, @Alizter) - feature: `$ dune subst` use version from `dune-project` when no version control repository has been detected (ocaml/dune#11801, @btjorge) - Allow `dune exec` to run concurrently with another instance of dune in watch mode (ocaml/dune#11840, @gridbugs) - Introduce `%{os}`, `%{os_version}`, `%{os_distribution}`, and `%{os_family}` percent forms. These have the same values as their opam counterparts. (ocaml/dune#11863, @rgrinberg) - Introduce option `(implicit_transitive_deps false-if-hidden-includes-supported)` that is equivalent to `(implicit_transitive_deps false)` when `-H` is supported by the compiler (OCaml >= 5.2) and equivalent to `(implicit_transitive_deps true)` otherwise. (ocaml/dune#11866, fixes ocaml/dune#11212, @nojb) - Add `dune describe location` for printing the path to the executable that would be run (ocaml/dune#11905, @gridbugs) - `dune runtest` can now understand absolute paths as well as run tests in specific build contexts (ocaml/dune#11936, @Alizter). - Added 'empty' alias which contains no targets. (ocaml/dune#11556 ocaml/dune#11952 ocaml/dune#11955 ocaml/dune#11956, grants ocaml/dune#4161, @Alizter and @rgrinberg) - Allow `dune promote` to properly run while a watch mode server is running (ocaml/dune#12010, @ElectreAAS) - Add `--alias` and `--alias-rec` flags as an alternative to the `@@` and `@` syntax in the command line (ocaml/dune#12043, fixes ocaml/dune#5775, @rgrinberg) - Added a `(timeout <float>)` field to the `(cram)` stanza to specify per-test time limits. Tests exceeding the timeout are terminated with an error. (ocaml/dune#12041, @Alizter) ### Changed - Format long lists in s-expressions to fill the line instead of formatting them in a vertical way (ocaml/dune#10892, fixes ocaml/dune#10860, @nojb) - Switch from MD5 to BLAKE3 for digesting targets and rules. BLAKE3 is both more performant and difficult to break than MD5 (ocaml/dune#11735, @rgrinberg, @Alizter) - Print a warning when `dune build` runs over RPC (ocaml/dune#11833, @gridbugs) - Stop emitting empty module group wrapper `.js` file in `melange.emit` (ocaml/dune#11987, fixes ocaml/dune#11986, @anmonteiro)

@rgrinberg

CHANGES: ### Fixed - Stop re-running cram tests after promotion when it's not necessary (ocaml/dune#11994, @rgrinberg) - fix: `$ dune subst` should not fail when adding the version field in opam files (ocaml/dune#11801, fixes ocaml/dune#11045, @btjorge) - Kill all processes in the process group after the main process has terminated; in particular this avoids background processes in cram tests to stick around after the test finished (ocaml/dune#11841, fixes ocaml/dune#11820, @Alizter, @Leonidas-from-XIV) ### Added - `(tests)` stanzas now generate aliases with the test name. To run `(test (name a))` you can do `dune build @runtest-a`. (ocaml/dune#11558, grants part of ocaml/dune#10239, @Alizter) - Inline test libraries now produce aliases `runtest-name_of_lib` allowing users to run specific inline tests as `dune build @runtest-name_of_lib`. (ocaml/dune#11109, partially fixes ocaml/dune#10239, @Alizter) - feature: `$ dune subst` use version from `dune-project` when no version control repository has been detected (ocaml/dune#11801, @btjorge) - Allow `dune exec` to run concurrently with another instance of dune in watch mode (ocaml/dune#11840, @gridbugs) - Introduce `%{os}`, `%{os_version}`, `%{os_distribution}`, and `%{os_family}` percent forms. These have the same values as their opam counterparts. (ocaml/dune#11863, @rgrinberg) - Introduce option `(implicit_transitive_deps false-if-hidden-includes-supported)` that is equivalent to `(implicit_transitive_deps false)` when `-H` is supported by the compiler (OCaml >= 5.2) and equivalent to `(implicit_transitive_deps true)` otherwise. (ocaml/dune#11866, fixes ocaml/dune#11212, @nojb) - Add `dune describe location` for printing the path to the executable that would be run (ocaml/dune#11905, @gridbugs) - `dune runtest` can now understand absolute paths as well as run tests in specific build contexts (ocaml/dune#11936, @Alizter). - Added 'empty' alias which contains no targets. (ocaml/dune#11556 ocaml/dune#11952 ocaml/dune#11955 ocaml/dune#11956, grants ocaml/dune#4161, @Alizter and @rgrinberg) - Allow `dune promote` to properly run while a watch mode server is running (ocaml/dune#12010, @ElectreAAS) - Add `--alias` and `--alias-rec` flags as an alternative to the `@@` and `@` syntax in the command line (ocaml/dune#12043, fixes ocaml/dune#5775, @rgrinberg) - Added a `(timeout <float>)` field to the `(cram)` stanza to specify per-test time limits. Tests exceeding the timeout are terminated with an error. (ocaml/dune#12041, @Alizter) ### Changed - Format long lists in s-expressions to fill the line instead of formatting them in a vertical way (ocaml/dune#10892, fixes ocaml/dune#10860, @nojb) - Switch from MD5 to BLAKE3 for digesting targets and rules. BLAKE3 is both more performant and difficult to break than MD5 (ocaml/dune#11735, @rgrinberg, @Alizter) - Print a warning when `dune build` runs over RPC (ocaml/dune#11833, @gridbugs) - Stop emitting empty module group wrapper `.js` file in `melange.emit` (ocaml/dune#11987, fixes ocaml/dune#11986, @anmonteiro)

@rgrinberg

CHANGES: ### Fixed - Stop re-running cram tests after promotion when it's not necessary (ocaml/dune#11994, @rgrinberg) - fix: `$ dune subst` should not fail when adding the version field in opam files (ocaml/dune#11801, fixes ocaml/dune#11045, @btjorge) - Kill all processes in the process group after the main process has terminated; in particular this avoids background processes in cram tests to stick around after the test finished (ocaml/dune#11841, fixes ocaml/dune#11820, @Alizter, @Leonidas-from-XIV) ### Added - `(tests)` stanzas now generate aliases with the test name. To run `(test (name a))` you can do `dune build @runtest-a`. (ocaml/dune#11558, grants part of ocaml/dune#10239, @Alizter) - Inline test libraries now produce aliases `runtest-name_of_lib` allowing users to run specific inline tests as `dune build @runtest-name_of_lib`. (ocaml/dune#11109, partially fixes ocaml/dune#10239, @Alizter) - feature: `$ dune subst` use version from `dune-project` when no version control repository has been detected (ocaml/dune#11801, @btjorge) - Allow `dune exec` to run concurrently with another instance of dune in watch mode (ocaml/dune#11840, @gridbugs) - Introduce `%{os}`, `%{os_version}`, `%{os_distribution}`, and `%{os_family}` percent forms. These have the same values as their opam counterparts. (ocaml/dune#11863, @rgrinberg) - Introduce option `(implicit_transitive_deps false-if-hidden-includes-supported)` that is equivalent to `(implicit_transitive_deps false)` when `-H` is supported by the compiler (OCaml >= 5.2) and equivalent to `(implicit_transitive_deps true)` otherwise. (ocaml/dune#11866, fixes ocaml/dune#11212, @nojb) - Add `dune describe location` for printing the path to the executable that would be run (ocaml/dune#11905, @gridbugs) - `dune runtest` can now understand absolute paths as well as run tests in specific build contexts (ocaml/dune#11936, @Alizter). - Added 'empty' alias which contains no targets. (ocaml/dune#11556 ocaml/dune#11952 ocaml/dune#11955 ocaml/dune#11956, grants ocaml/dune#4161, @Alizter and @rgrinberg) - Allow `dune promote` to properly run while a watch mode server is running (ocaml/dune#12010, @ElectreAAS) - Add `--alias` and `--alias-rec` flags as an alternative to the `@@` and `@` syntax in the command line (ocaml/dune#12043, fixes ocaml/dune#5775, @rgrinberg) - Added a `(timeout <float>)` field to the `(cram)` stanza to specify per-test time limits. Tests exceeding the timeout are terminated with an error. (ocaml/dune#12041, @Alizter) ### Changed - Format long lists in s-expressions to fill the line instead of formatting them in a vertical way (ocaml/dune#10892, fixes ocaml/dune#10860, @nojb) - Switch from MD5 to BLAKE3 for digesting targets and rules. BLAKE3 is both more performant and difficult to break than MD5 (ocaml/dune#11735, @rgrinberg, @Alizter) - Print a warning when `dune build` runs over RPC (ocaml/dune#11833, @gridbugs) - Stop emitting empty module group wrapper `.js` file in `melange.emit` (ocaml/dune#11987, fixes ocaml/dune#11986, @anmonteiro)

gridbugs requested review from Leonidas-from-XIV and rgrinberg May 22, 2025 06:27

gridbugs force-pushed the dune-build-via-rpc-warning branch from 48478fc to 14c8b1b Compare May 22, 2025 06:29

maiste added the build Issue related to what dune build label May 22, 2025

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Allow concurrent exec with watch mode #11840

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gridbugs added 5 commits June 5, 2025 11:13

Replace [Out_channel] log file with [Stderr]

0daf309

The only [out_channel] that was ever passed in was stderr. Removing the [Out_channel] case allows us to more easily test [Log.File.t] for equality. Signed-off-by: Stephen Sherratt <[email protected]>

Add [Common.Builder.equal]

0d6a47a

Signed-off-by: Stephen Sherratt <[email protected]>

Extract default [Builder.t] from term

7b84515

Signed-off-by: Stephen Sherratt <[email protected]>

Expose lock held information when taking global lock

94c59ca

Signed-off-by: Stephen Sherratt <[email protected]>

gridbugs force-pushed the dune-build-via-rpc-warning branch from a635197 to 83da0d3 Compare June 5, 2025 01:13

gridbugs merged commit e117ae2 into ocaml:main Jun 5, 2025
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[new release] dune (15 packages) (3.20.0~alpha1) ocaml/opam-repository#28276

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[new release] dune (15 packages) (3.20.0~alpha2) ocaml/opam-repository#28298

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[new release] dune (15 packages) (3.20.0~alpha3) ocaml/opam-repository#28302

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[new release] dune (15 packages) (3.20.0~alpha4) ocaml/opam-repository#28333

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[new release] dune (15 packages) (3.20.0) ocaml/opam-repository#28357

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Display a warning when dune builds via RPC #11833

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