Firefox support #1606

juj · 2025-09-29T14:02:58Z

This PR adds downloadable firefox packages into emsdk.

The downloading of firefox will be done via the mozdownload pip package, which simplifies the installation a lot.

Installing and activating a Firefox package will set up the EMTEST_BROWSER variable, so running browser tests will then automatically use the activated browser.

The oldest supported Firefox version by Emscripten is 65. So add that version, and all ESR versions from 65 upwards, and the moving channels. This allows people to go back and forth testing different versions of interest.

sbc100 · 2025-10-01T00:38:49Z

emsdk_manifest.json

+    "version": "78.15.0esr",
+    "bitness": 64,
+    "url": "downloaded via mozdownload script, but a dummy directive is placed here so emsdk understands this Tool to be downloaded from the web",
+    "activated_cfg": "EMTEST_BROWSER=%installation_dir%/firefox%.exe%",


EMTEST_BROWSER is not a config file setting so I would hope this would not be needed?

Unfortunately that is the only way currently to distinguish whether the tool is set to be active or not.

Without this directive, there is no record of whether user has set, say, emsdk activate firefox-78.15.0esr or emsdk activate firefox-latest-esr-64bit.

I'll rename this cfg directive to EMSDK_ACTIVATED_TEST_BROWSER to help distinguish that is not actually used to set up EMTEST_BROWSER.

Without this directive, there is no record of whether user has set, say, emsdk activate firefox-78.15.0esr or emsdk activate firefox-latest-esr-64bit.

It is important to track that? What purpose does it serve?

Otherwise if you run emsdk_env, it will activate all Firefoxes, so the very last one in emsdk_manifest.json will win.

I guess mean all the ff versions you have installed?

Its a shame we don't have any other way to track activated status, other than writing to the config file

I guess mean all the ff versions you have installed?

Err yeah, that's the case.

sbc100

This seems to add a lot of extra complexity, but I'm not sure I see the benefit outside of your specific internal CI setup.

Can we at least try to reduce the extra lines of code somehow? For example do we really need all those FF versions?

sbc100 · 2025-10-01T15:31:51Z

emsdk_manifest.json

    "activated_env": "EMTEST_BROWSER=%installation_dir%/firefox%.exe%",
-    "mac_activated_cfg": "EMTEST_BROWSER=%installation_dir%/Contents/MacOS/firefox%.exe%",
+    "mac_activated_cfg": "EMSDK_ACTIVATED_TEST_BROWSER=%installation_dir%/Contents/MacOS/firefox%.exe%",
    "mac_activated_env": "EMTEST_BROWSER=%installation_dir%/Contents/MacOS/firefox%.exe%",


Can we modify the extraction process to strip the Contents/MacOS prefix, and avoid adding this new mac_activated_cfg and mac_activated_env concepts?

There are files in the other directories, e.g. Contents/Resources/. I could maybe remove the Contents/ part, but that would be very non-Apple'esque, and any Apple native devs reading the code would likely read it to be a silly hack.

juj · 2025-10-01T16:21:05Z

I'm not sure I see the benefit outside of your specific internal CI setup.

Users can

emsdk install firefox-x-64bit
emsdk activate firefox-x-64bit
test/runner browser.test_x

to test in any Firefox?

do we really need all those FF versions?

Yes, otherwise we blind our eyes from bugs, and saying we would support codegen down to Firefox 65 would be lip service.

sbc100 · 2025-10-01T18:43:05Z

I'm not sure I see the benefit outside of your specific internal CI setup.

Users can
emsdk install firefox-x-64bit
emsdk activate firefox-x-64bit
test/runner browser.test_x
to test in any Firefox?

do we really need all those FF versions?

Yes, otherwise we blind our eyes from bugs, and saying we would support codegen down to Firefox 65 would be lip service.

I'm not saying that testing old versions of FF is not good, I'm just not sure if emsdk is needs to be the way firefox gets installed. Up until now we have not installed browser, or stuff needed for testing only as part of emsdk.

Would it possible perhaps to write a script that downloads FF, without complicating emsdk?

juj · 2025-10-01T18:55:56Z

I'm just not sure if emsdk is needs to be the way firefox gets installed.

This way I can spin up Emscripten testing the same way in Node, vs in Firefox.

Would it possible perhaps to write a script that downloads FF, without complicating emsdk?

Yes, but then I will have to go through hoops to install some other git repository in tandem with installing emsdk, which would be a massive hassle. With this I can install Firefox at the same line where I install rest of Emscripten tools. It can be of big value in user bug reports as well.

This reverts commit cdb956d.

juj · 2025-10-07T00:55:50Z

Ping, further thoughts here?

sbc100

lgtm since I don't want to keep blocking your progress.

But I do have some concerns:

I'm generally against adding a more untested code to emsdk (I do get it is being testing on your end but that doesn't stop future changes breaking it)

I don't love adding this many new entries to the manifest... maybe there is some way to templatize so we don't need to repeat ourselves so much? I get that its just a bunch of json, but I also find myself paging through it fairly often by hand and lots of mostly-unused (i.e. used only on your CI bots) entries are somewhat annoying here.

I would love to:

Find a way to avoid the new mac_activated_env and mac_activated_cfg which duplicate the non-man versions. Could magically also look in Contents/MacOS without needing the include this in the json?
Find some way to avoid the duplication in the many new json entries?
Find a way another way to signal activation other than presence in the config file? We have a lot of tools now that don't ever want to be the .emscripten config file since emscripten itself doesn't use them. Perhaps a separately activated.json file that gets written separately to the config file?

Perhaps a secondary firefox_manifest.json, perhaps even allowing your to maintain that externally?

juj added 30 commits September 28, 2025 01:04

Add emsdk manifest entries for downloading Firefox.

a8ac2cd

Add support for installing Firefox on Linux

45112a3

Add git branch markers

e64ba76

Fix daily path

8c0b743

Autoinstall mozdownload

4dd06a2

Add firefox 90.0

6c58b2a

Firefox 120

b48c933

Add Firefox 130

bd4cab3

Add Firefox 125

c5fbe8a

125.0.1

9ce1de9

Add 122.0

801073c

MacOS support

8ebe2eb

Add Firefox 123.0

fd0aeb7

Fix is_firefox_installed on MacOS.

6003b3e

Add Firefox 100.0 and 110.0

65521c7

Add Firefox esr

8a3b828

Only attempt mozdownload reinstall if mozdownload import does not work.

3377c89

flake

6516449

Fix MacOS for Firefox Nightly

bf39cf7

Fix attach

ec0cf2b

fix 2

2687a33

daily -> nightly (they are the same)

7d9ac48

Add 140.3.1esr

faac848

nightly->daily

a273a9b

Fix typo

ab1547e

Fix mac cfg

9c1bdf5

Fix save version

d78bb89

no f

1cc37cd

Add Firefox beta

ac87ea1

ImportError

fe8c557

juj added 2 commits September 29, 2025 15:42

Cleanup

214c810

Fix typo

538cdab

sbc100 reviewed Oct 1, 2025

View reviewed changes

Rename config field for browsers

ab8744a

sbc100 reviewed Oct 1, 2025

View reviewed changes

juj added 3 commits October 2, 2025 16:02

Set Firefox 79 as the minimum supported version

cdb956d

Revert "Set Firefox 79 as the minimum supported version"

199f4c9

This reverts commit cdb956d.

Remove the redundant temp directory after move

4e59bf9

juj mentioned this pull request Oct 3, 2025

Support for Windows ARM64 (aarch64) builds mozilla/mozdownload#681

Open

juj added 3 commits October 4, 2025 00:34

Add Linux ARM64 download support

886e67f

Remove Firefox 65

bf8924d

Hide old Firefox versions from install list by default

4d5276b

sbc100 approved these changes Oct 7, 2025

View reviewed changes

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Firefox support #1606

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