Add environment variable with installer file path #1151

lrandersson · 2026-01-21T19:10:14Z

Description

This PR adds an environment variable INSTALLER_PATH for installers that have post_install: ... defined.

Checklist - did you ...

Add a file to the news directory (using the template) for the next release's release notes?
Add / update necessary tests?
Add / update outdated documentation?

lrandersson · 2026-01-21T21:22:06Z

news/1151-installer-path-variable

@@ -0,0 +1,19 @@
+### Enhancements
+
+* EXE: An environment variable `INSTALLER_PATH` is now defined for `post_install` scripts and set to the path of installer executable while the installer is running.


Suggested change

* EXE: An environment variable `INSTALLER_PATH` is now defined for `post_install` scripts and set to the path of installer executable while the installer is running.

* EXE: An environment variable `INSTALLER_PATH` is now defined for `post_install` scripts and set to the path of the installer executable while the installer is running.

049b6d6 and 64aaf24

marcoesters

It might be worth adding that variable to the SH and PKG installers, too, while we're at it.

marcoesters · 2026-01-22T23:46:29Z

constructor/nsis/main.nsi.tmpl

    Push $R2

+{%- if post_install_exists %}
+    System::Call 'Kernel32::SetEnvironmentVariable(t, t) i("INSTALLER_PATH", "$EXEPATH")'


I would add this to where the other variables are defined in the Install section, and not make this a condition for post-install. It could also be used in pre-install scripts, maybe.

PLUGINSDIR may also be a good variable to add here.

I've moved it and added INSTALLER_PLUGINSDIR, see f8da863.
I also considered if we should have it as:

... SetEnvironmentVariable INSTALLER_PLUGINSDIR... {%- if pre_install_exists or post_install_exists %} SetEnvironmentVariable INSTALLER_PATH... {%- endif %}

Thoughts? It doesn't hurt having INSTALLER_PATH always defined, but I also wonder if it is unnecessary, is it always safe?

Why would it be unsafe?

I can't think of any reason, but I am bringing it up just for consideration.

I don't see an attack vector right now. The environment variable is not available outside the installation process. So, they can only be used through in scripts. Apart from the pre-install or post-install scripts of the installer, those are the pre-link or pre-unlink scripts of the packages.

However, even if someone were to place a malicious package into an installer, this doesn't give the attacker any more privileges that they'd already have. So, the limitation won't reduce the overall exposure.

I agree, good assessment!

lrandersson · 2026-01-27T19:44:26Z

constructor/header.sh

+case "$0" in
+  */*) SCRIPT_PATH="$0" ;;
+  *)   SCRIPT_PATH="$(command -v -- "$0" 2>/dev/null)" ;;
+esac
+
+[ -z "$SCRIPT_PATH" ] && {
+  echo "ERROR: Cannot determine installer path"
+  exit 1
+}
+# Resolve the directory to an absolute path
+SCRIPT_DIR=$(cd -- "$(dirname -- "$SCRIPT_PATH")" && pwd)
+INSTALLER_PATH="$SCRIPT_DIR/$(basename -- "$SCRIPT_PATH")"
+export INSTALLER_PATH


For visibility, note that this is based on a proposed AI solution and is said to be robust for both linux/mac with a #!/bin/sh shebang. I simplified it a bit because I removed an assumption to follow symlinks, I don't think that is necessary in this case?

It also is a bit extra because it is trying to determine if the script was invoked using ., source or if the script was on $PATH.

The script location is already a local variable, so you can just reuse that:

constructor/constructor/header.sh

Line 89 in dccf7d6

THIS_FILE=$(basename "$0")

Thanks, I noticed the entire path was already defined, I removed the earlier implementation and simply reuse the existing one: 8cf48d3

lrandersson · 2026-01-27T20:39:27Z

constructor/osx/run_user_script.sh

+
+# PACKAGE_PATH is poorly documented, and might not exist across all OS versions
+if [ -n "${PACKAGE_PATH:-}" ]; then
+    export INSTALLER_PATH="$PACKAGE_PATH" # The path to the .pkg installer


Do we want to add a default value? What we are trying to achieve here doesn't seem to be well-supported by Apple for .pkg installers, however, I found this and it worked for me when I tested locally. However, it's a poorly documented variable and might not always work.

However, it's a poorly documented variable

That is, unfortunately, not unusual. This code may fail though with set -u. Here is how I solved it for another variable:

constructor/constructor/osx/run_user_script.sh

Lines 33 to 40 in dccf7d6

# The value for COMMAND_LINE_INSTALL is not documented,

# but it is unset for interactive installations. To be

# safe, set the variable for non-interactive installation

# in a roundabout way.

export INSTALLER_UNATTENDED="${COMMAND_LINE_INSTALL:-0}"

if [[ "${INSTALLER_UNATTENDED}" != "0" ]]; then

INSTALLER_UNATTENDED="1"

fi

I don't think a default variable makes sense here. If the location of the installer cannot be detected because the variable is not defined, then it shouldn't be set.

I don't think the 0 is necessary, I used the :- syntax as well (if [ -n "${PACKAGE_PATH:-}" ]; then) but this situation evaluates to an empty string if unset.

marcoesters · 2026-01-29T15:28:04Z

news/1151-installer-path-variable

+An environment variable `INSTALLER_PATH` is now defined for `post_install` scripts and set to the path of the installer executable while the installer is running.
+* EXE: An environment variable `INSTALLER_PLUGINSDIR` is now also defined, it serves the same purpose as the NSIS variable `PLUGINSDIR`.


Suggested change

An environment variable `INSTALLER_PATH` is now defined for `post_install` scripts and set to the path of the installer executable while the installer is running.

* EXE: An environment variable `INSTALLER_PLUGINSDIR` is now also defined, it serves the same purpose as the NSIS variable `PLUGINSDIR`.

* An environment variable `INSTALLER_PATH` is now defined for pre-install and post-install scripts, and set to the path of the installer executable while the installer is running. (#1151)

* EXE: An environment variable `INSTALLER_PLUGINSDIR` is now also defined, it serves the same purpose as the NSIS variable `$PLUGINSDIR`. (#1151)

Please always add the PR number (and issue number, not applicable here) to the new items.

You're right, I keep forgetting that. Thanks for the reminder!

Co-authored-by: Marco Esters <[email protected]>

Added file check and set env variable for post_install installers

24cdd0c

lrandersson requested a review from a team as a code owner January 21, 2026 19:10

conda-bot added the cla-signed [bot] added once the contributor has signed the CLA label Jan 21, 2026

conda-bot added this to 🔎 Review Jan 21, 2026

github-project-automation bot moved this to 🆕 New in 🔎 Review Jan 21, 2026

lrandersson added 2 commits January 21, 2026 16:19

Add one more check to a post install script

b8b365f

Add news

247a620

lrandersson changed the title ~~[WIP] Add environment variable with installer file path~~ Add environment variable with installer file path Jan 21, 2026

lrandersson commented Jan 21, 2026

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marcoesters reviewed Jan 22, 2026

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lrandersson mentioned this pull request Jan 23, 2026

Add path to MSI as an environment variable for installers. beeware/briefcase-windows-VisualStudio-template#80

Merged

4 tasks

lrandersson added 3 commits January 23, 2026 09:22

Relocate var def, add INSTALLER_PLUGINSDIR

f8da863

Update news

049b6d6

Update language

64aaf24

lrandersson mentioned this pull request Jan 23, 2026

Account for state of option before running pre install script #1152

Merged

3 tasks

Add INSTALLER_PATH for .sh installers

067f478

lrandersson commented Jan 27, 2026

View reviewed changes

Add INTALLER_PATH for .pkg installers too

0247784

lrandersson commented Jan 27, 2026

View reviewed changes

Review fixes

8cf48d3

lrandersson requested a review from marcoesters January 27, 2026 21:06

marcoesters reviewed Jan 29, 2026

View reviewed changes

Update news/1151-installer-path-variable

b5cf2d0

Co-authored-by: Marco Esters <[email protected]>

marcoesters approved these changes Jan 29, 2026

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github-project-automation bot moved this from 🆕 New to ✅ Approved in 🔎 Review Jan 29, 2026

lrandersson merged commit 8336f18 into conda:main Jan 29, 2026
18 of 20 checks passed

github-project-automation bot moved this from ✅ Approved to 🏁 Done in 🔎 Review Jan 29, 2026

		@@ -0,0 +1,19 @@
		### Enhancements

		* EXE: An environment variable `INSTALLER_PATH` is now defined for `post_install` scripts and set to the path of installer executable while the installer is running.

	# The value for COMMAND_LINE_INSTALL is not documented,
	# but it is unset for interactive installations. To be
	# safe, set the variable for non-interactive installation
	# in a roundabout way.
	export INSTALLER_UNATTENDED="${COMMAND_LINE_INSTALL:-0}"
	if [[ "${INSTALLER_UNATTENDED}" != "0" ]]; then
	INSTALLER_UNATTENDED="1"
	fi

		An environment variable `INSTALLER_PATH` is now defined for `post_install` scripts and set to the path of the installer executable while the installer is running.
		* EXE: An environment variable `INSTALLER_PLUGINSDIR` is now also defined, it serves the same purpose as the NSIS variable `PLUGINSDIR`.

Add environment variable with installer file path #1151

Add environment variable with installer file path #1151

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lrandersson commented Jan 21, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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lrandersson Jan 27, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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lrandersson commented Jan 21, 2026 •

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