Fix apt-cache package lookup failure in nektos/act environments by Copilot · Pull Request #172 · awalsh128/cache-apt-pkgs-action

Copilot · 2025-09-30T07:27:10Z

Fixes apt-cache package lookup failures when using nektos/act for local GitHub Actions testing by automatically updating stale APT package lists, with zero performance impact on normal GitHub Actions runs.

Problem

When running this action with nektos/act (local GitHub Actions runner), the package normalization step fails because apt-cache show is called before apt update has refreshed the package lists. This works fine on GitHub's runners which have pre-updated package lists, but nektos/act containers typically start with empty/stale package lists.

Error encountered running apt-cache --quiet=0 --no-all-versions show python3-semver python3-requests
Exited with status code 100; see combined output below:
N: Unable to locate package python3-semver
N: Unable to locate package python3-requests
E: No packages found

Solution

Created a shared update_apt_lists_if_stale() function in lib.sh that:

Detects nektos/act environment by checking the ACT environment variable
Only runs when ACT=true - normal GitHub Actions runs skip this check entirely for zero performance impact
Checks package list freshness - only updates if /var/lib/apt/lists is older than 5 minutes
Updates package lists when stale using apt-fast (if available) or apt with proper error handling
Used in both scripts - pre_cache_action.sh and install_and_cache_pkgs.sh share the same logic

Changes Made

Created update_apt_lists_if_stale() function in lib.sh with ACT environment detection
Modified pre_cache_action.sh to call the shared function before package normalization
Modified install_and_cache_pkgs.sh to use the shared function instead of inline logic
Added proper error handling to prevent breaking existing functionality
Updated .gitignore to prevent committing build artifacts

Testing

✅ All existing Go tests pass
✅ Manual testing confirms packages resolve correctly with ACT=true
✅ Verified zero performance impact when ACT is not set (normal GitHub Actions)
✅ Verified update logic activates correctly when ACT=true (nektos/act)
✅ Tested with python3-semver and python3-requests from the original issue

Performance Impact

Normal GitHub Actions (ACT not set): Zero overhead - function returns immediately without any checks

nektos/act (ACT=true): Checks package list freshness and updates only if stale (>5 minutes old)

This approach specifically targets the nektos/act issue while maintaining optimal performance for standard GitHub Actions workflows.

Fixes #125

Original prompt

This section details on the original issue you should resolve

<issue_title>apt-cache does not find packages with nektos/act</issue_title>
<issue_description>I use nektos act to debug my workflows locally before committing them.

The following minimal reproducible example:
name: CI
on:
  workflow_dispatch:

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - uses: awalsh128/cache-apt-pkgs-action@latest
        with:
          packages: python3-semver python3-requests
fails:
[CI/build] ⭐ Run Main awalsh128/cache-apt-pkgs-action@latest
[CI/build]   🐳  docker cp src=/home/vagrant/.cache/act/awalsh128-cache-apt-pkgs-action@latest/ dst=/var/run/act/actions/awalsh128-cache-apt-pkgs-action@latest/
[CI/build] ⭐ Run Main ${GITHUB_ACTION_PATH}/pre_cache_action.sh \
  ~/cache-apt-pkgs \
  "$VERSION" \
  "$EXEC_INSTALL_SCRIPTS" \
  "$DEBUG" \
  "$PACKAGES"
echo "CACHE_KEY=$(cat ~/cache-apt-pkgs/cache_key.md5)" >> $GITHUB_ENV
[CI/build]   🐳  docker exec cmd=[bash --noprofile --norc -e -o pipefail /var/run/act/workflow/0-composite-pre-cache.sh] user= workdir=
| 08:35:29.331 Normalizing package list...
| Error encountered running apt-cache --quiet=0 --no-all-versions show python3-semver python3-requests
| Exited with status code 100; see combined output below:
| N: Unable to locate package python3-semver
| N: Unable to locate package python3-requests
| N: Unable to locate package python3-semver
| N: Unable to locate package python3-requests
| E: No packages found
[CI/build]   ❌  Failure - Main ${GITHUB_ACTION_PATH}/pre_cache_action.sh \
  ~/cache-apt-pkgs \
  "$VERSION" \
  "$EXEC_INSTALL_SCRIPTS" \
  "$DEBUG" \
  "$PACKAGES"
echo "CACHE_KEY=$(cat ~/cache-apt-pkgs/cache_key.md5)" >> $GITHUB_ENV
[CI/build] exitcode '1': failure
[CI/build]   ⚙  ::set-output:: package-version-list=
[CI/build]   ⚙  ::set-output:: all-package-version-list=
[CI/build]   ⚙  ::set-output:: cache-hit=false
[CI/build]   ❌  Failure - Main awalsh128/cache-apt-pkgs-action@latest
[CI/build] exitcode '1': failure
[CI/build] ⭐ Run Post awalsh128/cache-apt-pkgs-action@latest
[CI/build]   🐳  docker cp src=/home/vagrant/.cache/act/awalsh128-cache-apt-pkgs-action@latest/ dst=/var/run/act/actions/awalsh128-cache-apt-pkgs-action@latest/
[CI/build]   ✅  Success - Post awalsh128/cache-apt-pkgs-action@latest
[CI/build] 🏁  Job failed
It looks like, at the heart of it, apt-cache is unable to find the requested packages, but I haven't been able to find an exact explanation for its exit codes.

It works when I actually run it on GitHub, just not locally.</issue_description>

Comments on the Issue (you are @copilot in this section)
@awalsh128 I would look at the package on install and then on update on the logs to see what the difference is. That would be a good start to the investigation. Post it here. @awalsh128 I am wondering if `apt-fast update` is the issue here. It would be helpful to know the difference in installs.
What would be helpful here is to compare the diff between the 2 commands. Could one you try that?</comment_new>
<comment_new>@awalsh128
Hi @hbontempo-cw could you do some work on my last comment? Also if you use @master it will have more debugging until I create a release in testing.</comment_new>
<comment_new>@awalsh128

@hbontempo-cw it's pretty expected to have to run apt-get update once before you can install any package inside a docker container because otherwise the indexes are uninitialized. If I'm using dind for my runner, as in action-runner-controller, then it's inside a docker container. Can we just get it as an option that's off by default?

Can you clarify what you mean by off as default?</comment_new>

Fixes #125

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Co-authored-by: awalsh128 <2087466+awalsh128@users.noreply.github.com>

…5efb5c

awalsh128 · 2025-09-30T08:10:00Z

pre_cache_action.sh


 # Trim commas, excess spaces, and sort.
 log "Normalizing package list..."
+


Move this block to a library function in lib.sh and have it used in both locations

Refactored the apt list update logic into update_apt_lists_if_stale() function in lib.sh and updated both pre_cache_action.sh and install_and_cache_pkgs.sh to use it. See commit d6013a0.

awalsh128 · 2025-09-30T08:10:39Z

pre_cache_action.sh

+# Uses the same logic as install_and_cache_pkgs.sh
+if [[ -z "$(find -H /var/lib/apt/lists -maxdepth 0 -mmin -5 2>/dev/null)" ]]; then
+  log "APT package lists are stale, updating..."
+  if command -v apt-fast > /dev/null 2>&1; then


Will this ever happen? apt-fast should have a guarantee of being installed

The check for apt-fast is necessary in pre_cache_action.sh because apt-fast is not installed at that point (unlike in install_and_cache_pkgs.sh where it's installed first). The shared function now checks for apt-fast availability and falls back to apt if it's not present, making it work correctly in both contexts. See commit d6013a0.

This will slow down the action though. The point is that this part run without needing to update. Is there a way to detect if the nektos/act is being ran?

Modified the function to only check/update package lists when ACT=true (nektos/act environment). Normal GitHub Actions runs are unaffected and have zero performance overhead. See commit for details.

awalsh128 · 2025-10-01T01:37:30Z

@copilot Please continue working on this PR.

Co-authored-by: awalsh128 <2087466+awalsh128@users.noreply.github.com>

Copilot · 2025-10-01T01:44:51Z

Just as a heads up, I was blocked by some firewall rules while working on your feedback. Expand below for details.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

esm.ubuntu.com
- Triggering command: /usr/lib/apt/methods/https (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

Configure Actions setup steps to set up my environment, which run before the firewall is enabled
Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

awalsh128 · 2025-10-04T06:46:10Z

@copilot Please continue working on this PR.

Co-authored-by: awalsh128 <2087466+awalsh128@users.noreply.github.com>

Copilot · 2025-10-04T06:51:23Z

Just as a heads up, I was blocked by some firewall rules while working on your feedback. Expand below for details.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

esm.ubuntu.com
- Triggering command: /usr/lib/apt/methods/https (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

Configure Actions setup steps to set up my environment, which run before the firewall is enabled
Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Mynacol · 2025-10-08T15:25:58Z

This actually fixes a problem I have in the following action: https://codeberg.org/Mynacol/flowpipeline/actions/runs/197#jobstep-2-21

Unfortunately, it still doesn't work when using this PR. But that's on the runner environment: https://codeberg.org/Mynacol/flowpipeline/actions/runs/200#jobstep-2-1421

Initial plan

dde77c3

Copilot AI assigned Copilot and awalsh128 Sep 30, 2025

Copilot started work on behalf of awalsh128 September 30, 2025 07:27 View session

Copilot AI and others added 2 commits September 30, 2025 07:36

Add apt package list update to fix nektos/act compatibility

8c82e59

Co-authored-by: awalsh128 <2087466+awalsh128@users.noreply.github.com>

Remove build artifacts and update .gitignore

5ff1c7b

Co-authored-by: awalsh128 <2087466+awalsh128@users.noreply.github.com>

Copilot AI changed the title ~~[WIP] apt-cache does not find packages with nektos/act~~ Fix apt-cache package lookup failure in nektos/act environments Sep 30, 2025

Copilot AI requested a review from awalsh128 September 30, 2025 07:39

Copilot finished work on behalf of awalsh128 September 30, 2025 07:39

Merge branch 'master' into copilot/fix-674930a1-c588-408c-9a64-b575dc…

6be0984

…5efb5c

awalsh128 requested changes Sep 30, 2025

View reviewed changes

awalsh128 removed their assignment Sep 30, 2025

awalsh128 marked this pull request as ready for review October 1, 2025 01:34

awalsh128 marked this pull request as draft October 1, 2025 01:34

awalsh128 self-assigned this Oct 1, 2025

Copilot started work on behalf of awalsh128 October 1, 2025 01:37 View session

Refactor apt list update logic into shared library function

d6013a0

Co-authored-by: awalsh128 <2087466+awalsh128@users.noreply.github.com>

Copilot AI requested a review from awalsh128 October 1, 2025 01:44

Copilot finished work on behalf of awalsh128 October 1, 2025 01:44

Copilot started work on behalf of awalsh128 October 4, 2025 06:46 View session

Only update apt lists when running in nektos/act environment

75561fd

Co-authored-by: awalsh128 <2087466+awalsh128@users.noreply.github.com>

Copilot finished work on behalf of awalsh128 October 4, 2025 06:51

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Fix apt-cache package lookup failure in nektos/act environments#172

Fix apt-cache package lookup failure in nektos/act environments#172
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I tried to connect to the following addresses, but was blocked by firewall rules:

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I tried to connect to the following addresses, but was blocked by firewall rules:

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		# Trim commas, excess spaces, and sort.
		log "Normalizing package list..."

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Copilot AI commented Oct 1, 2025

I tried to connect to the following addresses, but was blocked by firewall rules:

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awalsh128 commented Oct 4, 2025

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Copilot AI commented Oct 4, 2025

I tried to connect to the following addresses, but was blocked by firewall rules:

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Mynacol commented Oct 8, 2025

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Copilot AI commented Sep 30, 2025 •

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