feat: add package-repo-broken troubleshooting lab

labs/package-repo-broken/cloud-init.yaml

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+#cloud-config
+runcmd:
+  - |
+    # 1. Create a broken repository file
+    # We use a non-existent codename like 'broken-release'
+    cat <<EOF > /etc/apt/sources.list.d/broken.list
+    deb http://archive.ubuntu.com/ubuntu/ broken-release main restricted
+    EOF
+
+    # 2. To ensure it really fails, we can also mess with the main sources.list
+    # But usually a single broken file in sources.list.d is enough to block apt update
+    # effectively with a non-zero exit code.

labs/package-repo-broken/lab.yaml

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+id: package-repo-broken
+name: Package Manager Repository Misconfigured
+category: linux
+difficulty: beginner
+vm:
+  name: repo-lab
+  image: ubuntu-24.04-base.qcow2
+  memory: 1024
+  cpu: 1
+  disk: 10G
+cloud_init: cloud-init.yaml
+verify_script: verify.sh
+
+description:
+  summary: "The system is unable to install or update software because the package manager's repository configuration is broken."
+  story: "A systems administrator tried to switch the server to a faster local repository mirror, but something went wrong. Now, every time you try to run 'apt update', you get errors about invalid URLs or missing release files. You need to identify the broken repository configuration and restore access to the official Ubuntu repositories."
+  objectives:
+    - Reproduce the repository update failure
+    - Identify the incorrectly configured source file in /etc/apt/sources.list.d/
+    - Restore a valid repository configuration and verify that 'apt update' succeeds
+tags:
+  - linux
+  - apt
+  - maintenance

labs/package-repo-broken/question.md

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+### Scenario
+You are trying to install a necessary utility on this server using `apt`, but you find that any attempt to update the package lists results in errors. It seems like the repository configuration has been tampered with or misconfigured, preventing the system from reaching the official Ubuntu sources.
+
+### Objective
+Diagnose the failure in the package manager, identify the problematic configuration file, and restore the system's ability to update and install software.
+
+### Useful Commands
+- `sudo apt update`
+- `ls /etc/apt/sources.list.d/`
+- `cat /etc/apt/sources.list`
+- `sudo rm [file]`

labs/package-repo-broken/solution.md

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+### The Issue
+The Debian/Ubuntu package manager (`apt`) relies on repository definition files located in `/etc/apt/sources.list` and the `/etc/apt/sources.list.d/` directory. If any of these files contains an invalid URL, a non-existent release codename, or a malformed entry, the entire `apt update` process will fail with an error.
+
+In this case, a file named `/etc/apt/sources.list.d/broken.list` was created with an invalid release name (`broken-release`), causing the package manager to stop functioning correctly.
+
+### Step-by-Step Fix
+
+1. **Reproduce the error**:
+   Run the update command to see the failure.
+   ```bash
+   sudo apt update
+   ```
+   You will see errors like: `The repository 'http://archive.ubuntu.com/ubuntu broken-release Release' does not have a Release file.`
+
+2. **Locate the broken configuration**:
+   Check the contents of the sources directory.
+   ```bash
+   ls /etc/apt/sources.list.d/
+   ```
+   You will see a file named `broken.list`.
+
+3. **Inspect the file**:
+   ```bash
+   cat /etc/apt/sources.list.d/broken.list
+   ```
+   Confirm that it points to a non-existent release.
+
+4. **Remove the problematic file**:
+   ```bash
+   sudo rm /etc/apt/sources.list.d/broken.list
+   ```
+
+5. **Verify the fix**:
+   Run the update command again.
+   ```bash
+   sudo apt update
+   ```
+   It should now complete successfully without repository errors.

labs/package-repo-broken/solution.sh

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+#!/bin/bash
+
+# Remove the broken repository file
+rm -f /etc/apt/sources.list.d/broken.list
+
+# Run apt update to confirm fix
+apt-get update

labs/package-repo-broken/verify.sh

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+#!/bin/bash
+
+# Check if 'apt update' succeeds
+if apt-get update; then
+    echo "SUCCESS: Package manager repositories are working correctly."
+    exit 0
+else
+    echo "FAILURE: Package manager repository update failed."
+    exit 1
+fi