[16.0] Harden NI Reconciler to prevent and recover from dnsmasq host file conflicts#5384
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rene merged 2 commits intoNov 12, 2025
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…uring removal Previously, when two applications accidentally shared the same DNS host file (for example, due to a duplicate DisplayName), the removal of the second application would fail because the shared file had already been deleted during the removal of the first app. This failure caused the dnsmasq configuration item to enter a broken state, preventing any new applications from being deployed into the same network instance. The only workaround in such cases was to redeploy the entire network instance and all applications connected to it. This change hardens the Dnsmasq configurator by handling missing DNS and DHCP host files gracefully. If a host file is not found during removal, a warning is logged, but the configuration item is not marked as failed. Although the original issue only affected DNS host files, it is also prudent to handle missing DHCP host files in the same way to ensure that their absence does not leave the network instance in a permanently broken state. Signed-off-by: Milan Lenco <[email protected]> (cherry picked from commit 3536a1f)
Normally, deploying two applications with the same DisplayName is not allowed. However, it is possible for user to replace an existing app definition inside EdgeDevConfig with a new one that has a different UUID but reuses the same DisplayName. Because shutting down the original app takes some time, zedmanager may start bringing up the new app while the old one is still connected. In this window, zedrouter may attempt to connect both apps to the same network instance. Since dnsmasq DNS host files are named after the app DisplayName, both apps would end up using the same file. Once the obsolete app is disconnected, it removes the shared host file, breaking name-to-IP resolution for the new app inside the NI. To prevent this, zedrouter now disallows multiple apps with the same DisplayName from being connected to a network instance simultaneously. In such cases, the new app will be marked with an error until the old app is fully removed. Once cleanup completes, the retry timer will reconnect the new app and clear the error state. Signed-off-by: Milan Lenco <[email protected]> (cherry picked from commit 347b860)
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Description
Backport of #5361
How to test and validate this PR
This issue was originally detected during internal automated testing. Re-running the same test suite should confirm whether the fix is effective.
To reproduce and verify manually:
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