Fix panic in agent #3024
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Fix panic in agent #3024
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Previously, there was an issue where the agent could panic while attempting to determine if an error was temporary. Before the change, in `agent/exec/errors.go`, the function `IsTemporary` attempted to drill down to a root cause by iterating through the causes of an error by calling `errors.Cause`. If an error has no cause, then `errors.Cause` returns that same error. The issue is that somewhere in the depths of some code, it was posssible for the error to have an underlying type that was non-comparable; for example, maps and slices are uncomparable types. This would cause a panic, as the uncomparable type cannot be compared even to itself. However, one can see that `errors.Cause` has its own loop, and drills down to the root cause in its own way. There is no need for us to iterate here. Instead, we can just take a look at the error itself, and then take a look at its cause once. If neither is temporary, the error is not temporary, and we have nothing to worry about. Signed-off-by: Drew Erny <derny@mirantis.com>
Codecov Report
@@ Coverage Diff @@
## master #3024 +/- ##
==========================================
+ Coverage 62.27% 62.37% +0.09%
==========================================
Files 142 155 +13
Lines 22888 24531 +1643
==========================================
+ Hits 14254 15301 +1047
- Misses 7130 7622 +492
- Partials 1504 1608 +104 |
dperny
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Oct 18, 2021
For details, see github.com/moby/swarmkit/pull/3024. Vendors a backport of that change. Signed-off-by: Drew Erny <derny@mirantis.com>
This was referenced Oct 27, 2021
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Previously, there was an issue where the agent could panic while attempting to determine if an error was temporary.
Before the change, in
agent/exec/errors.go, the functionIsTemporaryattempted to drill down to a root cause by iterating through the causes of an error by callingerrors.Cause. If an error has no cause, thenerrors.Causereturns that same error.The issue is that somewhere in the depths of some code, it was possible for the error to have an underlying type that was non-comparable; for example, maps and slices are uncomparable types. This would cause a panic, as the uncomparable type cannot be compared even to itself.
However, one can see that
errors.Causehas its own loop, and drills down to the root cause in its own way. There is no need for us to iterate here.Instead, we can just take a look at the error itself, and then take a look at its cause once. If neither is temporary, the error is not temporary, and we have nothing to worry about.