In order to support an HA mode for the service-mirror component, some
form of synchronization should be used to coordinate between replicas of
the service-mirror controller. Although in practice most of the updates
done by the replicas are idempotent (and have benign effects on
correctness), there are some downsides, such as: resource usage
implications from setting-up multiple watches, log pollution, errors
associated with writes on resources that out of date, and increased
difficulty in debugging.
This change adds coordination between the replicas through leader
election. To achieve leader election, client-go's `coordination` package
is used. The change refactors the existing code; the previous nested
loops now reside in a closure (to capture the necessary configuration),
and the closure is run when a leader is elected.
Leader election functions as part of a loop: a lease resource is created
(if it does not exist), and the controller blocks until it has acquired
the lease. The loop is terminated only on shutdown from an interrupt
signal. If the lease is lost, it is released, watchers are cleaned-up,
and the controller returns to blocking until it acquires the lease once
again.
Shutdown logic has been changed to rely on context cancellation
propagation so that the watchers may be ended either by the leader
elector (when claim is lost) or by the main routine when an interrupt is
handled.
---------
Signed-off-by: Matei David <matei@buoyant.io>
Co-authored-by: Alejandro Pedraza <alejandro@buoyant.io>
Closes#7826
This adds the `gosec` and `errcheck` lints to the `golangci` configuration. Most significant lints have been fixed my individual changes, but this enables them by default so that all future changes are caught ahead of time.
A significant amount of these lints are been exluced by the various `exclude-rules` rules added to `.golangci.yml`. These include operations are files that generally do not fail such as `Copy`, `Flush`, or `Write`. We also choose to ignore most errors when cleaning up functions via the `defer` keyword.
Aside from those, there are several other rules added that all have comments explaining why it's okay to ignore the errors that they cover.
Finally, several smaller fixes in the code have been made where it seems necessary to catch errors or at least log them.
Signed-off-by: Kevin Leimkuhler <kleimkuhler@icloud.com>
Since Go 1.13, errors may "wrap" other errors. [`errorlint`][el] checks
that error formatting and inspection is wrapping-aware.
This change enables `errorlint` in golangci-lint and updates all error
handling code to pass the lint. Some comparisons in tests have been left
unchanged (using `//nolint:errorlint` comments).
[el]: https://github.com/polyfloyd/go-errorlint
Signed-off-by: Oliver Gould <ver@buoyant.io>
Fixes#5257
This branch movies mc charts and cli level code to a new
top level directory. None of the logic is changed.
Also, moves some common types into `/pkg` so that they
are accessible both to the main cli and extensions.
Signed-off-by: Tarun Pothulapati <tarunpothulapati@outlook.com>
Matei David