libct/cg/sd: reconnect and retry on dbus connection error #2923
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@wzshiming PTAL |
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kolyshkin
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cyphar
mrunalp
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Apr 27, 2021
kolyshkin
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I was wrong in my initial analysis that this is a regression caused by PR #2203. In fact it's not, it has always been working that way (see e.g. https://bugzilla.redhat.com/show_bug.cgi?id=1634092 from 2018). |
[@kolyshkin: documentation nits] Signed-off-by: Shiming Zhang <wzshiming@foxmail.com> Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
Generalize isUnitExists as isDbusError, and use errors.As while at it (which can handle wrapped errors as well). Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
[@kolyshkin: doc nits, use dbus.ErrClosed and isDbusError] Signed-off-by: Shiming Zhang <wzshiming@foxmail.com> Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
Signed-off-by: Shiming Zhang <wzshiming@foxmail.com> Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
Instead of reconnecting to dbus after some failed operations, and returning an error (so a caller has to retry), reconnect AND retry in place for all such operations. This should fix issues caused by a stale dbus connection after e.g. a dbus daemon restart. Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
mrunalp
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Apr 27, 2021
cyphar
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Apr 28, 2021
Comment on lines
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| d.RLock() | ||
| if conn := d.conn; conn != nil { | ||
| d.RUnlock() | ||
| return conn, nil | ||
| } | ||
| d.RUnlock() |
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This could be
d.RLock()
conn := d.conn
d.RUnlock()
if conn != nil { ... }But it doesn't really matter.
This was referenced Apr 30, 2021
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PR #2203 started to reuse the same dbus connection. While this improves the performance,In case the dbus daemon is ever restarted, the connection is no longer valid and every operation
fails. This is a minor concern for short-lived runc, but much more of a issue in case there is
a long-running daemon (e.g.
cri-o) is using runc's libcontainer, as the connection is neverretried and the only remedy is to restart the daemon.
The solution to the above is to check the errors returned for
dbus: connection closed by usererror, and try to re-connect on that. This is what PR #2862 does.
This is a carry of #2862, implementing the idea of retry-in-place (first described
at #2862 (comment) and #2862 (comment)) on top of what it does.
For more info, see commit messages as well as #2862.
Fixes:
Changelog entry