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| author | Jean-Sébastien Pédron <jean-sebastien@rabbitmq.com> | 2019-10-07 12:01:32 +0200 |
|---|---|---|
| committer | Jean-Sébastien Pédron <jean-sebastien@rabbitmq.com> | 2019-10-07 12:01:32 +0200 |
| commit | fbdef3c51acbc8d221e734f9f29683ba38a01250 (patch) | |
| tree | e7b05eeef0aae0b481d112812f4e71936f8f8274 /src | |
| parent | 0332d2e30bc2498ed81c4d65b399b183e2cfa96c (diff) | |
| download | rabbitmq-server-git-fbdef3c51acbc8d221e734f9f29683ba38a01250.tar.gz | |
rabbit_feature_flags: Prevent load of the module on pre-feature-flags nodes
In a cluster, if e.g. RabbitMQ 3.7.17 packages are deployed on all
cluster member, but the nodes are not restarted yet, the first node to
restart will fail.
The reason is that the `rabbit_feature_flags` module is available on all
nodes after the package deployment. However, the module may be loaded in
a pre-feature-flags already running node. In this unexpected context,
the module fails to respond properly to the queries of the remote
restarting node.
To fix this, we use an `on_lod()` hook to prevent this module from being
loaded by the Erlang code server if the context is unexpected. This will
cause the query to abort with an undefined function call, exactly like
if the module was missing.
Fixes #2132.
Diffstat (limited to 'src')
| -rw-r--r-- | src/rabbit_feature_flags.erl | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/src/rabbit_feature_flags.erl b/src/rabbit_feature_flags.erl index cdf9090cf0..9591cd691d 100644 --- a/src/rabbit_feature_flags.erl +++ b/src/rabbit_feature_flags.erl @@ -246,6 +246,8 @@ migration_fun/0, migration_fun_context/0]). +-on_load(on_load/0). + -spec list() -> feature_flags(). %% @doc %% Lists all supported feature flags. @@ -2265,3 +2267,15 @@ maybe_enable_locally_after_app_load([FeatureName | Rest]) -> share_new_feature_flags_after_app_load(FeatureFlags, Timeout) -> push_local_feature_flags_from_apps_unknown_remotely( node(), FeatureFlags, Timeout). + +on_load() -> + case application:get_env(rabbit, feature_flags_file) of + {ok, _} -> + ok; + _ -> + "Refusing to load '" ?MODULE_STRING "' in what appears to " + "be a pre-feature-flags running node " + "(" ++ rabbit_misc:version() ++ "). This is fine: it is " + "probably a remote node querying this node for its feature " + "flags." + end. |