Vincent White created CASSANDRA-14463:
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Summary: Prevent the generation of new tokens when using
replace_address flag
Key: CASSANDRA-14463
URL: https://issues.apache.org/jira/browse/CASSANDRA-14463
Project: Cassandra
Issue Type: Bug
Reporter: Vincent White
This is a follow up to/replacement of CASSANDRA-14073.
The behaviour that I want to avoid is someone trying to replace a node with the
replace_address flag and mistakenly having that node listed in its own seed
list which causes the node to generate a new set of random tokens before
joining the ring.
Currently anytime an unbootstrapped node is listed in its own seed list and
initial_token isn't set in the yaml, Cassandra will generate a new set of
random tokens and join the ring regardless of whether it was replacing a
previous node or not.
We could simply check for this configuration and refuse to start but I it's
probably better (particularly for 3.0.X) if it's handled in the same manner as
skipping streaming with the allow_unsafe_replace flag that was introduced in
3.X . This would still allow 3.0.X users the ability to re-bootstrap nodes
without needing to re-stream all the data to the node again, which can be
useful.
We currently handle replacing without streaming different;y between 3.0.X and
3.X. In 3.X we have the allow_unsafe_replace JVM flag to allow the use of
auto_bootstrap: false in combination with the replace_address option. But in
3.0.X to perform the replacement of a node with the same IP address without
streaming I believe you need to:
* Set replace_address (because the address is already in gossip)
* Include the node in its own seed list (to skip bootstrapping/streaming)
* Set the initial_token to the token/s owned by the previous node (to prevent
it generating new tokens.
I believe if 3.0.X simply refused to start when a node has itself in its seed
list and replace_address set this will completely block this operation.
Example patches to fix this edge case using allow_unsafe_replace:
||Branch||
|[3.0.x\|https://github.com/apache/cassandra/compare/trunk...vincewhite:30-no_clobber]|
|[3.x\|https://github.com/apache/cassandra/compare/trunk...vincewhite:311-no_clobber]|
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