Clean server rename#17
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…ommand for runtime server renaming
Add the ability to rename a HAProxy server at runtime via the CLI
command:
set server <backend>/<server> name <newname>
This is useful in slot-based dynamic scaling setups where servers are
pre-allocated with generic names (e.g. srv001, srv002) but the operator
wants the names to reflect the current workload (e.g. pod name or
IP:port) for observability and server-state-file consistency.
A per-backend opt-in directive 'option server-rename' is required to
allow renaming. It may be placed in a defaults section to apply to all
backends without per-backend configuration.
The implementation:
- validates the new name: non-empty, passes invalid_char() check
(allows [A-Za-z0-9_:.-]), and fits in the event data name field
- requires the server to be administratively in maintenance mode
- rejects rename if the server has SRV_F_NON_PURGEABLE set (covers
servers referenced by a static 'use-server' rule, servers tracked
by another server via 'track', servers used by resolvers, and other
configuration elements pointing to the server)
- re-indexes the server in the cebtree under thread_isolate()
- publishes a new EVENT_HDL_SUB_SERVER_NAME event with old/new names
Note: sample fetches with ARG_SRV arguments (srv_queue(), srv_conn(),
srv_is_up(), etc.) are resolved to pointers at config-check time and
will continue to work after a rename, but leave the config text
inconsistent with the running state. Operators should audit their ACL
expressions manually before renaming a server.
This feature was discussed in:
haproxy#952
Tests cover:
- error cases: missing name, no opt-in, not-in-maintenance, invalid
chars, duplicate name, non-purgeable server (use-server reference,
track reference)
- same-name rename as a no-op success
- successful rename with verification via 'show servers state'
- old name no longer resolves after rename
- round-trip rename back to original name
- traffic still works after rename round-trip
…I command Document the new 'option server-rename' backend directive and the 'set server <b>/<s> name <newname>' CLI command in configuration.txt and management.txt respectively.
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