Live and restart-only
Which directives can be applied now, and which are commented out because they cannot
maxmemory 2gb maxmemory-policy allkeys-lru port 6380
redis.conf to CONFIG SET
Paste a redis.conf and get the CONFIG SET commands that apply it live. Directives that need a restart are commented out with the reason, because CONFIG SET on a read-only parameter is an error rather than a no-op.
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The answer appears here
Paste on the left and press Convert. Nothing leaves this tab.
Formatted
Results
Nothing else to flag.
No formatting problems, and nothing the rules object to. Worth remembering what that covers: this reads the file you pasted, not the account or cluster it will be applied to.
No finding matches that filter.
Examples
Real input you can load into the tool above. Each one shows a different thing going wrong, because that is what the tool is for.
Common mistakes
These are the ones that fail silently. The config is accepted, nothing raises an error, and the consequence arrives later.
Applying a fix with CONFIG SET and stopping there
It changes memory only. The next restart, for any reason, reverts it. The classic version is a limit raised during an incident and undone weeks later by an unrelated deploy.
Instead:Follow with CONFIG REWRITE, or make the same edit in the file.
Running CONFIG SET appendonly yes at peak
It starts an AOF rewrite immediately, which forks the process. On a large dataset that is a memory spike and a latency event.
Instead:Do it during a quiet period, and watch used_memory_rss while it runs.
CONFIG SET changes memory, not the file
This is the detail that turns a good fix into a future incident, and it catches experienced people because nothing about the command suggests it.
Nothing you set survives a restart
CONFIG SET changes the running server only. The file is untouched, so the next restart, whenever and for whatever reason it happens, reverts everything. The classic version of this is a memory limit raised during an incident at 3am and undone weeks later by an unrelated deploy, with nobody connecting the two.
CONFIG REWRITE is the other half
It writes the running configuration back to the config file, preserving comments and structure. It requires that Redis was started with a config file: an instance started with command line arguments only has nowhere to write, and the command errors.
Some directives genuinely need a restart
port, bind, databases, cluster-enabled, io-threads and appendfilename are fixed at startup. CONFIG SET on those returns an error naming the parameter rather than accepting and ignoring it, so nothing fails silently, but a script that assumes success will do the wrong thing.
appendonly is settable, and it does real work
CONFIG SET appendonly yes starts an AOF rewrite immediately, which forks the process. On a large dataset that is a memory spike and a latency event, so it is not a change to make casually during peak traffic.
What this cannot see
Whether your server accepts a given parameter depends on its version, and directives are renamed between versions: hash-max-ziplist-entries became hash-max-listpack-entries in 7.0, with the old name kept as an alias. This page does not know your version, so it cannot tell you which spelling yours wants.
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