Ipns cache is not invalidated

[kpp]

Version information:

go-ipfs version: 0.4.22-
Repo version: 7
System version: amd64/linux
Golang version: go1.12.7

Description:

Run 2 nodes on the server and on the client. Add a file on the server and call ipfs name publish --ttl 1h .... Cat that file via /ipns on the server. Add a new file on the server and publish the cid again. The client caches /ipns and the second file is impossible to get via /ipns (cache is not invalidated). The error I got is Error: no link named "file2" under QmUYfCbJoPwifhhrqXzJBXaeScF3MwKXA3sTkCx6BbbmpU. To invalidate the cache I have to restart the daemon which is weird.

[Stebalien]

This is the point of the TTL:

--ttl string - Time duration this record should be cached for.

It's the same as a DNS TTL.

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You may be looking for --lifetime which allows one to specify how long the record should be valid.

[kpp]

I completely disagree. If you failed to resolve a path via /ipns/old_path/new_file, then the cache is invalid and ipfs needs to find the actual value in the DHT.
cc @postables

[bonedaddy]

Is the search not checking the DHT and invalidating the cache automatically when this happens? If not it should definitely be doing this.

It seems like the restart fixes the issue because it clears the LRU cache.

If we're going with a cache then it should be proactively managed.

[Stebalien]

If you need immediate updates, I recommend enabling IPNS over pubsub and setting the TTL to 0 on publish.

Unfortunately, /ipns/old_path/new_file is indistinguishable from /ipns/new_path/nonexistent_file. If we invalidated the cache every time we can't find a file, a tool trying to lookup a bunch of /ipns/QmFoo/*/.well-known-file files in every directory would force us to repeatedly re-query the network.