custom-ipfs-repo example broken

[alanshaw]

With dependencies upgraded to:

"datastore-fs": "~0.5.0",
"ipfs-repo": "~0.23.1"

Error: unexpected error getting the ipns record  Q,ALPl|���;GVM�t�Н����ʨ from datastore
    at ReadFileContext._repo.datastore.get (/Users/alan/Code/protocol-labs/js-ipfs/src/core/ipns/publisher.js:198:35)
    at ReadFileContext.callback (/Users/alan/Code/protocol-labs/js-ipfs/examples/custom-ipfs-repo/node_modules/graceful-fs/graceful-fs.js:78:16)
    at FSReqWrap.readFileAfterOpen [as oncomplete] (fs.js:235:13)
Emitted 'error' event at:
    at done (/Users/alan/Code/protocol-labs/js-ipfs/src/core/components/init.js:21:14)
    at /Users/alan/Code/protocol-labs/js-ipfs/node_modules/async/internal/once.js:12:16
    at next (/Users/alan/Code/protocol-labs/js-ipfs/node_modules/async/waterfall.js:21:29)
    at /Users/alan/Code/protocol-labs/js-ipfs/node_modules/async/internal/onlyOnce.js:12:16
    at parallel (/Users/alan/Code/protocol-labs/js-ipfs/src/core/components/init.js:130:13)
    at /Users/alan/Code/protocol-labs/js-ipfs/node_modules/async/internal/parallel.js:39:9
    at /Users/alan/Code/protocol-labs/js-ipfs/node_modules/async/internal/once.js:12:16
    at iteratorCallback (/Users/alan/Code/protocol-labs/js-ipfs/node_modules/async/eachOf.js:58:13)
    at /Users/alan/Code/protocol-labs/js-ipfs/node_modules/async/internal/onlyOnce.js:12:16
    at /Users/alan/Code/protocol-labs/js-ipfs/node_modules/async/internal/parallel.js:36:13

[jacobheun]

So the end error that's showing up here is a bit misleading as it's a result of different errors wrapping each other. Fun stuff!

The root issue here is around the work we need to do with adding error codes to all errors. In js-ipfs-ms it does a check to see if the repo has its mfs key. When it doesn't exist, mfs will create it and everyone is happy. The problem is with the current check, https://github.com/ipfs/js-ipfs-mfs/blob/v0.3.2/src/core/utils/with-mfs-root.js#L25. This check is specific to a LevelDown not found error, so datastore-fs and datastore-s3 are breaking.

The reason they break is that since the error isn't properly identified, they go ahead and try to create a cid with the undefined result, https://github.com/ipfs/js-ipfs-mfs/blob/v0.3.2/src/core/utils/with-mfs-root.js#L41, which throws an error, making everyone sad.

Options

I have verified these work with some quick node_module modifications.

1. The quick (gross) fix: update js-ipfs-mfs to do more checks to account for the different errors the datastores throw. For example, datastore-fs can be checked with error.code === 'ENOENT'.
2. The better thing: Use the err-code module we are using elsewhere to standardize the interface-datastore error codes in interface-datastore and have all other datastores use those.
   2.1 Update js-ipfs-mfs to check for the correct error code ie: ERR_NOT_FOUND.

@alanshaw @vasco-santos what do you think? I could probably get PRs out for option 2 to all the datastores and possibly releases (provided I have permissions to all of them) tomorrow.

[jacobheun]

Also, I was wrong about the error wrapping, they're just two different areas with the same problem.

https://github.com/ipfs/js-ipfs/blob/v0.32.0/src/core/ipns/publisher.js#L194

ipns publisher is also only checking for the LevelDown not found. This will need to be updated like mfs.

[jacobheun]

I've got an initial implementation of some of the base codes over at interface-datastore#22. There's a link there to the datastore-fs update that includes those.

[alanshaw]

@jacobheun 👍 to option 2

[vasco-santos]

Thanks for your analyze @jacobheun ! 🙂

I agree with the Option 2!

Yes, IPNS publish also uses the levelDown not found error! I will create a PR for that as well, adding the error code validation.