Working with meta in IPFS
You can extract meta from your file with Pravda bytecode and place it in the IPFS. It can help to dramatically reduce size of data you are writing to the blockchain and thus save your money. Since meta doesn't affect the runtime behaviour of your program, extracting it is safe and won't cause any problems even if the IPFS is not avaliable.
Deploying Pravda program
Extracting of meta happens when you deploy your Pravda program to the blockchain:
pravda broadcast deploy \ -w <your-wallet> \ -p <program-wallet> \ -i <bytecode-of-your-program> \ --meta-to-ipfs \ --ipfs-node "/ip4/127.0.0.1/tcp/5001"
You should specify
--meta-to-ipfs parameter to enable meta extracting
--ipfs-node to select necessary IPFS node (by default it uses localhost).
This command will extract all meta from your bytecode and place it in the IPFS, after that it will deploy program without meta to the Pravda blockchain.
You can also use
pravda broadcast update to extract meta with the same CLI parameters.
Reading meta from IPFS
If you need to read meta from IPFS, for example when you are disassembling bytecode, you also use special CLI parameters:
pravda compile disasm \ -i <bytecode-of-your-program> \ --meta-from-ipfs --ipfs-node "/ip4/127.0.0.1/tcp/5001"
This command will read IPFS hash of file with meta from the bytecode, read this file from IPFS and disassemble bytecode with this new information.
Hosting open IPFS is dangerous, thus we suggest you to run your own IPFS node on your private host if you want to write meta to IPFS, if you just want to read meta from IPFS you can use any open IPFS node (for example, ipfs.io).