subwasm
Unfortunately, the crate of the project and its dependencies are squatted on crates.io. The squatter remains unresponsive and the crates.io team does not care. I strongly recommend NOT to install the old version from crates.io. Check the Install chapter below to see how to install from this repo or use the official binary packages.
Introduction
The metadata of a given runtime is a critical piece of information as it describes how one can interact with the runtime, what operations are possible and what are the signatures of the calls. It contains the exhaustive list of all the features publicly exposed by the runtime.
This tool only works with Substrate-based runtimes which are >=V11. For earlier versions, you’ll need to connect to an archive node.
Any node can be queried to provide its current metadata. This can be displayed in json format for instance. This is a great way to have a peek at what the runtime can do.
Sample runs
Capabilities
subwasm allows:
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getting the latest metadata from a running node
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getting the latest runtime (wasm) from a running node
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getting runtime and metadata at any point of time using a Block hash as reference
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getting the metadata from a a wasm file without any node
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extracting information (those not requiring storage) from a runtime as wasm file
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(de)compress a given runtime WASM
Install
Using Cargo
cargo install --locked --git https://github.com/chevdor/subwasm --tag v0.16.1
Homebrew
MacOS Homebrew users can use:
brew tap chevdor/subwasm https://github.com/chevdor/subwasm
brew install subwasm
Linux
wget https://github.com/chevdor/subwasm/releases/download/v0.16.1/subwasm_linux_amd64_v0.16.1 -O subwasm.deb
sudo dpkg -i subwasm.deb
subwasm --help
Usage
Command: --help
`subwasm` allows fetching, parsing and calling some methods on WASM runtimes of Substrate based chains
Usage: subwasm [OPTIONS] <COMMAND>
Commands:
get Get/Download the runtime wasm from a running node through rpc
info The `info` command returns summarized information about a runtime
version The `version` command returns summarized information about the versions of a runtime
metadata Returns the metadata as a json object. You may also use the "meta" alias
diff Compare 2 runtimes
compress Compress a given runtime wasm file. You will get an error if you try compressing a runtime that is already compressed
decompress Decompress a given runtime wasm file. You may pass a runtime that is uncompressed already. In that case, you will get the same content as output. This is useful if you want to decompress "no matter what" and don't really know whether the input will be compressed or not
help Print this message or the help of the given subcommand(s)
Options:
-j, --json Output as json
-q, --quiet Less output
-h, --help Print help information
-V, --version Print version information
Command: get
Get/Download the runtime wasm from a running node through rpc
Usage: subwasm get [OPTIONS] [URL]
Arguments:
[URL] The node url including (mandatory) the port number. Example: ws://localhost:9944 or http://localhost:9933 [default: http://localhost:9933]
Options:
--chain <CHAIN> Provide the name of a chain and a random url amongst a list of known nodes will be used. If you pass a valid --chain, --url will be ignored --chain local = http://localhost:9933
-j, --json Output as json
-b, --block <BLOCK> The optional block where to fetch the runtime. That allows fetching older runtimes but you will need to connect to archive nodes. Currently, you must pass a block hash. Passing the block numbers is not supported
-o, --output <OUTPUT> You may specifiy the output filename where the runtime will be saved. If not provided, we will figure out an appropriate default name based on a counter: runtime_NNN.wasm where NNN is incrementing to make sure you do not override previous runtime. If you specify an existing file as output, it will be overwritten
-h, --help Print help information
-V, --version Print version information
Command: info
The `info` command returns summarized information about a runtime
Usage: subwasm info [OPTIONS] [SOURCE]
Arguments:
[SOURCE] The wasm file to load. It can be a path on your local filesystem such as /tmp/runtime.wasm or a node url such as http://localhost:9933 or ws://localhost:9944 [default: runtime_000.wasm]
Options:
--chain <CHAIN> Provide the name of a chain and a random url amongst a list of known nodes will be used. If you pass a valid --chain, --url will be ignored --chain local = http://localhost:9933
-j, --json Output as json
-b, --block <BLOCK> The optional block where to fetch the runtime. That allows fetching older runtimes but you will need to connect to archive nodes. Currently, you must pass a block hash. Passing the block numbers is not supported
-h, --help Print help information
-V, --version Print version information
By default, the ID for the Parachain pallet is expected to be 0x01 and the call ID for authorize_upgrade is expected to be 0x03.
This default behavior can be overriden by setting the PARACHAIN_PALLET_ID to the ID of your parachain pallet and the AUTHORIZE_UPGRADE_PREFIX to the ID of your choice.
Command: version
The `version` command returns summarized information about the versions of a runtime
Usage: subwasm version [OPTIONS] [SOURCE]
Arguments:
[SOURCE] The wasm file to load. It can be a path on your local filesystem such as /tmp/runtime.wasm or a node url such as http://localhost:9933 or ws://localhost:9944 [default: runtime_000.wasm]
Options:
--chain <CHAIN> Provide the name of a chain and a random url amongst a list of known nodes will be used. If you pass a valid --chain, --url will be ignored --chain local = http://localhost:9933
-j, --json Output as json
-b, --block <BLOCK> The optional block where to fetch the runtime. That allows fetching older runtimes but you will need to connect to archive nodes. Currently, you must pass a block hash. Passing the block numbers is not supported
-h, --help Print help information
-V, --version Print version information
Command: meta
Returns the metadata as a json object. You may also use the "meta" alias
Usage: subwasm metadata [OPTIONS] [SOURCE]
Arguments:
[SOURCE] The wasm file to load. It can be a path on your local filesystem such as /tmp/runtime.wasm or a node url such as http://localhost:9933 or ws://localhost:9944 [default: runtime_000.wasm]
Options:
--chain <CHAIN> Provide the name of a chain and a random url amongst a list of known nodes will be used. If you pass a valid --chain, --url will be ignored --chain local = http://localhost:9933
-j, --json Output as json
-m, --module <MODULE> Without this flag, the metadata command display the list of all modules. Using this flag, you will only see the module of your choice and a few details about it
-b, --block <BLOCK> The optional block where to fetch the runtime. That allows fetching older runtimes but you will need to connect to archive nodes. Currently, you must pass a block hash. Passing the block numbers is not supported
-f, --format <FORMAT> You may specifiy the output format. One of "human", "scale", "json", "json+scale", "hex+scale" [default: human]
-o, --output <OUTPUT> You may specifiy the output filename where the metadata will be saved. Alternatively, you may use `auto` and an appropriate name will be generated according to the `format` your chose
-h, --help Print help information
-V, --version Print version information
Command: diff
Compare 2 runtimes
Usage: subwasm diff [OPTIONS] [SRC_A] [SRC_B]
Arguments:
[SRC_A] The first source [default: runtime_000.wasm]
[SRC_B] The second source [default: runtime_001.wasm]
Options:
-a, --chain-a <CHAIN_A> Provide the name of a chain and a random url amongst a list of known nodes will be used. If you pass a valid --chain, --url will be ignored --chain local = http://localhost:9933
-j, --json Output as json
-b, --chain-b <CHAIN_B> Provide the name of a chain and a random url amongst a list of known nodes will be used. If you pass a valid --chain, --url will be ignored --chain local = http://localhost:9933
-h, --help Print help information
-V, --version Print version information
Command: compress
Compress a given runtime wasm file. You will get an error if you try compressing a runtime that is already compressed
Usage: subwasm compress [OPTIONS] <INPUT> <OUTPUT>
Arguments:
<INPUT> The path of uncompressed wasm file to load
<OUTPUT> The path of the file where the compressed runtime will be stored
Options:
-j, --json Output as json
-h, --help Print help information
-V, --version Print version information
Command: decompress
Decompress a given runtime wasm file. You may pass a runtime that is uncompressed already. In that case, you will get the same content as output. This is useful if you want to decompress "no matter what" and don't really know whether the input will be compressed or not
Usage: subwasm decompress [OPTIONS] <INPUT> <OUTPUT>
Arguments:
<INPUT> The path of the compressed or uncompressed wasm file to load
<OUTPUT> The path of the file where the uncompressed runtime will be stored
Options:
-j, --json Output as json
-h, --help Print help information
-V, --version Print version information
Environment variables
In addition to the command line flags, you can also pass one of the following ENV variables:
# This is a sample .env file. It is not needed if you
# are using defaults if you want to use the default defined
# below.
# POLKADOT_HTTP=http://localhost:9933
# POLKADOT_WS=ws://localhost:9944
# PARACHAIN_PALLET_ID=0x01
# AUTHORIZE_UPGRADE_PREFIX=0x03
Sample runs
Fetch a runtime from a running node
We will start by fetching the runtime from a node.
Please note that you will likely need to connect to an archive node to retrieve an older runtime (<V11). A runtime takes around 2MB of storage on-chain and thus, older versions are pruned and will no longer be accessible if you are connecting to a non-archive node.
Here we get the latest version of the runtime, the 3 commands do the same since they all use the default values:
subwasm get
subwasm get --url http://localhost:9933
subwasm get --url http://localhost:9933 --output runtime_000.wasm
Here we get an older runtime, back when Polkadot was at block 20 !
subwasm get brew tap chevdor/subwasm --block 0x4d6a0bca208b85d41833a7f35cf73d1ae6974f4bad8ab576e2c3f751d691fe6c
By default, your runtime will be saved as runtime_000.wasm. Running this command again will increase the counter so we you don’t lose your previous runtime. You may also use the --output flag to provide the destination and filename of your choice. Beware, in this case, there will be no incremented counter.
Get quick check of a runtime
# Show the runtime version and exit with status 0
subwasm info --input kusama-2030.wasm
# Provide a few explanations and exit with a status that is not 0
subwasm info --input tictactoe.wasm
Metadata JSON and jq tricks
jq can be used to reprocess the json output. For instance, removing all the documentation from the metadata makes it significantly smaller. The example below shows how to remove documentation, value and default making it much easier on the eyes for human parsing…
subwasm --json meta runtime.wasm | jq 'del( .. | .documentation?, .default?, .value? )'
Alternatives
Here is a list of other projects allowing to get the raw metadata through a rpc call:
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PolkadotJS from Jaco / Parity
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subsee from Andrew / Parity
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substrate-api-client from SCS
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subxt from Parity
All those alternatives require a running node and access it via jsonrpc.