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119 lines
4.2 KiB
ReStructuredText
119 lines
4.2 KiB
ReStructuredText
Tutorial: Build a personalized daemon
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=====================================
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For the following tutorial, we will make references to https://github.com/Giulio2002/hello-tg-daemon.
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We are going to build our daemon using golang and Erigon packages, so first of all we are going to create a file in which we are going to store our API methods and informations. (`api.go`).
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our daemon will only contain one method: `myNamespace_getBlockNumberByHash` which will return the block number associated to certain hash.
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.. code-block:: go
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package main
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import (
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"context"
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"github.com/ledgerwatch/erigon/common"
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"github.com/ledgerwatch/erigon/core/rawdb"
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"github.com/ledgerwatch/erigon/ethdb"
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)
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// API - implementation of ExampleApi
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type API struct {
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kv ethdb.RwKV
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db ethdb.Getter
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}
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type ExampleAPI interface {
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GetBlockNumberByHash(ctx context.Context, hash common.Hash) (uint64, error)
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}
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func NewAPI(kv ethdb.RwKV, db ethdb.Getter) *API {
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return &API{kv: kv, db: db}
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}
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func (api *API) GetBlockNumberByHash(ctx context.Context, hash common.Hash) (uint64, error) {
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return rawdb.ReadBlockByHash(api.db, hash).NumberU64(), nil
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}
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The type `Api` is the type that is going to contain the methods for our custom daemon. This type has two members: `kv` and `db` which are objects used to interact with the Erigon node remotely. they behave like normal db objects and can be used alongside with the rawdb package.
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In our example we are making an rpcdaemon call that by receiving a certain block hash, it give the block number associated as an output. this is all done in `GetBlockNumberByHash`.
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Now we are going to make our `main.go` where we are going to serve the api we made in `api.go`.
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.. code-block:: go
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package main
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import (
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"context"
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"os"
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"github.com/ledgerwatch/erigon/cmd/rpcdaemon/cli"
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"github.com/ledgerwatch/erigon/cmd/rpcdaemon/commands"
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"github.com/ledgerwatch/erigon/cmd/utils"
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"github.com/ledgerwatch/erigon/common"
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"github.com/ledgerwatch/erigon/ethdb"
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"github.com/ledgerwatch/erigon/log"
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"github.com/ledgerwatch/erigon/rpc"
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"github.com/spf13/cobra"
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)
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func main() {
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cmd, cfg := cli.RootCommand()
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cmd.RunE = func(cmd *cobra.Command, args []string) error {
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db, backend, err := cli.OpenDB(*cfg)
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if err != nil {
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log.Error("Could not connect to remoteDb", "error", err)
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return nil
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}
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apiList := APIList(db, backend, cfg)
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return cli.StartRpcServer(cmd.Context(), *cfg, apiList)
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}
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if err := cmd.ExecuteContext(utils.RootContext()); err != nil {
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log.Error(err.Error())
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os.Exit(1)
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}
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}
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func APIList(kv ethdb.RwKV, eth ethdb.Backend, cfg *cli.Flags) []rpc.API {
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dbReader := ethdb.NewObjectDatabase(kv)
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api := NewAPI(kv, dbReader)
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customAPIList := []rpc.API{
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{
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Namespace: "myNamespace",
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Public: true,
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Service: ExampleAPI(api),
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Version: "1.0",
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},
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}
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// Add default Erigon api's
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return commands.APIList(kv, eth, *cfg, customAPIList)
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}
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In the main we are just running our rpcdaemon as we defined it in `APIList`, in fact in `APIList` we are configuring our custom rpcdaemon to serve the ExampleAPI's mathods on namespace `myNamespace` meaning that in order to call GetBlockNumberByHash via json rpc we have to call method `myNamespace_getBlockNumberByHash`.
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Let's now try it:
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.. code-block:: sh
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$ go build
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$ ./hello-tg-daemon --http.api=myNamespace # the flag enables our namespace.
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**Note: Remember to run Erigon with --private.api.addr=localhost:9090**
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now it should be all set and we can test it with:
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.. code-block:: sh
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curl -H "Content-Type: application/json" -X POST --data '{"jsonrpc":"2.0","method":"myNamespace_getBlockNumberByHash","params":["ANYHASH"],"id":1}' localhost:8545
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another example of custom daemon can be found at https://github.com/torquem-ch/project-1/blob/master/api.go.
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Happy Building ~~~. |