feat(cmd/network): Autodetect chain context if none passed

cmd/network/set_chain_context.go

@@ -1,30 +1,59 @@
 package network
 
 import (
+	"context"
 	"fmt"
 
 	"github.com/spf13/cobra"
+	flag "github.com/spf13/pflag"
+
+	"github.com/oasisprotocol/oasis-sdk/client-sdk/go/config"
 
 	cliConfig "github.com/oasisprotocol/cli/config"
+	"github.com/oasisprotocol/oasis-sdk/client-sdk/go/connection"
+)
+
+var (
+	chainContext string
+
+	setChainContextCmd = &cobra.Command{
+		Use:   "set-chain-context <name>",
+		Short: "Sets the chain context of the given network",
+		Args:  cobra.ExactArgs(1),
+		Run: func(cmd *cobra.Command, args []string) {
+			cfg := cliConfig.Global()
+			name := args[0]
+
+			net := cfg.Networks.All[name]
+			if net == nil {
+				cobra.CheckErr(fmt.Errorf("network '%s' does not exist", name))
+				return // To make staticcheck happy as it doesn't know CheckErr exits.
+			}
+
+			if chainContext != "" {
+				net.ChainContext = chainContext
+			} else {
+				// Connect to the network and query the chain context.
+				network := config.Network{
+					RPC: net.RPC,
+				}
+				ctx := context.Background()
+				conn, err := connection.ConnectNoVerify(ctx, &network)
+				cobra.CheckErr(err)
+				chainContext, err := conn.Consensus().GetChainContext(ctx)
+				cobra.CheckErr(err)
+				net.ChainContext = chainContext
+				cobra.CheckErr(net.Validate())
+			}
+
+			err := cfg.Save()
+			cobra.CheckErr(err)
+		},
+	}
 )
 
-var setChainContextCmd = &cobra.Command{
-	Use:   "set-chain-context <name> <chain-context>",
-	Short: "Sets the chain context of the given network",
-	Args:  cobra.ExactArgs(2),
-	Run: func(cmd *cobra.Command, args []string) {
-		cfg := cliConfig.Global()
-		name, chainContext := args[0], args[1]
-
-		net := cfg.Networks.All[name]
-		if net == nil {
-			cobra.CheckErr(fmt.Errorf("network '%s' does not exist", name))
-			return // To make staticcheck happy as it doesn't know CheckErr exits.
-		}
-
-		net.ChainContext = chainContext
-
-		err := cfg.Save()
-		cobra.CheckErr(err)
-	},
+func init() {
+	chainContextFlag := flag.NewFlagSet("", flag.ContinueOnError)
+	chainContextFlag.StringVar(&chainContext, "chain-context", "", "set chain-context")
+	setChainContextCmd.Flags().AddFlagSet(chainContextFlag)
 }

docs/network.md

@@ -110,12 +110,19 @@ documentation.
 
 ![code shell](../examples/network/04-list.out)
 
-![code shell](../examples/network/05-set-chain-context.in)
+![code shell](../examples/network/07-set-chain-context-ctx.in)
 
 ![code shell](../examples/network/06-list.in)
 
 ![code shell](../examples/network/06-list.out)
 
+To automatically detect the chain context, simply run the command without the
+`chain-context` flag. This is especially useful for Localnet, where the chain
+context often changes each time you restart the `oasis-net-runner`.
+
+![code shell](../examples/network/05-set-chain-context.in)
+
+
 [Mainnet]: https://github.com/oasisprotocol/docs/blob/main/docs/node/mainnet/README.md
 [Testnet]: https://github.com/oasisprotocol/docs/blob/main/docs/node/testnet/README.md
 

examples/network/05-set-chain-context.in

@@ -1 +1 @@
-oasis network set-chain-context mainnet_local 01234513331133a715c7a150313877dF1d33e77a715c7a150313877dF1d33e77
+oasis network set-chain-context mainnet_local

examples/network/07-set-chain-context-ctx.in

@@ -0,0 +1 @@
+oasis network set-chain-context mainnet_local --chain-context 01234513331133a715c7a150313877dF1d33e77a715c7a150313877dF1d33e77