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

cmd/network/set_chain_context.go

@@ -1,28 +1,46 @@
 package network
 
 import (
+	"context"
 	"fmt"
 
 	"github.com/spf13/cobra"
 
+	"github.com/oasisprotocol/oasis-sdk/client-sdk/go/config"
+	"github.com/oasisprotocol/oasis-sdk/client-sdk/go/connection"
+
 	cliConfig "github.com/oasisprotocol/cli/config"
 )
 
 var setChainContextCmd = &cobra.Command{
-	Use:   "set-chain-context <name> <chain-context>",
+	Use:   "set-chain-context <name> [chain-context]",
 	Short: "Sets the chain context of the given network",
-	Args:  cobra.ExactArgs(2),
+	Args:  cobra.RangeArgs(1, 2),
 	Run: func(cmd *cobra.Command, args []string) {
 		cfg := cliConfig.Global()
-		name, chainContext := args[0], args[1]
+		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.
 		}
 
-		net.ChainContext = chainContext
+		if len(args) >= 2 {
+			net.ChainContext = args[1]
+		} 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)
+			chainCtx, err := conn.Consensus().GetChainContext(ctx)
+			cobra.CheckErr(err)
+			net.ChainContext = chainCtx
+			cobra.CheckErr(net.Validate())
+		}
 
 		err := cfg.Save()
 		cobra.CheckErr(err)

docs/network.md

@@ -95,7 +95,7 @@ You can also delete network in non-interactive mode format by passing the
 ## Set Network Chain Context {#set-chain-context}
 
 To change the chain context of a network, use
-`network set-chain-context <name> <chain-context>`.
+`network set-chain-context <name> [chain-context]`.
 
 :::caution
 
@@ -110,12 +110,18 @@ documentation.
 
 ![code shell](../examples/network/04-list.out)
 
-![code shell](../examples/network/05-set-chain-context.in)
+![code shell](../examples/network/05-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 omit the `[chain-context]`
+argument. This is especially useful for Localnet, where the chain context
+changes each time you restart the `oasis-net-runner`:
+
+![code shell](../examples/network/set-chain-context.in.static)
+
 [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/set-chain-context.in.static

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