fix: make config files & evm/tron chain load optional (#530)

Fixes issue where users needed dummy config files with evm deployer key
to analyze MCMS proposals locally.

Context:
https://chainlink-core.slack.com/archives/C08QF1BEW4T/p1761128244593229

Changes:
- Config files now optional, falls back to environment variables
- EVM and Tron chains only load when credentials provided (key or KMS)
- Added tests for optional config and credential scenarios

Users can now analyze proposals without credentials.

No breaking changes.

Author: graham-chainlink

.changeset/some-plants-doubt.md

@@ -0,0 +1,5 @@
+---
+"chainlink-deployments-framework": patch
+---
+
+fix: make config files and chain credentials optional

engine/cld/chains/chains.go

@@ -168,10 +168,20 @@ func LoadChains(
 func newChainLoaders(
 	lggr logger.Logger, networks *cfgnet.Config, cfg cfgenv.OnchainConfig,
 ) map[string]ChainLoader {
-	// EVM chains are always loaded.
-	loaders := map[string]ChainLoader{
-		chainsel.FamilyEVM:  newChainLoaderEVM(networks, cfg, lggr),
-		chainsel.FamilyTron: newChainLoaderTron(networks, cfg),
+	loaders := map[string]ChainLoader{}
+
+	// EVM chains are loaded if either KMS or deployer key is configured.
+	if useKMS(cfg.KMS) || cfg.EVM.DeployerKey != "" {
+		loaders[chainsel.FamilyEVM] = newChainLoaderEVM(networks, cfg, lggr)
+	} else {
+		lggr.Warn("Skipping EVM chains, no private key or KMS config found in secrets")
+	}
+
+	// Tron chains are loaded if either KMS or deployer key is configured.
+	if useKMS(cfg.KMS) || cfg.Tron.DeployerKey != "" {
+		loaders[chainsel.FamilyTron] = newChainLoaderTron(networks, cfg)
+	} else {
+		lggr.Warn("Skipping Tron chains, no private key or KMS config found in secrets")
 	}
 
 	if cfg.Solana.ProgramsDirPath != "" && cfg.Solana.WalletKey != "" {

engine/cld/chains/chains_test.go

@@ -21,6 +21,114 @@ import (
 	cfgnet "github.com/smartcontractkit/chainlink-deployments-framework/engine/cld/config/network"
 )
 
+func Test_newChainLoaders(t *testing.T) {
+	t.Parallel()
+
+	lggr := logger.Test(t)
+	networks := &cfgnet.Config{}
+
+	tests := []struct {
+		name          string
+		onchainConfig cfgenv.OnchainConfig
+		wantLoaders   []string // Expected chain families with loaders
+	}{
+		{
+			name: "All credentials provided",
+			onchainConfig: cfgenv.OnchainConfig{
+				EVM: cfgenv.EVMConfig{
+					DeployerKey: "0x1234567890abcdef1234567890abcdef1234567890abcdef1234567890abcdef",
+				},
+				Tron: cfgenv.TronConfig{
+					DeployerKey: "0x1234567890abcdef1234567890abcdef1234567890abcdef1234567890abcdef",
+				},
+				Solana: cfgenv.SolanaConfig{
+					WalletKey:       "test-key",
+					ProgramsDirPath: "/tmp/programs",
+				},
+				Aptos: cfgenv.AptosConfig{
+					DeployerKey: "0x1234567890abcdef1234567890abcdef1234567890abcdef1234567890abcdef",
+				},
+				Sui: cfgenv.SuiConfig{
+					DeployerKey: "0x1234567890abcdef1234567890abcdef1234567890abcdef1234567890abcdef",
+				},
+				Ton: cfgenv.TonConfig{
+					DeployerKey: "0x1234567890abcdef1234567890abcdef1234567890abcdef1234567890abcdef",
+				},
+			},
+			wantLoaders: []string{
+				chainsel.FamilyEVM,
+				chainsel.FamilyTron,
+				chainsel.FamilySolana,
+				chainsel.FamilyAptos,
+				chainsel.FamilySui,
+				chainsel.FamilyTon,
+			},
+		},
+		{
+			name: "No EVM credentials - EVM skipped",
+			onchainConfig: cfgenv.OnchainConfig{
+				Tron: cfgenv.TronConfig{
+					DeployerKey: "0x1234567890abcdef1234567890abcdef1234567890abcdef1234567890abcdef",
+				},
+			},
+			wantLoaders: []string{
+				chainsel.FamilyTron,
+			},
+		},
+		{
+			name: "KMS configured - EVM and Tron loaded",
+			onchainConfig: cfgenv.OnchainConfig{
+				KMS: cfgenv.KMSConfig{
+					KeyID:     "test-key-id",
+					KeyRegion: "us-west-2",
+				},
+			},
+			wantLoaders: []string{
+				chainsel.FamilyEVM,
+				chainsel.FamilyTron,
+			},
+		},
+		{
+			name:          "No credentials - all chains skipped",
+			onchainConfig: cfgenv.OnchainConfig{},
+			wantLoaders:   []string{},
+		},
+		{
+			name: "Only EVM deployer key",
+			onchainConfig: cfgenv.OnchainConfig{
+				EVM: cfgenv.EVMConfig{
+					DeployerKey: "0x1234567890abcdef1234567890abcdef1234567890abcdef1234567890abcdef",
+				},
+			},
+			wantLoaders: []string{
+				chainsel.FamilyEVM,
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			loaders := newChainLoaders(lggr, networks, tt.onchainConfig)
+
+			// Check that we got the expected number of loaders
+			assert.Len(t, loaders, len(tt.wantLoaders),
+				"Expected %d loaders but got %d", len(tt.wantLoaders), len(loaders))
+
+			// Check that each expected family has a loader
+			for _, family := range tt.wantLoaders {
+				assert.Contains(t, loaders, family, "Expected loader for family %s", family)
+			}
+
+			// Check that we don't have unexpected loaders
+			for family := range loaders {
+				assert.Contains(t, tt.wantLoaders, family, "Unexpected loader for family %s", family)
+			}
+		})
+	}
+}
+
 func Test_LoadChains(t *testing.T) {
 	t.Parallel()
 

engine/cld/config/config_test.go

@@ -38,14 +38,14 @@ func Test_Load(t *testing.T) {
 			wantErr: "failed to load networks",
 		},
 		{
-			name: "fails to load env config",
+			name: "loads config without local config file (falls back to env vars)",
 			beforeFunc: func(t *testing.T, dom fdomain.Domain, envKey string) {
 				t.Helper()
 
 				writeConfigNetworksFile(t, dom, "networks.yaml", "networks-testnet.yaml")
 				writeConfigDomainFile(t, dom, "domain.yaml")
+				// Note: not creating a local config file - it should fall back to env vars
 			},
-			wantErr: "failed to load env config",
 		},
 	}
 

engine/cld/config/env.go

@@ -30,7 +30,8 @@ func LoadDatastoreType(dom fdomain.Domain, env string) (cfgdomain.DatastoreType,
 //
 // Loading strategy:
 //   - In CI environments: Loads configuration exclusively from environment variables set by the CI pipeline.
-//   - In local development: Loads configuration from a local config file specific to the domain and environment.
+//   - In local development: Loads configuration from a local config file if it exists, otherwise falls back
+//     to environment variables. Environment variables can override file values when both are present.
 func LoadEnvConfig(dom fdomain.Domain, env string) (*cfgenv.Config, error) {
 	if isCI() {
 		cfg, err := cfgenv.LoadEnv()
@@ -43,5 +44,5 @@ func LoadEnvConfig(dom fdomain.Domain, env string) (*cfgenv.Config, error) {
 
 	fp := filepath.Join(dom.ConfigLocalFilePath(env))
 
-	return cfgenv.LoadFile(fp)
+	return cfgenv.Load(fp)
 }