feat: support SLACK_CLI_APP_ICON_PATH env var for icon override

internal/config/config.go

@@ -22,6 +22,7 @@ import (
 )
 
 // Environment Variable constants
+const slackCLIAppIconPathEnv = "SLACK_CLI_APP_ICON_PATH"
 const slackAutoRequestAAAEnv = "SLACK_AUTO_REQUEST_AAA"
 const slackConfigDirEnv = "SLACK_CONFIG_DIR"
 const slackDisableTelemetryEnv = "SLACK_DISABLE_TELEMETRY"
@@ -41,6 +42,7 @@ type Config struct {
 	APIHostFlag             string
 	APIHostResolved         string
 	AppFlag                 string
+	AppIconPathFlag         string
 	AutoRequestAAAFlag      bool
 	ConfigDirFlag           string
 	DebugEnabled            bool

internal/config/dotenv.go

@@ -45,6 +45,12 @@ func (c *Config) LoadEnvironmentVariables() error {
 		c.ConfigDirFlag = configDir
 	}
 
+	// Load app icon path from environment variables
+	var appIconPath = strings.TrimSpace(c.os.Getenv(slackCLIAppIconPathEnv))
+	if appIconPath != "" {
+		c.AppIconPathFlag = appIconPath
+	}
+
 	// Disable telemetry if either disable-telemetry or test-version environment variables
 	var disableTelemetry = strings.TrimSpace(c.os.Getenv(slackDisableTelemetryEnv))
 	var testVersion = strings.TrimSpace(c.os.Getenv(version.EnvTestVersion))

internal/config/dotenv_test.go

@@ -153,6 +153,27 @@ func Test_DotEnv_LoadEnvironmentVariables(t *testing.T) {
 				assert.Equal(t, false, cfg.AutoRequestAAAFlag)
 			},
 		},
+		"SLACK_CLI_APP_ICON_PATH=/path/to/icon.png should set AppIconPathFlag": {
+			envName:  "SLACK_CLI_APP_ICON_PATH",
+			envValue: "/path/to/icon.png",
+			assertOnConfig: func(t *testing.T, cfg *Config) {
+				assert.Equal(t, "/path/to/icon.png", cfg.AppIconPathFlag)
+			},
+		},
+		"SLACK_CLI_APP_ICON_PATH= should not set AppIconPathFlag": {
+			envName:  "SLACK_CLI_APP_ICON_PATH",
+			envValue: "",
+			assertOnConfig: func(t *testing.T, cfg *Config) {
+				assert.Equal(t, "", cfg.AppIconPathFlag)
+			},
+		},
+		"SLACK_CLI_APP_ICON_PATH with whitespace should be trimmed": {
+			envName:  "SLACK_CLI_APP_ICON_PATH",
+			envValue: "  /path/to/icon.png  ",
+			assertOnConfig: func(t *testing.T, cfg *Config) {
+				assert.Equal(t, "/path/to/icon.png", cfg.AppIconPathFlag)
+			},
+		},
 		"SLACK_CONFIG_DIR=/path/to/config should set the config dir": {
 			envName:  "SLACK_CONFIG_DIR",
 			envValue: "/path/to/config",

internal/icon/icon.go

@@ -0,0 +1,38 @@
+// Copyright 2022-2026 Salesforce, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package icon
+
+import (
+	"path/filepath"
+
+	"github.com/spf13/afero"
+)
+
+var SupportedExtensions = []string{".png", ".jpg", ".jpeg", ".gif"}
+
+func ResolveIconPath(fs afero.Fs, manifestIcon string) string {
+	if manifestIcon != "" {
+		return manifestIcon
+	}
+	for _, dir := range []string{"assets", "."} {
+		for _, ext := range SupportedExtensions {
+			candidate := filepath.Join(dir, "icon"+ext)
+			if _, err := fs.Stat(candidate); err == nil {
+				return candidate
+			}
+		}
+	}
+	return ""
+}

internal/icon/icon_test.go

@@ -0,0 +1,86 @@
+// Copyright 2022-2026 Salesforce, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package icon
+
+import (
+	"testing"
+
+	"github.com/spf13/afero"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func Test_ResolveIconPath(t *testing.T) {
+	tests := map[string]struct {
+		manifestIcon string
+		files        []string
+		expected     string
+	}{
+		"manifest icon set returns it directly": {
+			manifestIcon: "custom/my-icon.png",
+			expected:     "custom/my-icon.png",
+		},
+		"assets/icon.png found": {
+			files:    []string{"assets/icon.png"},
+			expected: "assets/icon.png",
+		},
+		"assets/icon.jpg found": {
+			files:    []string{"assets/icon.jpg"},
+			expected: "assets/icon.jpg",
+		},
+		"assets/icon.jpeg found": {
+			files:    []string{"assets/icon.jpeg"},
+			expected: "assets/icon.jpeg",
+		},
+		"assets/icon.gif found": {
+			files:    []string{"assets/icon.gif"},
+			expected: "assets/icon.gif",
+		},
+		"png wins over gif in assets": {
+			files:    []string{"assets/icon.png", "assets/icon.gif"},
+			expected: "assets/icon.png",
+		},
+		"jpg wins over gif in assets": {
+			files:    []string{"assets/icon.jpg", "assets/icon.gif"},
+			expected: "assets/icon.jpg",
+		},
+		"root icon.png found when no assets": {
+			files:    []string{"icon.png"},
+			expected: "icon.png",
+		},
+		"root icon.jpg found when no assets": {
+			files:    []string{"icon.jpg"},
+			expected: "icon.jpg",
+		},
+		"assets takes priority over root": {
+			files:    []string{"assets/icon.gif", "icon.png"},
+			expected: "assets/icon.gif",
+		},
+		"no icon files returns empty": {
+			files:    []string{},
+			expected: "",
+		},
+	}
+	for name, tc := range tests {
+		t.Run(name, func(t *testing.T) {
+			fs := afero.NewMemMapFs()
+			for _, f := range tc.files {
+				require.NoError(t, afero.WriteFile(fs, f, []byte("img"), 0o644))
+			}
+			result := ResolveIconPath(fs, tc.manifestIcon)
+			assert.Equal(t, tc.expected, result)
+		})
+	}
+}

internal/pkg/apps/install.go

@@ -17,14 +17,14 @@ package apps
 import (
 	"context"
 	"fmt"
-	"os"
 	"strings"
 	"time"
 
 	"github.com/opentracing/opentracing-go"
 	"github.com/slackapi/slack-cli/internal/api"
 	"github.com/slackapi/slack-cli/internal/config"
 	"github.com/slackapi/slack-cli/internal/experiment"
+	"github.com/slackapi/slack-cli/internal/icon"
 	"github.com/slackapi/slack-cli/internal/pkg/manifest"
 	"github.com/slackapi/slack-cli/internal/shared"
 	"github.com/slackapi/slack-cli/internal/shared/types"
@@ -218,13 +218,7 @@ func Install(ctx context.Context, clients *shared.ClientFactory, auth types.Slac
 		}
 	}
 
-	// upload icon, default to icon.png
-	var iconPath = slackManifest.Icon
-	if iconPath == "" {
-		if _, err := os.Stat("icon.png"); !os.IsNotExist(err) {
-			iconPath = "icon.png"
-		}
-	}
+	iconPath := resolveIconPath(ctx, clients, slackManifest.Icon)
 	if iconPath != "" {
 		err = updateIcon(ctx, clients, iconPath, app.AppID, token, manifest.IsFunctionRuntimeSlackHosted())
 		if err != nil {
@@ -524,12 +518,7 @@ func InstallLocalApp(ctx context.Context, clients *shared.ClientFactory, orgGran
 
 	// upload icon for non-hosted apps (gated behind set-icon experiment)
 	if clients.Config.WithExperimentOn(experiment.SetIcon) {
-		var iconPath = slackManifest.Icon
-		if iconPath == "" {
-			if _, err := os.Stat("icon.png"); !os.IsNotExist(err) {
-				iconPath = "icon.png"
-			}
-		}
+		iconPath := resolveIconPath(ctx, clients, slackManifest.Icon)
 		if iconPath != "" {
 			_, iconErr := clients.API().IconSet(ctx, clients.Fs, token, app.AppID, iconPath)
 			if iconErr != nil {
@@ -649,6 +638,28 @@ func appendLocalToDisplayName(manifest *types.AppManifest) {
 	}
 }
 
+// resolveIconPath determines the icon file path using the priority chain:
+// SLACK_CLI_APP_ICON_PATH env var > manifest icon field > assets/ and root fallback
+func resolveIconPath(ctx context.Context, clients *shared.ClientFactory, manifestIcon string) string {
+	if envIconPath := clients.Config.AppIconPathFlag; envIconPath != "" {
+		if _, err := clients.Fs.Stat(envIconPath); err == nil {
+			return envIconPath
+		}
+		clients.IO.PrintDebug(ctx, "SLACK_CLI_APP_ICON_PATH file not found: %s", envIconPath)
+		_, _ = clients.IO.WriteOut().Write([]byte(style.SectionSecondaryf("Warning: icon path from SLACK_CLI_APP_ICON_PATH not found: %s", envIconPath)))
+		return ""
+	}
+	if manifestIcon != "" {
+		if _, err := clients.Fs.Stat(manifestIcon); err == nil {
+			return manifestIcon
+		}
+		clients.IO.PrintDebug(ctx, "manifest icon file not found: %s", manifestIcon)
+		_, _ = clients.IO.WriteOut().Write([]byte(style.SectionSecondaryf("Warning: icon path from manifest not found: %s", manifestIcon)))
+		return ""
+	}
+	return icon.ResolveIconPath(clients.Fs, "")
+}
+
 // updateIcon will upload the new icon to the Slack API
 func updateIcon(ctx context.Context, clients *shared.ClientFactory, iconPath, appID string, token string, isHosted bool) error {
 	var span opentracing.Span

internal/pkg/apps/install_test.go

@@ -29,6 +29,7 @@ import (
 	"github.com/slackapi/slack-cli/internal/shared/types"
 	"github.com/slackapi/slack-cli/internal/slackcontext"
 	"github.com/slackapi/slack-cli/internal/slackerror"
+	"github.com/spf13/afero"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/mock"
 	"github.com/stretchr/testify/require"
@@ -1728,6 +1729,86 @@ func TestContinueDespiteWarning(t *testing.T) {
 	}
 }
 
+func Test_resolveIconPath(t *testing.T) {
+	tests := map[string]struct {
+		envIconPath  string
+		manifestIcon string
+		setupFiles   func(t *testing.T, fs afero.Fs)
+		expected     string
+	}{
+		"env var takes priority over manifest icon": {
+			envIconPath:  "env-icon.png",
+			manifestIcon: "manifest-icon.png",
+			setupFiles: func(t *testing.T, fs afero.Fs) {
+				require.NoError(t, afero.WriteFile(fs, "env-icon.png", []byte("img"), 0o644))
+				require.NoError(t, afero.WriteFile(fs, "manifest-icon.png", []byte("img"), 0o644))
+			},
+			expected: "env-icon.png",
+		},
+		"env var takes priority over fallback": {
+			envIconPath: "env-icon.png",
+			setupFiles: func(t *testing.T, fs afero.Fs) {
+				require.NoError(t, afero.WriteFile(fs, "env-icon.png", []byte("img"), 0o644))
+				require.NoError(t, afero.WriteFile(fs, "assets/icon.png", []byte("img"), 0o644))
+			},
+			expected: "env-icon.png",
+		},
+		"manifest icon used when no env var": {
+			manifestIcon: "manifest-icon.png",
+			setupFiles: func(t *testing.T, fs afero.Fs) {
+				require.NoError(t, afero.WriteFile(fs, "manifest-icon.png", []byte("img"), 0o644))
+			},
+			expected: "manifest-icon.png",
+		},
+		"falls back to assets/icon.png when no env var or manifest": {
+			setupFiles: func(t *testing.T, fs afero.Fs) {
+				require.NoError(t, afero.WriteFile(fs, "assets/icon.png", []byte("img"), 0o644))
+			},
+			expected: "assets/icon.png",
+		},
+		"falls back to icon.png in root when no assets": {
+			setupFiles: func(t *testing.T, fs afero.Fs) {
+				require.NoError(t, afero.WriteFile(fs, "icon.png", []byte("img"), 0o644))
+			},
+			expected: "icon.png",
+		},
+		"returns empty when no icon found": {
+			setupFiles: func(t *testing.T, fs afero.Fs) {},
+			expected:   "",
+		},
+		"env var file not found returns empty": {
+			envIconPath:  "missing-icon.png",
+			manifestIcon: "manifest-icon.png",
+			setupFiles: func(t *testing.T, fs afero.Fs) {
+				require.NoError(t, afero.WriteFile(fs, "manifest-icon.png", []byte("img"), 0o644))
+			},
+			expected: "",
+		},
+		"manifest icon file not found returns empty with warning": {
+			manifestIcon: "missing-manifest-icon.png",
+			setupFiles: func(t *testing.T, fs afero.Fs) {
+				require.NoError(t, afero.WriteFile(fs, "assets/icon.png", []byte("img"), 0o644))
+			},
+			expected: "",
+		},
+	}
+	for name, tc := range tests {
+		t.Run(name, func(t *testing.T) {
+			ctx := slackcontext.MockContext(t.Context())
+			clientsMock := shared.NewClientsMock()
+			clientsMock.AddDefaultMocks()
+			clientsMock.Config.AppIconPathFlag = tc.envIconPath
+			tc.setupFiles(t, clientsMock.Fs)
+			output := &bytes.Buffer{}
+			clientsMock.IO.Stdout.SetOutput(output)
+			clients := shared.NewClientFactory(clientsMock.MockClientFactory())
+
+			result := resolveIconPath(ctx, clients, tc.manifestIcon)
+			assert.Equal(t, tc.expected, result)
+		})
+	}
+}
+
 func Test_updateIcon(t *testing.T) {
 	tests := map[string]struct {
 		isHosted      bool