feat(docker-out): add configPath option

README.md

@@ -75,13 +75,36 @@ As the remote can be configured differently (e.g. by including or excluding sub-
 
 See [override-all.env](./override-all.env) for a file with all possible override variables.
 
+The precedence for the overrides is:
+
+1. Value set via feature parameter
+2. Value set via environment variable
+3. Values from `DEV_FEATURE_OVERRIDE_LOCATION`
+
 #### Special overrides
 
 There are a few sources which are used in multiple installations. For those sources, there is an override that globaly overrides all installations from this sources. Here is the list of those sources and their keys.
 
 ```
 DEV_FEATURE_OVERRIDE_GITHUB_DOWNLOAD_URL=...
 ```
+#### Unset an Override via Parameter
+
+If an override is set, setting the corresponding parameter to `""` will not unset the override. To achieve this, set the parameter to `none`.
+
+**Example:**  
+This environment variable is set: `DOCKER_OUT_CONFIG_PATH=https://example.com/config.json`
+
+Then set this in your feature to explicitly unset it:
+
+```json
+{
+    "ghcr.io/postfinance/devcontainer-features/docker-out:0.3.0": {
+        "version": "28.3.3",
+        "configPath": "none"
+    }
+}
+```
 
 ### Extend an existing feature
 

features/src/docker-out/README.md

@@ -6,10 +6,11 @@ Installs a Docker client which re-uses the host Docker socket.
 
 ```json
 "features": {
-    "ghcr.io/postfinance/devcontainer-features/docker-out:0.2.0": {
+    "ghcr.io/postfinance/devcontainer-features/docker-out:0.3.0": {
         "version": "latest",
         "composeVersion": "latest",
         "buildxVersion": "latest",
+        "configPath": "",
         "downloadUrl": "",
         "versionsUrl": "",
         "composeDownloadUrl": "",
@@ -25,6 +26,7 @@ Installs a Docker client which re-uses the host Docker socket.
 | version | The version of the Docker CLI to install. | string | latest | latest, 28.3.3, 20.10 |
 | composeVersion | The version of the Compose plugin to install. | string | latest | latest, none, 2.39.1, 2.29 |
 | buildxVersion | The version of the buildx plugin to install. | string | latest | latest, none, 0.26.1, 0.10 |
+| configPath | Path or URL to a custom Docker client config.json file to copy into the container. | string | <empty> | /home/user/.docker/config.json, https://raw.githubusercontent.com/devcontainers/features/main/src/docker-out/config.json, none |
 | downloadUrl | The download URL to use for Docker binaries. | string | <empty> |  |
 | versionsUrl | The URL to use for checking available versions. | string | <empty> |  |
 | composeDownloadUrl | The download URL to use for Docker Compose binaries. | string | <empty> |  |

features/src/docker-out/devcontainer-feature.json

@@ -1,6 +1,6 @@
 {
     "id": "docker-out",
-    "version": "0.2.0",
+    "version": "0.3.0",
     "name": "Docker outside Docker",
     "description": "Installs a Docker client which re-uses the host Docker socket.",
     "options": {
@@ -36,6 +36,16 @@
             "default": "latest",
             "description": "The version of the buildx plugin to install."
         },
+        "configPath": {
+            "type": "string",
+            "default": "",
+            "description": "Path or URL to a custom Docker client config.json file to copy into the container.",
+            "proposals": [
+                "/home/user/.docker/config.json",
+                "https://raw.githubusercontent.com/devcontainers/features/main/src/docker-out/config.json",
+                "none"
+            ]
+        },
         "downloadUrl": {
             "type": "string",
             "default": "",

features/src/docker-out/install.sh

@@ -4,6 +4,7 @@
     -version="${VERSION:-"latest"}" \
     -composeVersion="${COMPOSEVERSION:-"latest"}" \
     -buildxVersion="${BUILDXVERSION:-"latest"}" \
+    -configPath="${CONFIGPATH:-""}" \
     -downloadUrl="${DOWNLOADURL:-""}" \
     -versionsUrl="${VERSIONSURL:-""}" \
     -composeDownloadUrl="${COMPOSEDOWNLOADURL:-""}" \

features/src/docker-out/installer.go

@@ -5,8 +5,10 @@ import (
 	"flag"
 	"fmt"
 	"os"
+	"os/user"
 	"path/filepath"
 	"regexp"
+	"strconv"
 
 	"github.com/roemer/gotaskr/execr"
 	"github.com/roemer/gover"
@@ -36,10 +38,11 @@ func runMain() error {
 	version := flag.String("version", "latest", "")
 	composeVersion := flag.String("composeVersion", "latest", "")
 	buildxVersion := flag.String("buildxVersion", "latest", "")
+	buildxDownloadUrl := flag.String("buildxDownloadUrl", "", "")
 	downloadUrl := flag.String("downloadUrl", "", "")
 	versionsUrl := flag.String("versionsUrl", "", "")
 	composeDownloadUrl := flag.String("composeDownloadUrl", "", "")
-	buildxDownloadUrl := flag.String("buildxDownloadUrl", "", "")
+	configPath := flag.String("configPath", "", "")
 	flag.Parse()
 
 	// Load settings from an external file
@@ -51,13 +54,15 @@ func runMain() error {
 	installer.HandleOverride(versionsUrl, "https://download.docker.com/linux/static/stable", "docker-out-versions-url")
 	installer.HandleGitHubOverride(composeDownloadUrl, "docker/compose", "docker-out-compose-download-url")
 	installer.HandleGitHubOverride(buildxDownloadUrl, "docker/buildx", "docker-out-buildx-download-url")
+	installer.HandleOverride(configPath, "", "docker-out-config-path")
 
 	// Create and process the feature
 	feature := installer.NewFeature("Docker-Out", false,
 		&dockerCliComponent{
 			ComponentBase: installer.NewComponentBase("Docker CLI", *version),
 			DownloadUrl:   *downloadUrl,
 			VersionsUrl:   *versionsUrl,
+			ConfigPath:    *configPath,
 		},
 		&dockerComposeComponent{
 			ComponentBase: installer.NewComponentBase("Docker Compose", *composeVersion),
@@ -81,6 +86,7 @@ type dockerCliComponent struct {
 	*installer.ComponentBase
 	DownloadUrl string
 	VersionsUrl string
+	ConfigPath  string
 }
 
 func (c *dockerCliComponent) GetAllVersions() ([]*gover.Version, error) {
@@ -136,6 +142,41 @@ func (c *dockerCliComponent) InstallVersion(version *gover.Version) error {
 	if err := execr.Run(true, "cp", "-prf", "docker-init.sh", "/usr/local/share/docker-init.sh"); err != nil {
 		return err
 	}
+	// Copy the default config.json
+	if c.ConfigPath != "" {
+		fileContent, err := installer.ReadFileFromUrlOrLocal(c.ConfigPath)
+		if err != nil {
+			return err
+		}
+		userName := os.Getenv("_REMOTE_USER")
+		homeDir := os.Getenv("_REMOTE_USER_HOME")
+		if homeDir == "" {
+			homeDir = filepath.Join("/home", userName)
+		}
+		dockerDir := filepath.Join(homeDir, ".docker")
+		configDest := filepath.Join(dockerDir, "config.json")
+		// Ensure directory exists
+		if err := os.MkdirAll(dockerDir, 0700); err != nil {
+			return err
+		}
+		// Write config file
+		if err := os.WriteFile(configDest, fileContent, 0600); err != nil {
+			return err
+		}
+		// Set ownership
+		usr, err := user.Lookup(userName)
+		if err != nil {
+			return err
+		}
+		uid, _ := strconv.Atoi(usr.Uid)
+		gid, _ := strconv.Atoi(usr.Gid)
+		if err := os.Chown(dockerDir, uid, gid); err != nil {
+			return err
+		}
+		if err := os.Chown(configDest, uid, gid); err != nil {
+			return err
+		}
+	}
 
 	return nil
 }

features/test/docker-out/install-config.sh

@@ -0,0 +1,9 @@
+#!/bin/bash
+set -e
+
+[[ -f "$(dirname "$0")/../functions.sh" ]] && source "$(dirname "$0")/../functions.sh"
+[[ -f "$(dirname "$0")/functions.sh" ]] && source "$(dirname "$0")/functions.sh"
+
+check_version "$(docker version -f '{{.Client.Version}}')" "28.3.3"
+check_file_exists "/home/vscode/.docker/config.json"
+cat /home/vscode/.docker/config.json | grep "######" >/dev/null 2>&1 || (echo "Custom Docker config.json has a wrong content!" && exit 1)

features/test/docker-out/scenarios.json

@@ -28,5 +28,21 @@
                 "buildxVersion": "0.21.2"
             }
         }
+    },
+    "install-config": {
+        "build": {
+            "dockerfile": "Dockerfile",
+            "options": [
+                "--add-host=host.docker.internal:host-gateway"
+            ]
+        },
+        "features": {
+            "./docker-out": {
+                "version": "28.3.3",
+                "composeVersion": "none",
+                "buildxVersion": "none",
+                "configPath": "https://raw.githubusercontent.com/postfinance/devcontainer-features/refs/heads/main/override-all.env"
+            }
+        }
     }
 }

installer/overrides.go

@@ -8,22 +8,10 @@ import (
 
 // Loads the feature overrides from a specified location.
 func LoadOverrides() error {
-	var fileContent []byte
-	var err error
 	if overrideLocation := os.Getenv("DEV_FEATURE_OVERRIDE_LOCATION"); overrideLocation != "" {
-		// Load the overrides from the specified location
-		if strings.HasPrefix(overrideLocation, "http://") || strings.HasPrefix(overrideLocation, "https://") {
-			// Load from URL
-			fileContent, err = Tools.Download.AsBytes(overrideLocation)
-			if err != nil {
-				return fmt.Errorf("error downloading override file: %v", err)
-			}
-		} else {
-			// Load from file
-			fileContent, err = os.ReadFile(overrideLocation)
-			if err != nil {
-				return fmt.Errorf("error reading override file: %v", err)
-			}
+		fileContent, err := ReadFileFromUrlOrLocal(overrideLocation)
+		if err != nil {
+			return err
 		}
 		if len(fileContent) > 0 {
 			lines := strings.SplitSeq(strings.ReplaceAll(strings.TrimSpace(string(fileContent)), "\r\n", "\n"), "\n")
@@ -49,6 +37,23 @@ func LoadOverrides() error {
 	return nil
 }
 
+// ReadFileFromUrlOrLocal loads a file from a URL or local path and returns its contents as bytes.
+func ReadFileFromUrlOrLocal(location string) ([]byte, error) {
+	if strings.HasPrefix(location, "http://") || strings.HasPrefix(location, "https://") {
+		fileContent, err := Tools.Download.AsBytes(location)
+		if err != nil {
+			return nil, fmt.Errorf("error downloading file: %v", err)
+		}
+		return fileContent, nil
+	} else {
+		fileContent, err := os.ReadFile(location)
+		if err != nil {
+			return nil, fmt.Errorf("error reading file: %v", err)
+		}
+		return fileContent, nil
+	}
+}
+
 func HandleOverride(passedValue *string, defaultValue string, key string) {
 	if *passedValue == "" {
 		// Convert the key to a compatible format
@@ -61,6 +66,12 @@ func HandleOverride(passedValue *string, defaultValue string, key string) {
 		// Otherwise set to default value
 		*passedValue = defaultValue
 	}
+	// Handle "none" value to explicitly unset the value if an override env variable is set to a different value
+	// e.g. --configPath="none" and DOCKER_OUT_CONFIG_PATH=https://example.com/config.json
+	// If we do not explicitly handle this, you could not unset a value once an override env variable is set
+	if strings.ToLower(*passedValue) == "none" {
+		*passedValue = ""
+	}
 }
 
 func HandleGitHubOverride(downloadUrl *string, gitHubPath string, key string) {

override-all.env

@@ -17,6 +17,7 @@ DOCKER_OUT_DOWNLOAD_URL=""
 DOCKER_OUT_VERSIONS_URL=""
 DOCKER_OUT_COMPOSE_DOWNLOAD_URL=""
 DOCKER_OUT_BUILDX_DOWNLOAD_URL=""
+DOCKER_OUT_CONFIG_PATH=""
 
 # git-lfs
 GIT_LFS_DOWNLOAD_URL=""