feat: Make buildx builder the default

Author: Junkern

docs/resources/image.md

@@ -127,7 +127,7 @@ Optional:
 - `build_args` (Map of String) Pairs for build-time variables in the form of `ENDPOINT : "https://example.com"`
 - `build_id` (String) BuildID is an optional identifier that can be passed together with the build request. The same identifier can be used to gracefully cancel the build with the cancel request.
 - `build_log_file` (String) Path to a file where the buildx log are written to. Only available when `builder` is set. If not set, no logs are available. The path is taken as is, so make sure to use a path that is available.
-- `builder` (String) Set the name of the buildx builder to use. If not set, the legacy builder is used.
+- `builder` (String) The name of the buildx builder to use. If BUILDX_BUILDER environment variable is set, it will be used. If left empty, the provider tries to resolve to the default builder - which might not always work. If you are in Windows, the legacy builder is used.
 - `cache_from` (List of String) External cache sources (e.g., `user/app:cache`, `type=local,src=path/to/dir`). Only supported when using a buildx builder.
 - `cache_to` (List of String) Cache export destinations (e.g., `user/app:cache`, `type=local,dest=path/to/dir`). Only supported when using a buildx builder.
 - `cgroup_parent` (String) Optional parent cgroup for the container

docs/resources/registry_image.md

@@ -73,7 +73,7 @@ Optional:
 - `build_args` (Map of String) Pairs for build-time variables in the form of `ENDPOINT : "https://example.com"`
 - `build_id` (String) BuildID is an optional identifier that can be passed together with the build request. The same identifier can be used to gracefully cancel the build with the cancel request.
 - `build_log_file` (String) Path to a file where the buildx log are written to. Only available when `builder` is set. If not set, no logs are available. The path is taken as is, so make sure to use a path that is available.
-- `builder` (String) Set the name of the buildx builder to use. If not set, the legacy builder is used.
+- `builder` (String) The name of the buildx builder to use. If BUILDX_BUILDER environment variable is set, it will be used. If left empty, the provider tries to resolve to the default builder - which might not always work. If you are in Windows, the legacy builder is used.
 - `cache_from` (List of String) External cache sources (e.g., `user/app:cache`, `type=local,src=path/to/dir`). Only supported when using a buildx builder.
 - `cache_to` (List of String) Cache export destinations (e.g., `user/app:cache`, `type=local,dest=path/to/dir`). Only supported when using a buildx builder.
 - `cgroup_parent` (String) Optional parent cgroup for the container

docs/v3_v4_migration.md

@@ -6,6 +6,9 @@ Bump of minimum terraform version to `1.1.5` or newer. This is done as part of i
 
 ## `docker_image`
 
+**Default usage of buildx:** For all platforms (except for Windows) the provider now uses buildx to build images. If you do not have the `build.builder` 
+ attribute set, the provider will try to resolve the default buildx builder. In case it is set - no changes for you. It also mimics the behaviour of the docker cli and looks for the `BUILDX_BUILDER` env variable.
+
 **Reworked handling of context and Dockerfile:** This probably is not a breaking change, but more a big bugfix. The build logic now correctly resolves the Dockerfile path for both relative and absolute cases.
 
 

internal/provider/resource_docker_image.go

@@ -445,9 +445,10 @@ var buildSchema = &schema.Resource{
 		},
 		"builder": {
 			Type:        schema.TypeString,
-			Description: "Set the name of the buildx builder to use. If not set, the legacy builder is used.",
+			Description: "The name of the buildx builder to use. If BUILDX_BUILDER environment variable is set, it will be used. If left empty, the provider tries to resolve to the default builder - which might not always work. If you are in Windows, the legacy builder is used.",
 			Optional:    true,
 			ForceNew:    true,
+			DefaultFunc: schema.EnvDefaultFunc("BUILDX_BUILDER", ""),
 		},
 		"build_log_file": {
 			Type:        schema.TypeString,

internal/provider/resource_docker_image_funcs.go

@@ -63,17 +63,16 @@ func buildImage(ctx context.Context, rawBuild interface{}, client *client.Client
 		return true, diag.FromErr(err)
 	}
 
-	builder := rawBuildValue["builder"].(string)
-	log.Printf("[DEBUG] canUseBuildx: %v, builder %s", canUseBuildx, builder)
+	log.Printf("[DEBUG] canUseBuildx: %v", canUseBuildx)
 	// buildx is enabled
-	if canUseBuildx && builder != "" {
+	if canUseBuildx {
 		log.Printf("[DEBUG] Using buildx")
 		dockerCli, err := createAndInitDockerCli(client)
 		if err != nil {
 			return true, diag.FromErr(fmt.Errorf("failed to create and init Docker CLI: %w", err))
 		}
 
-		options, err := mapBuildAttributesToBuildOptions(rawBuildValue, imageName)
+		options, err := mapBuildAttributesToBuildOptions(rawBuildValue, imageName, dockerCli)
 
 		if err != nil {
 			return true, diag.FromErr(fmt.Errorf("Error mapping build attributes: %v", err))