Fix a panic that could occur when context was omitted (#83)

I could have sworn the context property was required, but evidently it
isn't and we weren't handling the case when it was missing.

This PR updates things to set a default location of the current
directory if the context is absent. Some unit tests are also added.

Fixes #78.

provider/internal/context.go

@@ -26,12 +26,14 @@ import (
 	"os"
 	"path"
 	"path/filepath"
+	"slices"
 	"syscall"
 
 	buildx "github.com/docker/buildx/build"
 	"github.com/moby/patternmatcher/ignorefile"
 	"github.com/spf13/afero"
 	"github.com/tonistiigi/fsutil"
+	"golang.org/x/exp/maps"
 
 	"github.com/pulumi/pulumi-go-provider/infer"
 	"github.com/pulumi/pulumi/sdk/v3/go/common/util/contract"
@@ -90,7 +92,9 @@ func (c *Context) Annotate(a infer.Annotator) {
 
 // validate returns a non-nil CheckError if the Context is invalid. The
 // returned Dockerfile may have defaults set to match Docker's default
-// handling. The returned Dockerfile should be validated separately.
+// handling. The returned Dockerfile should be validated separately. Non-nil
+// values are returned even in the case of errors to allow additional
+// validation to be performed.
 func (bc *BuildContext) validate(preview bool, d *Dockerfile) (*Dockerfile, *Context, error) {
 	if d == nil {
 		d = &Dockerfile{}
@@ -107,6 +111,11 @@ func (bc *BuildContext) validate(preview bool, d *Dockerfile) (*Dockerfile, *Con
 		// a build later.
 		return d, c, nil
 	}
+	// If this isn't a preview but our location still isn't set, default it to
+	// the current directory.
+	if c.Location == "" {
+		c.Location = "."
+	}
 
 	if buildx.IsRemoteURL(c.Location) {
 		// We assume remote URLs are always valid.
@@ -225,8 +234,11 @@ func hashBuildContext(
 		}
 	}
 
-	// Hash any local named contexts.
-	for _, namedContext := range namedContexts {
+	// Hash any local named contexts. Sort keys for stable iteration order.
+	keys := maps.Keys(namedContexts)
+	slices.Sort(keys)
+	for _, key := range keys {
+		namedContext := namedContexts[key]
 		if isLocalDir(fs, namedContext) {
 			fs, err := rootFS(namedContext, excludes)
 			if err != nil {

provider/internal/context_test.go

@@ -33,62 +33,69 @@ func TestValidateContext(t *testing.T) {
 	t.Parallel()
 	tests := []struct {
 		name    string
-		c       Context
+		c       *BuildContext
 		givenD  Dockerfile
 		preview bool
 
 		wantD   *Dockerfile
+		wantC   *Context
 		wantErr string
 	}{
 		{
 			name: "relative",
-			c: Context{
+			c: &BuildContext{Context: Context{
 				Location: "../internal/../internal/testdata/noop",
-			},
+			}},
 			wantD: &Dockerfile{
 				Location: "../internal/testdata/noop/Dockerfile",
 			},
 		},
 		{
 			name: "missing directory",
-			c: Context{
+			c: &BuildContext{Context: Context{
 				Location: "/does/not/exist/",
-			},
+			}},
 			wantErr: "not a valid directory",
 		},
 		{
 			name: "missing default Dockerfile",
-			c: Context{
+			c: &BuildContext{Context: Context{
 				Location: "testdata",
-			},
+			}},
 			wantD: &Dockerfile{Location: "testdata/Dockerfile"},
 		},
 		{
 			name: "with explicit Dockerfile",
-			c: Context{
+			c: &BuildContext{Context: Context{
 				Location: "testdata",
-			},
+			}},
 			givenD: Dockerfile{
 				Location: "testdata/Dockerfile.invalid",
 			},
 		},
 		{
 			name:  "default location",
-			c:     Context{},
+			c:     &BuildContext{Context: Context{}},
 			wantD: &Dockerfile{Location: "Dockerfile"},
 		},
 		{
 			name: "remote context doesn't default to local Dockerfile",
-			c: Context{
+			c: &BuildContext{Context: Context{
 				Location: "https://raw.githubusercontent.com/pulumi/pulumi-docker/api-types/provider/testdata/Dockerfile",
-			},
+			}},
 			wantD: &Dockerfile{},
 		},
 		{
 			name:    "preview",
-			c:       Context{},
+			c:       &BuildContext{Context: Context{}},
 			preview: true,
 		},
+		{
+			name:  "missing context defaults to current directory",
+			c:     nil,
+			wantC: &Context{Location: "."},
+			wantD: &Dockerfile{Location: "Dockerfile"},
+		},
 	}
 
 	for _, tt := range tests {
@@ -96,8 +103,7 @@ func TestValidateContext(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 
-			bc := &BuildContext{Context: tt.c}
-			d, _, err := bc.validate(tt.preview, &tt.givenD)
+			d, c, err := tt.c.validate(tt.preview, &tt.givenD)
 
 			if tt.wantErr == "" {
 				assert.NoError(t, err)
@@ -109,6 +115,9 @@ func TestValidateContext(t *testing.T) {
 				assert.Equal(t, tt.wantD.Location, d.Location)
 				assert.Equal(t, tt.wantD.Inline, d.Inline)
 			}
+			if tt.wantC != nil {
+				assert.Equal(t, tt.wantC.Location, c.Location)
+			}
 		})
 	}
 }

provider/internal/host.go

@@ -16,8 +16,10 @@ package internal
 
 import (
 	"context"
+	"fmt"
 	"path/filepath"
 	"sync"
+	"time"
 
 	"github.com/docker/buildx/builder"
 	"github.com/docker/buildx/store/storeutil"
@@ -72,7 +74,7 @@ func (h *host) builderFor(build Build) (*cachedBuilder, error) {
 
 	txn, release, err := storeutil.GetStore(h.cli)
 	if err != nil {
-		return nil, err
+		return nil, fmt.Errorf("getting store: %w", err)
 	}
 	defer release()
 
@@ -86,7 +88,7 @@ func (h *host) builderFor(build Build) (*cachedBuilder, error) {
 		builder.WithStore(txn),
 	)
 	if err != nil {
-		return nil, err
+		return nil, fmt.Errorf("new builder: %w", err)
 	}
 
 	// If we didn't request a particular builder, and we loaded a default
@@ -95,7 +97,7 @@ func (h *host) builderFor(build Build) (*cachedBuilder, error) {
 	if b.Driver == "" && opts.Builder == "" {
 		builders, err := builder.GetBuilders(h.cli, txn)
 		if err != nil {
-			return nil, err
+			return nil, fmt.Errorf("getting builders: %w", err)
 		}
 	nextbuilder:
 		for _, bb := range builders {
@@ -128,6 +130,7 @@ func (h *host) builderFor(build Build) (*cachedBuilder, error) {
 	}
 
 	if b.Driver == "" && opts.Builder == "" {
+
 		// If we STILL don't have a builder, create a docker-container instance.
 		b, err = builder.Create(
 			context.Background(),
@@ -136,7 +139,12 @@ func (h *host) builderFor(build Build) (*cachedBuilder, error) {
 			builder.CreateOpts{Driver: "docker-container"},
 		)
 		if err != nil {
-			return nil, err
+			return nil, fmt.Errorf("creating builder: %w", err)
+		}
+		ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
+		defer cancel()
+		if _, err := b.Boot(ctx); err != nil {
+			return nil, fmt.Errorf("booting builder: %w", err)
 		}
 	}
 
@@ -145,7 +153,7 @@ func (h *host) builderFor(build Build) (*cachedBuilder, error) {
 	// drivers that are unknown to us.
 	nodes, err := b.LoadNodes(context.Background())
 	if err != nil && !build.ShouldExec() {
-		return nil, err
+		return nil, fmt.Errorf("loading nodes: %w", err)
 	}
 
 	cached := &cachedBuilder{name: b.Name, driver: b.Driver, nodes: nodes}

provider/internal/image.go

@@ -153,7 +153,7 @@ func (ia *ImageArgs) Annotate(a infer.Annotator) {
 		Equivalent to Docker's "--cache-to" flag.
 	`))
 	a.Describe(&ia.Context, dedent(`
-		Build context settings.
+		Build context settings. Defaults to the current directory.
 
 		Equivalent to Docker's "PATH | URL | -" positional argument.
 	`))
@@ -546,6 +546,10 @@ func (ia *ImageArgs) validate(preview bool) (controllerapi.BuildOptions, error)
 		multierr = errors.Join(multierr, err)
 	}
 	ia.Dockerfile = dockerfile
+	// Set a default context if one wasn't provided.
+	if ia.Context == nil {
+		ia.Context = &BuildContext{Context: *context}
+	}
 
 	if err := ia.Dockerfile.validate(preview, context); err != nil {
 		multierr = errors.Join(multierr, err)

provider/internal/image_test.go

@@ -273,6 +273,48 @@ func TestImageLifecycle(t *testing.T) {
 				}
 			},
 		},
+		{
+			name: "context defaults to current directory (pulumi-docker-build#78)",
+			client: func(t *testing.T) Client {
+				ctrl := gomock.NewController(t)
+				c := NewMockClient(ctrl)
+				c.EXPECT().BuildKitEnabled().Return(true, nil).AnyTimes()
+				c.EXPECT().Build(gomock.Any(), gomock.AssignableToTypeOf(build{})).DoAndReturn(
+					func(_ context.Context, b Build) (*client.SolveResponse, error) {
+						assert.Equal(t, "FROM alpine:latest", b.Inline())
+						return &client.SolveResponse{
+							ExporterResponse: map[string]string{"image.name": "alpine:latest"},
+						}, nil
+					},
+				).AnyTimes()
+				c.EXPECT().Delete(gomock.Any(), "inline-dockerfile").Return(nil)
+				return c
+			},
+			op: func(t *testing.T) integration.Operation {
+				return integration.Operation{
+					Inputs: resource.PropertyMap{
+						"push": resource.NewBoolProperty(false),
+						"tags": resource.NewArrayProperty(
+							[]resource.PropertyValue{
+								resource.NewStringProperty("inline-dockerfile"),
+							},
+						),
+						"buildOnPreview": resource.NewBoolProperty(true),
+						"dockerfile": resource.NewObjectProperty(resource.PropertyMap{
+							"inline": resource.NewStringProperty("FROM alpine:latest"),
+						}),
+					},
+					Hook: func(_, output resource.PropertyMap) {
+						context := output["context"]
+						require.NotNil(t, context)
+						require.True(t, context.IsObject())
+						location := context.ObjectValue()["location"]
+						require.True(t, location.IsString())
+						assert.Equal(t, ".", location.StringValue())
+					},
+				}
+			},
+		},
 	}
 
 	for _, tt := range tests {