feat: show Terraform error details (#6643)

provisioner/terraform/diagnostic.go

@@ -0,0 +1,68 @@
+package terraform
+
+import (
+	"bytes"
+	"fmt"
+	"sort"
+	"strings"
+
+	tfjson "github.com/hashicorp/terraform-json"
+)
+
+// This implementation bases on the original Terraform formatter, which unfortunately is internal:
+// https://github.com/hashicorp/terraform/blob/6b35927cf0988262739a5f0acea4790ae58a16d3/internal/command/format/diagnostic.go#L125
+
+func FormatDiagnostic(diag *tfjson.Diagnostic) string {
+	var buf bytes.Buffer
+	appendSourceSnippets(&buf, diag)
+	_, _ = buf.WriteString(diag.Detail)
+	return buf.String()
+}
+
+func appendSourceSnippets(buf *bytes.Buffer, diag *tfjson.Diagnostic) {
+	if diag.Range == nil {
+		return
+	}
+
+	if diag.Snippet == nil {
+		// This should generally not happen, as long as sources are always
+		// loaded through the main loader. We may load things in other
+		// ways in weird cases, so we'll tolerate it at the expense of
+		// a not-so-helpful error message.
+		_, _ = fmt.Fprintf(buf, "on %s line %d:\n  (source code not available)\n", diag.Range.Filename, diag.Range.Start.Line)
+	} else {
+		snippet := diag.Snippet
+		code := snippet.Code
+
+		var contextStr string
+		if snippet.Context != nil {
+			contextStr = fmt.Sprintf(", in %s", *snippet.Context)
+		}
+		_, _ = fmt.Fprintf(buf, "on %s line %d%s:\n", diag.Range.Filename, diag.Range.Start.Line, contextStr)
+
+		// Split the snippet into lines and render one at a time
+		lines := strings.Split(code, "\n")
+		for i, line := range lines {
+			_, _ = fmt.Fprintf(buf, "  %d: %s\n", snippet.StartLine+i, line)
+		}
+
+		if len(snippet.Values) > 0 {
+			// The diagnostic may also have information about the dynamic
+			// values of relevant variables at the point of evaluation.
+			// This is particularly useful for expressions that get evaluated
+			// multiple times with different values, such as blocks using
+			// "count" and "for_each", or within "for" expressions.
+			values := make([]tfjson.DiagnosticExpressionValue, len(snippet.Values))
+			copy(values, snippet.Values)
+			sort.Slice(values, func(i, j int) bool {
+				return values[i].Traversal < values[j].Traversal
+			})
+
+			_, _ = buf.WriteString("    ├────────────────\n")
+			for _, value := range values {
+				_, _ = fmt.Fprintf(buf, "    │ %s %s\n", value.Traversal, value.Statement)
+			}
+		}
+	}
+	_ = buf.WriteByte('\n')
+}

provisioner/terraform/diagnostic_test.go

@@ -0,0 +1,63 @@
+package terraform_test
+
+import (
+	"encoding/json"
+	"strings"
+	"testing"
+
+	tfjson "github.com/hashicorp/terraform-json"
+	"github.com/stretchr/testify/require"
+
+	"github.com/coder/coder/provisioner/terraform"
+)
+
+type hasDiagnostic struct {
+	Diagnostic *tfjson.Diagnostic `json:"diagnostic"`
+}
+
+func TestFormatDiagnostic(t *testing.T) {
+	t.Parallel()
+
+	tests := map[string]struct {
+		input    string
+		expected []string
+	}{
+		"Expression": {
+			input: `{"@level":"error","@message":"Error: Unsupported attribute","@module":"terraform.ui","@timestamp":"2023-03-17T10:33:38.761493+01:00","diagnostic":{"severity":"error","summary":"Unsupported attribute","detail":"This object has no argument, nested block, or exported attribute named \"foobar\".","range":{"filename":"main.tf","start":{"line":230,"column":81,"byte":5648},"end":{"line":230,"column":88,"byte":5655}},"snippet":{"context":"resource \"docker_container\" \"workspace\"","code":"  name = \"coder-${data.coder_workspace.me.owner}-${lower(data.coder_workspace.me.foobar)}\"","start_line":230,"highlight_start_offset":80,"highlight_end_offset":87,"values":[]}},"type":"diagnostic"}`,
+			expected: []string{
+				"on main.tf line 230, in resource \"docker_container\" \"workspace\":",
+				"  230:   name = \"coder-${data.coder_workspace.me.owner}-${lower(data.coder_workspace.me.foobar)}\"",
+				"",
+				"This object has no argument, nested block, or exported attribute named \"foobar\".",
+			},
+		},
+		"DynamicValues": {
+			input: `{"@level":"error","@message":"Error: Invalid value for variable","@module":"terraform.ui","@timestamp":"2023-03-17T12:25:37.864793+01:00","diagnostic":{"severity":"error","summary":"Invalid value for variable","detail":"Invalid Digital Ocean Project ID.\n\nThis was checked by the validation rule at main.tf:27,3-13.","range":{"filename":"main.tf","start":{"line":18,"column":1,"byte":277},"end":{"line":18,"column":31,"byte":307}},"snippet":{"context":null,"code":"variable \"step1_do_project_id\" {","start_line":18,"highlight_start_offset":0,"highlight_end_offset":30,"values":[{"traversal":"var.step1_do_project_id","statement":"is \"magic-project-id\""}]}},"type":"diagnostic"}`,
+			expected: []string{
+				"on main.tf line 18:",
+				"  18: variable \"step1_do_project_id\" {",
+				"    ├────────────────",
+				"    │ var.step1_do_project_id is \"magic-project-id\"",
+				"",
+				"Invalid Digital Ocean Project ID.",
+				"",
+				"This was checked by the validation rule at main.tf:27,3-13.",
+			},
+		},
+	}
+
+	for name, tc := range tests {
+		tc := tc
+
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+
+			var d hasDiagnostic
+			err := json.Unmarshal([]byte(tc.input), &d)
+			require.NoError(t, err)
+
+			output := terraform.FormatDiagnostic(d.Diagnostic)
+			require.Equal(t, tc.expected, strings.Split(output, "\n"))
+		})
+	}
+}

provisioner/terraform/executor.go

@@ -496,8 +496,10 @@ func provisionReadAndLog(sink logSink, r io.Reader, done chan<- any) {
 		if log.Diagnostic == nil {
 			continue
 		}
-		logLevel = convertTerraformLogLevel(log.Diagnostic.Severity, sink)
-		sink.Log(&proto.Log{Level: logLevel, Output: log.Diagnostic.Detail})
+		logLevel = convertTerraformLogLevel(string(log.Diagnostic.Severity), sink)
+		for _, diagLine := range strings.Split(FormatDiagnostic(log.Diagnostic), "\n") {
+			sink.Log(&proto.Log{Level: logLevel, Output: diagLine})
+		}
 	}
 }
 
@@ -509,7 +511,7 @@ func convertTerraformLogLevel(logLevel string, sink logSink) proto.LogLevel {
 		return proto.LogLevel_DEBUG
 	case "info":
 		return proto.LogLevel_INFO
-	case "warn":
+	case "warn", "warning":
 		return proto.LogLevel_WARN
 	case "error":
 		return proto.LogLevel_ERROR
@@ -526,13 +528,7 @@ type terraformProvisionLog struct {
 	Level   string `json:"@level"`
 	Message string `json:"@message"`
 
-	Diagnostic *terraformProvisionLogDiagnostic `json:"diagnostic"`
-}
-
-type terraformProvisionLogDiagnostic struct {
-	Severity string `json:"severity"`
-	Summary  string `json:"summary"`
-	Detail   string `json:"detail"`
+	Diagnostic *tfjson.Diagnostic `json:"diagnostic,omitempty"`
 }
 
 // syncWriter wraps an io.Writer in a sync.Mutex.