golang

name: golang description: Rules and best practices when writing and editing Go (Golang) code metadata: relevant_files: - "server//*.go" - "functions//.go" - "cli/**/.go"

This codebases uses features from Go 1.25 and above.

• Be pragmatic about introducing third-party dependencies beyond what is available in go.mod and lean on the standard library when appropriate.
• Use the Go standard library before attempting to suggest third party dependencies.
• Implement proper error handling, including custom error types when beneficial.
• Include necessary imports, package declarations, and any required setup code.
• Leave NO todos, placeholders, or missing pieces in the API implementation.
• Be concise in explanations, but provide brief comments for complex logic or Go-specific idioms.
• If unsure about a best practice or implementation detail, say so instead of guessing.
• Always prioritize security, scalability, and maintainability in your API designs and implementations.
• Avoid editing any source files that have a "DO NOT EDIT" comment at start of them.
• Store dependencies on service structs via constructor-based dependency injection. Do NOT hide dependencies in session manager state.
• Avoid shallow helpers that are just a one-line wrapper around another method, especially when they are only used once.
• When using a slog logger, always use the context-aware methods: DebugContext, InfoContext, WarnContext, ErrorContext.
• When logging errors make sure to always include them in the log payload using attr.SlogError(err). Example: logger.ErrorContext(ctx, "failed to write to database", attr.SlogError(err)).
• Any functions or methods that relate to making API calls or database queries or working with timers should take a context.Context value as their first argument.
• Always run linters as part of finalizing your code changes. Use mise lint:server to run the linters on the server codebase.
• The exhaustruct linter requires all struct fields to be explicitly set in struct literals. When adding new fields to a type, update ALL call sites — including places that construct the struct with zero values (e.g., MyStruct{} → MyStruct{NewField: nil}).

Updating the API

We use Goa to design our API and generate server code. All Goa code lives in server/design. The Goa DSL is documented in https://pkg.go.dev/goa.design/goa/v3/dsl.

To make an API change such as creating a new service or update an existing one:

• Update the Goa design files in server/design to reflect the API change.
• Run mise run gen:goa-server
• This will regenerate the server code in server/gen with the new API changes. It's best to use git to discover the added/changed files.

When implementing Goa services:

• Ensure the service lives in a separate go package with an impl.go file such as server/internal/<service>/impl.go.
• The general layout of the impl.go file should be as follows:

package assets

import (
    "context"

    "log/slog"

    goahttp "goa.design/goa/v3/http"

    gen "github.com/speakeasy-api/gram/server/gen/assets"
    srv "github.com/speakeasy-api/gram/server/gen/http/assets/server"
    "github.com/speakeasy-api/gram/server/internal/auth"
)

type Service struct {
    tracer    trace.Tracer
    logger    *slog.Logger
    auth      *auth.Auth
  // dependencies
}

func NewService(
    logger *slog.Logger,
    tracerProvider trace.TracerProvider,
  auth *auth.Auth,
  // dependencies
) *Service {
  return &Service{
    // initialize dependencies
  }
}

var _ gen.Service = (*Service)(nil)
var _ gen.Auther = (*Service)(nil)

func Attach(mux goahttp.Muxer, service *Service) {
    endpoints := gen.NewEndpoints(service)
    endpoints.Use(middleware.MapErrors())
    endpoints.Use(middleware.TraceMethods(service.tracer))
    srv.Mount(
        mux,
        srv.New(endpoints, mux, goahttp.RequestDecoder, goahttp.ResponseEncoder, nil, nil),
    )
}

func (s *Service) APIKeyAuth(ctx context.Context, key string, schema *security.APIKeyScheme) (context.Context, error) {
    return s.auth.Authorize(ctx, key, schema)
}

func (s *Service) ListAssets(ctx context.Context, payload *gen.ListAssetsPayload) (*gen.ListAssetsResult, error) {
  // implementation
}

If you are creating a new Goa service, then make sure to attach it to the http server in server/cmd/gram/start.go.

Dependency injection

• Always inject dependencies directly into service structs via the constructor.
• Do NOT use a session manager to stash dependencies that the service needs later.
• When a service needs database access, inject the DB connection and initialize query helpers (repo.New) when needed in functions.
• Do NOT store repo.Queries directly on a service struct for a new service.

type Service struct {
    queries *repo.Queries
}

func NewService(db *pgxpool.Pool) *Service {
    return &Service{
        queries: repo.New(db),
    }
}

type Service struct {
    db *pgxpool.Pool
}

func NewService(db *pgxpool.Pool) *Service {
    return &Service{db: db}
}

func (s *Service) Handler(ctx context.Context) error {
    queries := repo.New(s.db)

    if err := queries.DoThing(ctx); err != nil {
        return fmt.Errorf("do thing: %w", err)
    }

    return nil
}

Auth context assumptions

• When reading authctx, assume ActiveOrganisationID is present.
• Do NOT add defensive empty checks for ActiveOrganisationID unless there is a concrete code path proving otherwise.

Avoid patterns that treat ActiveOrganisationID as optional when reading authctx. That adds defensive code around an invariant that should already hold.

Third-party clients

• Constructors for third-party clients should always return a usable client implementation.
• Avoid designs where internal code has to repeatedly check whether a client is nil before calling it.
• Provide a stub implementation for local development and tests, but choose between the real and stub implementation in deps.go based on c.String("environment").
• Do NOT expose third-party request/response types from your wrapper to the rest of our codebase. Define our own types at the boundary.

type Service struct {
    client *vendor.Client
}

func NewService(cfg Config) *Service {
    if cfg.APIKey == "" {
        return nil
    }

    return &Service{client: vendor.New(cfg.APIKey)}
}

func (s *Service) Send(ctx context.Context, req *vendor.Request) error {
    if s.client == nil {
        return nil
    }

    return s.client.Send(ctx, req)
}

type Client interface {
    Send(ctx context.Context, message Message) error
}

type Message struct {
    To      string
    Subject string
    Body    string
}

type Service struct {
    client Client
}

func NewService(client Client) *Service {
    return &Service{client: client}
}

Transactional email (Loops)

Sending transactional email goes through server/internal/email. The package wraps Loops and enforces a strongly typed Template interface.

Adding a new template

Follow these four steps:

1. Add a TransactionalID constant to server/internal/email/templates.go — single registry, grep-friendly.
2. Create server/internal/email/template_<name>.go with a struct implementing the Template interface (TransactionalID(), Variables(), AddToAudience()).
3. Append a zero value of the struct to RegisteredTemplates in templates.go so tests catch duplicate IDs (e.g. AccessRequestCreated{}).
4. Write server/internal/email/template_<name>_test.go covering: TransactionalID returns the expected constant, Variables returns the correct snake_case keys with all keys present, AddToAudience returns the expected bool.

To send: call s.emailSvc.Send(ctx, recipientEmail, tmpl) where tmpl is your populated template struct.

Variable key naming

Variables() must return snake_case keys. Loops substitutes these keys directly into template variables — camelCase keys silently render as blank fields in the delivered email.

Every declared key must be present in the returned map even when the value is empty. A missing key causes partial template rendering.

func (t MyTemplate) Variables() map[string]string {
    return map[string]string{
        "approvalUrl":    t.ApprovalURL,
        "requesterEmail": t.RequesterEmail,
    }
}

func (t MyTemplate) Variables() map[string]string {
    return map[string]string{
        "approval_url":    t.ApprovalURL,
        "requester_email": t.RequesterEmail,
    }
}

AddToAudience semantics

Controls whether Loops upserts the recipient as a contact in the audience when the email is sent.

• Return true for user-facing emails that are part of the recipient's product journey (team invites, onboarding).
• Return false for operational/admin emails where the recipient is incidental (admin alerts, system notifications).

Testing patterns

Base test setup — never pass nil for *email.Service:

loopsClient := loops.New(ctx, logger, nil, "") // nil guardian policy is safe when key is empty; returns noop client
noopEmailSvc := email.NewService(logger, loopsClient)

Asserting on sent emails — use a capture client:

loops.Client is our own interface (not a vendor type), so a hand-rolled capture client is appropriate here. The capture pattern lets tests assert on the exact payload sent — use it instead of testify/mock for Loops email assertions.

type captureLoopsClient struct {
    mu   sync.Mutex
    sent []loops.SendTransactionalInput
}

func (c *captureLoopsClient) SendTransactional(_ context.Context, input loops.SendTransactionalInput) error {
    c.mu.Lock()
    defer c.mu.Unlock()
    c.sent = append(c.sent, input)
    return nil
}

func (c *captureLoopsClient) Sent() []loops.SendTransactionalInput {
    c.mu.Lock()
    defer c.mu.Unlock()
    out := make([]loops.SendTransactionalInput, len(c.sent))
    copy(out, c.sent)
    return out
}

To use it in a test, declare an instance and swap it into the service:

captured := &captureLoopsClient{}
svc.emailSvc = email.NewService(testenv.NewLogger(t), captured)

(This assigns an unexported field — works from within the same package, which is the convention for access package tests.)

Optional display fields — use conv.Default:

DisplayName: conv.Default(request.DisplayName, "(unknown resource)"),

Never send a template with a blank field that produces broken email copy. Apply a meaningful fallback at the Go layer, not in the Loops template.

Function shape

• Avoid helper functions and methods that only forward to another method with no meaningful logic.
• Avoid extracting single-use one-liners into separate methods just for indirection.
• Prefer inlining trivial behavior at the call site unless the extracted function adds reuse, naming value, or non-trivial logic.

func (s *Service) listWidgets(ctx context.Context) error {
    return s.repo.ListWidgets(ctx)
}

func (s *Service) List(ctx context.Context) error {
    return s.listWidgets(ctx)
}

func (s *Service) List(ctx context.Context) error {
    return s.repo.ListWidgets(ctx)
}

Error handling

In low-level functions, use fmt.Errorf to wrap errors with distinct and useful context:

func SaveUser(repo Repository, u User) error {
  err := repo.Save(u)
  if err != nil {
    return fmt.Errorf("failed to save user: %w", err)
  }
  return nil
}

func SaveUser(repo Repository, u User) error {
  err := repo.Save(u)
  if err != nil {
    return fmt.Errorf("run database query: %w", err)
  }
  return nil
}

func SaveUser(repo Repository, u User) error {
  err := repo.Save(u)
  if err != nil {
    return fmt.Errorf("save user: %w", err)
  }
  return nil
}

In higher-level functions of the server/ codebase, which include HTTP service handlers, use the server/internal/oops package which allows us to wrap internal errors with user-facing error messages.

func (s *Service) ListDeployments(ctx context.Context, form *gen.ListDeploymentsPayload) (res *gen.ListDeploymentResult, err error) {
  var cursor uuid.NullUUID
    if form.Cursor != nil {
        c, err := uuid.Parse(*form.Cursor)
        if err != nil {
            return nil, oops.E(oops.CodeBadRequest, err, "invalid cursor").Log(ctx, s.logger)
        }

        cursor = uuid.NullUUID{UUID: c, Valid: true}
    }
}

Logging

• Use log/slog for logging.
• ALWAYS use logging attributes defined in server/internal/attr/conventions.go when logging in the server codebase.
• Where appropriate, create child loggers using logger.With(attr.SlogXXX(...)) to capture contextual attributes for logging in later parts of code.
• DO NOT spam the codebase with log statements. Focus on logging errors where appropriate and reduce the noise from excessive info-level logs.

logger.InfoContext(ctx, "user created", "user_id", userID)

import "github.com/speakeasy-api/gram/functions/internal/attr"

func Example() {
  logger.Error("failed to create user", attr.SlogError(err))
}

import "github.com/speakeasy-api/gram/functions/internal/attr"

func Example(ctx context.Context) {
  logger.ErrorContext(ctx, "failed to create user", attr.SlogError(err))
}

Conversion utilities (server/internal/conv)

Use the conv package for common type conversions instead of writing inline helpers. Key functions:

• conv.PtrEmpty(v) — If v is not the zero value, return a pointer to v; otherwise, return nil.
• conv.PtrValOr(ptr, default) — dereference a pointer with a fallback default.
• conv.Default(val, default) — return val unless it is the zero value, then return default.
• conv.ToPGText, conv.ToPGTextEmpty, conv.PtrToPGText, conv.PtrToPGTextEmpty — convert strings to pgtype.Text.
• conv.FromPGText, conv.FromPGBool — convert pgtype values to Go pointer types.
• conv.PtrToPGBool — convert a *bool to pgtype.Bool.
• conv.Ternary(cond, trueVal, falseVal) — inline conditional expression.

Observability (server/internal/o11y)

Use the o11y package for deferred cleanup and error logging. Two key functions:

o11y.LogDefer

func LogDefer(ctx context.Context, logger *slog.Logger, cb func() error) error

Use LogDefer when a cleanup operation's error should be logged. Wrap cleanup calls with defer o11y.LogDefer(...) so failures are always visible in logs.

defer o11y.LogDefer(ctx, logger, func() error { return file.Close() })

o11y.NoLogDefer

func NoLogDefer(cb func() error)

Use NoLogDefer when a cleanup operation's error can be silently discarded — for example, rolling back a database transaction (which is a no-op if the transaction already committed) or closing an HTTP response body.

dbtx, err := s.repo.DB().Begin(ctx)
if err != nil {
    return nil, oops.E(oops.CodeUnexpected, err, "error accessing resource").Log(ctx, logger)
}
defer o11y.NoLogDefer(func() error { return dbtx.Rollback(ctx) })

defer o11y.NoLogDefer(func() error { return resp.Body.Close() })

Testing

• When writing assertions, use github.com/stretchr/testify/require exclusively.
• In tests, use t.Context() instead of context.Background(), except inside t.Cleanup(func()) callbacks.
• IMPORTANT: avoid using t.Run to create subtests. Prefer writing separate test functions instead.
• All test setup which includes spinning up databases, caches and background workers must go in setup_test.go files. Look for these across the codebase for inspiration and guidance.
• NEVER write raw SQL in tests for any Postgres operation — SELECT, INSERT, UPDATE, DELETE, transactions (Begin/BeginTx), CopyFrom, and SendBatch are all covered. Use SQLc-generated methods. Default to adding new fixture queries in the relevant domain package's own queries.sql (e.g. a toolsets-shaped fixture goes in server/internal/toolsets/queries.sql, not in testenv). Reach for server/internal/testenv/queries.sql (and testenv/testrepo) only when a fixture query is genuinely reused across multiple packages. The glint no-testing-raw-sql rule enforces this against *pgxpool.Pool, *pgx.Conn, pgx.Tx, and pgx.Querier receivers in *_test.go. ClickHouse uses a different driver and is not flagged.
• Use github.com/stretchr/testify/mock for mocking third-party libraries in tests instead of ad hoc fakes around vendor types.
• Use testenv.NewLogger(t), testenv.NewTracerProvider(t), and testenv.NewMeterProvider(t) instead of constructing loggers or noop OTel providers inline. testenv.NewLogger(t) discards in normal runs and emits pretty logs under go test -v, which inline slog.New(slog.DiscardHandler) and slog.New(slog.NewTextHandler(os.Stdout, nil)) do not. Exception: tests that assert on log output should use a capturing handler over a bytes.Buffer.

ctx := context.Background()

ctx := t.Context()

type mockEmailClient struct {
    mock.Mock
}

func (m *mockEmailClient) Send(ctx context.Context, message Message) error {
    args := m.Called(ctx, message)
    return args.Error(0)
}