Merge pull request #35 from cschleiden/logging

Add simple logging implementation

Author: cschleiden

README.md

@@ -141,6 +141,7 @@ The Sqlite backend implementation supports two different modes, in-memory and on
 b := mysql.NewMysqlBackend("localhost", 3306, "root", "SqlPassw0rd", "simple")
 ```
 
+
 ## Guide
 
 ### Registering workflows
@@ -454,6 +455,43 @@ func TestWorkflow(t *testing.T) {
 - Timers are automatically fired by advancing a mock workflow clock that is used for testing workflows
 - You can register callbacks to fire at specific times (in mock-clock time). Callbacks can send signals, cancel workflows etc.
 
+### Logging
+
+For logging, you can pass a type to the backend via the `WithLogger` option to set a custom logger. The type has to implement this simple interface:
+
+```go
+type Logger interface {
+	Debug(msg string, fields ...interface{})
+	Warn(msg string, fields ...interface{})
+	Error(msg string, fields ...interface{})
+	Panic(msg string, fields ...interface{})
+
+	With(fields ...interface{}) Logger
+}
+```
+
+If you don't pass a logger, a very simple, unoptimized default logger is used. For production use it is strongly recommended to pass another logger.
+
+#### Workflows
+
+For logging in workflows, you can get a logger using
+
+```go
+logger := workflow.Logger(ctx)
+```
+
+The returned `logger` implements the `Logger` interface, and already has the workflow instance and execution IDs set as default fields.
+
+#### Activities
+
+For logging in activities, you can get a logger using
+
+```go
+logger := activity.Logger(ctx)
+```
+
+The returned `logger` implements the `Logger` interface, and already has the id of the activity, and the workflow instance and execution IDs set as default fields.
+
 ## Versioning
 
 For now, I've intentionally left our versioning. Cadence, Temporal, and DTFx all support the concept of versions for workflows as well as activities. This is mostly required when you make changes to workflows and need to keep backwards compatibility with workflows that are being executed at the time of the upgrade.

activity/logger.go

@@ -0,0 +1,13 @@
+package activity
+
+import (
+	"context"
+
+	"github.com/cschleiden/go-workflows/internal/activity"
+	"github.com/cschleiden/go-workflows/log"
+)
+
+// Logger returns a logger with the workflow instance this activity is executed for set as default fields
+func Logger(ctx context.Context) log.Logger {
+	return activity.GetActivityState(ctx).Logger
+}

backend/backend.go

@@ -7,6 +7,7 @@ import (
 	core "github.com/cschleiden/go-workflows/internal/core"
 	"github.com/cschleiden/go-workflows/internal/history"
 	"github.com/cschleiden/go-workflows/internal/task"
+	"github.com/cschleiden/go-workflows/log"
 	"github.com/cschleiden/go-workflows/workflow"
 )
 
@@ -59,4 +60,7 @@ type Backend interface {
 
 	// ExtendActivityTask extends the lock of an activity task
 	ExtendActivityTask(ctx context.Context, activityID string) error
+
+	// Logger returns the configured logger for the backend
+	Logger() log.Logger
 }

backend/mock_Backend.go

@@ -12,6 +12,7 @@ import (
 	"github.com/cschleiden/go-workflows/internal/core"
 	"github.com/cschleiden/go-workflows/internal/history"
 	"github.com/cschleiden/go-workflows/internal/task"
+	"github.com/cschleiden/go-workflows/log"
 	"github.com/cschleiden/go-workflows/workflow"
 	_ "github.com/go-sql-driver/mysql"
 	"github.com/google/uuid"
@@ -83,6 +84,10 @@ func (b *mysqlBackend) CreateWorkflowInstance(ctx context.Context, m history.Wor
 	return nil
 }
 
+func (b *mysqlBackend) Logger() log.Logger {
+	return b.options.Logger
+}
+
 func (b *mysqlBackend) CancelWorkflowInstance(ctx context.Context, instance *workflow.Instance, event *history.Event) error {
 	tx, err := b.db.BeginTx(ctx, nil)
 	if err != nil {

backend/mysql/mysql.go

@@ -1,8 +1,15 @@
 package backend
 
-import "time"
+import (
+	"time"
+
+	"github.com/cschleiden/go-workflows/internal/logger"
+	"github.com/cschleiden/go-workflows/log"
+)
 
 type Options struct {
+	Logger log.Logger
+
 	StickyTimeout time.Duration
 
 	WorkflowLockTimeout time.Duration
@@ -24,12 +31,22 @@ func WithStickyTimeout(timeout time.Duration) BackendOption {
 	}
 }
 
+func WithLogger(logger log.Logger) BackendOption {
+	return func(o *Options) {
+		o.Logger = logger
+	}
+}
+
 func ApplyOptions(opts ...BackendOption) Options {
 	options := DefaultOptions
 
 	for _, opt := range opts {
 		opt(&options)
 	}
 
+	if options.Logger == nil {
+		options.Logger = logger.NewDefaultLogger()
+	}
+
 	return options
 }

backend/options.go

@@ -44,6 +44,8 @@ func (rb *redisBackend) CreateWorkflowInstance(ctx context.Context, event histor
 		}
 	}
 
+	rb.options.Logger.Debug("Created new workflow instance")
+
 	return nil
 }
 

backend/redis/instance.go

@@ -6,6 +6,7 @@ import (
 	"github.com/cschleiden/go-workflows/backend"
 	"github.com/cschleiden/go-workflows/backend/redis/taskqueue"
 	"github.com/cschleiden/go-workflows/internal/history"
+	"github.com/cschleiden/go-workflows/log"
 	"github.com/go-redis/redis/v8"
 	"github.com/pkg/errors"
 )
@@ -57,7 +58,7 @@ func NewRedisBackend(address, username, password string, db int, opts ...RedisBa
 
 	// Default options
 	options := &RedisOptions{
-		Options:      backend.DefaultOptions,
+		Options:      backend.ApplyOptions(),
 		BlockTimeout: time.Second * 5,
 	}
 
@@ -94,3 +95,7 @@ type activityData struct {
 type workflowTaskData struct {
 	LastPendingEventMessageID string `json:"last_pending_event_message_id,omitempty"`
 }
+
+func (rb *redisBackend) Logger() log.Logger {
+	return rb.options.Logger
+}

backend/redis/redis.go

@@ -12,6 +12,10 @@ import (
 )
 
 func Test_RedisBackend(t *testing.T) {
+	if testing.Short() {
+		t.Skip()
+	}
+
 	test.BackendTest(t, func() backend.Backend {
 		address := "localhost:6379"
 		user := ""

backend/redis/redis_test.go

@@ -12,6 +12,7 @@ import (
 	"github.com/cschleiden/go-workflows/internal/core"
 	"github.com/cschleiden/go-workflows/internal/history"
 	"github.com/cschleiden/go-workflows/internal/task"
+	"github.com/cschleiden/go-workflows/log"
 	"github.com/cschleiden/go-workflows/workflow"
 	"github.com/google/uuid"
 	"github.com/pkg/errors"
@@ -58,6 +59,10 @@ type sqliteBackend struct {
 	options    backend.Options
 }
 
+func (sb *sqliteBackend) Logger() log.Logger {
+	return sb.options.Logger
+}
+
 func (sb *sqliteBackend) CreateWorkflowInstance(ctx context.Context, m history.WorkflowEvent) error {
 	tx, err := sb.db.BeginTx(ctx, nil)
 	if err != nil {