[receiver/sqlquery] add support for logs (open-telemetry#20730)

Fixes open-telemetry#20284 

This introduces initial support for retrieving rows from SQL databases
into logs.

This PR aims to provide an initial, not feature rich, but production
ready implementation. The following features are available:

- Use `body_column` to select the column to use to fill the Body field
of the created log
- Use `tracking_start_value` and `tracking_column` properties to track
rows that were already ingested
- Use `storage` property to persist the tracking value across collector
restarts

In this state and marked as "development" stability, the component can
be used for experimentation and to guide future development.

There are definitely more things that need to be implemented for this
component to be considered "alpha" quality - like filling in other [log
fields](https://github.com/open-telemetry/opentelemetry-specification/blob/v1.21.0/specification/logs/data-model.md#log-and-event-record-definition)
like Timestamp, ObservedTimestamp and others. I would like to add them
in subsequent pull requests, as this pull request is already way too
big.

---------

Co-authored-by: Dominika Molenda <[email protected]>
Co-authored-by: Dominika Molenda <[email protected]>
Co-authored-by: Katarzyna Kujawa <[email protected]>
Co-authored-by: Katarzyna Kujawa <[email protected]>

.chloggen/sqlquery-receiver-add-logs.yaml

@@ -0,0 +1,16 @@
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: enhancement
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: sqlqueryreceiver
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Add support for logs
+
+# One or more tracking issues related to the change
+issues: [20284]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:

receiver/sqlqueryreceiver/README.md

@@ -4,9 +4,11 @@
 | Status        |           |
 | ------------- |-----------|
 | Stability     | [alpha]: metrics   |
+|               | [development]: logs   |
 | Distributions | [contrib], [observiq], [splunk], [sumo] |
 
 [alpha]: https://github.com/open-telemetry/opentelemetry-collector#alpha
+[development]: https://github.com/open-telemetry/opentelemetry-collector#development
 [contrib]: https://github.com/open-telemetry/opentelemetry-collector-releases/tree/main/distributions/otelcol-contrib
 [observiq]: https://github.com/observIQ/observiq-otel-collector
 [splunk]: https://github.com/signalfx/splunk-otel-collector
@@ -28,29 +30,88 @@ The configuration supports the following top-level fields:
   a driver-specific string usually consisting of at least a database name and connection information. This is sometimes
   referred to as the "connection string" in driver documentation.
   e.g. _host=localhost port=5432 user=me password=s3cr3t sslmode=disable_
-- `queries`(required): A list of queries, where a query is a sql statement and one or more metrics (details below).
+- `queries`(required): A list of queries, where a query is a sql statement and one or more `logs` and/or `metrics` sections (details below).
 - `collection_interval`(optional): The time interval between query executions. Defaults to _10s_.
+- `storage` (optional, default `""`): The ID of a [storage][storage_extension] extension to be used to [track processed results](#tracking-processed-results).
+
+[storage_extension]: https://github.com/open-telemetry/opentelemetry-collector-contrib/tree/main/extension/storage/filestorage
 
 ### Queries
 
-A _query_ consists of a sql statement and one or more _metrics_, where each metric consists of a
+A _query_ consists of a sql statement and one or more `logs` and/or `metrics` section.
+At least one `logs` or one `metrics` section is required.
+Note that technically you can put both `logs` and `metrics` sections in a single query section,
+but it's probably not a real world use case, as the requirements for logs and metrics queries
+are quite different.
+
+Additionally, each `query` section supports the following properties:
+
+- `tracking_column` (optional, default `""`) Applies only to logs. In case of a parameterized query,
+  defines the column to retrieve the value of the parameter on subsequent query runs.
+  See the below section [Tracking processed results](#tracking-processed-results).
+- `tracking_start_value` (optional, default `""`) Applies only to logs. In case of a parameterized query, defines the initial value for the parameter.
+  See the below section [Tracking processed results](#tracking-processed-results).
+
+Example:
+
+```yaml
+receivers:
+  sqlquery:
+    driver: postgres
+    datasource: "host=localhost port=5432 user=postgres password=s3cr3t sslmode=disable"
+    queries:
+      - sql: "select * from my_logs where log_id > $$1"
+        tracking_start_value: "10000"
+        tracking_column: log_id
+        logs:
+          - body_column: log_body
+      - sql: "select count(*) as count, genre from movie group by genre"
+        metrics:
+          - metric_name: movie.genres
+            value_column: "count"
+```
+
+#### Logs Queries
+
+The `logs` section is in development.
+
+- `body_column` (required) defines the column to use as the log record's body.
+
+##### Tracking processed results
+
+With the default configuration and a non-parameterized logs query like `select * from my_logs`,
+the receiver will run the same query every collection interval, which can cause reading the same rows
+over and over again, unless there's an external actor removing the old rows from the `my_logs` table.
+
+To prevent reading the same rows on every collection interval, use a parameterized query like `select * from my_logs where id_column > ?`,
+together with the `tracking_start_value` and `tracking_column` configuration properties.
+The receiver will use the configured `tracking_start_value` as the value for the query parameter when running the query for the first time.
+After each query run, the receiver will store the value of the `tracking_column` from the last row of the result set and use it as the value for the query parameter on next collection interval. To prevent duplicate log downloads, make sure to sort the query results in ascending order by the tracking_column value.
+
+Note that the notation for the parameter depends on the database backend. For example in MySQL this is `?`, in PostgreSQL this is `$1`, in Oracle this is any string identifier starting with a colon `:`, for example `:my_parameter`.
+
+Use the `storage` configuration property of the receiver to persist the tracking value across collector restarts.
+
+#### Metrics queries
+
+Each `metrics` section consists of a
 `metric_name`, a `value_column`, and additional optional fields.
 Each _metric_ in the configuration will produce one OTel metric per row returned from its sql query.
 
-* `metric_name`(required): the name assigned to the OTel metric.
-* `value_column`(required): the column name in the returned dataset used to set the value of the metric's datapoint.
+- `metric_name`(required): the name assigned to the OTel metric.
+- `value_column`(required): the column name in the returned dataset used to set the value of the metric's datapoint.
   This may be case-sensitive, depending on the driver (e.g. Oracle DB).
-* `attribute_columns`(optional): a list of column names in the returned dataset used to set attibutes on the datapoint.
+- `attribute_columns`(optional): a list of column names in the returned dataset used to set attibutes on the datapoint.
   These attributes may be case-sensitive, depending on the driver (e.g. Oracle DB).
-* `data_type` (optional): can be `gauge` or `sum`; defaults to `gauge`.
-* `value_type` (optional): can be `int` or `double`; defaults to `int`.
-* `monotonic` (optional): boolean; whether a cumulative sum's value is monotonically increasing (i.e. never rolls over
+- `data_type` (optional): can be `gauge` or `sum`; defaults to `gauge`.
+- `value_type` (optional): can be `int` or `double`; defaults to `int`.
+- `monotonic` (optional): boolean; whether a cumulative sum's value is monotonically increasing (i.e. never rolls over
   or resets); defaults to false.
-* `aggregation` (optional): only applicable for `data_type=sum`; can be `cumulative` or `delta`; defaults
+- `aggregation` (optional): only applicable for `data_type=sum`; can be `cumulative` or `delta`; defaults
   to `cumulative`.
-* `description` (optional): the description applied to the metric.
-* `unit` (optional): the units applied to the metric.
-* `static_attributes` (optional): static attributes applied to the metrics
+- `description` (optional): the description applied to the metric.
+- `unit` (optional): the units applied to the metric.
+- `static_attributes` (optional): static attributes applied to the metrics
 
 ### Example
 
@@ -59,28 +120,34 @@ receivers:
   sqlquery:
     driver: postgres
     datasource: "host=localhost port=5432 user=postgres password=s3cr3t sslmode=disable"
+    storage: file_storage
     queries:
+      - sql: "select * from my_logs where log_id > $$1"
+        tracking_start_value: "10000"
+        tracking_column: log_id
+        logs:
+          - body_column: log_body
       - sql: "select count(*) as count, genre from movie group by genre"
         metrics:
           - metric_name: movie.genres
             value_column: "count"
-            attribute_columns: [ "genre" ]
+            attribute_columns: ["genre"]
             static_attributes:
               dbinstance: mydbinstance
 ```
 
 Given a `movie` table with three rows:
 
 | name      | genre  |
-|-----------|--------|
+| --------- | ------ |
 | E.T.      | sci-fi |
 | Star Wars | sci-fi |
 | Die Hard  | action |
 
 If there are two rows returned from the query `select count(*) as count, genre from movie group by genre`:
 
 | count | genre  |
-|-------|--------|
+| ----- | ------ |
 | 2     | sci-fi |
 | 1     | action |
 
@@ -94,7 +161,7 @@ Descriptor:
 NumberDataPoints #0
 Data point attributes:
      -> genre: STRING(sci-fi)
-     -> dbinstance: STRING(mydbinstance)     
+     -> dbinstance: STRING(mydbinstance)
 Value: 2
 
 Metric #1
@@ -121,4 +188,3 @@ Oracle DB driver to connect and query the same table schema and contents as the
 The Oracle DB driver documentation can be found [here.](https://github.com/sijms/go-ora)
 Another usage example is the `go_ora`
 example [here.](https://blogs.oracle.com/developers/post/connecting-a-go-application-to-oracle-database)
-

receiver/sqlqueryreceiver/config.go

@@ -17,9 +17,10 @@ import (
 
 type Config struct {
 	scraperhelper.ScraperControllerSettings `mapstructure:",squash"`
-	Driver                                  string  `mapstructure:"driver"`
-	DataSource                              string  `mapstructure:"datasource"`
-	Queries                                 []Query `mapstructure:"queries"`
+	Driver                                  string        `mapstructure:"driver"`
+	DataSource                              string        `mapstructure:"datasource"`
+	Queries                                 []Query       `mapstructure:"queries"`
+	StorageID                               *component.ID `mapstructure:"storage"`
 }
 
 func (c Config) Validate() error {
@@ -41,17 +42,25 @@ func (c Config) Validate() error {
 }
 
 type Query struct {
-	SQL     string      `mapstructure:"sql"`
-	Metrics []MetricCfg `mapstructure:"metrics"`
+	SQL                string      `mapstructure:"sql"`
+	Metrics            []MetricCfg `mapstructure:"metrics"`
+	Logs               []LogsCfg   `mapstructure:"logs"`
+	TrackingColumn     string      `mapstructure:"tracking_column"`
+	TrackingStartValue string      `mapstructure:"tracking_start_value"`
 }
 
 func (q Query) Validate() error {
 	var errs error
 	if q.SQL == "" {
 		errs = multierr.Append(errs, errors.New("'query.sql' cannot be empty"))
 	}
-	if len(q.Metrics) == 0 {
-		errs = multierr.Append(errs, errors.New("'query.metrics' cannot be empty"))
+	if len(q.Logs) == 0 && len(q.Metrics) == 0 {
+		errs = multierr.Append(errs, errors.New("at least one of 'query.logs' and 'query.metrics' must not be empty"))
+	}
+	for _, logs := range q.Logs {
+		if err := logs.Validate(); err != nil {
+			errs = multierr.Append(errs, err)
+		}
 	}
 	for _, metric := range q.Metrics {
 		if err := metric.Validate(); err != nil {
@@ -61,6 +70,18 @@ func (q Query) Validate() error {
 	return errs
 }
 
+type LogsCfg struct {
+	BodyColumn string `mapstructure:"body_column"`
+}
+
+func (config LogsCfg) Validate() error {
+	var errs error
+	if config.BodyColumn == "" {
+		errs = multierr.Append(errs, errors.New("'body_column' must not be empty"))
+	}
+	return errs
+}
+
 type MetricCfg struct {
 	MetricName       string            `mapstructure:"metric_name"`
 	ValueColumn      string            `mapstructure:"value_column"`

receiver/sqlqueryreceiver/config_test.go

@@ -96,15 +96,44 @@ func TestLoadConfig(t *testing.T) {
 			errorMessage: "'driver' cannot be empty",
 		},
 		{
-			fname:        "config-invalid-missing-metrics.yaml",
+			fname:        "config-invalid-missing-logs-metrics.yaml",
 			id:           component.NewIDWithName(metadata.Type, ""),
-			errorMessage: "'query.metrics' cannot be empty",
+			errorMessage: "at least one of 'query.logs' and 'query.metrics' must not be empty",
 		},
 		{
 			fname:        "config-invalid-missing-datasource.yaml",
 			id:           component.NewIDWithName(metadata.Type, ""),
 			errorMessage: "'datasource' cannot be empty",
 		},
+		{
+			fname: "config-logs.yaml",
+			id:    component.NewIDWithName(metadata.Type, ""),
+			expected: &Config{
+				ScraperControllerSettings: scraperhelper.ScraperControllerSettings{
+					CollectionInterval: 10 * time.Second,
+					InitialDelay:       time.Second,
+				},
+				Driver:     "mydriver",
+				DataSource: "host=localhost port=5432 user=me password=s3cr3t sslmode=disable",
+				Queries: []Query{
+					{
+						SQL:                "select * from test_logs where log_id > ?",
+						TrackingColumn:     "log_id",
+						TrackingStartValue: "10",
+						Logs: []LogsCfg{
+							{
+								BodyColumn: "log_body",
+							},
+						},
+					},
+				},
+			},
+		},
+		{
+			fname:        "config-logs-missing-body-column.yaml",
+			id:           component.NewIDWithName(metadata.Type, ""),
+			errorMessage: "'body_column' must not be empty",
+		},
 		{
 			fname:        "config-unnecessary-aggregation.yaml",
 			id:           component.NewIDWithName(metadata.Type, ""),
@@ -113,7 +142,7 @@ func TestLoadConfig(t *testing.T) {
 	}
 
 	for _, tt := range tests {
-		t.Run(tt.id.String(), func(t *testing.T) {
+		t.Run(tt.fname, func(t *testing.T) {
 			cm, err := confmaptest.LoadConf(filepath.Join("testdata", tt.fname))
 			require.NoError(t, err)
 

receiver/sqlqueryreceiver/db_client.go

@@ -20,7 +20,7 @@ import (
 type stringMap map[string]string
 
 type dbClient interface {
-	metricRows(ctx context.Context) ([]stringMap, error)
+	queryRows(ctx context.Context, args ...any) ([]stringMap, error)
 }
 
 type dbSQLClient struct {
@@ -37,8 +37,8 @@ func newDbClient(db db, sql string, logger *zap.Logger) dbClient {
 	}
 }
 
-func (cl dbSQLClient) metricRows(ctx context.Context) ([]stringMap, error) {
-	sqlRows, err := cl.db.QueryContext(ctx, cl.sql)
+func (cl dbSQLClient) queryRows(ctx context.Context, args ...any) ([]stringMap, error) {
+	sqlRows, err := cl.db.QueryContext(ctx, cl.sql, args...)
 	if err != nil {
 		return nil, err
 	}

receiver/sqlqueryreceiver/db_client_test.go

@@ -21,7 +21,7 @@ func TestDBSQLClient_SingleRow(t *testing.T) {
 		logger: zap.NewNop(),
 		sql:    "",
 	}
-	rows, err := cl.metricRows(context.Background())
+	rows, err := cl.queryRows(context.Background())
 	require.NoError(t, err)
 	assert.Len(t, rows, 1)
 	assert.EqualValues(t, map[string]string{
@@ -42,7 +42,7 @@ func TestDBSQLClient_MultiRow(t *testing.T) {
 		logger: zap.NewNop(),
 		sql:    "",
 	}
-	rows, err := cl.metricRows(context.Background())
+	rows, err := cl.queryRows(context.Background())
 	require.NoError(t, err)
 	assert.Len(t, rows, 2)
 	assert.EqualValues(t, map[string]string{
@@ -69,7 +69,7 @@ func TestDBSQLClient_Nulls(t *testing.T) {
 		logger: zap.NewNop(),
 		sql:    "",
 	}
-	rows, err := cl.metricRows(context.Background())
+	rows, err := cl.queryRows(context.Background())
 	assert.Error(t, err)
 	assert.True(t, errors.Is(err, errNullValueWarning))
 	assert.Len(t, rows, 1)
@@ -88,7 +88,7 @@ func TestDBSQLClient_Nulls_MultiRow(t *testing.T) {
 		logger: zap.NewNop(),
 		sql:    "",
 	}
-	rows, err := cl.metricRows(context.Background())
+	rows, err := cl.queryRows(context.Background())
 	assert.Error(t, err)
 	errs := multierr.Errors(err)
 	for _, err := range errs {
@@ -152,7 +152,7 @@ type fakeDBClient struct {
 	err            error
 }
 
-func (c *fakeDBClient) metricRows(context.Context) ([]stringMap, error) {
+func (c *fakeDBClient) queryRows(context.Context, ...any) ([]stringMap, error) {
 	if c.err != nil {
 		return nil, c.err
 	}

receiver/sqlqueryreceiver/factory.go

@@ -15,6 +15,7 @@ func NewFactory() receiver.Factory {
 	return receiver.NewFactory(
 		metadata.Type,
 		createDefaultConfig,
-		receiver.WithMetrics(createReceiverFunc(sql.Open, newDbClient), metadata.MetricsStability),
+		receiver.WithLogs(createLogsReceiverFunc(sql.Open, newDbClient), metadata.LogsStability),
+		receiver.WithMetrics(createMetricsReceiverFunc(sql.Open, newDbClient), metadata.MetricsStability),
 	)
 }

receiver/sqlqueryreceiver/factory_test.go

@@ -21,4 +21,11 @@ func TestNewFactory(t *testing.T) {
 		consumertest.NewNop(),
 	)
 	require.NoError(t, err)
+	_, err = factory.CreateLogsReceiver(
+		context.Background(),
+		receivertest.NewNopCreateSettings(),
+		factory.CreateDefaultConfig(),
+		consumertest.NewNop(),
+	)
+	require.NoError(t, err)
 }