allow setting tags directly on span/transaction objects (#384)

this is a pre-requisite for the opentracing bridge

refs #249
closes #384

Author: beniwohli

elasticapm/traces.py

@@ -96,6 +96,17 @@ def ensure_parent_id(self):
             logger.debug("Set parent id to generated %s", self.trace_parent.span_id)
         return self.trace_parent.span_id
 
+    def tag(self, **tags):
+        """
+        Tag this transaction with one or multiple key/value tags. Both the values should be strings
+
+            transaction_obj.tag(key1="value1", key2="value2")
+
+        Note that keys will be dedotted, replacing dot (.), star (*) and double quote (") with an underscore (_)
+        """
+        for key in tags.keys():
+            self.tags[TAG_RE.sub("_", compat.text_type(key))] = encoding.keyword_field(compat.text_type(tags[key]))
+
     def to_dict(self):
         self.context["tags"] = self.tags
         result = {
@@ -161,12 +172,20 @@ def __init__(self, transaction, name, span_type, context=None, leaf=False, tags=
         self.duration = None
         self.parent = None
         self.frames = None
-        self.tags = tags
-        if self.tags:
-            for key in list(self.tags.keys()):
-                self.tags[TAG_RE.sub("_", compat.text_type(key))] = encoding.keyword_field(
-                    compat.text_type(self.tags.pop(key))
-                )
+        self.tags = {}
+        if tags:
+            self.tag(**tags)
+
+    def tag(self, **tags):
+        """
+        Tag this span with one or multiple key/value tags. Both the values should be strings
+
+            span_obj.tag(key1="value1", key2="value2")
+
+        Note that keys will be dedotted, replacing dot (.), star (*) and double quote (") with an underscore (_)
+        """
+        for key in tags.keys():
+            self.tags[TAG_RE.sub("_", compat.text_type(key))] = encoding.keyword_field(compat.text_type(tags[key]))
 
     def to_dict(self):
         result = {
@@ -300,13 +319,10 @@ def tag(**tags):
     Tags current transaction. Both key and value of the tag should be strings.
     """
     transaction = get_transaction()
-    for name, value in tags.items():
-        if not transaction:
-            error_logger.warning("Ignored tag %s. No transaction currently active.", name)
-            return
-        # replace invalid characters for Elasticsearch field names with underscores
-        name = TAG_RE.sub("_", compat.text_type(name))
-        transaction.tags[compat.text_type(name)] = encoding.keyword_field(compat.text_type(value))
+    if not transaction:
+        error_logger.warning("Ignored tags %s. No transaction currently active.", ", ".join(tags.keys()))
+    else:
+        transaction.tag(**tags)
 
 
 def set_transaction_name(name, override=True):

tests/fixtures.py

@@ -34,7 +34,7 @@
 
 assert os.path.exists(ERRORS_SCHEMA) and os.path.exists(
     TRANSACTIONS_SCHEMA
-), 'JSON Schema files not found. Run "make update-json-schema to download'
+), 'JSON Schema files not found. Run "make update-json-schema" to download'
 
 
 with codecs.open(ERRORS_SCHEMA, encoding="utf8") as errors_json, codecs.open(

tests/instrumentation/transactions_store_tests.py

@@ -186,13 +186,14 @@ def test_get_transaction_clear():
 
 def test_tag_transaction():
     requests_store = Tracer(lambda: [], lambda: [], lambda *args: None)
-    t = requests_store.begin_transaction("test")
+    transaction = requests_store.begin_transaction("test")
     elasticapm.tag(foo="bar")
+    transaction.tag(baz="bazzinga")
     requests_store.end_transaction(200, "test")
 
-    assert t.tags == {"foo": "bar"}
-    transaction_dict = t.to_dict()
-    assert transaction_dict["context"]["tags"] == {"foo": "bar"}
+    assert transaction.tags == {"foo": "bar", "baz": "bazzinga"}
+    transaction_dict = transaction.to_dict()
+    assert transaction_dict["context"]["tags"] == {"foo": "bar", "baz": "bazzinga"}
 
 
 def test_tag_while_no_transaction(caplog):
@@ -328,8 +329,8 @@ def test_transaction_without_name_result(elasticapm_client):
 
 def test_span_tagging(elasticapm_client):
     elasticapm_client.begin_transaction("test")
-    with elasticapm.capture_span("test", tags={"foo": "bar", "ba.z": "baz.zinga"}):
-        pass
+    with elasticapm.capture_span("test", tags={"foo": "bar", "ba.z": "baz.zinga"}) as span:
+        span.tag(lorem="ipsum")
     elasticapm_client.end_transaction("test", "OK")
     span = elasticapm_client.events[SPAN][0]
-    assert span["context"]["tags"] == {"foo": "bar", "ba_z": "baz.zinga"}
+    assert span["context"]["tags"] == {"foo": "bar", "ba_z": "baz.zinga", "lorem": "ipsum"}