[core] Parse and send container id with payloads to the agent

ddtrace/api.py

@@ -8,6 +8,7 @@
 from .encoding import get_encoder, JSONEncoder
 from .compat import httplib, PYTHON_VERSION, PYTHON_INTERPRETER, get_connection_response
 from .internal.logger import get_logger
+from .internal.runtime import container
 from .payload import Payload, PayloadFull
 from .utils.deprecation import deprecated
 
@@ -151,6 +152,13 @@ def __init__(self, hostname, port, uds_path=None, headers=None, encoder=None, pr
             'Datadog-Meta-Tracer-Version': ddtrace.__version__,
         })
 
+        # Add container information if we have it
+        self._container_info = container.get_container_info()
+        if self._container_info and self._container_info.container_id:
+            self._headers.update({
+                'Datadog-Container-Id': self._container_info.container_id,
+            })
+
     def __str__(self):
         if self.uds_path:
             return self.uds_path

ddtrace/internal/runtime/container.py

@@ -0,0 +1,110 @@
+import re
+
+from ..logger import get_logger
+
+log = get_logger(__name__)
+
+
+class CGroupInfo(object):
+    """
+    CGroup class for container information parsed from a group cgroup file
+    """
+    __slots__ = ('id', 'groups', 'path', 'container_id', 'controllers', 'pod_id')
+
+    UUID_SOURCE_PATTERN = r'[0-9a-f]{8}[-_][0-9a-f]{4}[-_][0-9a-f]{4}[-_][0-9a-f]{4}[-_][0-9a-f]{12}'
+    CONTAINER_SOURCE_PATTERN = r'[0-9a-f]{64}'
+
+    LINE_RE = re.compile(r'^(\d+):([^:]*):(.+)$')
+    POD_RE = re.compile(r'pod({0})(?:\.slice)?$'.format(UUID_SOURCE_PATTERN))
+    CONTAINER_RE = re.compile(r'({0}|{1})(?:\.scope)?$'.format(UUID_SOURCE_PATTERN, CONTAINER_SOURCE_PATTERN))
+
+    def __init__(self, **kwargs):
+        # Initialize all attributes in __slots__ to `None`
+        # DEV: Otherwise we'll get `AttributeError` when trying to access if they are unset
+        for attr in self.__slots__:
+            setattr(self, attr, kwargs.get(attr))
+
+    @classmethod
+    def from_line(cls, line):
+        """
+        Parse a new :class:`CGroupInfo` from the provided line
+
+        :param line: A line from a cgroup file (e.g. /proc/self/cgroup) to parse information from
+        :type line: str
+        :returns: A :class:`CGroupInfo` object with all parsed data, if the line is valid, otherwise `None`
+        :rtype: :class:`CGroupInfo` | None
+
+        """
+        # Clean up the line
+        line = line.strip()
+
+        # Ensure the line is valid
+        match = cls.LINE_RE.match(line)
+        if not match:
+            return None
+
+        # Create our new `CGroupInfo` and set attributes from the line
+        info = cls()
+        info.id, info.groups, info.path = match.groups()
+
+        # Parse the controllers from the groups
+        info.controllers = [c.strip() for c in info.groups.split(',') if c.strip()]
+
+        # Break up the path to grab container_id and pod_id if available
+        # e.g. /docker/<container_id>
+        # e.g. /kubepods/test/pod<pod_id>/<container_id>
+        parts = [p for p in info.path.split('/')]
+
+        # Grab the container id from the path if a valid id is present
+        if len(parts):
+            match = cls.CONTAINER_RE.match(parts.pop())
+            if match:
+                info.container_id = match.group(1)
+
+        # Grab the pod id from the path if a valid id is present
+        if len(parts):
+            match = cls.POD_RE.match(parts.pop())
+            if match:
+                info.pod_id = match.group(1)
+
+        return info
+
+    def __str__(self):
+        return self.__repr__()
+
+    def __repr__(self):
+        return '{}(id={!r}, groups={!r}, path={!r}, container_id={!r}, controllers={!r}, pod_id={!r})'.format(
+            self.__class__.__name__,
+            self.id,
+            self.groups,
+            self.path,
+            self.container_id,
+            self.controllers,
+            self.pod_id,
+        )
+
+
+def get_container_info(pid='self'):
+    """
+    Helper to fetch the current container id, if we are running in a container
+
+    We will parse `/proc/{pid}/cgroup` to determine our container id.
+
+    The results of calling this function are cached
+
+    :param pid: The pid of the cgroup file to parse (default: 'self')
+    :type pid: str | int
+    :returns: The cgroup file info if found, or else None
+    :rtype: :class:`CGroupInfo` | None
+    """
+    try:
+        cgroup_file = '/proc/{0}/cgroup'.format(pid)
+        with open(cgroup_file, mode='r') as fp:
+            for line in fp:
+                info = CGroupInfo.from_line(line)
+                if info and info.container_id:
+                    return info
+    except Exception:
+        log.exception('Failed to parse cgroup file for pid %r', pid)
+
+    return None