InfluxDB Bridge

The goal of this ROS2 package is to provide a simple interface to log data coming from different topics and upload them into a Influx Database.

Usage

The library exposes the influxdb-bridge executable that can be used to log data coming from particular topics.

To properly work it's necessary to setup in this folder (the source directory of the package) at least the mandatory config.txt file as follows:

path/to/workspace/src/influxdb-bridge-cpp
├── config.txt [mandatory]
├── fields.txt [optional]
├── points.txt [automatically generated]
├── CMakeLists.txt
├── include
├── launch
├── package.xml
├── README.md
└── src

The config.txt must contain a list of lines consisting of <topic> <msg_type> <measure_name (optional)>, e.g.

/turtle1/pose turtlesim/Pose
/coppelia_joint_states sensor_msgs/JointState RobState

The fields.txt file is instead optional and can contain a list of extra fields that will be applied to each collected measurement; fields are specified with the format <field_key> = <field_value>, e.g.

robot = ur5e
test=2

The points.txt file is instead generated by the node and contains all the insertion queries to the database. To push the data one can create an upload.sh shell script, make it executable (chmod +x upload.sh) and run it (./upload.sh). An example of the file could be:

HOST=localhost      # or the IP/URL of the server
PORT=8086           # default port
ORG=IDRA            # change at will
BUCKET=MAGICIAN     # change at will
TOKEN=<your_token>  # must be set
curl --request POST \
    "http://$HOST:$PORT/api/v2/write?org=$ORG&bucket=$BUCKET&precision=ns" \
    --header "Authorization: Token $TOKEN" \
    --header "Content-Type: text/plain; charset=utf-8" \
    --header "Accept: application/json" \
    --data-binary @points.txt   # this line loads the data from the 'points.txt' file

Adding support for new messages

To add suppport for a new message type follow this steps:

• Make sure that to list the optional dependency on the package that contains the message definition by checking (and eventually adding) the CMakeLists file:

  set(COMPILABLE_MESSAGE_PACKAGES
      ...
      <package_name, e.g. std_msgs>
      ...
      )
  

  This will automatically define the preprocessor macro WITH_<PACKAGE_NAME>

• Taking reference from here, create (if not existing) the header file that includes the necessary header files (e.g. std_msgs.hpp for the standard message); file must be created in this folder. If the file already exists, simply add the include statement for the particular message.

• Similarly, the actual message implementation must be inserted in a .cpp file inside the measurements implementation folder. The point.hpp defines for convenience the macro IMPLEMENT_MEASUREMENT that can be used. As example, to export a std_msgs/msg/String

  IMPLEMENT_MEASUREMENT(
      std_msgs::msg::String,    // variable type
      "string",                 // default measure name
      point.add_key<decltype(message->data)>("content", message->data); // implementation
      );

  The macro defines internally a point object of type Point on which different key can be added. The template library should admit only types that actually can be converted (in some way) in a format manageable by Influx; in case, error will be issued at compile time.

• Finally, register the measurement to the ROS2 node in the file influx_bridge_node.cpp. Inside the InfluxBridgeNode::add_subscriber function implementation, register each type by specifying the string that must be parsed to create the binding and the corresponding type:

  #ifdef WITH_STD_MSGS
      REGISTER_NEW_MSG_TYPE("std_msgs/String", std_msgs::msg::String)
      ...
  #endif

As shown here, remember to use the inclusion guards to allow everyone to build the library (even though they don't have all packages installed). For this very reason, in each implementation file include always only the header file interface defined within this package.