The Datawire Microservices Development Kit

The Datawire Microservices Development Kit lets developers code and test microservices using their native languages and frameworks. The MDK includes APIs for:

• registering and locating microservices
• distributed logging
• resilient connections (e.g., circuit breakers)

The MDK is currently available in Java, JavaScript, Ruby, and Python versions.

Quick Start

Visit https://app.datawire.io to create a free Datawire account, and see step-by-step instructions.

Slow Start (for developers)

See https://datawire.github.io/mdk-docs/latest/main/getting-started/index.html on how to install the MDK from the command line. Currently, there is an implementation dependency on the Datawire cloud services for service discovery. We plan to remove this requirement in the near future.

Architecture

The MDK is implemented as a series of protocols. These protocols are defined in Quark. The Quark transpiler then compiles these protocol definitions into language native MDKs.

Environment Variables

The MDK can be configured via environment variables. The officially supported ones will be described in the user-facing documentation, but here is a list of the ones the code currently supports:

• DATAWIRE_TOKEN: Authentication token for Mission Control server (or the MCP server set with MDK_SERVER_URL, see below). If set the MDK will talk to the MCP and send log messages there, as well as using it for discovery.
• MDK_ENVIRONMENT: Operational environment to use. Services in different environments can't see each other. If in the form <fallback>:<name> then services not found in <name> will be looked up in the <fallback> operational environment. If not set the environment defaults to sandbox.
• MDK_DISCOVERY_SOURCE: Discovery source to use, overriding default discovery source set by DATAWIRE_TOKEN.
  • A value of datawire:<token> is the same as setting DATAWIRE_TOKEN.
  • A value of synapse:path=</path/to/synapse_dir> will read from Synapse filesystem dump.
  • A value of static:nodes=<json list of encoded Nodes> will use the specified mdk_discovery.Node instances.
• MDK_SERVER_URL: The server to talk to. Override to point at local MCP, or at the development server (wss://mcp-develop.datawire.io/rtp.)
• MDK_FAILURE_POLICY allows overriding the default 3-strikes-and-you're-blacklisted-for-30-seconds circuit breaker policy.
  • A value of recording sets a mdk_discovery.RecordingFailurePolicyFactory, which useful when writing unit tests.
• MDK_EXPERIMENTAL: If set enables experimental features, some of which may be insecure.
• MDK_LOG_MESSAGES: If set, e.g. to 1, sent and received messages will be written out to files at /tmp/mdk*.log.