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DODO - C++ framework for Docker applications

About

Dodo is a C++ framework to GNU/Linux development and aims to integrate seamlessly with Docker containers and k8s (kubernetes). Capable by itself, projects can obviously add other dependenices to realize any type of service at C++ speed and resource requirements.

A skeleton for services

The dodo::common::Application reads its run-time configuration from a YAML file, typically presented to the container as a ConfigMap. Framework objects can be iniltialized (constructed) with a YAML document fragment, so the application can retrieve its runtime configuration from a single source.

An dodo::common::Application instance implicitly installs signal handlers that are triggered on Docker stop requests, so that the container can shut down cleanly and quickly when requested.

Logging (dodo::common::Logger) can be configured to write to one or more of these targets:

A directory with a configured trail (size, history) of log files.
A syslog call to rsyslog.
Console aka standard out of the container entrypoint.

Docker healthchecks that run an in-container command (such as pidof myservice) are expensive on CPU, especially if the healthchecks need to be frequent or there are a lot of pods. The dodo::common::Application class can be instructed to setup a tiny healthceck listener (dodo::common::Application::HealthChecker) that responds to network-probed by the Docker host, which is much more efficient. This HealthChecker can be declared sick or healthy by application code as well.

High level APIs to common functionality

Most services will require at least some of the functionality dodo provides as high-level C++ abstractions without compromising low-level C/Linux performance.

Binary data as the dodo::common::Bytes datatype used by a variety of the other interfaces.
Encryption and compression.
Transparent ipv4 and ipv6 Address classes, name resolution.
TCPSocket (insecure) and TLSSocket classes (encryption and trust).
TCPServer and TLSServer classes ready for subclassing a custom protocol.
Standard protocols:
- HTTP
- STOMP
HTTP(S)Server and HTTP(S)Client handling HTTP server and client red tape.
REST(S)Listener as a specialization of HTTP(S)Server where a YAML section specifies the REST API.
C++ APIs to persistency solutions:
- SQLite relational database
- PostgreSQL relational database
- MongoDB relational database
Explicit persistent data stores implemented against SQLite
- Persistent key-value store
- Persistent fifo queue.
- Persistent Priority queue.

Dependencies

OpenSSL For TLS, hashing and encryption.
SQLite Persistent storage.
yaml-cpp Read and write YAML.
rapidjson Read and write JSON.
crc32 CRC32 verfication codes (dependency included in the source tree).

Using the dodo framework

See the developer manual for an overview.

The source code is documented for Doxygen and automatically generated to github pages.

Maintaining the dodo framework

See the maintainer manual for an overview.

Build

git clone https://github.com/jmspit/dodo.git
cd dodo && \
   mkdir build && \
   cd build && \
   cmake ..  -DCMAKE_INSTALL_PREFIX=/opt/dodo && \
   cmake --build . && \
   cmake --install .

If installed to a location outside the library paths the link-loader searches, set the LD_LIBRARY_PATH to <CMAKE_INSTALL_PREFIX>/lib.

To generate Doxygen API documentation, make doc will generate doxygen documentation in the build/doxygen/html directory, which contains an index.html.

Docker

A multistage build example (src/examples/docker/minideb/Dockerfile).

FROM bitnami/minideb:latest AS builder

RUN echo 'debconf debconf/frontend select Noninteractive' | debconf-set-selections
RUN apt-get update && \
    apt-get install -y apt-utils && \
    apt-get install -y libssl-dev git g++ cmake

RUN mkdir -p /opt/dodo/build && mkdir -p /opt/dodo/bin && mkdir -p /opt/dodo/lib
WORKDIR /opt/dodo/build
RUN git clone --branch latest https://github.com/jmspit/dodo.git
RUN cd dodo && \
    mkdir build && \
    cd build && \
    cmake ..  -DCMAKE_INSTALL_PREFIX=/opt/dodo && \
    make && \
    make install

FROM bitnami/minideb:latest
ENV LD_LIBRARY_PATH=${LD_LIBRARY_PATH}/opt/dodo/lib
ENV PATH=${PATH}:/opt/dodo/bin
RUN apt-get update && \
    apt-get install -y openssl
COPY --from=builder /opt/dodo/lib /opt/dodo/lib
COPY --from=builder /opt/dodo/bin /opt/dodo/bin
WORKDIR /opt/dodo