mqbridge

Stream messages from PG/NATS/File channel to another PG/NATS/File channel

Sending string from source to destination is a very primitive task. But it’s solution might include some usefull technics. MQBridge uses this case for attempting to be example of doing things right.

Message queue systems supported

Installation

• Linux: just download & run. See Latest release
• Docker: docker pull ghcr.io/lekovr/mqbridge

Plugins

mqbridge has 2 build modes - standalone (default) and plugin mode.

To activate plugin mode, run

make plugin-on
make run

You will see Loading plugin in program output (using make run).

To deactivate plugin mode, run

make clean plugin-off

Application config

$ ./mqbridge -h
Usage:
  mqbridge [OPTIONS]
Application Options:
  --version      Show version and exit
  --debug        Show debug data
MQ Bridge Options:
  --delim=       Bridge definition delimiter (default: ,)
  --path_format= Path format (default: ./%s.so)
  --point=       Endpoints connect string in form 'tag[:plugin[://dsn]]' (default: io:file)
  --bridge=      Bridge in form 'in_tag:in_channel:out_tag[:out_channel]' (default: io:src.txt,io:dst.txt)
Help Options:
  -h, --help         Show this help message

Connect strings

• file - ${TAG)//
• pg - ${TAG}postgres://user:pass@host:port/db?sslmode=disable
• nats - ${TAG}nats://user:pass@host:port

Where ${TAG} is the name of endpoint given in config.

Usage

Producers

mqbridge uses the following as data source:

• file - tail files named as in_channel
• pg - listen in_channel
• nats - subscribe to in_channel

Consumers

mqbridge sends received messages as

• file - add lines to file named as out_channel
• pg - calls sql select out_channel(data)
• nats - publish message to out_channel

pg usage sample

This sample shows how to setup pg -> pg bridge.

1. Setup pg consumer (db1) for out_channel = bridge (see function name)

create table mqbridge_data (line text);
create or replace function bridge(a text) returns void language plpgsql as
$_$ 
  begin insert into mqbridge_data (line) values(a); end 
$_$;

1. Run mqbridge

./mqbridge --bridge in:event,out:bridge \
  --point in:pg:postgres://op:op@localhost:5432/db0?sslmode=disable \
  --point out:pg:postgres://op:op@localhost:5432/db1?sslmode=disable

1. Run at pg producer db (db0)

notify event, '{"test": 1972}';

1. See results in consumer db (db1)

select * from mqbridge_data ;
      line     
----------------
 {"test": 1972}

See also: Examples

Developer notes

This project solves quite simple task, but it shows some more important things named tests.
There are the following tests presented here:

• tests which use prepared docker environment
• golang test which runs docker container
• tests with gomock
• not so smart testing for unmockable package

Makefile

Project contains Makefile with the following targets:

$ make
mqbridge Makefile: Stream messages from PG/NATS/File channel to another PG/NATS/File channel
Compile operations
    lint            run `golint` and `golangci-lint`
    vet             run `go vet`
    test            run tests
    test-docker     run tests that use services from docker-compose.yml
    test-docker-self run tests that run docker themselves
    cov-html        show package coverage in html (make cov-html PKG=counter)
    build           build app
    run             build and run in foreground
Plugin support
    plugin-on       enable plugin mode (this command changes source files)
    plugin-off      disable plugin mode (this command changes source files back)
Prepare distros
    build-standalone build like docker image from scratch
    buildall        build app for all platforms
    dist            create disro files
Docker operations
    up              start service in container
    down            stop service
    docker-build    build docker image
    docker-clean    remove docker image & temp files
    dc              run $(CMD) via docker-compose
Other
    clean           clean generated files
    update-godoc    update docs at pkg.go.dev
    update-ghcr     update latest docker image tag at ghcr.io
    help            list Makefile targets (this is default target)

Project stats

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License

The MIT License (MIT), see LICENSE.

Copyright (c) 2017-2021 Aleksey Kovrizhkin lekovr+mqbridge@gmail.com