< which adds an opt-in feature to test the scenarios where the downstream services become flaky/down/slow.
It also provides a UI port to control the behavior of all the downstream services in real time. On start, all the downstream services behave as normal i.e. the proxy exhibits dummy behvaior.
Compose Monkey :
* Smartly suggests port and TCP protocol for the destination link
* Option to skip proxy creation for any link
* UI controller to change the behvaior of the link in real time.
##How it works
Internally, it uses a package [Vaurien](http://vaurien.readthedocs.org/) which provides TCP proxy and behavior simulation. For every link, ComposeMonkey injects a Vaurien container between the source and the destination service. To start a Vaurien container, it needs the TCP [protocol](http://vaurien.readthedocs.org/en/1.8/protocols.html) and the port needed to talk to the destination. ComposeMonkey makes a best effort strategy to find those and shows them to the user as defaults.
Destination Port is found by searching for `exposed port` of the destination, if any. Protocol is suggested naively by checking the downstream service name. User has the option to provide port/protocol of their choice if not satisfied with the defaults.
```
+------------+ +-------------+
| | | |
| WEB +-----------> REDIS |
| | | |
+------------+ +-------------+
Without --monkey
| |
|---------------------------------------------------------------|
| |
+------------+ +------------+ +------------+
| | | | | |
| WEB +--------> COMPOSMNKY +--------> REDIS |
| | | | | |
+------------+ +-----^------+ +------------+
|
|
|
+-----+------+
| |
| UI |
| |
+------------+
With --monkey
```
##Future Work
ComposeMonkey can also be built and packaged outside of docker-compose. This can be implemented by creating a temporary `fig.yml` from the original config yaml file which has a vaurien container entry for each downstream link and single UI container which links all the proxy containers. This work is still in development.
]]>
