b014c0f91b
see: https://github.com/hashicorp/consul/issues/1173 #1173 Reasoning: somewhere during consul development Pause()/Resume() and PauseSync()/ResumeSync() were added to protect larger changes to agent's localState. A few of the places that it tries to protect are: - (a *Agent) AddService(...) # part of the method - (c *Command) handleReload(...) # almost the whole method - (l *localState) antiEntropy(...)# isPaused() prevents syncChanges() The main problem is, that in the middle of handleReload(...)'s critical section it indirectly (loadServices()) calls AddService(...). AddService() in turn calls Pause() to protect itself against syncChanges(). At the end of AddService() a defered call to Resume() is made. With the current implementation, this releases isPaused() "lock" in the middle of handleReload() allowing antiEntropy to kick in while configuration reload is still in progress. Specifically almost all services and probably all check are unloaded when syncChanges() is allowed to run. This in turn can causes massive service/check de-/re-registration, and since checks are by default registered in the critical state, a majority of services on a node can be marked as failing. It's made worse with automation, often calling `consul reload` in close proximity on many nodes in the cluster. This change basically turns Pause()/Resume() into P()/V() of a garden-variety semaphore. Allowing Pause() to be called multiple times, and releasing isPaused() only after all matching/defered Resumes() are called as well. TODO/NOTE: as with many semaphore implementations, it might be reasonable to panic() if l.paused ever becomes negative. |
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| acl | ||
| api | ||
| bench | ||
| command | ||
| consul | ||
| contrib/zsh-completion | ||
| demo/vagrant-cluster | ||
| deps | ||
| scripts | ||
| terraform | ||
| test | ||
| testutil | ||
| tlsutil | ||
| ui | ||
| watch | ||
| website | ||
| .gitignore | ||
| .travis.yml | ||
| CHANGELOG.md | ||
| LICENSE | ||
| Makefile | ||
| README.md | ||
| Vagrantfile | ||
| commands.go | ||
| main.go | ||
| main_test.go | ||
| make.bat | ||
| version.go | ||
README.md
Consul 
- Website: http://www.consul.io
- IRC:
#consulon Freenode - Mailing list: Google Groups
Consul is a tool for service discovery and configuration. Consul is distributed, highly available, and extremely scalable.
Consul provides several key features:
-
Service Discovery - Consul makes it simple for services to register themselves and to discover other services via a DNS or HTTP interface. External services such as SaaS providers can be registered as well.
-
Health Checking - Health Checking enables Consul to quickly alert operators about any issues in a cluster. The integration with service discovery prevents routing traffic to unhealthy hosts and enables service level circuit breakers.
-
Key/Value Storage - A flexible key/value store enables storing dynamic configuration, feature flagging, coordination, leader election and more. The simple HTTP API makes it easy to use anywhere.
-
Multi-Datacenter - Consul is built to be datacenter aware, and can support any number of regions without complex configuration.
Consul runs on Linux, Mac OS X, and Windows. It is recommended to run the Consul servers only on Linux, however.
Quick Start
An extensive quick quick start is viewable on the Consul website:
http://www.consul.io/intro/getting-started/install.html
Documentation
Full, comprehensive documentation is viewable on the Consul website:
Developing Consul
If you wish to work on Consul itself, you'll first need Go installed (version 1.4+ is required). Make sure you have Go properly installed, including setting up your GOPATH.
Next, clone this repository into $GOPATH/src/github.com/hashicorp/consul and
then just type make. In a few moments, you'll have a working consul executable:
$ go get -u ./...
$ make
...
$ bin/consul
...
note: make will also place a copy of the binary in the first part of your $GOPATH
You can run tests by typing make test.
If you make any changes to the code, run make format in order to automatically
format the code according to Go standards.
Building Consul on Windows
Make sure Go 1.4+ is installed on your system and that the Go command is in your %PATH%.
For building Consul on Windows, you also need to have MinGW installed. TDM-GCC is a simple bundle installer which has all the required tools for building Consul with MinGW.
Install TDM-GCC and make sure it has been added to your %PATH%.
If all goes well, you should be able to build Consul by running make.bat from a
command prompt.
See also golang/winstrap and golang/wiki/WindowsBuild for more information of how to set up a general Go build environment on Windows with MinGW.