Firstly, I'm going to describe what is cloudy, Cloudy is a distribution based on Debian GNU/Linux, aimed at end users, to foster the transition and adoption of the Community Network cloud environment.
Cloudy use Serf in order to add or delete nodes from Cloudy.
- Transform 4 raspberrys pi on Cloudy distro Cloudyning these.
- Use 1 raspberry as Bootstrap Server.
- Join the other raspberrys to cluster.
- Check the resilence.
- Expose services and watch how Serf through gossip will be able to communicate the changes to other nodes.
sudo apt-get update; sudo apt-get install -y curl lsb-release
curl -k https://raw.githubusercontent.com/Clommunity/cloudynitzar/master/cloudynitzar.sh |sudo bash -- When the process is finished you will be able to connect to 127.0.0.1:7000
cloudy:~$ nc -zv 127.0.0.1 7000
Connection to 127.0.0.1 7000 port [tcp/afs3-fileserver] succeeded!- You can check it in your navigator and you should watch something like:
As I said before, Cloudy uses Serf in order to get Failure detection, Service Discovery with Gossip and Custom Events.
- First of all, I put the first member of the cluster as Bootsrap Server.
pi@raspberrypi:~ $ serf agent -bind=192.168.1.141
==> Starting Serf agent...
==> Starting Serf agent RPC...
==> Serf agent running!
Node name: 'raspberrypi'
Bind addr: '192.168.1.141:7946'
RPC addr: '127.0.0.1:7373'
Encrypted: false
Snapshot: false
Profile: lan
==> Log data will now stream in as it occurs:
2019/03/09 16:46:57 [INFO] agent: Serf agent starting
2019/03/09 16:46:57 [INFO] serf: EventMemberJoin: raspberrypi 192.168.1.141
2019/03/09 16:46:58 [INFO] agent: Received event: member-join
2019/03/09 16:50:02 [INFO] agent.ipc: Accepted client: 127.0.0.1:41974
2019/03/09 16:50:02 [INFO] serf: EventMemberUpdate: raspberrypi
2019/03/09 16:50:03 [INFO] agent: Received event: member-updateThen, I can see the node inside the cluster:
pi@raspberrypi:~ $ serf members
raspberrypi 192.168.1.141:7946 alive - Joining more nodes to cluster:
pi@raspberry-1:~ $ serf agent -join=192.168.1.141 -bind=192.168.1.140
==> Starting Serf agent...
==> Starting Serf agent RPC...
==> Serf agent running!
Node name: 'raspberry-1'
Bind addr: '192.168.1.140:7946'
RPC addr: '127.0.0.1:7373'
Encrypted: false
Snapshot: false
Profile: lan
==> Joining cluster...(replay: false)
Join completed. Synced with 1 initial agents
==> Log data will now stream in as it occurs:
2019/03/09 17:05:36 [INFO] agent: Serf agent starting
2019/03/09 17:05:36 [INFO] serf: EventMemberJoin: raspberry-1 192.168.1.140
2019/03/09 17:05:36 [INFO] agent: joining: [192.168.1.141] replay: false
2019/03/09 17:05:36 [INFO] serf: EventMemberJoin: raspberrypi 192.168.1.141
2019/03/09 17:05:36 [INFO] agent: joined: 1 nodes
2019/03/09 17:05:37 [INFO] agent: Received event: member-joinNOTE: You can see the flag -join in the command, that is the reference to bootstrap server (you could do it from config files too).
pi@raspberrypi:~ $ serf members
raspberrypi 192.168.1.141:7946 alive
raspberry-1 192.168.1.140:7946 alive- I added the last one:
pi@raspberrypi:~ $ serf members
raspberrypi 192.168.1.141:7946 alive
raspberry-1 192.168.1.140:7946 alive
raspberry-1 192.168.1.143:7946 aliveBefore to start to add services I want to test the cluster's resilience.
- I'm going to stop the node which role is bootstrap server.
2019/03/10 09:50:30 [INFO] agent: Received event: member-update
^C==> Caught signal: interrupt
==> Gracefully shutting down agent...
2019/03/10 09:59:41 [INFO] agent: requesting graceful leave from Serf
2019/03/10 09:59:42 [INFO] serf: EventMemberLeave: raspberrypi 192.168.1.141
2019/03/10 09:59:42 [INFO] agent: requesting serf shutdown
2019/03/10 09:59:42 [INFO] agent: shutdown complete- I can see how the node has sent a new event "member-leave" to cluster.
2019/03/10 09:59:42 [INFO] serf: EventMemberLeave: raspberrypi 192.168.1.141
2019/03/10 09:59:43 [INFO] agent: Received event: member-leave- Watching members status again:
pi@raspberry-1:~ $ serf members
raspberrypi 192.168.1.141:7946 left
raspberry-1 192.168.1.140:7946 alive
raspberry-1 192.168.1.143:7946 alive- Addding again the node to whichever 2 nodes with status alive.
pi@raspberrypi:~ $ serf agent -bind=192.168.1.141 -join 192.168.1.140pi@raspberry-1:~ $ serf members
raspberrypi 192.168.1.141:7946 alive
raspberrypi 192.168.1.140:7946 alive
raspberrypi 192.168.1.143:7946 aliveAWESOME: While a node keep alive, you can add as nodes as you want.
Thanks to Cloudy and using avahi-ps script I can publish or unpublish service through Serf:
pi@raspberrypi:~ $ avahi-ps
avahi-ps (Avahi Publish and Search) is a system to publish local services and
discover remote ones using Avahi and other available modules plugged-in.
Usage: /usr/sbin/avahi-ps publish|unpublish|search|info <options>
Examples:
- Publishing a local service to the network:
/usr/sbin/avahi-ps publish <description> <type> <port> [txt]
<description>: a short text describing the service
<type>: service type
<port>: service port
<txt>: additional information, formatted as
'attribute1=value1&attribute2=value2&...&attributeN=valueN'
- Unpublishing a local service to the network
/usr/sbin/avahi-ps unpublish [type] [port]
- Searching for services on the network:
/usr/sbin/avahi-ps search [type] [hostname]
- Showing available information:
/usr/sbin/avahi-ps info <variable>
<variable>: ip|cloud|tincdev|communitydevThis script is calling to avahi-ps-serf adding, searching and deleting tags, it's how Cloudy exposes and propagate services to other nodes.
- I'm going to publish a new service called TEST:
pi@raspberry-1:/etc/init.d $ /usr/sbin/avahi-ps publish TEST TEST TEST TEST
Successfully updated agent tags- Cluster gets the new event:
2019/03/10 11:13:22 [INFO] serf: EventMemberUpdate: raspberry-1
2019/03/10 11:13:23 [INFO] agent: Received event: member-update- And now the command
serf memberslooks like:
pi@raspberry-1:/etc/init.d $ serf members
raspberry-2 192.168.1.143:7946 alive services=QlpoOTFBWSZTWfn5OQ0AABtfgAAQEAcTEAABTQq/p98qIABBEaTNTRoADT1GgxDGExNBgjEMjCZc1Bt4MgWb/IGXhWoBMhGpCJZOxzBYAGrzVDafCo5vimkNvb+qPpelFkCc0O1dTFl4tMWJnkyU1/i7kinChIfPycho
raspberry-1 192.168.1.140:7946 alive services=QlpoOTFBWSZTWWfzP3wAAEdfgAAQEAd3cAIBTQq/p98qIACSCVU2h6kwATAQbII9T0EoVNGmT0jIaNqabQE0MU807XzNcXs4kI0gZ4GWa4RLKRRoTiCmgw0rlBNdT0eSoU6Dx48UJCs4FZuYYUYRHBC6AMWCdjhdrHxp6GNHu4fPpgXEB+P54iaIbxE0ZyPmw5QhUKIxahHnFqGG7kOhdyRThQkGfzP3wA==
raspberrypi 192.168.1.141:7946 alive services=QlpoOTFBWSZTWYyBIrAAACDfgAAQEAU3cAABTQq/p98qIAB0KmamNQAaA00NGmj1CE1DTTTIDTQD1BoCxgGvU1qSGcNuDVCWkQR6RLEbmWzg5wpel4RESCEcNtwe0nBHN0TiZsGXyr89gMVvEZjdByRAu5E6UKOTFfEn8XckU4UJCMgSKwA=- The tag is encoded in base64, I can see what is happening with:
echo "QlpoOTFBWSZTWRYvUqQAAEdfgAAQEAd3cAIBTQq/p98qIACSCVRoeoCYmTAmRtEw1PQShUyaY1DTQNqaPUzSYmmnXgnO/e1xezicmSBlE+ZLGRaCSZCoQU/DDOpQTXU8HcsFOI8ePFCctNpabGGFGERwQugEVgjhuuvV4YZmrB2IPvJcWD50fz1CwQ/Qk0ZwPGw1QhSKIxahHWlaFzd0OxdyRThQkBYvUqQ="|base64 -d - |bunzip2 -
[{"s":"TEST","d":"TEST","m":"raspberry-1.guifi.local","i":"192.168.1.140","p":"TEST","e":"","t":"TEST"},{"s":"tincvpn","d":"TincVPN_System","m":"raspberry-1.guifi.local","i":"192.168.1.140","p":"665","e":"","t":""}]- Or easier than before, I can check services exposed from Cloudy:
- I want to comment that you can expose services from Cloudy console but it is really limited.
At this point, I can say that Cloudy and Serf works very well together. With Serf we have a decentralized cluster membership, added failure detection and orchestration. Cloudy is a little wrapper who is making easier our life.
On the other hand, currently Cloudy doesn't have a huge list of services, so you should use the console in order to add more services to your microcloud or your community cloud.
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