coreos up and running etcd

info

1. open source

2. distibuted key value store

3. using raft algorithm

ops

1. reading and writing to etcd

   1. logging into the host

       $ cd coreos-vagrant
       $ vagrant up
       $ vagrant ssh
      

   2. from host machine

       # 1. set get
       $ etcdctl set /message1 book1
       $ etcdctl get /message1
      
       # 2. set get
       $ curl -L -X PUT http://127.0.0.1:2379/v2/keys/message2 -d value="book2"
       $ curl -L http://127.0.0.1:2379/v2/keys/message2
      
       # 3. delete
       $ etcdctl rm /message1
       $ curl -L -X DELETE http://127.0.0.1:2379/v2/keys/message2
      
       # 4. key value pair
       $ etcdctl set /foo-dict/foo-key somekey
       $ etcdctl ls  /foo-dict --recursive
       /foo-dict/foo-key
      		
       $etcdctl get /foo-dict/foo-key
       somekey
      

   3. from application container

       # 1. check docker0's ip
       $ echo "$(ifconfig docker0 | awk '/\<inet\>/ { print $2 }'):2379"
       192.168.99.100:2379
      
       # 2. run bash shell
       $ docker run -it alpine ash
      
       # 3. install curl to alpine linux
       $ apk update && apk add curl
       $ curl -L http://192.168.99.100:2379/v2/keys
      
       # 4. exit
       $ ^+d
      

2. watching changes in etcd

   1. create a dir in etcd

       $ etcdctl mkdir /foo-data
      

   2. watch for changes in this directory

       $ etcdctl watch /foo-data --recursive
      

   3. open new terminal

       $ cd coreos-vagrant
       $ vagrant ssh
      

   4. add a new key to /foo-data directory

       $ etcdctl set /foo-data/book is_cool
      

   5. in first terminal should see a notification

       is_cool
      

3. ttl

   1. set a ttl to 30 sec

       $ etcdctl set /foo "i'm expiring in 30 sec" --ttl 30
      

   2. verify that the key is still there

       $ etcdctl get /foo
       i'm expiring in 30 sec
      

   3. check again after 30 sec

       $ etcdctl get /foo
       Error: 100: Key not found (/foo) [17053]