How to add and remove node from docker swarm by Raj Gupta

Note:- We can run any command on only on master not on any worker node, If you run any command on any worker node it will give error.

it will good if Master is in number:- (n-1)/2   -----3,5,7


Master:-

If you want to know the master or worker token key then run below command

Key to join as worker:-

[root@ip-172-31-40-90 ~]# docker swarm join-token worker
To add a worker to this swarm, run the following command:

    docker swarm join --token SWMTKN-1-4z0bipbsxzoy2ccn5m22eiems1w0a5du8rlyt6nbvdq3pfegm8-1z76g4wwivmk1s0cp8dethxav 172.31.40.90:2377

Key to join as master:-

[root@ip-172-31-40-90 ~]# docker swarm join-token manager
To add a manager to this swarm, run the following command:

    docker swarm join --token SWMTKN-1-4z0bipbsxzoy2ccn5m22eiems1w0a5du8rlyt6nbvdq3pfegm8-5go59kirhawvq08kdot5umv0m 172.31.40.90:2377

[root@ip-172-31-40-90 ~]#

[root@ip-172-31-40-90 ~]# docker node ls
ID                            HOSTNAME            STATUS              AVAILABILITY        MANAGER STATUS      ENGINE VERSION
q0yqpe0fsihtmoaj1834s1tnf     ip-172-31-35-189    Ready               Active                                  18.06.1-ce
rby7qdb8hc3ebuuy78vpl0i4v *   ip-172-31-40-90     Ready               Active              Leader              18.06.1-ce
pzcz2fs38ks9vrwecn30txuv9     ip-172-31-43-91     Ready               Active                                  18.06.1-ce
[root@ip-172-31-40-90 ~]#

After Worker02 left

[root@ip-172-31-40-90 ~]# docker node ls
ID                            HOSTNAME            STATUS              AVAILABILITY        MANAGER STATUS      ENGINE VERSION
q0yqpe0fsihtmoaj1834s1tnf     ip-172-31-35-189    Ready               Active                                  18.06.1-ce
rby7qdb8hc3ebuuy78vpl0i4v *   ip-172-31-40-90     Ready               Active              Leader              18.06.1-ce
pzcz2fs38ks9vrwecn30txuv9     ip-172-31-43-91     Down                Active                                  18.06.1-ce
[root@ip-172-31-40-90 ~]#

To remove the Down node(Worker02)

[root@ip-172-31-40-90 ~]# docker node rm pzcz2fs38ks9vrwecn30txuv9
pzcz2fs38ks9vrwecn30txuv9
[root@ip-172-31-40-90 ~]# docker node ls
ID                            HOSTNAME            STATUS              AVAILABILITY        MANAGER STATUS      ENGINE VERSION
q0yqpe0fsihtmoaj1834s1tnf     ip-172-31-35-189    Ready               Active                                  18.06.1-ce
rby7qdb8hc3ebuuy78vpl0i4v *   ip-172-31-40-90     Ready               Active              Leader              18.06.1-ce
[root@ip-172-31-40-90 ~]#

Now to remove active node

[root@ip-172-31-40-90 ~]# docker node rm -f q0yqpe0fsihtmoaj1834s1tnf

q0yqpe0fsihtmoaj1834s1tnf

[root@ip-172-31-40-90 ~]# docker node ls

ID                            HOSTNAME            STATUS              AVAILABILITY        MANAGER STATUS      ENGINE VERSION

rby7qdb8hc3ebuuy78vpl0i4v *   ip-172-31-40-90     Ready               Active              Leader              18.06.1-ce

[root@ip-172-31-40-90 ~]#

Now again to add both worker node run the below command in both worker machine 

docker swarm join --token SWMTKN-1-4z0bipbsxzoy2ccn5m22eiems1w0a5du8rlyt6nbvdq3pfegm8-1z76g4wwivmk1s0cp8dethxav 172.31.40.90:2377

After running the above line in both the worker 

ID                            HOSTNAME            STATUS              AVAILABILITY        MANAGER STATUS      ENGINE VERSION

af3y6rhgp328s777kw26g7co2     ip-172-31-35-189    Ready               Active                                  18.06.1-ce

rby7qdb8hc3ebuuy78vpl0i4v *   ip-172-31-40-90     Ready               Active              Leader              18.06.1-ce

u9sg7rw8yvb75o5ybrnppeglo     ip-172-31-43-91     Ready               Active                                  18.06.1-ce

[root@ip-172-31-40-90 ~]#

again both worker added to cluster 

Worker01:-

After removing forcefully also by master here it will show active ,So to make it inactive run the below command

[root@ip-172-31-35-189 ~]# docker swarm leave
Node left the swarm.
[root@ip-172-31-35-189 ~]#

[root@ip-172-31-35-189 ~]# docker swarm join --token SWMTKN-1-4z0bipbsxzoy2ccn5m22eiems1w0a5du8rlyt6nbvdq3pfegm8-1z76g4wwivmk1s0cp8dethxav 172.31.40.90:2377
This node joined a swarm as a worker.
[root@ip-172-31-35-189 ~]#

Worker02:-

To leave the cluster 

[root@ip-172-31-43-91 ~]# docker swarm leave

Node left the swarm.
[root@ip-172-31-43-91 ~]# docker info

Swarm: inactive

[root@ip-172-31-43-91 ~]# docker swarm join --token SWMTKN-1-4z0bipbsxzoy2ccn5m22eiems1w0a5du8rlyt6nbvdq3pfegm8-1z76g4wwivmk1s0cp8dethxav 172.31.40.90:2377

This node joined a swarm as a worker.

[root@ip-172-31-43-91 ~]#