[ClusterLabs] related to fencing in general , docker containers

[Sridhar K]

Team,

Trying to test docker resource agent , getting below error , any issues
w.r.t below command ?

[root at 5e8851dac338 /]# pcs resource create test_docker2
ocf:heartbeat:docker image=nginx reuse=true  op monitor interval=30s

Docker container nginx is running
[root at 5e8851dac338 /]# docker ps
CONTAINER ID   IMAGE     COMMAND                  CREATED         STATUS
      PORTS                NAMES
3adb20c8a3fc   nginx     "/docker-entrypoint.…"   2 minutes ago   Up 2
minutes   0.0.0.0:80->80/tcp   mynginx1
[

pcs status command :
Failed Resource action
* test_docker2_stop_0 on 450196e74dc0 'unknown error' (1): call=42,
status=complete, exitreason='Docker service is in error state while
checking for test_docker2, based on image, nginx: Client: Docker Engine -
Community',
    last-rc-change='Sun Jun 19 20:51:58 2022', queued=0ms, exec=97ms

regards
Sridhar






On Sun, 19 Jun 2022 at 15:40, Sridhar K <sriatk at gmail.com> wrote:

> Thank you Ken,Andrei for the response
>
> As of now, I have completed the below  (below is for POC purpose) Ideally
> there will be 3 VM's and each VM will have one docker container
> [pacemaker + corosync + sqlServer] same network
> 1.Created a docker image with [pacemaker + corosync + sqlServer]
> 2. Created a docker network and brought up 3 containers of the above image
> which are part of the created network
> 3. Created  a pacemaker cluster out of 3 containers
> 4. Create AG group of sqlserver
> 5. Tested failover of Sqlserver , by making a container(i,e pcs cluster
> standby container id) to standby , failover was working.
>
> All above was in a VM , now need to think w.r.t fencing
> As the pacemaker is running within the docker container anything w.r.t
> fencing may not help
> next was checking, how about doing something w.r.t fencing at VM level so
> that fencing can kill/restart the docker container as required.
>
> considering 3 VMs
> If 1 VM itself goes down , SqlServer will be still up as two VM's are fine
> and within them, docker containers (pacemaker + corosync + sqlServer) are
> running
> If 2 VM goes down , then SqlServer will not be available.
>
>
> Related to Bundles
> I tried, and got an error posted the same  in the forum, also in Bundles
> required number of replicas will be spawned, How can I configure out of 3
> replicas which will be my master Sqlserver and the rest will be replicas
>
>
> Hi Ken,
> will check this, if am able to fence docker containers(pacemaker +
> corosync + sqlServer), it should be of some help, and will check how to
> handle VM failures
>
> You
> > will probably need one fencing agent for each physical host where
> > docker
> > is running and map cluster nodes (containers) to the correct agent
> > (i.e.
> > physical host).
>
> Regards
> Sridhar
>
>
>
>
> On Fri, 17 Jun 2022 at 20:29, Andrei Borzenkov <arvidjaar at gmail.com>
> wrote:
>
>> On 17.06.2022 16:53, Sridhar K wrote:
>> > Hi Team,
>> >
>> > Please share any pointers, references, example usage's w.r.t fencing in
>> > general and its use w.r.t docker containers.
>> >
>> > referring as of now
>> > https://clusterlabs.org/pacemaker/doc/crm_fencing.html
>> >
>> > need to check the feasibility of fencing w.r.t docker containers
>> >
>>
>> There is fence_docker, you will need to configure docker on each
>> physical host to accept remote connections from each cluster node. You
>> will probably need one fencing agent for each physical host where docker
>> is running and map cluster nodes (containers) to the correct agent (i.e.
>> physical host).
>>
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