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backend has no server available!

Posted by DHAVAL JAISWAL 
DHAVAL JAISWAL
backend has no server available!
November 13, 2017 08:40AM
I had the following config where we are using AWS ELB for load balancing.
However, now we are keep getting backend test_cluster has no server
available!

Under this ELB two servers attached. Both instance are in healthy state.
Healthy state we are checking on port 80 and tomcat response sending on
port 8080

internal-testtomcatautoscale-1314784611.ap-southeast-1.elb.amazonaws.com


resolvers testresolver
nameserver dns1 169.254.169.253:53
resolve_retries 3
timeout retry 1s
hold valid 10s

backend test_cluster
mode http
option forwardfor
fullconn 10000
option httpchk /test-testalive
http-check expect string OK
option http-server-close
option abortonclose
balance roundrobin
server server1
internal-testtomcatautoscale-1314784611.ap-southeast-1.elb.amazonaws.com:8080
check resolvers testresolver


What could be the cause of this issue. How can i fix it.
James Stroehmann
RE: backend has no server available!
November 13, 2017 01:40PM
I had a similar problem, and I believe reducing my ‘hold valid’ setting to 1s fixed it.


From: DHAVAL JAISWAL [mailto:[email protected]]
Sent: Monday, November 13, 2017 2:31 AM
To: HAproxy Mailing Lists <[email protected]>
Subject: backend has no server available!

[External Email]
I had the following config where we are using AWS ELB for load balancing. However, now we are keep getting backend test_cluster has no server available!

Under this ELB two servers attached. Both instance are in healthy state. Healthy state we are checking on port 80 and tomcat response sending on port 8080

internal-testtomcatautoscale-1314784611.ap-southeast-1.elb.amazonaws.comhttp://internal-testtomcatautoscale-1314784611.ap-southeast-1.elb.amazonaws.com


resolvers testresolver
nameserver dns1 169.254.169.253:53http://169.254.169.253:53
resolve_retries 3
timeout retry 1s
hold valid 10s

backend test_cluster
mode http
option forwardfor
fullconn 10000
option httpchk /test-testalive
http-check expect string OK
option http-server-close
option abortonclose
balance roundrobin
server server1 internal-testtomcatautoscale-1314784611.ap-southeast-1.elb.amazonaws.com:8080http://internal-testtomcatautoscale-1314784611.ap-southeast-1.elb.amazonaws.com:8080 check resolvers testresolver


What could be the cause of this issue. How can i fix it.
DHAVAL JAISWAL
Re: backend has no server available!
November 13, 2017 02:40PM
I will apply the suggested setting.

Any other parameters need to modify or add here.

On Mon, Nov 13, 2017 at 5:58 PM, James Stroehmann <
[email protected]> wrote:

> I had a similar problem, and I believe reducing my ‘hold valid’ setting to
> 1s fixed it.
>
>
>
>
>
> *From:* DHAVAL JAISWAL [mailto:[email protected]]
> *Sent:* Monday, November 13, 2017 2:31 AM
> *To:* HAproxy Mailing Lists <[email protected]>
> *Subject:* backend has no server available!
>
>
>
> [External Email]
>
> I had the following config where we are using AWS ELB for load balancing.
> However, now we are keep getting backend test_cluster has no server
> available!
>
>
>
> Under this ELB two servers attached. Both instance are in healthy state.
> Healthy state we are checking on port 80 and tomcat response sending on
> port 8080
>
>
>
> internal-testtomcatautoscale-1314784611.ap-southeast-1.elb.amazonaws.com
>
>
>
>
>
> resolvers testresolver
>
> nameserver dns1 169.254.169.253:53
>
> resolve_retries 3
>
> timeout retry 1s
>
> hold valid 10s
>
>
>
> backend test_cluster
>
> mode http
>
> option forwardfor
>
> fullconn 10000
>
> option httpchk /test-testalive
>
> http-check expect string OK
>
> option http-server-close
>
> option abortonclose
>
> balance roundrobin
>
> server server1 internal-testtomcatautoscale-1314784611.ap-southeast-1.elb..
> amazonaws.com:8080 check resolvers testresolver
>
>
>
>
>
> What could be the cause of this issue. How can i fix it.
>
>
>



--
Thanks & Regards
Dhaval Jaiswal
Igor Cicimov
Re: backend has no server available!
November 14, 2017 12:40AM
On Mon, Nov 13, 2017 at 11:28 PM, James Stroehmann <
[email protected]> wrote:

> I had a similar problem, and I believe reducing my ‘hold valid’ setting to
> 1s fixed it.
>
>
>
>
>

​Possible explanation is the "inter" parameter which is by default set to
2s for the "check" operation, see
https://cbonte.github.io/haproxy-dconv/1.7/configuration.html#inter for
details.

In other words, read the docs about ALL timeouts set in Haproxy to figure
out how they correlate between each other and how to set the proper values
for your user case.​




> *From:* DHAVAL JAISWAL [mailto:[email protected]]
> *Sent:* Monday, November 13, 2017 2:31 AM
> *To:* HAproxy Mailing Lists <[email protected]>
> *Subject:* backend has no server available!
>
>
>
> [External Email]
>
> I had the following config where we are using AWS ELB for load balancing.
> However, now we are keep getting backend test_cluster has no server
> available!
>
>
>
> Under this ELB two servers attached. Both instance are in healthy state.
> Healthy state we are checking on port 80 and tomcat response sending on
> port 8080
>
>
>
> internal-testtomcatautoscale-1314784611.ap-southeast-1.elb.amazonaws.com
>
>
>
>
>
> resolvers testresolver
>
> nameserver dns1 169.254.169.253:53
>
> resolve_retries 3
>
> timeout retry 1s
>
> hold valid 10s
>
>
>
> backend test_cluster
>
> mode http
>
> option forwardfor
>
> fullconn 10000
>
> option httpchk /test-testalive
>
> http-check expect string OK
>
> option http-server-close
>
> option abortonclose
>
> balance roundrobin
>
> server server1 internal-testtomcatautoscale-1314784611.ap-southeast-1.elb..
> amazonaws.com:8080 check resolvers testresolver
>
>
>
>
>
> What could be the cause of this issue. How can i fix it.
>
>
>



--
Igor Cicimov | DevOps


p. +61 (0) 433 078 728
e. igorc@encompasscorporation.com http://encompasscorporation.com/
w*.* www.encompasscorporation.com
a. Level 4, 65 York Street, Sydney 2000
DHAVAL JAISWAL
Re: backend has no server available!
November 14, 2017 06:10PM
Even after reducing "hold valid" to 1s shows the same behavior.

One more observation is that after introducing ELB in haproxy config, site
seems to have little late response.

Provided link is helpful, however if any one face same issue or can share
experience to solve it will be really helpful.

On Tue, Nov 14, 2017 at 5:00 AM, Igor Cicimov <
[email protected]> wrote:

>
>
> On Mon, Nov 13, 2017 at 11:28 PM, James Stroehmann <
> [email protected]> wrote:
>
>> I had a similar problem, and I believe reducing my ‘hold valid’ setting
>> to 1s fixed it.
>>
>>
>>
>>
>>
>
> ​Possible explanation is the "inter" parameter which is by default set to
> 2s for the "check" operation, see https://cbonte.github.io/
> haproxy-dconv/1.7/configuration.html#inter for details.
>
> In other words, read the docs about ALL timeouts set in Haproxy to figure
> out how they correlate between each other and how to set the proper values
> for your user case.​
>
>
>
>
>> *From:* DHAVAL JAISWAL [mailto:[email protected]]
>> *Sent:* Monday, November 13, 2017 2:31 AM
>> *To:* HAproxy Mailing Lists <[email protected]>
>> *Subject:* backend has no server available!
>>
>>
>>
>> [External Email]
>>
>> I had the following config where we are using AWS ELB for load balancing..
>> However, now we are keep getting backend test_cluster has no server
>> available!
>>
>>
>>
>> Under this ELB two servers attached. Both instance are in healthy state.
>> Healthy state we are checking on port 80 and tomcat response sending on
>> port 8080
>>
>>
>>
>> internal-testtomcatautoscale-1314784611.ap-southeast-1.elb.amazonaws.com
>>
>>
>>
>>
>>
>> resolvers testresolver
>>
>> nameserver dns1 169.254.169.253:53
>>
>> resolve_retries 3
>>
>> timeout retry 1s
>>
>> hold valid 10s
>>
>>
>>
>> backend test_cluster
>>
>> mode http
>>
>> option forwardfor
>>
>> fullconn 10000
>>
>> option httpchk /test-testalive
>>
>> http-check expect string OK
>>
>> option http-server-close
>>
>> option abortonclose
>>
>> balance roundrobin
>>
>> server server1 internal-testtomcatautoscale-1
>> 314784611.ap-southeast-1.elb.amazonaws.com:8080 check resolvers
>> testresolver
>>
>>
>>
>>
>>
>> What could be the cause of this issue. How can i fix it.
>>
>>
>>
>
>
>
> --
> Igor Cicimov | DevOps
>
>
> p. +61 (0) 433 078 728
> e. igorc@encompasscorporation.com http://encompasscorporation.com/
> w*.* www.encompasscorporation.com
> a. Level 4, 65 York Street, Sydney 2000
> https://maps.google.com/?q=Level+4,+65+York+Street,+Sydney+2000&entry=gmail&source=g
>



--
Thanks & Regards
Dhaval Jaiswal
Igor Cicimov
Re: backend has no server available!
November 15, 2017 12:00AM
Dhaval,

What I put in my resolvers is the EC2 instance subnet dns server which for
EC2 is always the second IP of the subnet range, xxx.xxx.xxx..2

You can also find this IP in your /etc/resolv.conf on the haproxy
instances. Try replacing

169.254.169.253:53 with that value and see how you go.

On Wed, Nov 15, 2017 at 4:04 AM, DHAVAL JAISWAL <[email protected]> wrote:

> Even after reducing "hold valid" to 1s shows the same behavior.
>
> One more observation is that after introducing ELB in haproxy config, site
> seems to have little late response.
>
> Provided link is helpful, however if any one face same issue or can share
> experience to solve it will be really helpful.
>
> On Tue, Nov 14, 2017 at 5:00 AM, Igor Cicimov <[email protected]
> com> wrote:
>
>>
>>
>> On Mon, Nov 13, 2017 at 11:28 PM, James Stroehmann <
>> [email protected]> wrote:
>>
>>> I had a similar problem, and I believe reducing my ‘hold valid’ setting
>>> to 1s fixed it.
>>>
>>>
>>>
>>>
>>>
>>
>> ​Possible explanation is the "inter" parameter which is by default set to
>> 2s for the "check" operation, see https://cbonte.github.io/hapro
>> xy-dconv/1.7/configuration.html#inter for details.
>>
>> In other words, read the docs about ALL timeouts set in Haproxy to figure
>> out how they correlate between each other and how to set the proper values
>> for your user case.​
>>
>>
>>
>>
>>> *From:* DHAVAL JAISWAL [mailto:[email protected]]
>>> *Sent:* Monday, November 13, 2017 2:31 AM
>>> *To:* HAproxy Mailing Lists <[email protected]>
>>> *Subject:* backend has no server available!
>>>
>>>
>>>
>>> [External Email]
>>>
>>> I had the following config where we are using AWS ELB for load
>>> balancing. However, now we are keep getting backend test_cluster has no
>>> server available!
>>>
>>>
>>>
>>> Under this ELB two servers attached. Both instance are in healthy state..
>>> Healthy state we are checking on port 80 and tomcat response sending on
>>> port 8080
>>>
>>>
>>>
>>> internal-testtomcatautoscale-1314784611.ap-southeast-1.elb.amazonaws.com
>>>
>>>
>>>
>>>
>>>
>>> resolvers testresolver
>>>
>>> nameserver dns1 http://169.254.169.253:53
>>> ​​ http://169.254.169.253:53
>>> 169.254.169.253:53
>>>
>>> resolve_retries 3
>>>
>>> timeout retry 1s
>>>
>>> hold valid 10s
>>>
>>>
>>>
>>> backend test_cluster
>>>
>>> mode http
>>>
>>> option forwardfor
>>>
>>> fullconn 10000
>>>
>>> option httpchk /test-testalive
>>>
>>> http-check expect string OK
>>>
>>> option http-server-close
>>>
>>> option abortonclose
>>>
>>> balance roundrobin
>>>
>>> server server1 internal-testtomcatautoscale-1
>>> 314784611.ap-southeast-1.elb.amazonaws.com:8080 check resolvers
>>> testresolver
>>>
>>>
>>>
>>>
>>>
>>> What could be the cause of this issue. How can i fix it.
>>>
>>>
>>>
>>
DHAVAL JAISWAL
Re: backend has no server available!
November 15, 2017 01:00PM
I did apply that and its under observation.

There is one more issue after introducing Internal ELB is overall
performance of site is slightly reduced. The response which I used to get
in less than 100 ms now some time is going beyond 100 ms.

Any clue how can I improve it.

On Wed, Nov 15, 2017 at 4:21 AM, Igor Cicimov <
[email protected]> wrote:

> Dhaval,
>
> What I put in my resolvers is the EC2 instance subnet dns server which for
> EC2 is always the second IP of the subnet range, xxx.xxx.xxx..2
>
> You can also find this IP in your /etc/resolv.conf on the haproxy
> instances. Try replacing
> ​
> 169.254.169.253:53 with that value and see how you go.
>
> On Wed, Nov 15, 2017 at 4:04 AM, DHAVAL JAISWAL <[email protected]>
> wrote:
>
>> Even after reducing "hold valid" to 1s shows the same behavior.
>>
>> One more observation is that after introducing ELB in haproxy config,
>> site seems to have little late response.
>>
>> Provided link is helpful, however if any one face same issue or can share
>> experience to solve it will be really helpful.
>>
>> On Tue, Nov 14, 2017 at 5:00 AM, Igor Cicimov <
>> [email protected]> wrote:
>>
>>>
>>>
>>> On Mon, Nov 13, 2017 at 11:28 PM, James Stroehmann <
>>> [email protected]> wrote:
>>>
>>>> I had a similar problem, and I believe reducing my ‘hold valid’ setting
>>>> to 1s fixed it.
>>>>
>>>>
>>>>
>>>>
>>>>
>>>
>>> ​Possible explanation is the "inter" parameter which is by default set
>>> to 2s for the "check" operation, see https://cbonte.github.io/hapro
>>> xy-dconv/1.7/configuration.html#inter for details.
>>>
>>> In other words, read the docs about ALL timeouts set in Haproxy to
>>> figure out how they correlate between each other and how to set the proper
>>> values for your user case.​
>>>
>>>
>>>
>>>
>>>> *From:* DHAVAL JAISWAL [mailto:[email protected]]
>>>> *Sent:* Monday, November 13, 2017 2:31 AM
>>>> *To:* HAproxy Mailing Lists <[email protected]>
>>>> *Subject:* backend has no server available!
>>>>
>>>>
>>>>
>>>> [External Email]
>>>>
>>>> I had the following config where we are using AWS ELB for load
>>>> balancing. However, now we are keep getting backend test_cluster has no
>>>> server available!
>>>>
>>>>
>>>>
>>>> Under this ELB two servers attached. Both instance are in healthy
>>>> state. Healthy state we are checking on port 80 and tomcat response sending
>>>> on port 8080
>>>>
>>>>
>>>>
>>>> internal-testtomcatautoscale-1314784611.ap-southeast-1.elb.a
>>>> mazonaws.com
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> resolvers testresolver
>>>>
>>>> nameserver dns1 http://169.254.169.253:53
>>>> ​​ http://169.254.169.253:53
>>>> 169.254.169.253:53
>>>>
>>>> resolve_retries 3
>>>>
>>>> timeout retry 1s
>>>>
>>>> hold valid 10s
>>>>
>>>>
>>>>
>>>> backend test_cluster
>>>>
>>>> mode http
>>>>
>>>> option forwardfor
>>>>
>>>> fullconn 10000
>>>>
>>>> option httpchk /test-testalive
>>>>
>>>> http-check expect string OK
>>>>
>>>> option http-server-close
>>>>
>>>> option abortonclose
>>>>
>>>> balance roundrobin
>>>>
>>>> server server1 internal-testtomcatautoscale-1
>>>> 314784611.ap-southeast-1.elb.amazonaws.com:8080 check resolvers
>>>> testresolver
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> What could be the cause of this issue. How can i fix it.
>>>>
>>>>
>>>>
>>>


--
Thanks & Regards
Dhaval Jaiswal
DHAVAL JAISWAL
Re: backend has no server available!
November 15, 2017 01:40PM
Some more information while showing backend not available.

Server test_cluster/server1 is DOWN, reason: Layer7 timeout, check
duration: 2001ms. 0 active and 0 backup servers left. 3 sessions active, 0
requeued, 0 remaining in queue.
backend test_cluster has no server available!
Server test_cluster/server1 is DOWN, reason: Layer7 timeout, check
duration: 2001ms. 0 active and 0 backup servers left. 1 sessions active, 0
requeued, 0 remaining in queue.
backend test_cluster has no server available!
Server test_cluster server1 is UP, reason: Layer7 check passed, code: 200,
info: "HTTP content check matched", check duration: 1ms. 1 active and 0
backup servers online. 0 sessions requeued, 0 total in queue.




On Wed, Nov 15, 2017 at 5:20 PM, DHAVAL JAISWAL <[email protected]> wrote:

> I did apply that and its under observation.
>
> There is one more issue after introducing Internal ELB is overall
> performance of site is slightly reduced. The response which I used to get
> in less than 100 ms now some time is going beyond 100 ms.
>
> Any clue how can I improve it.
>
> On Wed, Nov 15, 2017 at 4:21 AM, Igor Cicimov <[email protected]
> com> wrote:
>
>> Dhaval,
>>
>> What I put in my resolvers is the EC2 instance subnet dns server which
>> for EC2 is always the second IP of the subnet range, xxx.xxx.xxx..2
>>
>> You can also find this IP in your /etc/resolv.conf on the haproxy
>> instances. Try replacing
>> ​
>> 169.254.169.253:53 with that value and see how you go.
>>
>> On Wed, Nov 15, 2017 at 4:04 AM, DHAVAL JAISWAL <[email protected]>
>> wrote:
>>
>>> Even after reducing "hold valid" to 1s shows the same behavior.
>>>
>>> One more observation is that after introducing ELB in haproxy config,
>>> site seems to have little late response.
>>>
>>> Provided link is helpful, however if any one face same issue or can
>>> share experience to solve it will be really helpful.
>>>
>>> On Tue, Nov 14, 2017 at 5:00 AM, Igor Cicimov <
>>> [email protected]> wrote:
>>>
>>>>
>>>>
>>>> On Mon, Nov 13, 2017 at 11:28 PM, James Stroehmann <
>>>> [email protected]> wrote:
>>>>
>>>>> I had a similar problem, and I believe reducing my ‘hold valid’
>>>>> setting to 1s fixed it.
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>
>>>> ​Possible explanation is the "inter" parameter which is by default set
>>>> to 2s for the "check" operation, see https://cbonte.github.io/hapro
>>>> xy-dconv/1.7/configuration.html#inter for details.
>>>>
>>>> In other words, read the docs about ALL timeouts set in Haproxy to
>>>> figure out how they correlate between each other and how to set the proper
>>>> values for your user case.​
>>>>
>>>>
>>>>
>>>>
>>>>> *From:* DHAVAL JAISWAL [mailto:[email protected]]
>>>>> *Sent:* Monday, November 13, 2017 2:31 AM
>>>>> *To:* HAproxy Mailing Lists <[email protected]>
>>>>> *Subject:* backend has no server available!
>>>>>
>>>>>
>>>>>
>>>>> [External Email]
>>>>>
>>>>> I had the following config where we are using AWS ELB for load
>>>>> balancing. However, now we are keep getting backend test_cluster has no
>>>>> server available!
>>>>>
>>>>>
>>>>>
>>>>> Under this ELB two servers attached. Both instance are in healthy
>>>>> state. Healthy state we are checking on port 80 and tomcat response sending
>>>>> on port 8080
>>>>>
>>>>>
>>>>>
>>>>> internal-testtomcatautoscale-1314784611.ap-southeast-1.elb.a
>>>>> mazonaws.com
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> resolvers testresolver
>>>>>
>>>>> nameserver dns1 http://169.254.169.253:53
>>>>> ​​ http://169.254.169.253:53
>>>>> 169.254.169.253:53
>>>>>
>>>>> resolve_retries 3
>>>>>
>>>>> timeout retry 1s
>>>>>
>>>>> hold valid 10s
>>>>>
>>>>>
>>>>>
>>>>> backend test_cluster
>>>>>
>>>>> mode http
>>>>>
>>>>> option forwardfor
>>>>>
>>>>> fullconn 10000
>>>>>
>>>>> option httpchk /test-testalive
>>>>>
>>>>> http-check expect string OK
>>>>>
>>>>> option http-server-close
>>>>>
>>>>> option abortonclose
>>>>>
>>>>> balance roundrobin
>>>>>
>>>>> server server1 internal-testtomcatautoscale-1
>>>>> 314784611.ap-southeast-1.elb.amazonaws.com:8080 check resolvers
>>>>> testresolver
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> What could be the cause of this issue. How can i fix it.
>>>>>
>>>>>
>>>>>
>>>>
>
>
> --
> Thanks & Regards
> Dhaval Jaiswal
>



--
Thanks & Regards
Dhaval Jaiswal
Igor Cicimov
Re: backend has no server available!
November 16, 2017 01:20AM
Dhaval,

Looking again into your config, what is this:

option httpchk /test-testalive

suppose to be testing? Looks like instead of testing the ELB as an endpoint
you are actually testing your application so the timeouts are comming from
your app and not the ELB. I would suggest you remove that option and let
HAP do a simple tcp check to health check the ELB and not your app.


On Wed, Nov 15, 2017 at 11:26 PM, DHAVAL JAISWAL <[email protected]> wrote:

> Some more information while showing backend not available.
>
> Server test_cluster/server1 is DOWN, reason: Layer7 timeout, check
> duration: 2001ms. 0 active and 0 backup servers left. 3 sessions active, 0
> requeued, 0 remaining in queue.
> backend test_cluster has no server available!
> Server test_cluster/server1 is DOWN, reason: Layer7 timeout, check
> duration: 2001ms. 0 active and 0 backup servers left. 1 sessions active, 0
> requeued, 0 remaining in queue.
> backend test_cluster has no server available!
> Server test_cluster server1 is UP, reason: Layer7 check passed, code:
> 200, info: "HTTP content check matched", check duration: 1ms. 1 active and
> 0 backup servers online. 0 sessions requeued, 0 total in queue.
>
>
>
>
> On Wed, Nov 15, 2017 at 5:20 PM, DHAVAL JAISWAL <[email protected]>
> wrote:
>
>> I did apply that and its under observation.
>>
>> There is one more issue after introducing Internal ELB is overall
>> performance of site is slightly reduced. The response which I used to get
>> in less than 100 ms now some time is going beyond 100 ms.
>>
>> Any clue how can I improve it.
>>
>> On Wed, Nov 15, 2017 at 4:21 AM, Igor Cicimov <
>> [email protected]> wrote:
>>
>>> Dhaval,
>>>
>>> What I put in my resolvers is the EC2 instance subnet dns server which
>>> for EC2 is always the second IP of the subnet range, xxx.xxx.xxx..2
>>>
>>> You can also find this IP in your /etc/resolv.conf on the haproxy
>>> instances. Try replacing
>>> ​
>>> 169.254.169.253:53 with that value and see how you go.
>>>
>>> On Wed, Nov 15, 2017 at 4:04 AM, DHAVAL JAISWAL <[email protected]>
>>> wrote:
>>>
>>>> Even after reducing "hold valid" to 1s shows the same behavior.
>>>>
>>>> One more observation is that after introducing ELB in haproxy config,
>>>> site seems to have little late response.
>>>>
>>>> Provided link is helpful, however if any one face same issue or can
>>>> share experience to solve it will be really helpful.
>>>>
>>>> On Tue, Nov 14, 2017 at 5:00 AM, Igor Cicimov <
>>>> [email protected]> wrote:
>>>>
>>>>>
>>>>>
>>>>> On Mon, Nov 13, 2017 at 11:28 PM, James Stroehmann <
>>>>> [email protected]> wrote:
>>>>>
>>>>>> I had a similar problem, and I believe reducing my ‘hold valid’
>>>>>> setting to 1s fixed it.
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>> ​Possible explanation is the "inter" parameter which is by default set
>>>>> to 2s for the "check" operation, see https://cbonte.github.io/hapro
>>>>> xy-dconv/1.7/configuration.html#inter for details.
>>>>>
>>>>> In other words, read the docs about ALL timeouts set in Haproxy to
>>>>> figure out how they correlate between each other and how to set the proper
>>>>> values for your user case.​
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>> *From:* DHAVAL JAISWAL [mailto:[email protected]]
>>>>>> *Sent:* Monday, November 13, 2017 2:31 AM
>>>>>> *To:* HAproxy Mailing Lists <[email protected]>
>>>>>> *Subject:* backend has no server available!
>>>>>>
>>>>>>
>>>>>>
>>>>>> [External Email]
>>>>>>
>>>>>> I had the following config where we are using AWS ELB for load
>>>>>> balancing. However, now we are keep getting backend test_cluster has no
>>>>>> server available!
>>>>>>
>>>>>>
>>>>>>
>>>>>> Under this ELB two servers attached. Both instance are in healthy
>>>>>> state. Healthy state we are checking on port 80 and tomcat response sending
>>>>>> on port 8080
>>>>>>
>>>>>>
>>>>>>
>>>>>> internal-testtomcatautoscale-1314784611.ap-southeast-1.elb.a
>>>>>> mazonaws.com
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> resolvers testresolver
>>>>>>
>>>>>> nameserver dns1 http://169.254.169.253:53
>>>>>> ​​ http://169.254.169.253:53
>>>>>> 169.254.169.253:53
>>>>>>
>>>>>> resolve_retries 3
>>>>>>
>>>>>> timeout retry 1s
>>>>>>
>>>>>> hold valid 10s
>>>>>>
>>>>>>
>>>>>>
>>>>>> backend test_cluster
>>>>>>
>>>>>> mode http
>>>>>>
>>>>>> option forwardfor
>>>>>>
>>>>>> fullconn 10000
>>>>>>
>>>>>> option httpchk /test-testalive
>>>>>>
>>>>>> http-check expect string OK
>>>>>>
>>>>>> option http-server-close
>>>>>>
>>>>>> option abortonclose
>>>>>>
>>>>>> balance roundrobin
>>>>>>
>>>>>> server server1 internal-testtomcatautoscale-1
>>>>>> 314784611.ap-southeast-1.elb.amazonaws.com:8080 check resolvers
>>>>>> testresolver
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> What could be the cause of this issue. How can i fix it.
>>>>>>
>>>>>>
>>>>>>
>>>>>
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