----- Original Message -----
> From: "Dusmant Kumar Pati" <dp...@redhat.com>
> To: "Kanagaraj" <kmayi...@redhat.com>, "engine-devel" <engine-devel@ovirt.org>
> Sent: Friday, November 29, 2013 1:40:09 PM
> Subject: Re: [Engine-devel] Using config values
>
> On 11/29/2013 01:46 PM, Kanagaraj wrote:
>
>
> Hi All,
>
> The are some issues arising in configurations whenever we move up on the
> versions(3.3 => 3.4), because of the way we store and interpret them.
>
> Whenever there is a new cluster level, you will need to add a new entry for
> all(most) of the configuration. Mostly a copy paste if you see from 3.2 to
> 3.3, except some CPU/PM type related configurations.
> Better option would be to have the defaul config value in ConfigValues.java
> and the overrides will go to config.sql. In this approach you don't need a
> new entries to config.sql when there is a new cluster level.
>
> Lets take an exmaple, "SupportForceCreateVG" - This is supported from 3.1
> onwards,
>
> If you look at config.sql, you will see following entries
> select fn_db_add_config_value('SupportForceCreateVG','false','3.0');
> select fn_db_add_config_value('SupportForceCreateVG','true','3.1');
> select fn_db_add_config_value('SupportForceCreateVG','true','3.2');
> select fn_db_add_config_value('SupportForceCreateVG','true','3.3');
>
> And in ConfigValues.java
>
> @TypeConverterAttribute(Boolean.class)
> @DefaultValueAttribute("false")
> SupportForceCreateVG,
>
> Now if there is 3.4 and 3.5, the user needs to add 2 more entries, which i
> feel is redundant.
>
> Instead we can make
>
> @TypeConverterAttribute(Boolean.class)
> @DefaultValueAttribute("true")
> SupportForceCreateVG,
>
> and have only the following in config.sql
> select fn_db_add_config_value('SupportForceCreateVG','false','3.0');
>
> if a particular value(for a specific cluster level) is not found in
> Config.sql, the fallback is to use the value available in ConfigValues.java.
>
> Please share your thoughts on this.
Hi
First of all I think its a good idea
I have 2 questions
1) Which value will be stored as default in the java class for configuration
values that are not a boolean, that represents if a feature is active or not.
Is that the latest version value ? sounds not obvious to me
2) There are some configuration values that are exposed to the user via the
engine-config tool, how this will work, we can not remove the entries their
since the user may change and override those values.
I have a different suggestion:
Default value will stay as is , meaning , it will reflect the value that should
be used to keep the application running correctly if a value is not found in DB
(which should not occur)
Code of getting configuration value (getConfigValue(<key>,<version>) will be
changed to get the closest version value to the given one.
For example , if a 3.4 version is given for a given <key> and we have in DB
just values for 3.0 and 3.1 , the 3.1 value is returned.
I prefer this solution since it makes the config.sql file self documented ,
showing only value changes and in which version each change occurred.
To implement that, we should add this mechanism to the current code that caches
the DB content and as I see that it should be a simple change.
engine-config should be modified such that if the user change a value, this
value will be inserted to the database with the current release if not exists
and then the mechanism described above will get this value
Example:
VdsFenceType lists all the supported fencing agents for power management , it
currently has the following settings
option_value
| version
---------------------------------------------------------------------------------------------+---------
alom,apc,bladecenter,drac5,eps,ilo,ilo3,ipmilan,rsa,rsb,wti,cisco_ucs
| 3.0
alom,apc,bladecenter,drac5,eps,ilo,ilo3,ipmilan,rsa,rsb,wti,cisco_ucs
| 3.1
apc,apc_snmp,bladecenter,cisco_ucs,drac5,eps,ilo,ilo2,ilo3,ilo4,ipmilan,rsa,rsb,wti
| 3.2
apc,apc_snmp,bladecenter,cisco_ucs,drac5,eps,ilo,ilo2,ilo3,ilo4,ipmilan,rsa,rsb,wti
| 3.3
In the proposed solution, we will have
option_value
| version
---------------------------------------------------------------------------------------------+---------
alom,apc,bladecenter,drac5,eps,ilo,ilo3,ipmilan,rsa,rsb,wti,cisco_ucs
| 3.0
apc,apc_snmp,bladecenter,cisco_ucs,drac5,eps,ilo,ilo2,ilo3,ilo4,ipmilan,rsa,rsb,wti
| 3.2
This is clear and documents only the changes done between versions and serve
all values: boolean , string and complex type (those which requires any kind of
parsing)
What do you think?
Eli
>
> Thanks,
> Kanagaraj
>
>
>
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> I think, this is a good suggestion...
>
>
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