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On 07/04/14 00:27, Steve Baker wrote:
> On 05/04/14 04:47, Tomas Sedovic wrote:
>> Hi All,
>>
>> I was wondering if the time has come to document what exactly are we
>> doing with tripleo-heat-templates and merge.py[1], figure out what needs
>> to happen to move away and raise the necessary blueprints on Heat and
>> TripleO side.
>>
>> (merge.py is a script we use to build the final TripleO Heat templates
>> from smaller chunks)
>>
>> There probably isn't an immediate need for us to drop merge.py, but its
>> existence either indicates deficiencies within Heat or our unfamiliarity
>> with some of Heat's features (possibly both).
>>
>> I worry that the longer we stay with merge.py the harder it will be to
>> move forward. We're still adding new features and fixing bugs in it (at
>> a slow pace but still).
>>
>> Below is my understanding of the main marge.py functionality and a rough
>> plan of what I think might be a good direction to move to. It is almost
>> certainly incomplete -- please do poke holes in this. I'm hoping we'll
>> get to a point where everyone's clear on what exactly merge.py does and
>> why. We can then document that and raise the appropriate blueprints.
>>
>>
>> ## merge.py features ##
>>
>>
>> 1. Merging parameters and resources
>>
>> Any uniquely-named parameters and resources from multiple templates are
>> put together into the final template.
>>
>> If a resource of the same name is in multiple templates, an error is
>> raised. Unless it's of a whitelisted type (nova server, launch
>> configuration, etc.) in which case they're all merged into a single
>> resource.
>>
>> For example: merge.py overcloud-source.yaml swift-source.yaml
>>
>> The final template has all the parameters from both. Moreover, these two
>> resources will be joined together:
>>
>> #### overcloud-source.yaml ####
>>
>>   notCompute0Config:
>>     Type: AWS::AutoScaling::LaunchConfiguration
>>     Properties:
>>       ImageId: '0'
>>       InstanceType: '0'
>>     Metadata:
>>       admin-password: {Ref: AdminPassword}
>>       admin-token: {Ref: AdminToken}
>>       bootstack:
>>         public_interface_ip:
>>           Ref: NeutronPublicInterfaceIP
>>
>>
>> #### swift-source.yaml ####
>>
>>   notCompute0Config:
>>     Type: AWS::AutoScaling::LaunchConfiguration
>>     Metadata:
>>       swift:
>>         devices:
>>           ...
>>         hash: {Ref: SwiftHashSuffix}
>>         service-password: {Ref: SwiftPassword}
>>
>>
>> The final template will contain:
>>
>>   notCompute0Config:
>>     Type: AWS::AutoScaling::LaunchConfiguration
>>     Properties:
>>       ImageId: '0'
>>       InstanceType: '0'
>>     Metadata:
>>       admin-password: {Ref: AdminPassword}
>>       admin-token: {Ref: AdminToken}
>>       bootstack:
>>         public_interface_ip:
>>           Ref: NeutronPublicInterfaceIP
>>       swift:
>>         devices:
>>           ...
>>         hash: {Ref: SwiftHashSuffix}
>>         service-password: {Ref: SwiftPassword}
>>
>>
>> We use this to keep the templates more manageable (instead of having one
>> huge file) and also to be able to pick the components we want: instead
>> of `undercloud-bm-source.yaml` we can pick `undercloud-vm-source` (which
>> uses the VirtualPowerManager driver) or `ironic-vm-source`.
>>
>>
>>
>> 2. FileInclude
>>
>> If you have a pseudo resource with the type of `FileInclude`, we will
>> look at the specified Path and SubKey and put the resulting dictionary in:
>>
>> #### overcloud-source.yaml ####
>>
>>   NovaCompute0Config:
>>     Type: FileInclude
>>     Path: nova-compute-instance.yaml
>>     SubKey: Resources.NovaCompute0Config
>>     Parameters:
>>       NeutronNetworkType: "gre"
>>       NeutronEnableTunnelling: "True"
>>
>>
>> #### nova-compute-instance.yaml ####
>>
>>   NovaCompute0Config:
>>     Type: AWS::AutoScaling::LaunchConfiguration
>>     Properties:
>>       InstanceType: '0'
>>       ImageId: '0'
>>     Metadata:
>>       keystone:
>>         host: {Ref: KeystoneHost}
>>       neutron:
>>         host: {Ref: NeutronHost}
>>           tenant_network_type: {Ref: NeutronNetworkType}
>>           network_vlan_ranges: {Ref: NeutronNetworkVLANRanges}
>>           bridge_mappings: {Ref: NeutronBridgeMappings}
>>           enable_tunneling: {Ref: NeutronEnableTunnelling}
>>           physical_bridge: {Ref: NeutronPhysicalBridge}
>>           public_interface: {Ref: NeutronPublicInterface}
>>         service-password:
>>           Ref: NeutronPassword
>>       admin-password: {Ref: AdminPassword}
>>
>> The result:
>>
>>   NovaCompute0Config:
>>     Type: AWS::AutoScaling::LaunchConfiguration
>>     Properties:
>>       InstanceType: '0'
>>       ImageId: '0'
>>     Metadata:
>>       keystone:
>>         host: {Ref: KeystoneHost}
>>       neutron:
>>         host: {Ref: NeutronHost}
>>           tenant_network_type: "gre"
>>           network_vlan_ranges: {Ref: NeutronNetworkVLANRanges}
>>           bridge_mappings: {Ref: NeutronBridgeMappings}
>>           enable_tunneling: "True"
>>           physical_bridge: {Ref: NeutronPhysicalBridge}
>>           public_interface: {Ref: NeutronPublicInterface}
>>         service-password:
>>           Ref: NeutronPassword
>>       admin-password: {Ref: AdminPassword}
>>
>> Note the `NeutronNetworkType` and `NeutronEnableTunneling` parameter
>> substitution.
>>
>> This is useful when you want to pick only bits and pieces of an existing
>> template. In the example above, `nova-compute-instance.yaml` is a
>> standalone template you can launch on its own. But when launching the
>> overcloud, you don't want to merge nova-compute-instance wholesale. All
>> you want is the NovaCompute0Config resource plus a few others.
>>
>> I admit I'm not entirely clear on how/why do we need this, though.
>> FileInclude is being used just for the overcloud nova compute resources
>> (server, config, waitcondition, etc.).
>>
>> The undercloud as well as the additional overcloud resources (swift,
>> block storage) seem get by without FileInclude.
>>
>>
>> 3. OpenStack::Role metadata key
>>
>> I'm not sure what this does or why would we need it. The Ironic
>> templates used it but it was removed because they were broken.
>>
>> Right now it's used in `tuskar-source.yaml` and `undercloud-source.yaml`
>> only.
>>
>>
>> 4. OpenStack::ImageBuilder::Elements metadata key
>>
>> Again, this seems to receive custom handling by merge.py, but I'm
>> unclear as to why.
>>
>>
>> 5. Scaling
>>
>> We can mark resources in a Heat template as scalable by giving them the
>> '0' suffix. We can then use the `--scale` parameter to make copies of these:
>>
>>   SwiftStorage0CompletionHandle:
>>     Type: AWS::CloudFormation::WaitConditionHandle
>>
>>   SwiftStorage0:
>>     Type: OS::Nova::Server
>>     Properties:
>>       image:
>>         {Ref: SwiftStorageImage}
>>       flavor: {Ref: OvercloudSwiftStorageFlavor}
>>       key_name: {Ref: KeyName}
>>     ...
>>
>> $ merge.py swift-storage-source.yaml --scale SwiftStorage=2
>>
>> result:
>>
>>   SwiftStorage0CompletionHandle:
>>     Type: AWS::CloudFormation::WaitConditionHandle
>>
>>   SwiftStorage0:
>>     Type: OS::Nova::Server
>>     Properties:
>>       image:
>>         {Ref: SwiftStorageImage}
>>       flavor: {Ref: OvercloudSwiftStorageFlavor}
>>       key_name: {Ref: KeyName}
>>     ...
>>
>>   SwiftStorage1CompletionHandle:
>>     Type: AWS::CloudFormation::WaitConditionHandle
>>
>>   SwiftStorage1:
>>     Type: OS::Nova::Server
>>     Properties:
>>       image:
>>         {Ref: SwiftStorageImage}
>>       flavor: {Ref: OvercloudSwiftStorageFlavor}
>>       key_name: {Ref: KeyName}
>>     ...
>>
>> This seems rather close to what OS::Heat::ResourceGroup[2] does. Can we
>> just switch to using that instead? I seem to remember reading something
>> about the order of deleted resources of being wrong for our purposes.
>>
>> Is that correct? What are the specifics?
>>
>>
>> 6. Merge::Map helper function
>>
>> Returns the list of values from a dictionary given as a parameter.
>>
>> I'm assuming this would be great to have, but isn't blocking us from
>> moving to native Heat templates.
>>
>> Clint sent a proposal of this to the Heat developers but it went largely
>> unanswered. Perhaps we could revisit it?
>>
>>
>> 7-... Whatever I've missed!
>>
>> (here's where you get to point out my vast ignorance)
>>
>>
>>
>> ## a vision of a world without merge.py ##
>>
>> Seems to me provider resources ought be able to handle the composability
>> side of things (while still allowing us to use them as standalone
>> templates) and resource groups should handle the scaling.
>>
>> We could keep roughly the same structure: a separate template for each
>> OpenStack service (compute, block storage, object storage, ironic, nova
>> baremetal). We would then use Heat environments to treat each of these
>> templates as a custom resource (e.g. OS::TripleO::Nova,
>> OS::TripleO::Swift, etc.).
>>
>> Our overcloud and undercloud templates would then reference all these
>> each wrapped in a ResourceGroup or a more sophisticated scaling mechanism.
>>
>>
>>
>> ## tangential but nice to have stuff ##
>>
>> * move to HOT
>>   - It's where any new syntax extensions will happen
>>
>> * move to Software Config
>>   - Clint has a WIP patch:
>>   - https://review.openstack.org/#/c/81666/
>>
>>
>> What have I missed and what are your thoughts?
>> Tomas
>>
>>
>> [1]:
>> https://github.com/openstack/tripleo-heat-templates/blob/master/tripleo_heat_merge/merge.py
>> [2]:
>> http://docs.openstack.org/developer/heat/template_guide/openstack.html#OS::Heat::ResourceGroup
>> [3]:
>> http://docs.openstack.org/developer/heat/template_guide/environment.html
>>
> The maintenance burden of merge.py can be gradually reduced if features
> in it can be deleted when they are no longer needed. At some point in
> this process merge.py will need to accept HOT templates, and risk of
> breakage during this changeover would be reduced the smaller merge.py is.

thanks for starting the discussion Tomas - 'we will kill merge.py' is
something many of us have heard/said for at least the last 6 months

> 
> How about this for the task order?
> 1. remove OpenStack::ImageBuilder::Elements support from merge.py
> 2. move to software-config based templates
> 3. remove the following from merge.py
>    3.1. merging params and resources
>    3.2. FileInclude
>    3.3. OpenStack::Role
> 4. port tripleo templates and merge.py to HOT
> 5. use some HOT replacement for Merge::Map, delete Merge::Map from tripleo
> 6. move to resource providers/scaling groups for scaling
> 7. rm -f merge.py

I think this is a good suggestion - Clint identified some obvious things
to remove (I think these are all above right?). That should immediately
make merge.py simpler +1 to the idea of gradually removing features from
merge.py and discussing a reference plan/list as above

marios

> 
> 
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