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https://issues.apache.org/jira/browse/AMBARI-15395?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15296656#comment-15296656
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Robert Nettleton commented on AMBARI-15395:
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I've reviewed the proposal document attached to this JIRA, and have included my
review comments below.
Generally, I'm not sure that using references here is a good fit for
Blueprints.
1. The Reference format is used by the Ambari REST API, but doesn't necessarily
make much sense with respect to a Blueprints deployment. The syntax and
structure of a Blueprints deployment is such that much of the information
(property name, configuration type, etc) would be duplicated, and likely
confusing for users. I’m also concerned about the idea of configuration
versions (mentioned in the reference format) being introduced into Blueprint
documents. This could introduce a variety of compatibility problems, as users
try to re-use Blueprints across versions of Ambari.
2. In the "Requirements", section, point #5 mentions having a separate JSON
document to abstract out Path references. I'm not sure I agree that this is
necessary. The stacks do define what appear to be valid defaults for these
path properties. In addition, the Blueprints deployer is always free to
customize these properties, either in the Blueprint or Cluster Creation
Template. While I agree that we should do as much error-checking upfront as
possible, this seems like an issue that will vary from user-to-user, and so I'm
not sure we should add a new Blueprints feature to accomodate this use case. I
also think that adding a new JSON document needlessly complicates things, for
very little benefit. It's important to note that Blueprints is meant as a
"power-user" feature, and so will never have as much error-checking/convenience
as the UI.
3. Regarding the potential application of this proposal towards Password fields:
a. In general, I don't think this is necessary. The Blueprint configuration
processor already removes all passwords from an exported Blueprint. At
deployment time, the error-checking already exists to fail a deployment if a
given password is missing. The Blueprints configuration processor already uses
the Ambari Stack definitions to determine the list of required passwords.
b. In addition, the “default password” feature already exists in order to
allow a customer to override this validation, and simply use a given password
for all unset passwords.
c. I’m concerned about the suggestion to use the “default password”
configuration property in the Cluster Creation Template in the way described in
this document. The “default password” feature is not meant for production
environments, and in general should only be used for developer-level clusters
during the creation/debugging of Blueprint documents.
d. As mentioned above, the Reference structure duplicates much of the
Blueprints structure already, and so would be confusing for existing Blueprint
users.
4. Regarding the potential application of this proposal towards Hostname fields:
a. We need to make a distinction between the types of hostname fields we’re
talking about. In general, any hostname information that points to services
managed by Ambari can be handled by the Blueprints processor already. The
specific case where some support would be useful here is in services not
managed by Ambari. An example would be: A Hive Database that is running on a
host that is not managed by Ambari. During Blueprint export currently, this
hostname property is excluded, since the processor cannot portably include this
property value, since there is no host group to reference.
b. In the case I just described above, I think some support could be added,
but I would recommend something much simpler than using references in this
case.
c. I’d recommend modifying the BlueprintConfigurationProcessor to possibly
detect this case (service’s host not managed by Ambari), and allowing the
export of this property, but marking the value with a simple token, such as
property value being set equal to something like: “EXTERNAL_HOSTNAME”, or
“UNMANAGED_HOST”. This would allow the user of the exported Blueprint to
detect when some additional configuration is required. The
BlueprintConfigurationProcessor could also be updated to error-check against
this token, to report an error back to the caller when a Blueprint or Cluster
Creation Template included this token. This type of approach would probably
handle the External DB and Kerberos Host cases, and others as well.
5. Regarding the potential application of this proposal towards path fields:
I’m not sure I agree that this would be something that should be added to
Blueprints. The Ambari Stack definitions already provide valid defaults for
most use cases for the HDFS paths mentioned in this document. If these
settings are not acceptable to a subset of users, the Blueprint feature
provides the facility to override these defaults in the Blueprint or Cluster
Creation Template.
Thanks.
CC [~mahadev], [~antndk], [~arborkar], [~sumitmohanty], [~stoader]
> Enhance blueprint support for using references
> ----------------------------------------------
>
> Key: AMBARI-15395
> URL: https://issues.apache.org/jira/browse/AMBARI-15395
> Project: Ambari
> Issue Type: Story
> Components: ambari-server
> Affects Versions: 2.4.0
> Reporter: Shantanu Mundkur
> Assignee: Amruta Borkar
> Attachments: Blueprints_enhancement-AMBARI-15395-v3.docx,
> Blueprints_enhancement-AMBARI-15395-v3.pdf
>
>
> An exported blueprint should provide ready portability i.e. an exported
> blueprint be usable without changes to deploy another cluster. Some elements
> that are masked or omitted use tokens or placeholders. These have been called
> references in previous Jiras. A reference follow some convention that
> indicates that it is a reference by using a keyword and a pattern e.g.
> ReferenceName:configType:configVersion:propertyName
> References would be a good indicators of properties that user could choose to
> customize before deploying the cluster. It could also indicate the need for a
> "global" default for that property in the cluster template. Examples:
> - Passwords
> - Hostnames
> - External databases
> Currently Ambari has a concept of SECRET references. E.g.
> SECRET:hive-site:2:hive.server2.keystore.password
> These are used for masking the password when a blueprint is exported and the
> reference itself is not exported. It would be useful to have an reference
> exported as long as it is processed appropriately during deployment.
> Similar to the secret reference, for hostnames in a one could have,
> HOST:kerberos-env:-1:kdc_host
> and so forth.
> For any reference, in the cluster template there would be a corresponding
> property that would be used for substituting a value for the reference during
> deployment if the registered blueprint had such references. Currently such
> behavior is used if a property of type password is not specified
> (default_password). Such references could be used to tag properties to flag
> them to be the ones that users must customize or include in the cluster
> template. They can also serve a way to annotate/comment parts of the
> blueprint JSON.
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