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From Ignasi Barrera <n...@apache.org>
Subject Re: warning during BlobStore.getBlobStore()
Date Sun, 16 Apr 2017 09:39:47 GMT
Hi Ryan,

The warning you're getting is particular to OpenStack. jclouds
provides several internal classes to provide the existing regions,
region ids, their corresponding URIs, etc. A group of those classes is
what we call the "implicit" location suppliers, that just return the
information of one location (region, szone, whatever), that will be
used if the user does not specify a region when interacting with the
cloud provider.

Those implicit location suppliers are always initialized, and the
default implementation looks for a region that has the same URI as the
provider endpoint. In the case of OpenStack, the endpoint is always
the Keystone endpoint, and that default logic does not "fit well",
thus the warning you get. It just says that there is no better way to
determine a "default/fallback" region than picking the first one.

To be more specific, jclouds loads a Map of known region ids to
endpoints, and then looking for the default region, it inspects that
map and looks for the endpoint configured when creating the context.
In the case of OpenStack, that map is built by inspecting the Service
Catalog returned by Keystone, so the right endpoint for the service
(swift, nova, etc) is configured for each region. That is done by
using a custom implementation of the supplier that builds the
mentioned map. You can read the implementation used for Keystone here
[1]. I hope reading it will make more sense and show why you get he
values you get in the map.

Regarding that "FOO" key. It is just a convenience use of a Guava
cache. There is an utility method to memoize a Supplier for a given
amount of time, and short-circuiting any AuthenticationException to
avoid having the supplier call the provider APIs when we already know
authentication will fail (and this preventing potential account
locks). The implementation of that supplier internally uses a Cache to
deal with concurrency. It will actually hold just one value (the
memoized one), and completely ignore any key (FOO) that is provided
when client code asks for the cached value. I couldn't say why the
Guava's LoadingCache is used instead of manually implementing the
locking, or why the "Suppliers.memoizeWithExpiration" isn't used
instead, which is thread-safe too.



[1] https://github.com/jclouds/jclouds/blob/master/apis/openstack-keystone/src/main/java/org/jclouds/openstack/keystone/v2_0/suppliers/LocationIdToURIFromAccessForTypeAndVersion.java

On 14 April 2017 at 00:28, Ryan Shoemaker
<ryan.shoemaker@enterprisedb.com> wrote:
> Hi,
> I've been seeing this warning pop out of my code for awhile and have finally
> gotten around to investigating it:
> org.jclouds.location.suppliers.implicit.GetRegionIdMatchingProviderURIOrNull|_ThreadID=10;_ThreadName=Thread-2;|failed
> to find key for value http://keystone.domainname.com:5000/v2.0 in
> {uk=http://swift.domainname.com:8080/v1/AUTH_813b8f3ec69a460caf6efc2ea32bafb8};
> choosing first: uk
> Why is there a mismatch between the uri and what's in the map?  The uri is
> pointing to our keystone service and the map contains our swift service.
> The actual log message appears to be coming from:
> org.jclouds.suppliers.SupplyKeyMatchingValueOrNull.get()
> As I was debugging this, I noticed this code on the stack:
> org.jclouds.rest.suppliers.MemoizedRetryOnTimeOutButNotOnAuthorizationExceptionSupplier.get()
> (line 150)
> @Override
> public T get() {
>    try {
>       return cache.get("FOO").orNull();
>    } catch (UncheckedExecutionException e) {
>       throw propagate(e.getCause());
>    } catch (ExecutionException e) {
>       throw propagate(e.getCause());
>    }
> }
> What's going on with that key name? Here's the calling code in my app - we
> have a method to get the storage context:
> public BlobStoreContext getStorageContext(@Nullable String tenant) {
>     String providerOrApi = ProviderFactory.getSupportedProviderFromId(
>         user.getServiceProvider()).getObjectStorageProvider();
>     Properties overrides = new Properties();
>     overrides.setProperty(KeystoneProperties.CREDENTIAL_TYPE,
>     ContextBuilder builder = ContextBuilder.newBuilder(providerOrApi)
>         .credentials(tenant + ":" + serviceLogin, servicePassword)
>         .endpoint(identityServiceEndpoint)
>         .modules(ImmutableSet.of(new JDKLoggingModule(), new
> JschSshClientModule()))
>         .overrides(overrides);
>     return builder.buildView(BlobStoreContext.class);
> }
> And then code grabs the context and calls getBlobStore() on it - this is
> what causes the warning to be printed:
> BlobStoreContext storageContext = getStorageContext(firstTenant);
> if (storageContext != null) {
>     BlobStore blobStore = storageContext.getBlobStore();
>     etc...
> We're running jclouds 2.0.0 on OpenStack.  Despite the warning, everything
> appears to work fine. Thanks! --Ryan

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