Tamás Hanicz created KNOX-3528:
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Summary: DeploymentFactory mutates the cached Topology, so
topologies without an identity-assertion provider are marked UPDATED on every
reload
Key: KNOX-3528
URL: https://issues.apache.org/jira/browse/KNOX-3528
Project: Apache Knox
Issue Type: Bug
Components: Server
Affects Versions: 3.0.0
Reporter: Tamás Hanicz
Assignee: Tamás Hanicz
When any file in the topologies directory changes, every topology that does not
declare an \{{identity-assertion}} provider gets an UPDATED event and is
reactivated, even if its file has not changed.
h3. Root cause
{\{DeploymentFactory.selectContextProviders()}} calls
\{{addMissingDefaultProviders(topology)}}. If the topology has no
\{{identity-assertion}} provider, that method adds a \{{Default}} one directly
to \{{topology.getProviders()}}.
That \{{Topology}} instance is the same object \{{DefaultTopologyService}}
stores in its in-memory topology map, because it is passed through the
\{{TopologyEvent}} into \{{GatewayServer.handleCreateDeployment}} and
\{{DeploymentFactory.createDeployment}}. After the first deployment, the stored
copy has one more provider than a topology freshly parsed from the unchanged
file.
On the next \{{reloadTopologies()}}, \{{shouldMarkTopologyUpdated()}} sees
\{{!oldTopology.equals(newTopology)}} because \{{equalProviders}} fails, and
emits UPDATED regardless of
\{{gateway.topology.redeployment.requires.changes}}. The deployment directory
already exists for the unchanged timestamp, so the gateway reactivates the
topology ("Loading topology X from ...") rather than building a new one. That
is still a deactivate/activate cycle for a topology that did not change.
h3. Example
{\{metadata.xml}} has not been modified since deployment and has no
\{{identity-assertion}} provider. A change to \{{health.xml}} produces:
{noformat}
INFO ... Loading topology metadata from
.../data/deployments/metadata.topo.16fcdcdcfd8
INFO ... Activating topology metadata
{noformat}
h3. Steps to reproduce
Deploy a topology with no \{{identity-assertion}} provider, for example the
shipped \{{metadata.xml}}.
Modify a different topology.
The first topology is reactivated even though its file has not changed.
h3. Expected
A topology whose file has not changed is not marked UPDATED. Adding default
providers at deploy time does not change the cached \{{Topology}} used for
change detection.
h3. Possible fix
Do one of the following:
- Apply \{{addMissingDefaultProviders}} to a copy of the topology, or keep the
added default provider in the deployment context only.
- Have \{{DefaultTopologyService}} keep its own parsed copy that is never
handed out for deployment.
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