You are viewing a plain text version of this content. The canonical link for it is here.
Posted to commits@ace.apache.org by ja...@apache.org on 2012/04/26 12:20:29 UTC
svn commit: r1330750 -
/ace/site/trunk/content/dev-doc/design/ace-authentication.mdtext
Author: jawi
Date: Thu Apr 26 10:20:29 2012
New Revision: 1330750
URL: http://svn.apache.org/viewvc?rev=1330750&view=rev
Log:
Finalized the article.
Modified:
ace/site/trunk/content/dev-doc/design/ace-authentication.mdtext
Modified: ace/site/trunk/content/dev-doc/design/ace-authentication.mdtext
URL: http://svn.apache.org/viewvc/ace/site/trunk/content/dev-doc/design/ace-authentication.mdtext?rev=1330750&r1=1330749&r2=1330750&view=diff
==============================================================================
--- ace/site/trunk/content/dev-doc/design/ace-authentication.mdtext (original)
+++ ace/site/trunk/content/dev-doc/design/ace-authentication.mdtext Thu Apr 26 10:20:29 2012
@@ -9,7 +9,8 @@ Revision 0.9, last updated: April 26th,
## Introduction
When provisioning software (partly) to targets, one has to rely upon the trustworthiness of both the network and the target. Even if everything is under your control and governance, one cannot entirely be sure that unwanted access takes place. A first step in order to prevent unwanted access is *authentication*, which gives you the ability to verify the identity of someone. Once the identity is known, one can apply *authorization* in order to determine what actions are allowed and which are not.
-In this article, the recently added authentication layer of ACE is explained in more depth, and some details on how extensions can be written for additional mechanisms are given. The remainder of this article assumes the reader has basic knowledge of the principles behind ACE, and has sufficient programming skills. For this article, the latest code of ACE (0.8.1-SNAPSHOT, rev.1329269) was used.
+In this article, the recently added authentication layer of ACE is explained in more depth and how to configure authentication to your situation.
+The remainder of this article assumes the reader has basic knowledge of the principles behind ACE, and has sufficient programming skills. For this article, the latest code of ACE (0.8.1-SNAPSHOT, rev.1329269) was used.
## Communication paths
@@ -17,9 +18,9 @@ In this article, the recently added auth
Before going in more detail on the design and configuration of the authentication layer in ACE, we first need to pinpoint all places were authentication needs to be applied. The following figure shows the main components in ACE and their communication paths, providing a global overview of where authentication is applicable to ACE.
-Figure 1: Overview of components and communication paths.
+**Figure 1**: Overview of components and communication paths.
-Figure 1 represents several of the communication paths that can be identified (denoted by the circled digits):
+In the above figure, several of the communication paths (denoted by the circled digits) that can be identified in ACE are represented:
1. the client communicates to the ACE server by means of both direct calls to its services as well as remote (HTTP[^1]) calls;
2. a management agent (representing the target) communicates to the ACE server through remote calls;
@@ -42,10 +43,10 @@ The high-level design for security in AC
2. should be optional. If no authentication is desired, one should be able to remove its services from the ACE distribution;
3. should be pluggable. Various ways of authentication exist, and new ones can emerge. Making the authentication mechanism pluggable allows new ways of authentication to be used easily.
-Based on these requirements, the design of the authentication layer is represented in the following figure:
+Based on these requirements, the design of the authentication layer is represented in the following figure: {#fig2}
-Figure 2: Authentication layer class diagram.
+**Figure 2**: Authentication layer class diagram.
The <tt>AuthenticationService</tt> is responsible for authenticating a user based on some piece of information. This piece of information can be an array containing a username/password combination, a <tt>HttpServletRequest</tt> containing authentication request headers, or any other type of information capable of uniquely identifying a user. The actual authentication itself is delegated to one or more <tt>AuthenticationProcessor</tt>s, which know how to handle a given set of information (e.g., <tt>HttpServletRequest</tt>) and can map this information to a particular user. In more detail, the calling sequence of <tt>AuthenticationService#authenticate</tt> would be:
@@ -58,7 +59,7 @@ The <tt>AuthenticationService</tt> is re
This is only half the story for authentication. As stated before, ACE internally also communicates through remote endpoints to access certain services. Without any changes, all those remote calls will fail due to missing credentials. If we would leave those means of communications as-is, we need to track down all places where remote calls are being made and inject the proper credentials at each of those places. However, doing this is not only *very* invasive and error prone but also not very developer friendly from a service-oriented perspective. Alternatively, we could try to include the credentials in the URL itself, making it self-contained. Not only would this approach limit our ability to use any kind of authentication mechanism (it only works for username/password combos), it also required us to supply the credentials manually each and every time we want to create a remote connection. Instead, we would like to refrain from passing around credentials, and leverage the s
ervice oriented aspects of OSGi to create remote connections for us. This service could then be responsible for adding the right credentials for us, leaving the calling party totally unaware about the fact authentication might be used (or not). Such a service is denoted in the following figure:
-Figure 3: Connection Factory class diagram.
+**Figure 3**: Connection Factory class diagram.
The <tt>ConnectionFactory</tt> is responsible for creating <tt>URLConnection</tt>s, given a "plain" URL. So, instead of calling <tt>URL#openConnection()</tt> or <tt>URL#openStream()</tt>, we'll now have to call <tt>ConnectionFactory#createConnection(url)</tt> instead. But what advantage does this give us? In order to allow the connection factory to supply the credentials to <tt>URLConnection</tt>s, it is also registered as <tt>ManagedServiceFactory</tt> that enables us to provide multiple configurations of which credentials should be supplied to what (sets of) URLs. The introduction of the connection factory thus allows us to abstract the creation of a connection and passing of credentials to it from the URL. Internally, the connection factory will match each URL given in <tt>createConnection</tt> with the URLs it is configured with. If a matching URL is found, it will use the credentials in that configuration to supply to the <tt>URLConnection</tt>.
@@ -77,7 +78,7 @@ Name | Description | Endpoint | Configur
<tt>RepositoryReplicationServlet</tt> | allows *relay nodes* to replicate the internal repositories of ACE | <tt>/replication</tt> | <tt>o.a.a.repository.servlet.<br/>RepositoryReplicationServlet</tt>
<tt>RESTClientServlet</tt> | provides the RESTful interface to ACE |<tt>/client</tt> | <tt>o.a.a.client.rest</tt>
<tt>VaadinServlet</tt> | provides the Vaadin web interface | <tt>/ace</tt> | <tt>o.a.a.webui.vaadin</tt>
-
+  |   |   |  
## Configuring authentication
@@ -188,7 +189,8 @@ For accessing our <tt>BundleServlet</tt>
# What is the base URL that these credentials apply to:
authentication.baseURL = http://localhost:8080/obr/
-When this configuration is supplied to the <tt>ConnectionFactory</tt>, it will provide a basic HTTP authentication header to each connection created for any URL starting with "<tt>http://localhost:8080/obr/</tt>"[^7].
+When this configuration is supplied to the <tt>ConnectionFactory</tt>, it will provide a basic HTTP authentication header to each connection created for any URL starting with "<tt>http://localhost:8080/obr/</tt>"[^7].
+To disable authentication for a particular URL, the <tt>authentication.type</tt> option can be set to <tt>none</tt>.
### Configuring the management agent
@@ -202,15 +204,32 @@ The management agent itself also needs t
Alternatively, one could adapt the code of the management agent to use the <tt>ConfigAdmin</tt> service directly for creating the individual configurations using the service factory PID <tt>org.apache.ace.connectionfactory</tt>.
-## Extending the authentication mechanism
+### Configuring users
+
+In order to successfully authenticate a user, it needs a corresponding <tt>User</tt> that can be obtained from the <tt>UserAdmin</tt> service. Initially, ACE imports a small set of users and roles defined in the "<tt>org.apache.ace.server.repository.factory/ace-user.cfg</tt>" configuration file. One could update this file in order to add users[^8], or add them, for example, to an LDAP-service and make the <tt>UserAdmin</tt> service retrieve users from this backend. The exact details on how to configure this are beyond this article.
+
+
+## Troubleshooting
+
+If after configuring the authentication of ACE things no longer work, it can be hard to find the exact cause of this. In this section, some pointers are given to help you to find the probably cause of the problem.
-â¦
+I've enabled authentication, but I can still use all services without passing any credentials!
+: if you've updated the configuration files of a running server or management agent, the configuration files are not automatically picked up by default. You need to stop the server/management agent, clean its felix-cache folder and start it again.
-### Authentication processors
+With authentication enabled, how can I test whether the endpoints accept my credentials?
+: In order to test the remote endpoints of ACE, you can use a tool like [REST client](http://code.google.com/p/rest-client/). It allows you to enter credentials for any given URL.
-â¦
+After enabling authentication, I do not get any errors after starting the ACE server, but it doesn't function correctly!
+: Is the connection factory properly configured? Are *all* <tt>authentication.type</tt> options correctly set to <tt>basic</tt> and are the username/passwords correctly set? Are the configured base URLs not overlapping each other (e.g.: <tt>baseURL = http://localhost:8080/</tt> and <tt>baseURL = http://localhost:8080/obr</tt>)?
-###
+After enabling authentication, the management agent(s) no longer functions/I do not see them added in the web UI.
+: Did you pass the <tt>auth=/path/to/config/file(s)</tt> option to the management agent to configure the connection factory? Are those files correctly stating the "<tt>authentication.type = basic</tt>", including the username and password for the desired URLs? Can you access the URLs mentioned in the configuration files with a tool like [REST client](http://code.google.com/p/rest-client/)?
+
+I do not want basic HTTP authentication, I want to use (fill in the kind of authentication)!
+: The current implementation is quite simple and basic, but it can be extended by means of custom authentication processors.
+
+
+## Notes
[^1]: Other communication protocols could be used as well. However, currently, only HTTP is natively supported by ACE. For the remainder of this article, we'll assume HTTP as protocol.
@@ -225,3 +244,5 @@ Alternatively, one could adapt the code
[^6]: Note that we're using a configuration dependency for this service. This way, the configuration **must** be present before the service itself is registered, which allows us to determine if authentication should be used or not.
[^7]: Currently, a simple <tt>String#startsWith()</tt> is used to determine whether or not a URL matches a configuration. This might change in the future when a more sophisticated URL-matching strategy is needed.
+
+[^8]: Make sure to clean the <tt>felix-cache</tt> directory before restarting the server, otherwise the new configuration files will not be picked up!
\ No newline at end of file