XmlConfigMerge - Merge config file settings

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Introduction

When deploying .NET applications, it is often desirable to "merge" configuration settings between a "distribution" .config file and an existing .config file.

This is particularly useful when new config parameters are added to a "distribution" config file, and an existing .config file (such as on an already-configured server) must have these new parameters added, while preserving existing parameter settings.

The XmlConfigMerge utility (provided both as a library assembly and as a console application) supports this merging of XML .config files, and also supports setting of specific parameters via XPath filtering and optional Regex pattern matching.

Example Usage Scenarios

• Code Promotion: Push release from development to staging: Use to add newly-added development parameters while preserving existing staging parameters. (See "Example C# Code" below.)
• Publisher Policy Files: Set the binding redirect parameters such that the AssemblyVersion in the latest build is specified (see "Example C# Code within a NAnt script" below.)
• Windows Installer Packages: Maintain existing application .config settings (from a prior install).

Example C# Code

//Merge an "existing" config's settings into a "distrib" config, 
//writing out results to "existing" config
ConfigFileManager config = new ConfigFileManager(DistribConfigFile,
        ExistingConfigFile,
        true); //makeMergeFromConfigPathTheSavePath

//Regex pattern replace having single regex group to be replaced within
//pattern, matching multiple config items
config.ReplaceXPathValues(
        "//@value", 
        "QAServer/QAVirtDir1", 
        new Regex(@"http://(.*)/service.ashx") );

//appsettings key-value pair set for existing param. 
//It is created if it does not exist.
config.ReplaceXPathValues(
        "/configuration/appSettings/add[@key='param2']/@value",
        "QA-value2");

config.Save();

Example C# Code within a NAnt script

<!-- Set the publisher-policy file newVersion attribute -->

<property value="policyTheAssemblyName.xml" name="policyFileName"/>
<property value="3.1.25.0" name="policyAssemblyVersion"/>
        
<script language="C#">
    <code><![CDATA[
        public static void ScriptMain(Project project) {
            policyFileName = project.Properties["policyFileName"];
            project.Log(Level.Info, "Modifying policy file: " + 
                        policyFileName);

            //Modify
            ConfigFileManager config = 
                  new ConfigFileManager(policyFileName);
            LogInfoLines(project, config.ReplaceXPathValues(
                    "//*[local-name()='bindingRedirect']/@newVersion",
                    project.Properties["policyAssemblyVersion"] ) );
            config.Save();
        }
                
        private static void LogInfoLines(Project project, 
                                         string[] lines) {
            foreach (string line in lines) {
                project.Log(Level.Info, line);
            }
        }
    ]]></code>
    <references>
        <includes name="${nant.location}\XmlConfigMerge.dll"/>
    </references>
    <imports>
        <import name="Tools.XmlConfigMerge"/>
    </imports>
</script>

Example Command-Line

XmlConfigMergeConsole.exe "..\MergeDistribConfigFiles\web.config" 
-m "..\MergeExistingConfigFiles\web.config" -mwritten
-r "//@value" "QAServer/QAVirtDir1" "http://(.*)/service.ashx"
-r "/configuration/appSettings/add[@key='param2']/@value" "QA-value2"

Further Examples

See the included unit-tests (utilizing NUnit) for additional usage examples.

Release Notes

• Version 1.3 - 11/06/2006: Changed to use share mode on file opens, added error handling.
• Version 1.2: Fix for master child nodes not being preserved when not present in merge-from doc.
• Version 1.1: Handles duplicate appSettings keys in a manner consistent with System.Configuration (uses last one); added precondition checks.