InfluxDB support (#52)

* adding step for writing metrics to InfluxDB including dependencies
* added documentation
* incorporated PR feedback

documentation/docs/scripts/configurationMerger.md

@@ -1,7 +1,7 @@
 # ConfigurationMerger
 
 ## Description
-A helper script that can merge the configurations from multiple sources. 
+A helper script that can merge the configurations from multiple sources.
 
 ## Static Method Details
 
@@ -10,8 +10,8 @@ A helper script that can merge the configurations from multiple sources.
 #### Description
 
 A step is usually configured by default values, configuration values from the configuration file and the parameters.
-The methods can merge these sources. 
-Default values are overwritten by configuration file values. 
+The method can merge these sources.
+Default values are overwritten by configuration file values.
 These are overwritten by parameters.
 
 #### Parameters
@@ -25,9 +25,9 @@ These are overwritten by parameters.
 | `defaults`         | yes       | Map                               |
 
 * `parameters` Parameters map given to the step
-* `parameterKeys` List of parameter names (keys) that should be considered while merging. 
+* `parameterKeys` List of parameter names (keys) that should be considered while merging.
 * `configurationMap` Configuration map loaded from the configuration file.
-* `configurationKeys` List of configuration keys that should be considered while merging. 
+* `configurationKeys` List of configuration keys that should be considered while merging.
 * `defaults` Map of default values, e.g. loaded from the default value configuration file.
 
 #### Side effects
@@ -62,3 +62,62 @@ List stepConfigurationKeys = [
 
 Map configuration = ConfigurationMerger.merge(parameters, parameterKeys, stepConfiguration, stepConfigurationKeys, stepDefaults)
 ```
+
+### mergeWithPipelineData
+
+#### Description
+
+A step is usually configured by default values, configuration values from the configuration file and the parameters.
+In certain cases also information previously generated in the pipeline should be mixed in, like for example an artifactVersion created earlier.
+The method can merge these sources.
+Default values are overwritten by configuration file values.
+Those are overwritten by information previously generated in the pipeline (e.g. stored in [commonPipelineEnvironment](../steps/commonPipelineEnvironment.md)).
+These are overwritten by parameters passed directly to the step.
+
+#### Parameters
+
+| parameter          | mandatory | Class                             |
+| -------------------|-----------|-----------------------------------|
+| `parameters`       | yes       | Map                               |
+| `parameterKeys`    | yes       | List                              |
+| `pipelineDataMap`  | yes       | Map                               |
+| `configurationMap` | yes       | Map                               |
+| `configurationKeys`| yes       | List                              |
+| `defaults`         | yes       | Map                               |
+
+* `parameters` Parameters map given to the step
+* `parameterKeys` List of parameter names (keys) that should be considered while merging.
+* `configurationMap` Configuration map loaded from the configuration file.
+* `pipelineDataMap` Values available to the step during pipeline run.
+* `configurationKeys` List of configuration keys that should be considered while merging.
+* `defaults` Map of default values, e.g. loaded from the default value configuration file.
+
+#### Side effects
+
+none
+
+#### Example
+
+```groovy
+def stepName = 'influxWriteData'
+prepareDefaultValues script: script
+
+final Map stepDefaults = ConfigurationLoader.defaultStepConfiguration(script, stepName)
+final Map stepConfiguration = ConfigurationLoader.stepConfiguration(script, stepName)
+final Map generalConfiguration = ConfigurationLoader.generalConfiguration(script)
+
+List parameterKeys = [
+    'artifactVersion',
+    'influxServer',
+    'influxPrefix'
+]
+Map pipelineDataMap = [
+    artifactVersion: commonPipelineEnvironment.getArtifactVersion()
+]
+List stepConfigurationKeys = [
+    'influxServer',
+    'influxPrefix'
+]
+
+Map configuration = ConfigurationMerger.mergeWithPipelineData(parameters, parameterKeys, pipelineDataMap, stepConfiguration, stepConfigurationKeys, stepDefaults)
+```

documentation/docs/scripts/jsonUtils.md

@@ -0,0 +1,30 @@
+# JsonUtils
+
+## Description
+Provides json related utility functions.
+
+## Constructors
+
+### JsonUtils()
+Default no-argument constructor. Instances of the Utils class does not hold any instance specific state.
+
+#### Example
+```groovy
+new JsonUtils()
+```
+
+## Method Details
+
+### getPrettyJsonString(object)
+
+#### Description
+Creates a pretty-printed json string.
+
+#### Parameters
+* `object` - A object (e.g. Map or List).
+
+#### Return value
+A pretty printed `String`.
+
+#### Side effects
+none

documentation/docs/scripts/utils.md

@@ -24,7 +24,7 @@ Retrieves the parameter value for parameter `paramName` from parameter map `map`
 #### Parameters
 * `map` - A map containing configuration parameters.
 * `paramName` - The key of the parameter which should be looked up.
-* `defaultValue` - The value which is returned in case there is no parameter with key `paramName` contained in `map`.
+* optional: `defaultValue` - The value which is returned in case there is no parameter with key `paramName` contained in `map`. If it is not provided the default is `null`.
 
 #### Return value
 The value to the parameter to be retrieved, or the default value if the former is `null`, either since there is no such key or the key is associated with value `null`. In case the parameter is not defined or the value for that parameter is `null`and there is no default value an exception is thrown.