software.amazon.lambda.powertools.parameters

Class BaseProvider

java.lang.Object

software.amazon.lambda.powertools.parameters.BaseProvider

All Implemented Interfaces:

ParamProvider

Direct Known Subclasses:

AppConfigProvider, DynamoDbProvider, SecretsProvider, SSMProvider

@NotThreadSafe
public abstract class BaseProvider
extends java.lang.Object
implements ParamProvider

Base class for all parameter providers.

Field Summary

Fields

Modifier and Type	Field and Description
protected CacheManager	cacheManager
static java.lang.String	PARAMETERS

Constructor Summary

Constructors

Constructor and Description
BaseProvider(CacheManager cacheManager)

Method Summary

Modifier and Type	Method and Description
protected BaseProvider	defaultMaxAge(int maxAge, java.time.temporal.ChronoUnit unit) (Optional) Set the default max age for the cache of all parameters.
java.lang.String	get(java.lang.String key) Get the value of a parameter, either from the underlying store or a cached value (if not expired). Using this method, you can apply a basic transformation (to String).
<T> T	get(java.lang.String key, java.lang.Class<T> targetClass) Get the value of a parameter, either from the underlying store or a cached value (if not expired). Using this method, you must apply a transformation (eg.
java.util.Map<java.lang.String,java.lang.String>	getMultiple(java.lang.String path) Retrieve multiple parameter values either from the underlying store or a cached value (if not expired). Cache all values with the 'path' as the key and also individually to be able to get(String) a single value later Does not support transformation.
protected abstract java.util.Map<java.lang.String,java.lang.String>	getMultipleValues(java.lang.String path) Retrieve multiple parameter values from the underlying parameter store. Abstract: Implement this method in a child class of BaseProvider
protected abstract java.lang.String	getValue(java.lang.String key) Retrieve the parameter value from the underlying parameter store. Abstract: Implement this method in a child class of BaseProvider
protected java.time.Instant	now()
protected void	resetToDefaults()
protected void	setTransformationManager(TransformationManager transformationManager)
BaseProvider	withMaxAge(int maxAge, java.time.temporal.ChronoUnit unit) (Optional) Builder method to call before get(String) or get(String, Class) to set cache max age for the parameter to get. The max age is reset to default (either 5 or a custom value set with defaultMaxAge(int, java.time.temporal.ChronoUnit)) after each get, so you need to use this method for each parameter to cache with non-default max age. Not Thread Safe: calling this method simultaneously by several threads can lead to unwanted cache time for some parameters.
BaseProvider	withTransformation(java.lang.Class<? extends Transformer> transformerClass) Builder method to call before get(String) (Optional) or get(String, Class) (Mandatory).

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

PARAMETERS

public static final java.lang.String PARAMETERS

See Also:

Constant Field Values

cacheManager

protected final CacheManager cacheManager

Constructor Detail

BaseProvider

public BaseProvider(CacheManager cacheManager)

Method Detail

getValue

protected abstract java.lang.String getValue(java.lang.String key)

Retrieve the parameter value from the underlying parameter store.
Abstract: Implement this method in a child class of BaseProvider

Parameters:

key - key of the parameter

Returns:

the value of the parameter identified by the key

getMultipleValues

protected abstract java.util.Map<java.lang.String,java.lang.String> getMultipleValues(java.lang.String path)

Retrieve multiple parameter values from the underlying parameter store.
Abstract: Implement this method in a child class of BaseProvider

Parameters:

path - Parameter store path

Returns:

Return map of parameter name value pairs

defaultMaxAge

protected BaseProvider defaultMaxAge(int maxAge,
                                     java.time.temporal.ChronoUnit unit)

(Optional) Set the default max age for the cache of all parameters. Override the default 5 seconds.
If for some parameters, you need to set a different maxAge, use withMaxAge(int, ChronoUnit).
Use withMaxAge(int, ChronoUnit) after {#defaultMaxAge(int, ChronoUnit)} in the chain.

Parameters:

maxAge - Maximum time to cache the parameter, before calling the underlying parameter store.

unit - Unit of time

Returns:

the provider itself in order to chain calls (eg.

provider.defaultMaxAge(10, SECONDS).get("key")

).

withMaxAge

public BaseProvider withMaxAge(int maxAge,
                               java.time.temporal.ChronoUnit unit)

(Optional) Builder method to call before get(String) or get(String, Class) to set cache max age for the parameter to get.

The max age is reset to default (either 5 or a custom value set with defaultMaxAge(int, java.time.temporal.ChronoUnit)) after each get, so you need to use this method for each parameter to cache with non-default max age.

Not Thread Safe: calling this method simultaneously by several threads can lead to unwanted cache time for some parameters.

Parameters:

maxAge - Maximum time to cache the parameter, before calling the underlying parameter store.

unit - Unit of time

Returns:

the provider itself in order to chain calls (eg.

provider.withMaxAge(10, SECONDS).get("key")

).

withTransformation

public BaseProvider withTransformation(java.lang.Class<? extends Transformer> transformerClass)

Builder method to call before get(String) (Optional) or get(String, Class) (Mandatory). to provide a Transformer that will transform the String parameter into something else (String, Object, ...)

Base64Transformer and JsonTransformer are provided for respectively base64 and json content. You can also write your own (see Transformer). Not Thread Safe: calling this method simultaneously by several threads can lead to errors (one Transformer for the wrong target type)

Parameters:

transformerClass - Class of the transformer to apply. For convenience, you can use Transformer.json or Transformer.base64 shortcuts.

Returns:

the provider itself in order to chain calls (eg.

provider.withTransformation(json).get("key", MyObject.class)

).

getMultiple

public java.util.Map<java.lang.String,java.lang.String> getMultiple(java.lang.String path)

Retrieve multiple parameter values either from the underlying store or a cached value (if not expired).
Cache all values with the 'path' as the key and also individually to be able to get(String) a single value later
Does not support transformation.

Specified by:

getMultiple in interface ParamProvider

Parameters:

path - path of the parameter

Returns:

a map containing parameters keys and values. The key is a subpart of the path
eg. getMultiple("/foo/bar") will retrieve [key="baz", value="valuebaz"] for parameter "/foo/bar/baz"

get

public java.lang.String get(java.lang.String key)

Get the value of a parameter, either from the underlying store or a cached value (if not expired).
Using this method, you can apply a basic transformation (to String).
Set a BasicTransformer with withTransformation(Class).

If you need a more complex transformation (to Object), use get(String, Class) method instead of this one.

Specified by:

get in interface ParamProvider

Parameters:

key - key of the parameter

Returns:

the String value of the parameter

Throws:

java.lang.IllegalStateException - if a wrong transformer class is provided through withTransformation(Class). Needs to be a BasicTransformer.

TransformationException - if the transformation could not be done, because of a wrong format or an error during transformation.

get

public <T> T get(java.lang.String key,
                 java.lang.Class<T> targetClass)

Get the value of a parameter, either from the underlying store or a cached value (if not expired).
Using this method, you must apply a transformation (eg. json/xml to Object).
Set a Transformer with withTransformation(Class).

If you need a simpler transformation (to String), use get(String) method instead of this one.

Specified by:

get in interface ParamProvider

Parameters:

key - key of the parameter

targetClass - class of the target Object (after transformation)

Returns:

the Object (T) value of the parameter

Throws:

java.lang.IllegalStateException - if no transformation class was provided through withTransformation(Class)

TransformationException - if the transformation could not be done, because of a wrong format or an error during transformation.

now

protected java.time.Instant now()

resetToDefaults

protected void resetToDefaults()

setTransformationManager

protected void setTransformationManager(TransformationManager transformationManager)