Initial version of dcaeapplib package

Change-Id: I54db903e59a67eb4423cacf10ea957d148b4f853
Issue-ID: DCAEGEN2-354
Signed-off-by: Andrew Gauld <ag1282@att.com>

1 files changed, 64 insertions, 0 deletions

diff --git a/dcaeapplib/README.md b/dcaeapplib/README.md
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+# dcaeapplib
+
+Library for building DCAE analytics applications
+
+# Example use:
+
+```
+
+class myapp:
+  def __init__(self):
+    # get the environment, and register callbacks for health checks and
+    # configuration changes
+    self.dcaeenv = dcaeapplib.DcaeEnv(healthCB=self.isHealthy, reconfigCB=self.reconfigure)
+    # simulate a configuration change - we want the initial configuration
+    self.reconfigure()
+    # start the environment (to wait for health checks and config changes)
+    self.dcaeenv.start()
+    # begin processing loop
+    while True:
+      if self.configchanged:
+	# fetch the updated configuration
+        self.conig = self.dcaeenv.getconfig()
+	self.configchanged = False
+	# do any setup relevant to the configuration
+      data = self.dcaeenv.getdata('myinputstream')
+      # Data is a UTF-8 string, 'myinputstream' is this application's logical
+      # name for this (one of potentially several) data sources.
+      # Can also specify timeout_ms and limit as arguments.
+      # timeout_ms (default 15,000) is the maximum time getdata() will block
+      # limit is the maximum number of records retrieved at a time.
+      # If no data is retrieved (timeout) the return will be None.
+      if data is not None:
+        # do something to process the data
+	self.dcaeenv.senddata('myoutputstream', 'somepartitionkey', data)
+	# data is a string, 'myoutputstream' is the application's logical
+	# name for this (one of potentially several) data sinks.
+	# somepartitionkey is used, by Kafka, to assign the data to a partition.
+
+  def isHealthy(self):
+    # return the health of the application (True/False)
+    return True
+
+  def reconfigure(self):
+    # Do whatever needs to be done to handle a configuration change
+    self.configchanged = True
+```
+
+# Environment Variables
+
+This library uses the onap-dcae-cbs-docker-client library to fetch
+configuration.  That library relies on the HOSTNAME and CONSUL_HOST
+environment variables to find the configuration.
+
+This library provides an HTTP interface for health checks.  By default this
+listens on port 80 but can be overridden to use another port by setting the
+DCAEPORT environment variable.  The HTTP interface supports getting 2 URLs:
+/healthcheck, which will return a status of 202 (Accepted) for healthy,
+and 503 (Service Unavailable) for unhealthy, and /reconfigure, which triggers
+the library to check for updated configuration.
+
+# Console Commands
+
+This library provides a single console command "reconfigure.sh" which
+performs an HTTP get of the /reconfigure URL