adding lambda handler

.gitignore

@@ -158,3 +158,5 @@ cython_debug/
 #  and can be added to the global gitignore or merged into this file.  For a more nuclear
 #  option (not recommended) you can uncomment the following to ignore the entire idea folder.
 #.idea/
+
+.aws-sam

Pipfile

@@ -8,6 +8,7 @@ boto3 = "*"
 
 [dev-packages]
 pytest = "*"
+aws-sam-cli = "*"
 
 [requires]
 python_version = "3.11"

README.md

@@ -1,4 +1,5 @@
 [![PyTest](https://github.com/socraticDevBlog/pastebin/actions/workflows/pytest.yml/badge.svg?branch=main)](https://github.com/socraticDevBlog/pastebin/actions/workflows/pytest.yml)
+
 # poor man cloud-native pastebin
 
 this project is about using AWS Free tier resources to host yourown pastebin
@@ -31,7 +32,37 @@ Install dependencies
 pipenv install --deploy --dev
 ```
 
-Start DynamoDB local instance
+### Run Lambda locally
+
+Using SAM (Serverless Application Model) CLI, you can easily execute the lambda
+locally
+
+We are using only one (1) lambda entrypoint to cover all http requests since
+our use case is pretty simple.
+
+Lambda code is located at `src/app.py`
+
+Stubbed lambda _event_ input arguments are located at `local/events/`. There is
+one file per http verb.
+
+#### simulate a POST request locally
+
+```bash
+pipenv run sam build
+
+pipenv run sam local invoke -e local/events/post.json
+
+# > Invoking app.lambda_handler (python3.9)
+# Local image is up-to-date
+# Using local image: public.ecr.aws/lambda/python:3.9-rapid-x86_64.
+
+# Mounting /Users/me/git/pastebin/.aws-sam/build/PastebinFunction as /var/task:ro,delegated, inside runtime container
+# START RequestId: 378e46ab-dd9b-4a31-bec7-1cc1b4a06ae8 Version: $LATEST
+# END RequestId: 378e46ab-dd9b-4a31-bec7-1cc1b4a06ae8
+# REPORT RequestId: 378e46ab-dd9b-4a31-bec7-1cc1b4a06ae8  Init Duration: 1.52 ms  Duration: 1021.66 ms    Billed Duration: 1022 ms        Memory Size: 128 MB     Max Memory Used: 128 MB
+```
+
+### Start DynamoDB local instance
 
 ```bash
  cd local
@@ -63,6 +94,8 @@ pipenv run test -v
 
 ## Tech Stack
 
+**dependencies management** pipenv
+
 **database:** aws DynamoDB
 
 **computing:** aws Lambda, python, boto3
@@ -76,4 +109,3 @@ pipenv run test -v
 - Docker
 - DynamoDB local
 - SAM (Lambda), awscli
-- localStack (API Gateway)

local/README.md

@@ -33,6 +33,14 @@ print out a list of tables in your DynamoDB instance:
 aws dynamodb list-tables --endpoint-url http://localhost:8000
 ```
 
+expect to find the "paste" table:
+
+```json
+{
+  "TableNames": ["paste"]
+}
+```
+
 ### stopping and removing dynamodb-local
 
 **use `-v` flag to completely delete database table "paste"**
@@ -42,9 +50,3 @@ docker compose down -v
 ```
 
 more info/examples: <https://github.com/aws-samples/aws-sam-java-rest>
-
-## SAM (serverless application model)
-
-````bash
-brew install aws-sam-cli
-````

local/events/delete.json

@@ -0,0 +1,4 @@
+{
+    "message": "user are not allowed to delete their pastes",
+    "method": "DELETE"
+  }

local/events/get.json

@@ -0,0 +1,4 @@
+{
+    "message": "test paste number two",
+    "method": "GET"
+  }

local/events/post.json

@@ -0,0 +1,4 @@
+{
+  "message": "test paste number one",
+  "method": "POST"
+}

samconfig.toml

@@ -0,0 +1,31 @@
+# More information about the configuration file can be found here:
+# https://docs.aws.amazon.com/serverless-application-model/latest/developerguide/serverless-sam-cli-config.html
+version = 0.1
+
+[default]
+[default.global.parameters]
+stack_name = "pastebin"
+
+[default.build.parameters]
+cached = true
+parallel = true
+
+[default.validate.parameters]
+lint = true
+
+[default.deploy.parameters]
+capabilities = "CAPABILITY_IAM"
+confirm_changeset = true
+resolve_s3 = true
+
+[default.package.parameters]
+resolve_s3 = true
+
+[default.sync.parameters]
+watch = true
+
+[default.local_start_api.parameters]
+warm_containers = "EAGER"
+
+[default.local_start_lambda.parameters]
+warm_containers = "EAGER"

src/app.py

@@ -0,0 +1,31 @@
+import json
+
+
+def lambda_handler(event, context):
+    """
+    lambda_handler
+
+    Handles all http requests (from API Gateway)
+
+    - receives requests
+    - dispatch request to appropriate function
+    - returns http "statusCode" + a "body" with at least:
+      a) "message" field
+      ...
+
+    """
+    method = event["method"]
+    message = event["message"]
+
+    if method == "GET":
+        return {
+            "statusCode": 200,
+            "body": json.dumps({"message": message}),
+        }
+    elif method == "POST":
+        return {
+            "statusCode": 201,
+            "body": json.dumps({"message": message}),
+        }
+    else:
+        return {"statusCode": 405, "body": json.dumps({"message": message})}

template.yml

@@ -0,0 +1,12 @@
+AWSTemplateFormatVersion: "2010-09-09"
+Transform: AWS::Serverless-2016-10-31
+
+Resources:
+  PastebinFunction:
+    Type: AWS::Serverless::Function
+    Properties:
+      CodeUri: src/
+      Handler: app.lambda_handler
+      Runtime: python3.9
+      Architectures:
+        - x86_64