{"id":3596,"date":"2015-10-21T07:35:00","date_gmt":"2015-10-21T07:35:00","guid":{"rendered":"http:\/\/blog.cloudthat.com\/?p=3596"},"modified":"2024-06-25T11:13:17","modified_gmt":"2024-06-25T11:13:17","slug":"deep-dive-into-the-aws-api-gateway","status":"publish","type":"blog","link":"https:\/\/www.cloudthat.com\/resources\/blog\/deep-dive-into-the-aws-api-gateway","title":{"rendered":"Deep dive into the AWS API Gateway"},"content":{"rendered":"

From my previous blog<\/strong><\/a>, you can get a hands on with the AWS API Gateway. Now we will deep dive into it. Following points will be covered.<\/p>\n

    \n
  1. How to pass Query String<\/strong> to the\u00a0method?<\/li>\n
  2. How to pass Headers<\/strong> to the\u00a0method?<\/li>\n
  3. How to Transform the Response<\/strong> of\u00a0the Method?<\/li>\n
  4. How to receive Custom Response Code<\/strong> (400,500,\u2026) for the method?<\/li>\n
  5. How partially secure your API using API Keys<\/strong><\/li>\n<\/ol>\n

    Prerequisites:<\/strong><\/span><\/h3>\n
      \n
    1. Create a lambda function with code given\u00a0here<\/strong><\/a><\/li>\n
    2. Create and Deploy the Product API with\u00a0the GET Method, which integrates with the above function<\/li>\n<\/ol>\n

      You can refer my previous blog <\/a><\/strong>to have the prerequisites.<\/p>\n

       <\/p>\n

      1.How to pass Query String to the method?<\/strong><\/h2>\n

      You have an API with you already, where you are calling an API with GET method, you get\u00a0all the records in response, but what if we want a specific record in response? How can we get it? In this scenario, we can use the Query String<\/strong>. We will get the query string parameter from the HTTP request and then integrate the request using Mapping Templates.<\/p>\n

      Step by Step process to pass the Query String Parameters\u00a0to the Method<\/strong><\/h4>\n

      [showhide type=”qs”\u00a0more_text=”click here for Detailed Instructions..\u00a0” less_text=”Hide Details” hidden=”yes”]<\/p>\n

      \u00a0<\/strong><\/p>\n

      Step 1: <\/strong>Go to your method, you will see\u00a0the below screen, click on\u00a0Integration R<\/strong>equest.<\/b><\/p>\n

      \"16\"<\/a><\/p>\n

      Step 2:<\/strong>\u00a0You will see the following screen<\/p>\n

      \"60\"<\/a><\/p>\n

       <\/p>\n

      Step 3:<\/strong>\u00a0Click on Mapping Templates<\/strong><\/p>\n

      \"17\"<\/a><\/p>\n

      Step 4:<\/strong> Click on Add mapping templates<\/strong><\/p>\n

      \"18\"<\/a><\/p>\n

      Step 5<\/strong>: Write “text\/plain”<\/strong> and click on the tick<\/strong> to save<\/p>\n

      \"19\"<\/a><\/p>\n

      Step 6:<\/strong> Click on pencil symbol<\/strong> near Input passthrough and select Mapping Template<\/strong><\/p>\n

       <\/p>\n

      Step 7:<\/strong> Enter following JSON string<\/p>\n

      {\r\n    \"prod_Id\" : \"$input.params('prod_Id')\"\r\n}\r\n<\/pre>\n
      \"20\"<\/a><\/p>\n
      Step 8<\/strong>: Save the Template by clicking on the\u00a0tick<\/strong>.<\/p>\n
      \"21\"<\/a><\/p>\n
      Step 9:<\/strong> Your API will accept the query string and it will be mapped as per our code.<\/p>\n
      Step 10<\/strong>: You can TEST<\/strong> your API using\u00a0REST Client. <\/strong>Call your API passing query string.<\/p>\n
      [\/showhide]<\/p>\n
       <\/p>\n
      2.How to pass Headers to the\u00a0method?<\/h2>\n
      [showhide type=”header”\u00a0more_text=”click here for Detailed Instructions..\u00a0” less_text=”Hide Details” hidden=”yes”]<\/p>\n
      Step 1: <\/strong>Go to the\u00a0Method\u00a0Request<\/strong> and Click on the\u00a0HTTP Request Headers<\/strong><\/p>\n
      \"5\"<\/a><\/p>\n
      Step 2:<\/strong> Click on the\u00a0Add Header<\/strong><\/p>\n
      \"6\"<\/a><\/p>\n
      Step 3:<\/strong> Enter Name<\/strong> of the Header parameter<\/p>\n
      \"7\"<\/a><\/p>\n
       <\/p>\n
       <\/p>\n
      Step 4:<\/strong>\u00a0Navigate back to the Method Execution Console and click on\u00a0Integration Request<\/strong><\/p>\n
      Step 5<\/strong>: Click on\u00a0<\/strong>the Mapping Templates<\/strong><\/p>\n
      \"17\"<\/a><\/p>\n
      Step 6<\/strong>: Click on the Add mapping <\/strong>templates<\/b><\/p>\n
      \"18\"<\/a><\/p>\n
      Step 7<\/strong>: Write “application\/json”<\/strong>\u00a0explicitly.<\/p>\n
      \"8\"<\/a><\/p>\n
      Step 8<\/strong>: Click on Input passthrough<\/strong><\/p>\n
       <\/p>\n
      \"9\"<\/a><\/p>\n
      Step 9:<\/strong> Enter the following JSON string<\/p>\n
      {\r\n    \"prod_Id\" : \"$input.params('prod_Id')\"\r\n}\r\n<\/pre>\n
       <\/p>\n
      Step 10:<\/strong> Save<\/strong> the Template<\/p>\n
      [\/showhide]<\/p>\n
       <\/p>\n
      3.How to Transform the Response of the method?<\/strong><\/h2>\n
      Converting the response helps when\u00a0we are returning in JSON,\u00a0but\u00a0we need the output in XML. We can achieve the same by\u00a0transforming the API response. For transforming the response, we will again use mapping templates. We will write a template which converts the response and gives the desired type in return.<\/p>\n
       <\/p>\n
      Step by Step process for transforming the JSON response to XML<\/strong><\/h4>\n
      [showhide type=”trans”\u00a0more_text=”click here for Detailed Instructions..\u00a0” less_text=”Hide Details” hidden=”yes”]<\/p>\n
      Step 1:<\/strong> Go to Integration Response<\/strong><\/p>\n
      \"29\"<\/a><\/p>\n
       <\/p>\n
      Step 2:<\/strong>\u00a0Expand the integration\u00a0response as shown below<\/p>\n
      \"30\"<\/a><\/p>\n
      Step 3:<\/strong> Click on add Mapping templates<\/strong><\/p>\n
      \"31\"<\/a><\/p>\n
      Step 4:<\/strong>\u00a0Click on add Mapping templates<\/p>\n
      \"32\"<\/a><\/p>\n
      Step 5:<\/strong>\u00a0Enter “application\/json”<\/strong> and click on tick to save it<\/p>\n
      \"10\"<\/a><\/p>\n
      Step 5:<\/strong>\u00a0Click on pencil icon to edit the select Mapping Template.Enter\u00a0the following Code and save<\/p>\n
       <\/p>\n
      #set ($response = $input.path('$'))\r\n<response>\r\n    <prod_Id>$response.productDetails.prod_Id<\/prod_Id>\r\n    <prod_Name>$response.productDetails.prod_Name<\/prod_Name>\r\n    <prod_Price>$response.productDetails.prod_Price<\/prod_Price>\r\n<\/response>\r\n<\/pre>\n
      \"33\"<\/a><\/p>\n
      Step 6:<\/strong>\u00a0Navigate back to the Method Execution console\u00a0and click on Method Response<\/strong><\/p>\n
      \"34\"<\/a><\/p>\n
       <\/p>\n
      Step 7:<\/strong>\u00a0Expand the Method response and \u00a0click on a pencil Icon as shown\u00a0below<\/p>\n
      \"35\"<\/a><\/p>\n
       <\/p>\n
      \"36\"<\/a><\/p>\n
       <\/p>\n
      Step 8:<\/strong> Replace \u201cjson\u201d with \u201cxml\u201d and save<\/p>\n
      \"37\"<\/a><\/p>\n
      Note: Again deploy your API to test your API from REST Client.<\/strong><\/p>\n
      Step 9:<\/strong> Test the API from the REST\u00a0client<\/p>\n
      \"38\"<\/a><\/p>\n
       <\/p>\n
      You will find the following response. Now check the Content-type<\/strong> in response.<\/p>\n
       <\/p>\n
      \"39\"<\/a><\/p>\n
       <\/p>\n
      [\/showhide]<\/p>\n
       <\/p>\n
      4.How to receive custom response code (400, 500,…) for the method?<\/strong><\/h2>\n
      When we are calling any method, by default it returns 200 as a response code in AWS API Gateway. Even though if the response is success or error still the code returned will be 200. AWS\u00a0API Gateway provides the feature where we can actually give the custom code for the response.<\/p>\n
      We have an API where we are passing a query string or header values like 1, 2 and 3. In response, we are getting the product detail about the respective product_Id. So we will set the custom code for the BAD REQUEST. If the person is passing the query string value more than 3, we will return an error with the custom code 400.<\/p>\n
       <\/p>\n
      Step by Step process to Receive Custom Response Code from the Method<\/strong><\/h4>\n
      [showhide type=”code”\u00a0more_text=”click here for Detailed Instructions..\u00a0” less_text=”Hide Details” hidden=”yes”]<\/p>\n
      \u00a0<\/strong><\/p>\n
      Step 1:<\/strong> On your Method screen click on Method Response.<\/strong><\/p>\n
      \"34\"<\/a><\/p>\n
      Step 2:<\/strong> Click on Add Response<\/strong>.<\/p>\n
      \"11\"<\/a><\/p>\n
      Step 3:<\/strong> Select the response code 400<\/strong> and click on the tick to save.<\/p>\n
      \"12\"<\/a><\/p>\n
      Step 4:<\/strong> Click on Integration Response<\/strong> and add an integration response<\/strong>.<\/p>\n
      \"29\"<\/a><\/p>\n
      Step 5:<\/strong> Provide Lambda Error Regex as “Bad Request: .*”<\/strong>. For Method Response, select the Method response status as the code that you have inserted and click on save.<\/p>\n
      \"13\"<\/a><\/p>\n
      Step 6:<\/strong> Now click on an arrow button as shown below and click on mapping templates and add a template.<\/p>\n
      \"14\"<\/a><\/p>\n
      Step 7:<\/strong> Provide \u201capplication\/json<\/strong>\u201d as a content type and provide following string as a template and save.<\/p>\n
      {\r\n        \u201cerrorMessage\u201d: \"Bad Request: You submitted invalid input\"\r\n}<\/pre>\n
      Step 8:<\/strong>\u00a0Enter\u00a0the below code in your lambda function<\/strong>\u00a0before the for loop<\/p>\n
      {\r\n    \"prod_Id\" : \"$input.params('prod_Id')\"\r\n}<\/pre>\n
      Step 9:<\/strong> Test your function with the value greater than 3.<\/p>\n
       <\/p>\n
      It will return you custom code with our custom error.<\/p>\n
       <\/p>\n
      \"15\"<\/a><\/p>\n
      \u00a0\"16\"<\/a><\/strong><\/p>\n
       <\/p>\n
      [\/showhide]<\/p>\n
       <\/p>\n
      5.How partially secure your API using\u00a0API Keys<\/strong><\/h2>\n
      API keys are key generated by the Developer. Developer\u00a0distributes the key to the third party users to restrict the unwanted user partially as well as to monitoring the API usage of the particular user. I have said that the API key is for the used for the authentication partially because AWS does not recommend to use only API Keys for the authentication.<\/p>\n
      When we\u00a0enable the API Keys, the user must pass the Key to call the API. Othervise it will give retuen a message\u00a0“Not able to access resources”<\/strong>.<\/span><\/p>\n
       <\/p>\n
      Step by Step process to call the API using API Key<\/strong><\/h4>\n
      [showhide type=”key”\u00a0more_text=”click here for Detailed Instructions..\u00a0” less_text=”Hide Details” hidden=”yes”]<\/p>\n
      Step 1: In AWS API Gateway Menu bar click on APIs<\/strong> and select API Keys<\/strong><\/p>\n
      \"17\"<\/a><\/p>\n
      Step 2: Click on Create API Key<\/p>\n
      \"18\"<\/a><\/p>\n
      Step 3: Provide and description, leave the check-box unchecked and save<\/p>\n
      \"19\"<\/a><\/p>\n
      Step 4: Your API key has been generated, select API and Stage and click on Add.<\/p>\n
      \"20\"<\/a><\/p>\n
      Step 5: You can see your stage\u00a0has been added to the\u00a0<\/strong>Stages Enabled.<\/p>\n
      Step 6: Now\u00a0navigate to the API Method Execution Console.<\/p>\n
      Step 7: Click on Method Response<\/p>\n
      Step 8: Make API Key Required as true<\/p>\n
      \"21\"<\/a><\/p>\n
      Step 9: Now you can call API from the REST client it will give you message that “Not able to access resource”<\/p>\n
      \"22\"<\/a><\/p>\n
       <\/p>\n
      Step 10: Now provide API key in headers of the API call as shown below<\/p>\n
      \"23\"<\/a><\/p>\n
      Step 11: You will get the proper response<\/p>\n
      \"24\"<\/a><\/strong><\/p>\n
       <\/p>\n
      [\/showhide]<\/p>\n
       <\/p>\n
      AWS API Gateway provides the service which provides the platform to create REST APIs with minimal efforts.it does not only provides the API calls as well as such a useful features as passing query string and header parameters, transforming the response type, returning the custom error code and using the API Keys for authentication.<\/p>\n
      The\u00a0AWS API is becoming the powerful tool to create and deploy the REST APIs with integrating with Lambda function, although you can use the other endpoints as well.It also provides many other features like Cloud watch Monitoring,caching.API Key to distribute to the third party users.<\/p>\n
      If you have any queries on API gateway or you have trouble getting it setup, feel free to drop a question into the comment section below.<\/p>\n","protected":false},"author":219,"featured_media":0,"parent":0,"comment_status":"open","ping_status":"open","template":"","blog_category":[3804,3606,3607,3665],"user_email":"prarthitm@cloudthat.com","published_by":"324","primary-authors":"","secondary-authors":"","acf":[],"_links":{"self":[{"href":"https:\/\/www.cloudthat.com\/resources\/wp-json\/wp\/v2\/blog\/3596"}],"collection":[{"href":"https:\/\/www.cloudthat.com\/resources\/wp-json\/wp\/v2\/blog"}],"about":[{"href":"https:\/\/www.cloudthat.com\/resources\/wp-json\/wp\/v2\/types\/blog"}],"author":[{"embeddable":true,"href":"https:\/\/www.cloudthat.com\/resources\/wp-json\/wp\/v2\/users\/219"}],"replies":[{"embeddable":true,"href":"https:\/\/www.cloudthat.com\/resources\/wp-json\/wp\/v2\/comments?post=3596"}],"version-history":[{"count":1,"href":"https:\/\/www.cloudthat.com\/resources\/wp-json\/wp\/v2\/blog\/3596\/revisions"}],"predecessor-version":[{"id":42350,"href":"https:\/\/www.cloudthat.com\/resources\/wp-json\/wp\/v2\/blog\/3596\/revisions\/42350"}],"wp:attachment":[{"href":"https:\/\/www.cloudthat.com\/resources\/wp-json\/wp\/v2\/media?parent=3596"}],"wp:term":[{"taxonomy":"blog_category","embeddable":true,"href":"https:\/\/www.cloudthat.com\/resources\/wp-json\/wp\/v2\/blog_category?post=3596"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}