SSM get_param

DESCRIPTION

@@ -1,12 +1,13 @@
 Package: aws.ec2
 Type: Package
 Title: Amazon Web Services EC2 Client Package
-Version: 0.1.13
-Date: 2018-06-02
+Version: 0.1.13-0.42
+Date: 2018-06-26
 Authors@R: c(person("Thomas J.", "Leeper", role = c("aut", "cre"),
                     email = "thosjleeper@gmail.com",
                     comment = c(ORCID = "0000-0003-4097-6326")),
-             person("Andrie", "de Vries", role = "ctb"))
+             person("Andrie", "de Vries", role = "ctb"),
+             person("Massimo", "Redaelli", role = "ctb"))
 Description: A simple client package for the Amazon Web Services ('AWS') Elastic
     Cloud Compute ('EC2') <https://aws.amazon.com/ec2/> 'API'.
 License: GPL (>= 2)
@@ -15,7 +16,8 @@ Imports:
     aws.signature (>= 0.4.0),
     httr,
     xml2,
-    base64enc
+    base64enc,
+    jsonlite
 Suggests:
     testthat,
     aws.ec2metadata,

NAMESPACE

@@ -45,6 +45,7 @@ export(ec2HTTP)
 export(get_console_output)
 export(get_image_attr)
 export(get_instance_attr)
+export(get_parameter)
 export(get_password_data)
 export(get_vpc_attr)
 export(import_keypair)
@@ -78,6 +79,7 @@ importFrom(httr,headers)
 importFrom(httr,http_error)
 importFrom(httr,http_status)
 importFrom(httr,warn_for_status)
+importFrom(jsonlite,fromJSON)
 importFrom(utils,head)
 importFrom(utils,tail)
 importFrom(xml2,as_list)

NEWS.md

@@ -1,3 +1,7 @@
+# aws.ec2 0.1.14
+
+* Support for reading SSM parameters (#4)
+
 # aws.ec2 0.1.13
 
 * Merge major PR (#38) from Andrie de Vries.

R/http.R

@@ -9,13 +9,15 @@
 #' @param secret A character string specifying an AWS Secret Key. See [aws.signature::locate_credentials()].
 #' @param session_token Optionally, a character string specifying an AWS temporary Session Token to use in signing a request. See [aws.signature::locate_credentials()].
 #' @param version A character string specifying an API version. Default is \dQuote{2015-10-01}.
+#' @param service The AWS service (`ec2` or `ssm`). Defaults to `ec2`.
 #' @param clean_response A logical indicating whether to remove line breaks from the response. This is useful for returning a clean response object, but may not be appropriate if the XML-formatted API response contains meaningful linebreaks (e.g., in a keypair).
 #' @param \dots Additional arguments passed to [httr::GET()].
 #' @return A list
 #' @importFrom aws.signature signature_v4_auth
 #' @importFrom aws.signature locate_credentials
 #' @importFrom httr add_headers headers content warn_for_status http_status http_error GET
 #' @importFrom xml2 read_xml as_list
+#' @importFrom jsonlite fromJSON
 #' @export
 ec2HTTP <- 
   function(
@@ -28,6 +30,7 @@ ec2HTTP <-
     secret = NULL, 
     session_token = NULL,
     version = "2016-11-15",
+    service = "ec2",
     clean_response = TRUE,
     ...
   ) {
@@ -43,21 +46,21 @@ ec2HTTP <-
       query$DryRun <- tolower(as.character(dryrun))
     }
     query$Version <- version
-    if (region == "us-east-1") {
+    if (region == "us-east-1" && service == "ec2") {
       url <- paste0("https://ec2.amazonaws.com")
     } else {
-      url <- paste0("https://ec2.",region,".amazonaws.com")
+      url <- paste0("https://",service,".",region,".amazonaws.com")
     }
     d_timestamp <- format(Sys.time(), "%Y%m%dT%H%M%SZ", tz = "UTC")
     Sig <- signature_v4_auth(
       datetime = d_timestamp,
       region = region,
-      service = "ec2",
+      service = service,
       verb = "GET",
       action = "/",
       query_args = query,
       canonical_headers = list(
-        host = if (region == "us-east-1") "ec2.amazonaws.com" else paste0("ec2.",region,".amazonaws.com"),
+        host = if (region == "us-east-1" && service == "ec2") paste0("ec2.amazonaws.com") else paste0(service, ".",region,".amazonaws.com"),
         `X-Amz-Date` = d_timestamp),
       request_body = "",
       key = key, 
@@ -83,16 +86,16 @@ ec2HTTP <-
     }
     if (http_error(r)) {
       tmp <- gsub("\n\\s*", "", content(r, "text"))
-      x <- try(as_list(read_xml(tmp)), silent = TRUE)
-      msg <- paste0(parse_errors(x), collapse = "\n")
+      x <- get(service, parse_response)(tmp)
+      msg <- paste0(get(service, parse_errors)(x), collapse = "\n")
       stop(msg, call. = FALSE)
     } else {
       if (isTRUE(clean_response)) {
         tmp <- gsub("\n\\s*", "", content(r, "text"))
       } else {
         tmp <- content(r, "text")
       }
-      out <- try(as_list(read_xml(tmp)), silent = TRUE)
+      out <- get(service, parse_response)(tmp)
       if (inherits(out, "try-error")) {
         out <- structure(content(r, "text"))
       }
@@ -101,10 +104,21 @@ ec2HTTP <-
     return(out)
   }
 
-parse_errors <- function(error) {
+parse_response = list()
+parse_response$ec2 <- function(res) try(as_list(read_xml(res)), silent = TRUE)
+parse_response$ssm <- function(res) try(fromJSON(res), silent = TRUE)
+
+
+parse_errors = list()
+parse_errors$ec2 <- function(error) {
   messages <- if (!is.null(error$Errors)) error$Errors else error$Response$Errors
   sapply(messages, function(z) {
     paste(z$Code[[1]], z$Message[[1]], sep = " : \n - ", collapse = "\n")
   },
   USE.NAMES = FALSE)
 }
+parse_errors$ssm <- function(error) {
+  messages <- if (!is.null(error$Error)) error$Error else error$Response$Error
+  paste0(messages$Code, " : ", messages$message)
+}
+

R/ssm_parameter.R

@@ -0,0 +1,22 @@
+#' gets a parameter from the parameter store
+#'
+#' @param name The parameter name
+#' @param with_decryption Specifies if the parameter should be decripted. Defaults to \code{TRUE}
+#' @param ... Additional arguments passed to \code{ec2HTTP}
+#'
+#' @return The value of the parameter
+#' @export
+get_parameter <- function(name, with_decryption=TRUE, ...) {
+  query <- list(Action = "GetParameter")
+  if (missing(name)) {
+    stop('Parameter name missing')
+  }
+  names(name) <- "Name"
+
+  with_decryption <- if( with_decryption ) "true" else "false"
+  names(with_decryption) <- "WithDecryption"
+
+  query <- c(query, name, with_decryption)
+  r <- ec2HTTP(version="2014-11-06", query = query, service="ssm", ...)
+  return(r$GetParameterResult$Parameter)
+}