Add ECS task credentials support

README.md

@@ -234,6 +234,7 @@ Wrapper recognizes these non-curl arguments:
 - `--region` - AWS region name, if can't be automatically detected from host or
   if not explicitly provided in `AWS_DEFAULT_REGION` environment variable
 - `--ec2-creds` - use attached to EC2 credentials (instance role)
+- `--ecs-creds` - use attached to ECS credentials (task role)
 
 ### Response format
 
@@ -307,10 +308,15 @@ including access key, secret key, session token and region.
 
 Just import from the shell as `source ec2-import-creds`.
 
-Or you can use `--ec2-creds` options of `aws-cli` to get the same effect, but
+Or you can use `--ec2-creds` option of `aws-curl` to get the same effect, but
 importing credentials once in beginning is faster than importing for every
 `aws-curl` invocation.
 
+## ECS attached role
+
+When your service runs as ECS task you can import the attached credentials
+using `source ecs-import-creds` or `--ecs-creds` option.
+
 ## Platforms
 
 The script has been tested on bash in posix mode on macOS and Linux. It should

aws-curl

@@ -1,7 +1,7 @@
 #!/bin/sh
 # shellcheck disable=SC2155,SC2001
 
-VERSION="1.0.9"
+VERSION="1.0.10"
 
 DATE_CMD="date"
 SED_CMD="sed"
@@ -21,7 +21,7 @@ fi
 #   safe url string
 ##
 urlsafe() {
-    echo "$1" | sed \
+    echo "$1" | $SED_CMD \
         -e 's!\x09!%09!g' \
         -e 's!\x0A!%0A!g' \
         -e 's!\x0B!%0B!g' \
@@ -336,15 +336,15 @@ sigv4_authorization_header() {
 }
 
 ##
-# Extracts key value from pretty-printed JSON-like structure.
+# Extracts key value from JSON-like structure.
 # Arguments:
 #   $1 payload
 #   $2 key name
 # Returns:
 #   key value
 ##
 get_key_value() {
-    echo "$1" | grep "$2" | cut -d ':' -f 2 | cut -d '"' -f 2
+    echo "$1" | $SED_CMD -n -e "s/.*\"$2\": *\"\([^\"]*\)\".*/\1/p"
 }
 
 ##
@@ -355,7 +355,7 @@ get_key_value() {
 #   region without az suffix
 ##
 strip_az_suffix() {
-    echo "$1" | sed -e 's![a-z]$!!'
+    echo "$1" | $SED_CMD -e 's![a-z]$!!'
 }
 
 ##
@@ -379,6 +379,21 @@ ec2_import_creds() {
     fi
 }
 
+##
+# Imports credentials attached to ECS task
+##
+ecs_import_creds() {
+    curl_opts="--silent --connect-timeout 1 --fail"
+    ecs_creds_url="http://169.254.170.2$AWS_CONTAINER_CREDENTIALS_RELATIVE_URI"
+    credentials=$(curl $curl_opts "$ecs_creds_url")
+
+    if [ -n "$credentials" ]; then
+        AWS_ACCESS_KEY_ID=$(get_key_value "$credentials" "AccessKeyId")
+        AWS_SECRET_ACCESS_KEY=$(get_key_value "$credentials" "SecretAccessKey")
+        AWS_SESSION_TOKEN=$(get_key_value "$credentials" "Token")
+    fi
+}
+
 ##
 # Show help
 ##
@@ -405,6 +420,7 @@ CURL_VERBOSE=""
 AWS_REGION=""
 AWS_SERVICE=""
 EC2_CREDS="0"
+ECS_CREDS="0"
 
 # read command line arguments
 while [ "$#" != 0 ]; do
@@ -460,6 +476,10 @@ while [ "$#" != 0 ]; do
             shift
             EC2_CREDS="1"
             ;;
+        --ecs-creds )
+            shift
+            ECS_CREDS="1"
+            ;;
         --data-ascii | --data-raw | --data-urlencode )
             echo "Option $1 is not supported at this time."
             exit 1
@@ -500,6 +520,11 @@ if [ "$EC2_CREDS" = 1 ]; then
     ec2_import_creds
 fi
 
+# import attached ecs credentials if enabled
+if [ "$ECS_CREDS" = 1 ]; then
+    ecs_import_creds
+fi
+
 # check mandatory environment variables
 if [ -z "$AWS_ACCESS_KEY_ID" ] || [ -z "$AWS_SECRET_ACCESS_KEY" ]; then
     echo "AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY are not set."

ec2-import-creds

@@ -6,7 +6,7 @@ credentials=$([ -n "$attached_role_name" ] && curl -m 1 -s "http://169.254.169.2
 availability_zone="$(curl -m 1 -s "http://169.254.169.254/latest/meta-data/placement/availability-zone")"
 
 get_key_value() {
-  echo "$1" | grep "$2" | cut -d ':' -f 2 | cut -d '"' -f 2
+  echo "$1" | sed -n -e "s/.*\"$2\": *\"\([^\"]*\)\".*/\1/p"
 }
 
 strip_az_suffix() {

ecs-import-creds

@@ -0,0 +1,14 @@
+#!/bin/sh
+# shellcheck disable=SC2155
+
+credentials=$(curl -m 1 -s "http://169.254.170.2$AWS_CONTAINER_CREDENTIALS_RELATIVE_URI")
+
+get_key_value() {
+  echo "$1" | sed -n -e "s/.*\"$2\": *\"\([^\"]*\)\".*/\1/p"
+}
+
+if [ -n "$credentials" ]; then
+  export AWS_ACCESS_KEY_ID=$(get_key_value "$credentials" "AccessKeyId")
+  export AWS_SECRET_ACCESS_KEY=$(get_key_value "$credentials" "SecretAccessKey")
+  export AWS_SESSION_TOKEN=$(get_key_value "$credentials" "Token")
+fi