Updating to version 0.3, with HA Proxy support

Author: rglaue

README.md

@@ -10,6 +10,13 @@ needs to store stateful information, consider writing a daemon that runs on its
 own as opposed to an xinetd application. However, if your needs are light, and
 you want HTTP REST-like capabilities, perhaps this meets your needs.
 
+##### Version 0.3 with support for HA Proxy HTTP header
+Version 0.3 was updated to parse HA Proxy's `X-Haproxy-Server-State` HTTP
+header when HAProxy uses the configuration `option httpchk` with `http-check
+send-state`. By default, this xinetd script can send results back to HA Proxy
+with both `option tcp-check` and `option httpchk` without differing
+configuration. See **HA Proxy Use** below.
+
 
 ## Using for your purposes
 
@@ -42,29 +49,43 @@ http_response 200 "Success"
 
 ### Available functions
 
-#### get_http_req_uri_params_value <param-name>
+* #### get_http_req_uri_params_value <param-name>
 This function will obtain the value of a paramter provided in the HTTP request.
 ```bash
 # if GET Request URI (GET_REQ_URI) is "/?uptime=seconds&format=json"
 format_value=$(get_http_req_uri_params_value "format")
 # Result: format_value == json
 ```
 
-#### http_response <http-code> <message>
+* #### get_haproxy_server_state_value <param-name>
+This function will obtain the value of a paramter provided in the HTTP request
+header **X-Haproxy-Server-State**.
+```bash
+# if `X-Haproxy-Server-State: UP; name=backend/server; node=haproxy-name; weight=1/2; scur=0/1; qcur=0; throttle=86%
+HA_NAME=$(get_haproxy_server_state_value name)
+# Result: HA_NAME == backend/server
+HA_WEIGHT=$(get_haproxy_server_state_value weight)
+# Result: HA_WEIGHT == 1/2
+HA_STATE=$(get_haproxy_server_state_value state)
+# Result: HA_STATE == UP
+```
+
+
+* #### http_response <http-code> <message>
 This function will return a HTTP response and exit.
 It will do nothing and return if the --http-response option is not set to 1,
 or if the request came from the command line and not as a HTTP request.
 ```bash
 http_response 301 "I did not find what you were looking for."
 ```
 
-#### decrease_health_value
+* #### decrease_health_value
 This function will decrease the global health value
 ```bash
 decrease_health_value
 ```
 
-#### display_health_value
+* #### display_health_value
 This function displays the global helath value in a HTTP response or standard
 output for the command line, and then exits.
 ```bash
@@ -76,7 +97,7 @@ display_health_value
 
 ```bash
 linux$ xinetdhttpservice.sh --help
-xinetd_http_service 0.2
+xinetd_http_service 0.3
 https://github.com/rglaue/xinetd_bash_http_service
 Copyright (C) 2018 Russell Glaue, CAIT, WIU <http://www.cait.org>
 
@@ -107,7 +128,7 @@ Examples:
 
 ### Test to see how HTTP headers are parsed
 
-#### HTTP GET
+* #### HTTP GET
 
 ```bash
 linux$ echo "GET /test123?var1=val1 HTTP/1.0" | xinetdhttpservice.sh --http-status --show-headers
@@ -124,7 +145,7 @@ HTTP_REQ_METHOD=GET
 HTTP_REQ_URI_PARAMS=var1=val1
 ```
 
-#### HTTP POST
+* #### HTTP POST
 
 ```bash
 linux$ xinetdhttpservice.sh --show-headers <<HTTP_EOF
@@ -170,7 +191,7 @@ HTTP_SERVER=127.0.0.1:8080
 --END:HTTP_POST_CONTENT--
 ```
 
-#### HTTP POST Config: MAX_HTTP_POST_LENGTH
+* #### HTTP POST Config: MAX_HTTP_POST_LENGTH
 
 At the top of the xinetdhttpservice.sh bash script, there is a global variable
 that define the maximum allowed length of posted data. Posted data that has a
@@ -180,7 +201,7 @@ length greater than this will be cut off.
 MAX_HTTP_POST_LENGTH=200
 ```
 
-#### HTTP POST Config: READ_BUFFER_LENGTH
+* #### HTTP POST Config: READ_BUFFER_LENGTH
 
 If a non-compliant HTTP client is posting data that is shorter than the
 Content-Length, then the READ_BUFFER_LENGTH should be set to 1. By default
@@ -249,6 +270,62 @@ WEIGHT_VALUE=119
 [xinetdhttpservice_config]: https://github.com/rglaue/xinetd_bash_http_service/blob/master/xinetdhttpservice_config
 
 
+### As a HAProxy server check
+
+First setup the xinetd service, as described previously. Once setup, you should
+be able to get the service status via TCP or HTTP check in HAProxy. This can be
+tested as follows. Both TCP and HTTP checks will work without differing
+configuration in the xinetd_bash_http_service script because the `http_response`
+function only delivers output if the client made an HTTP request.
+
+* #### Testing the health checks
+```bash
+# TCP Checks
+shell$ echo | nc 192.168.2.11 8080
+Service OK
+# HTTP Checks
+shell$ curl http://192.168.2.11:8080
+Service OK
+```
+
+* #### Ensure xinetd script outputs for both HTTP and TCP
+```bash
+# At the end of your xinetd_bash_http_service script
+# send the HTTP response and exit
+http_response 200 "Service OK"
+# or send a TCP response and exit
+echo "Service OK"
+exit 0
+# end of script
+```
+
+* #### Configure HA Proxy
+```bash
+frontend some-fe-server
+    bind 192.168.1.1:1234
+    mode tcp
+    default_backend some-be-server-pool
+
+# Both of these backends will work, but use http checks with the
+# 'http-check send-state' if you want to receive the HA Proxy state.
+
+# tcp checks
+#backend some-be-server-pool
+#    option tcp-check
+#    tcp-check expect string "Service OK"
+#    server srv1 192.168.2.11:80 check port 8080
+#    server srv2 192.168.2.12:80 check port 8080
+
+# http checks
+backend some-be-server-pool
+    option httpchk GET /
+    http-check send-state
+    http-check expect string "Service OK"
+    server srv1 192.168.2.11:80 check port 8080
+    server srv2 192.168.2.12:80 check port 8080
+```
+
+
 ## License
 
 Copyright (C) 2018 [Center for the Application of Information Technologies](http://www.cait.org),

xinetdhttpservice.sh

@@ -7,8 +7,8 @@
 PROG=xinetd_http_service
 DESCRIPTION="bash script called by xinetd to service a HTTP request; a farmework for reporting on health"
 SYNOPSIS="${PROG} [options]"
-VERSION=0.2
-LASTMOD=20180822
+VERSION=0.3
+LASTMOD=20180904
 MAX_HTTP_POST_LENGTH=200
 
 #
@@ -139,6 +139,9 @@ while read -t 0.01 line; do
     elif echo "${line}" | grep -qi "^Content-Type:"; then
       # Content-Type: application/x-www-form-urlencoded
       export HTTP_CONTENT_TYPE="$(echo "${line}"|cut -d" " -f 2-)"
+    elif echo "${line}" | grep -qi "^X-Haproxy-Server-State:"; then
+      # X-Haproxy-Server-State: UP; etc..
+      export HTTP_HAPROXY_SERVER_STATE="$(echo "${line}"|cut -d" " -f 2-)"
     elif [ ${#line} -ge 1 ]; then
       # <any header>
       continue
@@ -212,9 +215,42 @@ get_http_req_uri_params_value () {
     exit 1
 }
 
+#
+# A function for HAProxy
+# Parses the value in the HTTP header "X-Haproxy-Server-State"
+# Examples:
+#   HA_WEIGHT=$(get_haproxy_server_state_value weight) # HA_WEIGHT="1/2" 
+#   HA_STATE=$(get_haproxy_server_state_value state)   # UP, DOWN, NOLB
+#
+get_haproxy_server_state_value () {
+    # Example: "UP; name=backend/server; node=haproxy-name; weight=1/2; scur=0/1; qcur=0; throttle=86%"
+    PARAM_NAME=$1
+    IFS='; ' read -r -a params <<< "$HTTP_HAPROXY_SERVER_STATE"
+    if [ "$PARAM_NAME" == "state" ]; then
+      echo "${params[0]}"
+      exit 0
+    fi
+    for element in "${params[@]}"; do
+      element_name="$(echo "$element" | cut -d"=" -f 1)"
+      if [ "$element_name" == "$PARAM_NAME" ]; then
+        if echo "$element" | grep -q "="; then
+          element_value="$(echo "$element" | cut -d"=" -f 2-)"
+          echo "$element_value"
+        else
+          echo ""
+        fi
+        exit 0
+      fi
+    done
+    exit 1
+}
+
 #
 # Parse parameters from the HTTP request
 #
+if [ ! -z "${HTTP_REQ_URI_PATH}" ]; then
+  OPT_HTTP_STATUS=1
+fi
 if echo ${HTTP_REQ_URI_PATH} | grep -qi "health-value"; then
   OPT_HTTP_STATUS=1
   OPT_HEALTH_VALUE=1
@@ -341,7 +377,7 @@ decrease_health_value
 # display health value response, and exit
 display_health_value
 
-# send a http_response of 200
+# send a http_response of 200, and exit
 http_response 200 "Success"
 
 # End of program