Escape json posts in curl_json plugin

*If* in the 'post' parameter we've been given a valid json string, it
definately won't work unless we do some escaping of double quotes.

If any strings in the JSON also contain (correctly escaped) double
quotes, even more backslashes are needed.

eg. The following JSON

```
{"param1":"something with a double quote \" in it"}
```

Would end up in the config file as

```
Post "{\"param1\":\"something with a double quote \\\" in it\"}"
```

spec/classes/collectd_plugin_fscache_spec.rb

@@ -13,6 +13,7 @@
     let :facts do
       {
         osfamily: 'FreeBSD',
+        operatingsystem: 'FreeBSD',
         os: { family: 'FreeBSD' },
         collectd_version: '4.7.0',
         operatingsystemmajrelease: '7',
@@ -31,6 +32,7 @@
     let :facts do
       {
         osfamily: 'FreeBSD',
+        operatingsystem: 'FreeBSD',
         os: { family: 'FreeBSD' },
         collectd_version: '4.7.0',
         operatingsystemmajrelease: '7',

spec/defines/collectd_plugin_curl_json_spec.rb

@@ -28,8 +28,8 @@
           verifypeer: 'false',
           verifyhost: 'false',
           cacert: '/path/to/ca.crt',
-          header: 'Accept: application/json',
-          post: '{secret: \"mysecret\"}',
+          header: 'Content-Type: application/x-www-form-urlencoded',
+          post: 'secret=mysecret&foo=bar',
           timeout: 1000,
           keys: {
             'message_stats/publish' => {
@@ -106,8 +106,8 @@
         it { is_expected.to contain_file(filename).with_content(%r{VerifyPeer false}) }
         it { is_expected.to contain_file(filename).with_content(%r{VerifyHost false}) }
         it { is_expected.to contain_file(filename).with_content(%r{CACert "/path/to/ca.crt"}) }
-        it { is_expected.to contain_file(filename).with_content(%r{Header "Accept: application/json"}) }
-        it { is_expected.to contain_file(filename).with_content(%r|Post "{secret: \\"mysecret\\"}"|) }
+        it { is_expected.to contain_file(filename).with_content(%r{Header "Content-Type: application/x-www-form-urlencoded"}) }
+        it { is_expected.to contain_file(filename).with_content(%r{Post "secret=mysecret&foo=bar"}) }
         it { is_expected.to contain_file(filename).without_content(%r{Timeout}) }
         it { is_expected.to contain_file(filename).with_content(%r{Key "message_stats/publish">}) }
         it { is_expected.to contain_file(filename).with_content(%r{Type "gauge"}) }
@@ -139,8 +139,8 @@
         it { is_expected.to contain_file(filename).with_content(%r{VerifyPeer false}) }
         it { is_expected.to contain_file(filename).with_content(%r{VerifyHost false}) }
         it { is_expected.to contain_file(filename).with_content(%r{CACert "/path/to/ca.crt"}) }
-        it { is_expected.to contain_file(filename).with_content(%r{Header "Accept: application/json"}) }
-        it { is_expected.to contain_file(filename).with_content(%r|Post "{secret: \\"mysecret\\"}"|) }
+        it { is_expected.to contain_file(filename).with_content(%r{Header "Content-Type: application/x-www-form-urlencoded"}) }
+        it { is_expected.to contain_file(filename).with_content(%r{Post "secret=mysecret&foo=bar"}) }
         it { is_expected.to contain_file(filename).with_content(%r{Timeout 1000}) }
         it { is_expected.to contain_file(filename).with_content(%r{Key "message_stats/publish">}) }
         it { is_expected.to contain_file(filename).with_content(%r{Type "gauge"}) }
@@ -172,8 +172,8 @@
         it { is_expected.to contain_file(filename).with_content(%r{VerifyPeer false}) }
         it { is_expected.to contain_file(filename).with_content(%r{VerifyHost false}) }
         it { is_expected.to contain_file(filename).with_content(%r{CACert "/path/to/ca.crt"}) }
-        it { is_expected.to contain_file(filename).with_content(%r{Header "Accept: application/json"}) }
-        it { is_expected.to contain_file(filename).with_content(%r|Post "{secret: \\"mysecret\\"}"|) }
+        it { is_expected.to contain_file(filename).with_content(%r{Header "Content-Type: application/x-www-form-urlencoded"}) }
+        it { is_expected.to contain_file(filename).with_content(%r{Post "secret=mysecret&foo=bar"}) }
         it { is_expected.to contain_file(filename).with_content(%r{Timeout 1000}) }
         it { is_expected.to contain_file(filename).with_content(%r{Key "message_stats/publish">}) }
         it { is_expected.to contain_file(filename).with_content(%r{Type "gauge"}) }
@@ -211,6 +211,28 @@
         it { is_expected.to contain_file(filename).with_content(%r{Type "gauge"}) }
         it { is_expected.to contain_file(filename).with_content(%r{Instance "overview"}) }
       end
+
+      context 'json posts' do
+        let(:post) do
+          {
+            'type' => 'read',
+            'mbean' => 'Catalina:name="http-nio-127.0.0.1-8080",type=GlobalRequestProcessor'
+          }.to_json
+        end
+
+        let(:params) do
+          my_params.merge(header: 'Content-Type: application/json', post: post)
+        end
+
+        let :facts do
+          facts.merge(collectd_version: '5.6.0')
+        end
+
+        it { is_expected.to contain_file(filename).with_content(%r{Header "Content-Type: application/json"}) }
+
+        # In the regex below, we have to escape the backslashes in "{\"type\":\"read\",\"mbean\":\"Catalina:name=\\\"http-nio-127.0.0.1-8080\\\",type=GlobalRequestProcessor\"}"
+        it { is_expected.to contain_file(filename).with_content(%r|Post "{\\"type\\":\\"read\\",\\"mbean\\":\\"Catalina:name=\\\\\\"http-nio-127\.0\.0\.1-8080\\\\\\",type=GlobalRequestProcessor\\"}"|) }
+      end
     end
   end
 end

templates/curl_json.conf.erb

@@ -40,10 +40,22 @@ LoadPlugin "curl_json"
 <% if @header -%>
     Header "<%= @header %>"
 <% end -%>
+<%-
+  def valid_json?(json)
+    JSON.parse(json)
+    return true
+  rescue JSON::ParserError
+    return false
+  end
+-%>
 <% unless @post.nil? -%>
+<% if valid_json?(@post) -%>
+    Post "<%= @post.gsub('\\"','\\\\\\\\\"').gsub!(%r{(?<!\\)"},'\"') %>"
+<% else -%>
     Post "<%= @post %>"
 <% end -%>
 <% end -%>
+<% end -%>
 <% if scope.lookupvar('collectd::collectd_version_real') and (scope.function_versioncmp([scope.lookupvar('collectd::collectd_version_real'), '5.5']) >= 0) -%>
 <% unless @timeout.nil? -%>
     Timeout <%= @timeout %>