[Fleet] Fix incorrect conversion of string to numeric values in agent YAML

[jen-huang]

Summary

Resolves #89955. If the user enters an all-numeric value for an integration configuration field that should be text, even though Fleet does save the value correctly as a string in the saved object, it ends up as a number instead of string in the final agent yaml. This is due to the way we compile the agent yaml templates and convert it back to a JS object. Here's an example:

// User value as saved in the package policy saved object
{"some_key": {"type": "text", "value": "123"}}

// Agent yaml handlebars template defined by the package
some_key: {{some_key}}

// Compiled agent yaml using saved object values + the template
some_key: 123

// Conversion back to a JS object
{"some_key": 123}  <-- note that it is no longer a string, but a number, due to automatic typing during conversion from yaml

This PR adds another condition to our pre-compilation processing of template variables so that all-numeric values which should be treated as strings are escaped with quotes so that the compiled yaml has quotes around the value too.

[elasticmachine]

Pinging @elastic/fleet (Team:Fleet)

[elasticmachine]

Pinging @elastic/fleet (Feature:Fleet)

[nchaulet]

I am wondering if we could fix it when we generate the template if have this kind of template this will not work

// User value as saved in the package policy saved object
{"variableWithANameDifferentThanTheKey": {"type": "text", "value": "123"}}

// Agent yaml handlebars template defined by the package
some_key: {{variableWithANameDifferentThanTheKey}}

Could we escape the string when we generate the template like this ? and does it solve our issue?

some_key: "123"

[jen-huang]

Good catch @nchaulet, I'll modify the test case...

Could we escape the string when we generate the template like this ?

Do you mean after we compile the template? Could you suggest a way to do this?

[nchaulet]

@jen-huang I think it could work with something like this, not sure on the complexity this is adding

diff --git a/x-pack/plugins/fleet/server/services/epm/agent/agent.ts b/x-pack/plugins/fleet/server/services/epm/agent/agent.ts
index 6b1d84ea28b..c706f2a5ffe 100644
--- a/x-pack/plugins/fleet/server/services/epm/agent/agent.ts
+++ b/x-pack/plugins/fleet/server/services/epm/agent/agent.ts
@@ -84,6 +84,13 @@ function buildTemplateVariables(variables: PackagePolicyConfigRecord, templateSt
       const yamlKeyPlaceholder = `##${key}##`;
       varPart[lastKeyPart] = `"${yamlKeyPlaceholder}"`;
       yamlValues[yamlKeyPlaceholder] = recordEntry.value ? safeLoad(recordEntry.value) : null;
+    } else if (recordEntry.type && recordEntry.type === 'text') {
+      if (Array.isArray(recordEntry.value)) {
+        varPart[lastKeyPart] = recordEntry.value.map((val) => `"${recordEntry.value}"`);
+      } else {
+        // TODO escape double quote
+        varPart[lastKeyPart] = `"${recordEntry.value}"`;
+      }
     } else {
       varPart[lastKeyPart] = recordEntry.value;
     }
(END)

[jen-huang]

@nchaulet Thanks for the suggestion. I'll take a closer look to make sure this works for values which are already strings (and don't need escaping).

[jen-huang]

@nchaulet I've adjusted this PR to take most of your suggestion but restricting it to only numeric strings. Could you take another look?

[nchaulet]

🚀

[kibanamachine]

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• continuous-integration/kibana-ci/pull-request
• Commit: b804d8a

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• 💚 Build #104396 succeeded c1b8dd1
• 💚 Build #104101 succeeded 1e8bea4

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