If you are adding custom built-ins to OPA, consider namespacing The rules defined in a module are automatically exported. We also do clean up like remove whitespaces, spellchecks, basic validations, concatenations etc. Steps Several of the steps below require root or sudo access. Another rule thats enforced by OPA is that a variable appearing in a negated expression must also appear in another non-negated equality expression in the rule else it will throw an error. provisioned and the compliance team wants to periodically audit the system to However, there may be slight differences in the commands you need to run. For detailed information on Rego see the Policy Language documentation. We recommend using assignment (:=) and comparison (==) whenever possible for policies that are easier to read and write. In the unusual case that it is critical to use the same name, the function could be made to take the list of parameters as a single array. Commonly used flags include: OPA includes an interactive shell or REPL (Read-Eval-Print-Loop) accessible via See https://www.openpolicyagent.org/docs/latest/faq/#safety for more info on the safety concept. By clicking Sign up for GitHub, you agree to our terms of service and define policies that enumerate instances of data that violate the expected state Array Comprehensions have the form: For example, the following rule defines an object where the keys are application names and the values are hostnames of servers where the application is deployed. This ensures that built-in functions can be called with invalid evaluation. commonly used for constants: Documents produced by rules with complete definitions can only have one value at Rego is declarative so policy authors can focus on what queries should return This is useful to verify if an input exists in the array list. In some cases, rules must perform simple arithmetic, aggregation, and so on. There are just two important points: Using a different key on the same array or object provides the equivalent of self-join in SQL. He also rips off an arm to use as a sword, Copy the n-largest files from a certain directory to the current one. documents as arrays when serializing to JSON or other formats that do not order-sensitive system like IPTables. When a directory path is passed, annotations will be used in the code to indicate what expressions map to what schemas (see below). a reference to another (possibly custom) built-in function: a reference to a rule that will be used as the. GitHub open-policy-agent / gatekeeper Public Notifications Fork 663 Star 3.1k Code Issues 158 Pull requests 15 Actions Projects 1 Security Insights New issue that raw strings may not contain backticks themselves. variable names. See the Policy For example: Set documents are collections of values without keys. Care must also be taken when defining overrides so that the transformation of schemas is sensible and data can be validated against the transformed schema. In those cases, policies can use the Default Keyword to provide a fallback value. Inlined schemas are always used to inform type checking for the eval, check, and test commands; to your account. And its failing with the ingest error rego_unsafe_var_error: expression is unsafe. Comprehensions however may, as the result of a This is the case even if additionalProperties is set to true in the schema. If a query supplies a value for a variable, that variable is an input, and if the query does not supply a value for a variable, that variable is an output. value outside of the set. Rules can either be complete or partial. import future.keywords.every introduces the every keyword described here. Schema files can be referenced by path, where each path starts with the schema namespace, and trailing components specify That query is syntactically and semantically valid. The authors annotation is a list of author entries, where each entry denotes an author. following form: Built-ins usually take one or more input values and produce one output escape special characters. In that case, the equivalent opa eval invocation would be (essentially): You signed in with another tab or window. safety measure: With a new version of OPA, the set of all future keywords can grow, and policies that to match, if OPA is unable to find any variable assignments that satisfy all of All rules have the following form (where key, value, and body are all optional): For a more formal definition of the rule syntax, see the Policy Reference document. https://example.com/v1/data/opa/examples/pi, // data.foo at foo.rego:5 has annotations {"scope":"subpackages","organizations":["Acme Corp."]}, // data.foo.bar at mod:3 has annotations {"scope":"package","description":"A couple of useful rules"}, // data.foo.bar.p at mod:7 has annotations {"scope":"rule","title":"My Rule P"}, // # description: A couple of useful rules, "Pod is a collection of containers that can run on a host. (Importing every means also importing in without an extra import statement.). The scope of the schema annotation can be controlled through the scope annotation. I tried this rego policy on the playground and it worked just fine. Here's my constraint template. Undefined code and simple APIs to offload policy decision-making from your software. This is how we do it. They are optional, and you will find examples below of defining rules without them. as the literal text inside the backticks. In the first stage, users can opt-in to using the new keywords via a special import: We can extract object info corresponding to the same values in two lists along with their index as described below. Rego is declarative so policy authors can focus on what queries should return rather than how queries should be executed. objects is that sets are unkeyed while arrays and objects are keyed, i.e., you Try removing some i, j and see what happens! , So no patch yet, but I'm closing in on the problem. to the set of values assigned to the variable. I can share the exact policies privately if necessary. The data that your service and its users publish can be inspected and transformed using OPA's native query language Rego. inputs without causing the entire policy to stop evaluating. However, this approach is not generally recommended because it sacrifices some helpful compile-time checking and can be quite error-prone. If you select both lines in the rule body, the query should evaluate. For a concise reference, see the Policy In the following example, the rule defines a set of arrays where each array contains an application name and a hostname of a server where the application is deployed. For example, you can define a pi constant as via in : You can also iterate over the set of values by referencing the set elements with a the Policy Reference page. In such strings, certain characters must be escaped to appear in the string, such as double quotes themselves, backslashes, etc. app (which is easy using the some keyword). Often we come across use cases where data is static but it branches in various layers like a tree[JSON tree]. To control the remote hosts schemas will be fetched from, pass a capabilities I am finding that I can examine some variables and not others when I used the key binding OPA: Evaluate Selection. Just like references that refer to non-existent fields or expressions that fail and referencing a schema from http://localhost/ will fail. There are various ways we can solve for it. To learn more, see our tips on writing great answers. The text was updated successfully, but these errors were encountered: @prageetika the resourcequotas variable is not assigned anywhere. some in is used to iterate over the collection (its last argument), OPA returns an error in this case because the rule definitions are in conflict. If you could take a look, and perhaps try it with your real-world policies, that would be great. An incrementally defined rule can be intuitively understood as OR OR OR . There may be multiple sets of bindings that make the rule When we derive a type from a schema, we try to match what is known and unknown in the schema. All built-ins have the Note that there are four cases where brackets must be used: The prefix of a reference identifies the root document for that reference. Constants defined like this can be queried just like any other values: If OPA cannot find variable assignments that satisfy the rule body, we say that For a complete list of built-in functions supported in OPA out-of-the-box see It is sometimes useful to have different input schemas for different rules in the same package. And looking at the support module in my previous comment more closely, it exhibits the same problem: I'm not sure if it makes a difference but one thing to note is the policies here aren't exactly what we're using. immediately follows the annotation. Transforming variables with Jinja2 filters . What does 'They're at four. // Create a prepared query that can be evaluated. operator. import future.keywords.in introduces the in keyword described here. PrepareForEval error when using partial evaluation: "rego_unsafe_var_error: expression is unsafe", the "not-some-not" pattern mentioned in the docs, topdown/eval: fix 'every' term plugging on save, ast/compile: reorder body for safety differently, ast/compile: reorder body for safety differently (. Please try this branch. the rule is undefined. This error is therefore causing the policy not to catch violating inputs appropriately. For resources that are Pods, it checks that the image name allOf is implemented through merging the types from all of the JSON subSchemas listed under allOf before parsing the result to convert it to a Rego type. Connect and share knowledge within a single location that is structured and easy to search. This property ensures that if the rule is evaluated and all of the expressions evaluate to true for some set of variable bindings, the variable in the head of the rule will be defined. follows how requirements are stated, and thus enhances your policys readability. evaluated: The rego.Rego supports several options that let you customize evaluation. That is, they can be queried under OPAs Data API provided the appropriate package is given. a metadata block determines how that metadata block will be applied. scope field is omitted, it defaults to the scope for the statement that If we evaluate v, the result is undefined because the body of the rule never As there is no ordering across files in the same package, the document, package, and subpackages scope annotations Rule definitions can be more expressive when using the future keywords contains and protocols: The default keyword tells OPA to assign a value to the variable if all of On the other hand, if we evaluate q with an input value for name we can determine whether name exists in the document defined by q: Variables appearing in the head of a rule must also appear in a non-negated equality expression within the same rule. But sometimes we need to define our utility functions to fulfil the needs of the policy. To express FOR ALL in Rego complement the logic in the rule body (e.g., statically, or more importantly, the number of networks may not be known in where the name of the author is a sequence of whitespace-separated words. a documented temporarily provided to OPA as part of a transaction. Like other applications which support declarative query languages, OPA is able The related_resources annotation is a list of related-resource entries, where each links to some related external resource; such as RFCs and other reading material. You can start OPA as a server with -s or --server: By default OPA listens for HTTP connections on 0.0.0.0:8181. Without the default definition, the allow document would simply be undefined for the same input. The text was updated successfully, but these errors were encountered: Having a look, here's what the compiler does to your modules when running PrepareForEval with partial eval: Looks like we're losing our future.keywords.every imports along the way. Sanitizing HTML will see the unmodified value. Thanks for contributing an answer to Stack Overflow! Set Comprehensions have the form: For example, to construct a set from an array: Rules define the content of Virtual Documents in not the same as false.) A related-resource entry can either be an object or a short-form string holding a single URL. The error can be avoided by using different function names. When the body evaluates to true, the head of the comprehension is evaluated to produce an element in the result. open policy agent - rego_unsafe_var_error, but only in tests - Stack Well occasionally send you account related emails. in the expression. Based on the given input, how do we search and find a pattern? absolute path. The data that your service and its users publish can be inspected and Use the variables or references. This is useful for checking for the presence of composite values within a set, or extracting all values within a set matching some pattern. These are made of characters surrounded by backticks (`), with the exception The important distinction between sets and arrays or For all the above examples, please find Github repository below: Github-link: https://github.com/shubhi-8/RegoCheatSheetExamples, curl --location --request POST 'http://localhost:8181/v1/data/$policyPath$/{ruleName}' \. 2. The documents produced by rules with complete definitions may still be undefined: In some cases, having an undefined result for a document is not desirable. Attempting to add a validating capability with OPA Gatekeeper with a constraint template. Note that the (future) keyword if is optional here. You can query for the value generated by rules just like any other value: All values generated by rules can be queried via the global data variable. general-purpose policy engine that unifies policy enforcement across the stack. Why the obscure but specific description of Jane Doe II in the original complaint for Westenbroek v. Kappa Kappa Gamma Fraternity? rev2023.5.1.43405. If the left or right-hand side contains a variable that has not been assigned a value, the compiler throws an error. documents. API gateways, and more. To follow along as-is, please import the keywords: See the docs on future keywords for more information. privacy statement. allowed to have zero or more with modifiers. When using data.iam.bar(role, resource, ["foo"], "bar") in policy.rego, we get this rule body. The -s flag can be used to upload schemas for input and data documents in JSON Schema format. For example, if you select x := {"a": "b"} and evaluate it, the plugin essentially runs. By clicking Sign up for GitHub, you agree to our terms of service and set of values just like any other value: Iteration over the set of values can be done with the some in expression: With a literal, or a bound variable, you can check if the value exists in the set Dont worry about understanding everything in this example right now. With a regular string, the regex is "[a-zA-Z_]\\w*", but with raw strings, it becomes `[a-zA-Z_]\w*`. hierarchical data structures. A Journey With Trusted HTML in AngularJS Use of deprecated functions is prohibited, and these will be removed in OPA 1.0. An ast.AnnotationSet can be created from a slice of compiled modules: or can be retrieved from an ast.Compiler instance: The ast.AnnotationSet can be flattened into a slice of ast.AnnotationsRef, which is a complete, sorted list of all Like other applications which support declarative query languages, OPA is able to optimize queries to improve performance. The other type of string declaration is a raw string declaration. Comprehensions are similar to the same constructs found in other languages like Python. For example, an object that has no specified fields becomes the Rego type Object{Any: Any}. update their policies, so that the new keyword will not cause clashes with existing For example, if the input provided to OPA does not Metaschemas for different JSON Schema draft versions are not subject to this errors treated as exceptions that halt policy evaluation enable strict built-in document itself) or data document, or references to functions (built-in or not). This actually becomes a bit clearer if you include 'some' in the deny rule: Technically there would be an infinite number of assignments to label that satisfy this rule (e.g., the string "12345" would NOT be contained in valid_route_request and so would "123456" and so would ). Rules define the context of the policy document in OPA. Well occasionally send you account related emails. The exception to this rule is when multiple The comprehension version is more concise than the negation variant, and does not time, but have been introduced gradually. Deprecated built-in functions: String keys containing characters other than. In the software world, we dont make a release to prod directly instead we have various development environments for quality, performance, end to end testing before we make a release in production. body true. Function arguments may be any kind of term. Consider the following Rego and schema file containing allOf: We can see that request is an object with properties as indicated by the elements listed under allOf: The type checker finds the first error in the Rego code, suggesting that servers should be server. For reproduction steps, policies, and example go code that reproduces the problem, see below. The following rule defines a set containing the hostnames of all servers: Note that the (future) keywords contains and if are optional here. It is not safe because the comprehension on line 4 comes after the object.get call of line 1. rego_unsafe_var_error: expression is unsafe We only know that it refers to a collections of values. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, Parameters in Rego rules [Open Policy Agent], When AI meets IP: Can artists sue AI imitators? Successful creation of constraint template. And then you use negation to check undefined. OPA Pars So what does opa parse do? A simple example is a regex to match a valid Rego variable. details on each built-in function. ", "https://kubernetesjsonschema.dev/v1.14.0/_definitions.json#/definitions/io.k8s.apimachinery.pkg.apis.meta.v1.ObjectMeta", "Standard object's metadata. ), This is consistent with not having [ ] around the "foo" argument, see the last parts of #4766 (comment), @srenatus whoops my bad, just checked and the fix from sr/issue-4766 does indeed fix our actual usage of every where we originally saw this problem. There are explicit iteration constructs to express FOR ALL and FOR SOME, see Safety is a property of Rego that ensures that all variables can be assigned a finite number of values. what does this error really mean - why would my rule be "unsafe", any idea why this would work in the playground but not when running through the OPA binary. The rule itself is a little long to pull apart to post, but when I put the rule into the rego playground it works. To avoid this problem, we can Several variables appear more than once in the body. default value is used when all of the rules sharing the same name are undefined. in the chain. See Every Keyword for details. Object Comprehensions build object values out of sub-queries. # Python equivalent of Rego comprehension shown above. References can include Composite Values as keys if the key is being used to refer into a set. variable operands if variables contained in those statements are not supports so-called complete definitions of any type of document. Attempting to add a validating capability with OPA Gatekeeper with a constraint template. This flag can be repeated. update their policies, so that the new keyword will not cause clashes with existing Rego is declarative so policy authors can focus on what queries should return rather than how queries should be executed. Using some, we can express the rules introduced above in different ways: For details on some in , see the documentation of the in operator. Please tell us how we can improve. Please let me know if it would help to see the actual policies we're using (can share privately). Reference for a formal definition. Rego focuses on providing powerful support for referencing nested documents and When the default keyword is used, the rule syntax is restricted to: The term may be any scalar, composite, or comprehension value but it may not be Unification lets you ask for values for variables that make an expression true. If we fix the Rego code and change input.request.kind.kinds to input.request.kind.kind, then we obtain the expected result: With this feature, it is possible to pass a schema to opa eval, written in JSON Schema. require a helper rule while the negation version is more verbose but a bit simpler On a different note, schema annotations can also be added to policy files part of a bundle package loaded via opa eval --bundle along with the --schema parameter for type checking a set of *.rego policy files. The schemas field specifies an array associating schemas to data values. Output : rego_unsafe_var_error: var _ is unsafe Playground Link: https: . any kind of invariant in your policies. Set the output format to use. Rego lets you encapsulate and re-use logic with rules. Content Discovery initiative April 13 update: Related questions using a Review our technical responses for the 2023 Developer Survey, Open policy agent satisfy condition for all array items, Open policy agent define dynamic global variable, UTF-8 character support in Rego policies/rules, Is it possible to use the output of an external program in an Open policy agent policy, Open Policy Agent (OPA) Rego - Accessing Input Object Nested Fields At Runtime, Open Policy Agent - Improve performance of a grouping comprehension, How to compact and optimize open policy agent, in a single rego policy, Kubernetes Open Policy Agent (OPA) If Else, A boy can regenerate, so demons eat him for years. Schema definitions can be inlined by specifying the schema structure as a YAML or JSON map. Like other applications which support declarative query languages, OPA is able to optimize queries to improve performance. It is designed to work with the nested structure of JSON and YAML documents. Raw strings are what they sound like: escape sequences are not interpreted, but instead taken As you read through this section, try changing the input, queries, OPA. Note that the (future) keyword if is optional here. Therefore, there are other ways to express the desired policy. outside the set, OPA will complain: Because sets share curly-brace syntax with objects, and an empty object is it fails, complaining that the every expression wasn't safe because of __local21__3. If two function definitions are given with the same function name but different numbers of parameters, a compile-time type error is generated. Here are examples of unsafe expressions: # 'x' is unsafe because it does not appear as an output of a non-negated expression not p [x]; not q [x] # 'y' is unsafe because it only appears as a built-in function input count (y) Safety errors can also occur with variables that appear in the head of the rule: Import statements declare dependencies that modules have on documents defined outside the package.
