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With this commit we make it possible to adjust the request headers sent to Prometheus by the codemirror-promql extension. This enables customizing the headers sent, without re-implementing the Prometheus client completely. Signed-off-by: Jacob Baungard Hansen <jacobbaungard@redhat.com>
250 lines
8.8 KiB
Markdown
250 lines
8.8 KiB
Markdown
CodeMirror-promql
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=================
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This project provides a mode for [CodeMirror](https://codemirror.net/6/) that handles syntax highlighting, linting
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and autocompletion for PromQL ([Prometheus Query Language](https://prometheus.io/docs/introduction/overview/)).
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## Installation
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This mode is available as a npm package:
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```bash
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npm install --save @prometheus-io/codemirror-promql
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```
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**Note:** You will have to manually install different packages that are part
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of [CodeMirror](https://codemirror.net/6/), as they are a peer dependency to this package. Here are the different
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packages you need to install:
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* **@codemirror/autocomplete**
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* **@codemirror/language**
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* **@codemirror/lint**
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* **@codemirror/state**
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* **@codemirror/view**
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* **@lezer/common**
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```bash
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npm install --save @codemirror/autocomplete @codemirror/language @codemirror/lint @codemirror/state @codemirror/view @lezer/common
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```
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**Note 2**: that's the minimum required to install the lib. You would probably need to install as well the dependency
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**@codemirror/basic-setup** to ease the setup of codeMirror itself:
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```bash
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npm install --save @codemirror/basic-setup
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```
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## Usage
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As the setup of the PromQL language can a bit tricky in CMN, this lib provides a class `PromQLExtension`
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which is here to help you to configure the different extensions we aim to provide.
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### Default setup
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If you want to enjoy about the different features provided without taking too much time to understand how to configure
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them, then the easiest way is this one:
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```typescript
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import {PromQLExtension} from '@prometheus-io/codemirror-promql';
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import {basicSetup} from '@codemirror/basic-setup';
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import {EditorState} from '@codemirror/state';
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import {EditorView} from '@codemirror/view';
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const promQL = new PromQLExtension()
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new EditorView({
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state: EditorState.create({
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extensions: [basicSetup, promQL.asExtension()],
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}),
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// eslint-disable-next-line @typescript-eslint/no-non-null-assertion
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// tslint:disable-next-line:no-non-null-assertion
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parent: document.getElementById('editor')!,
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});
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```
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Using the default setup will activate:
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* syntax highlighting
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* an offline autocompletion that will suggest PromQL keywords such as functions / aggregations, depending on the
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context.
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* an offline linter that will display PromQL syntax errors (which is closer to what Prometheus returns)
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### Deactivate autocompletion - linter
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In case you would like to deactivate the linter and/or the autocompletion it's simple as that:
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```typescript
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const promQL = new PromQLExtension().activateLinter(false).activateCompletion(false) // here the linter and the autocomplete are deactivated
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```
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### Linter
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There is no particular configuration today for the linter. Feel free to file an issue if you have some use cases that
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would require configurability.
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### Autocompletion
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The autocompletion feature provides multiple different parameters that can be used to adapt this lib to your
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environment.
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#### maxMetricsMetadata
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`maxMetricsMetadata` is the maximum number of metrics in Prometheus for which metadata is fetched. If the number of
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metrics exceeds this limit, no metric metadata is fetched at all.
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By default, the limit is 10 000 metrics.
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Use it cautiously. A high value of this limit can cause a crash of your browser due to too many data fetched.
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```typescript
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const promQL = new PromQLExtension().setComplete({maxMetricsMetadata: 10000})
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```
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#### Connect the autocompletion extension to a remote Prometheus server
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Connecting the autocompletion extension to a remote Prometheus server will provide autocompletion of metric names, label
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names, and label values.
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##### Use the default Prometheus client
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###### Prometheus URL
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If you want to use the default Prometheus client provided by this lib, you have to provide the url used to contact the
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Prometheus server.
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Note: this is the only mandatory parameter in case you want to use the default Prometheus client. Without this
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parameter, the rest of the config will be ignored, and the Prometheus client won't be initialized.
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```typescript
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const promQL = new PromQLExtension().setComplete({remote: {url: 'https://prometheus.land'}})
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```
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###### Override FetchFn
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In case your Prometheus server is protected and requires a special HTTP client, you can override the function `fetchFn`
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that is used to perform any required HTTP request.
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```typescript
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const promQL = new PromQLExtension().setComplete({remote: {fetchFn: myHTTPClient}})
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```
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###### Duration to use for looking back when retrieving metrics / labels
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If you are a bit familiar with the Prometheus API, you are aware that you can pass a time interval that is used to tell
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to Prometheus which period of time you are looking for when retrieving metadata (like metrics / labels).
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In case you would like to provide your own duration, you can override the variable `lookbackInterval`. By default, the
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value is `12 * 60 * 60 * 1000` (12h). The value must be defined in **milliseconds**.
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```typescript
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const promQL = new PromQLExtension().setComplete({remote: {lookbackInterval: 12 * 60 * 60 * 1000}})
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```
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###### Error Handling
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You can set up your own error handler to catch any HTTP error that can occur when the PrometheusClient is contacting
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Prometheus.
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```typescript
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const promQL = new PromQLExtension().setComplete({remote: {httpErrorHandler: (error: any) => console.error(error)}})
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```
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###### HTTP method used
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By default, the Prometheus client will use the HTTP method `POST` when contacting Prometheus for the
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endpoints `/api/v1/labels` and `/api/v1/series`.
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You can change it to use the HTTP method `GET` if you prefer.
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```typescript
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const promQL = new PromQLExtension().setComplete({remote: {httpMethod: 'GET'}})
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```
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###### HTTP request headers
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If you need to send specific HTTP headers along with the requests to Prometheus, you can adjust that as follows:
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```typescript
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const customHeaders = new Headers({'header-name': 'test-value'});
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const promql = new PromQLExtension().setComplete({remote: {requestHeaders: customHeaders}})
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```
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###### Override the API Prefix
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The default Prometheus Client, when building the query to get data from Prometheus, is using an API prefix which is by
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default `/api/v1`.
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You can override this value like this:
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```typescript
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const promql = new PromQLExtension().setComplete({remote: {apiPrefix: '/my/api/prefix'}})
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```
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###### Cache
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The default client has an embedded cache that is used to store the different metrics and labels retrieved from a remote
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Prometheus server.
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###### Max Age
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The data are stored in the cache for a limited amount of time defined by the variable `maxAge` which is by default 5
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minutes. The value must be defined in **milliseconds**.
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```typescript
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const promQL = new PromQLExtension().setComplete({remote: {cache: {maxAge: 5 * 60 * 1000}}})
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```
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###### Initial Metric List
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The cache can be initialized with a list of metric names. It is useful when you already have the list of the metrics
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somewhere else in your application, and you would like to share this list with the embedded Prometheus client
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of `codemirror-promql`.
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Note: keep in mind that this list will be kept into the embedded Prometheus client until the time defined by `maxAge`.
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```typescript
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const promQL = new PromQLExtension().setComplete({
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remote: {
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cache: {
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initialMetricList: [
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'ALERTS',
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'ALERTS_FOR_STATE',
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'alertmanager_alerts',
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'alertmanager_alerts_invalid_total',
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'alertmanager_alerts_received_total',
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]
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}
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}
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})
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```
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##### Override the default Prometheus client
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In case you are not satisfied by our default Prometheus client, you can still provide your own. It has to implement the
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interface [PrometheusClient](https://github.com/prometheus/codemirror-promql/blob/main/src/client/prometheus.ts#L24-L39)
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.
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```typescript
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const promQL = new PromQLExtension().setComplete({remote: MyPrometheusClient})
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```
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#### Provide your own implementation of the autocompletion
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In case you would like to provide you own implementation of the autocompletion, you can simply do it like that:
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```typescript
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const promQL = new PromQLExtension().setComplete({completeStrategy: myCustomImpl})
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```
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Note: In case this parameter is provided, then the rest of the configuration is ignored.
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### Example
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* [ReactJS example](https://github.com/prometheus/prometheus/blob/431ea75a11ca165dad9dd5d629b3cf975f4c186b/web/ui/react-app/src/pages/graph/CMExpressionInput.tsx)
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* [Angular example](https://github.com/perses/perses/blob/28b3bdac88b0ed7a4602f9c91106442eafcb6c34/internal/api/front/perses/src/app/project/prometheusrule/promql-editor/promql-editor.component.ts)
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## License
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The code is licensed under an [Apache 2.0](https://github.com/prometheus/prometheus/blob/main/LICENSE) license.
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