ci/bin: Add utility to find jobs dependencies

Use GraphQL API from Gitlab to find jobs dependencies in a pipeline.
E.g: Find all dependencies for jobs starting with "iris-"

```sh
.gitlab-ci/bin/gitlab_gql.py --sha $(git -C ../mesa-fast-fix rev-parse HEAD) --print-dag --regex "iris-.*"
```

Signed-off-by: Guilherme Gallo <guilherme.gallo@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/17791>

.gitlab-ci/bin/download_gl_schema.sh

@@ -0,0 +1,11 @@
+#!/bin/sh
+
+# Helper script to download the schema GraphQL from Gitlab to enable IDEs to
+# assist the developer to edit gql files
+
+SOURCE_DIR=$(dirname "$(realpath "$0")")
+
+(
+    cd $SOURCE_DIR || exit 1
+    gql-cli https://gitlab.freedesktop.org/api/graphql --print-schema > schema.graphql
+)

.gitlab-ci/bin/gitlab_gql.py

@@ -0,0 +1,117 @@
+#!/usr/bin/env python3
+
+import re
+from argparse import ArgumentParser, Namespace
+from dataclasses import dataclass, field
+from itertools import chain
+from pathlib import Path
+from typing import Any, Pattern
+
+from gql import Client, gql
+from gql.transport.aiohttp import AIOHTTPTransport
+from graphql import DocumentNode
+
+Dag = dict[str, list[str]]
+
+
+@dataclass
+class GitlabGQL:
+    _transport: Any = field(init=False)
+    client: Client = field(init=False)
+    url: str = "https://gitlab.freedesktop.org/api/graphql"
+
+    def __post_init__(self):
+        self._setup_gitlab_gql_client()
+
+    def _setup_gitlab_gql_client(self) -> Client:
+        # Select your transport with a defined url endpoint
+        self._transport = AIOHTTPTransport(url=self.url)
+
+        # Create a GraphQL client using the defined transport
+        self.client = Client(
+            transport=self._transport, fetch_schema_from_transport=True
+        )
+
+    def query(self, gql_file: Path | str, params: dict[str, Any]) -> dict[str, Any]:
+        # Provide a GraphQL query
+        source_path = Path(__file__).parent
+        pipeline_query_file = source_path / gql_file
+
+        query: DocumentNode
+        with open(pipeline_query_file, "r") as f:
+            pipeline_query = f.read()
+            query = gql(pipeline_query)
+
+        # Execute the query on the transport
+        return self.client.execute(query, variable_values=params)
+
+
+def create_job_needs_dag(
+    gl_gql: GitlabGQL, params
+) -> tuple[Dag, dict[str, dict[str, Any]]]:
+
+    result = gl_gql.query("pipeline_details.gql", params)
+    dag = {}
+    jobs = {}
+    pipeline = result["project"]["pipeline"]
+    if not pipeline:
+        raise RuntimeError(f"Could not find any pipelines for {params}")
+
+    for stage in pipeline["stages"]["nodes"]:
+        for stage_job in stage["groups"]["nodes"]:
+            for job in stage_job["jobs"]["nodes"]:
+                needs = job.pop("needs")["nodes"]
+                jobs[job["name"]] = job
+                dag[job["name"]] = {node["name"] for node in needs}
+
+    for job, needs in dag.items():
+        needs: set
+        partial = True
+
+        while partial:
+            next_depth = {n for dn in needs for n in dag[dn]}
+            partial = not needs.issuperset(next_depth)
+            needs = needs.union(next_depth)
+
+        dag[job] = needs
+
+    return dag, jobs
+
+
+def filter_dag(dag: Dag, regex: Pattern) -> Dag:
+    return {job: needs for job, needs in dag.items() if re.match(regex, job)}
+
+
+def print_dag(dag: Dag) -> None:
+    for job, needs in dag.items():
+        print(f"{job}:")
+        print(f"\t{' '.join(needs)}")
+        print()
+
+
+def parse_args() -> Namespace:
+    parser = ArgumentParser()
+    parser.add_argument("-pp", "--project-path", type=str, default="mesa/mesa")
+    parser.add_argument("--sha", type=str, required=True)
+    parser.add_argument("--regex", type=str, required=False)
+    parser.add_argument("--print-dag", action="store_true")
+
+    return parser.parse_args()
+
+
+def main():
+    args = parse_args()
+    gl_gql = GitlabGQL()
+
+    if args.print_dag:
+        dag, jobs = create_job_needs_dag(
+            gl_gql, {"projectPath": args.project_path, "sha": args.sha}
+        )
+
+        if args.regex:
+            dag = filter_dag(dag, re.compile(args.regex))
+        print_dag(dag)
+
+
+if __name__ == "__main__":
+    main()

.gitlab-ci/bin/pipeline_details.gql

@@ -0,0 +1,86 @@
+fragment LinkedPipelineData on Pipeline {
+  id
+  iid
+  path
+  cancelable
+  retryable
+  userPermissions {
+    updatePipeline
+  }
+  status: detailedStatus {
+    id
+    group
+    label
+    icon
+  }
+  sourceJob {
+    id
+    name
+  }
+  project {
+    id
+    name
+    fullPath
+  }
+}
+
+query getPipelineDetails($projectPath: ID!, $sha: String!) {
+  project(fullPath: $projectPath) {
+    id
+    pipeline(sha: $sha) {
+      id
+      iid
+      complete
+      downstream {
+        nodes {
+          ...LinkedPipelineData
+        }
+      }
+      upstream {
+        ...LinkedPipelineData
+      }
+      stages {
+        nodes {
+          id
+          name
+          status: detailedStatus {
+            id
+            action {
+              id
+              icon
+              path
+              title
+            }
+          }
+          groups {
+            nodes {
+              id
+              status: detailedStatus {
+                id
+                label
+                group
+                icon
+              }
+              name
+              size
+              jobs {
+                nodes {
+                  id
+                  name
+                  kind
+                  scheduledAt
+                  needs {
+                    nodes {
+                      id
+                      name
+                    }
+                  }
+                }
+              }
+            }
+          }
+        }
+      }
+    }
+  }
+}

.gitlab-ci/bin/requirements.txt

@@ -1,2 +1,3 @@
 colorama==0.4.5
+gql==3.4.0
 python-gitlab==3.5.0

.graphqlrc.yml

@@ -0,0 +1,2 @@
+schema: 'schema.graphql'
+documents: 'src/**/*.{graphql,js,ts,jsx,tsx}'