chore(example): add example to test context propagation (#4046)

examples/testing-context-propagation/automatic-instrumentation/.gitignore

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+.env

examples/testing-context-propagation/automatic-instrumentation/README.md

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+## Testing Context Propagation with Automatic Instrumentation
+
+### Overview
+
+This example demonstrates how to test context propagation with automatic instrumentation. It consists of a simple application that uses a backend service to store data. The application is instrumented with OpenTelemetry and sends traces to an Jaeger backend. 
+
+```mermaid
+graph LR
+  User -- POST /sendData --> ServiceA
+  ServiceA -- POST /augmentData --> ServiceB
+```
+
+### Requirements
+
+To run it you need:
+
+- [Docker](https://www.docker.com/get-started/)
+- [Tracetest CLI](https://docs.tracetest.io/getting-started/overview)
+
+You will need to have a Tracetest.io account and an environment to run this example. Once that you created it, add an `.env` file with the following content:
+
+```bash
+TRACETEST_ENVIRONMENT_ID=...
+TRACETEST_API_KEY=...
+```
+
+You can get the values for both `TRACETEST_ENVIRONMENT_ID` and `TRACETEST_API_KEY` on the page: https://app.tracetest.io/retrieve-token
+
+### Running the Example
+
+After setting up the environment, you can run the example with the following commands:
+
+```bash
+docker compose up
+```
+
+And to run the test you can execute the following commands: 
+
+```bash
+tracetest configure ## connect to your environment
+
+tracetest apply datastore -f ./tracetest/tracing-backend.yaml
+```

examples/testing-context-propagation/automatic-instrumentation/docker-compose.yaml

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+services:
+  service-a:
+    build: ./service-a
+    command:
+      - opentelemetry-instrument
+      - python
+      - flask_app.py
+    extra_hosts:
+      - "host.docker.internal:host-gateway"
+    environment:
+      - API_PORT=8800
+      - SERVICE_B_URL=http://service-b:8801
+      - OTEL_SERVICE_NAME=service-a
+      - OTEL_TRACES_EXPORTER=otlp
+      - OTEL_METRICS_EXPORTER=none
+      - OTEL_EXPORTER_OTLP_TRACES_ENDPOINT=http://otel-collector:4317
+    ports:
+      - 8800:8800
+    depends_on:
+      otel-collector:
+        condition: service_started
+      service-b:
+        condition: service_started
+
+  service-b:
+    build: ./service-b
+    command:
+      - npm
+      - start
+    extra_hosts:
+      - "host.docker.internal:host-gateway"
+    environment:
+      - API_PORT=8801
+      - OTEL_SERVICE_NAME=service-b
+      - OTEL_TRACES_EXPORTER=otlp
+      - OTEL_METRICS_EXPORTER=none
+      - OTEL_EXPORTER_OTLP_TRACES_ENDPOINT=http://otel-collector:4318/v1/traces
+      - OTEL_NODE_DISABLED_INSTRUMENTATIONS="fs"
+    ports:
+      - 8801:8801
+    depends_on:
+      otel-collector:
+        condition: service_started
+
+  # Observability stack
+  otel-collector:
+    command:
+      - --config
+      - /otel-local-config.yaml
+    depends_on:
+      jaeger:
+        condition: service_started
+    image: otel/opentelemetry-collector:0.108.0
+    ports:
+      - 4317:4317
+    volumes:
+      - ./observability/otelcollector.config.yaml:/otel-local-config.yaml
+
+  jaeger:
+    healthcheck:
+      test:
+        - CMD
+        - wget
+        - --spider
+        - localhost:16686
+      timeout: 3s
+      interval: 1s
+      retries: 60
+    image: jaegertracing/all-in-one:latest
+    restart: unless-stopped
+    environment:
+      - COLLECTOR_OTLP_ENABLED=true
+    ports:
+      - 16686:16686
+      - 16685:16685
+
+  # Cloud-based Managed Tracetest
+  tracetest-agent:
+    image: kubeshop/tracetest-agent:latest
+    command: ["-v"]
+    environment:
+      # Get the required information here: https://app.tracetest.io/retrieve-token
+      - TRACETEST_API_KEY=${TRACETEST_API_KEY}
+      - TRACETEST_ENVIRONMENT_ID=${TRACETEST_ENVIRONMENT_ID}
+      - TRACETEST_MODE=verbose
+

examples/testing-context-propagation/automatic-instrumentation/observability/otelcollector.config.yaml

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+receivers:
+  otlp:
+    protocols:
+      grpc:
+        endpoint: 0.0.0.0:4317
+      http:
+        endpoint: 0.0.0.0:4318
+
+processors:
+  batch:
+    timeout: 100ms
+
+exporters:
+  debug:
+    verbosity: detailed
+
+  otlp/jaeger:
+    endpoint: jaeger:4317
+    tls:
+      insecure: true
+
+service:
+  pipelines:
+    traces:
+      receivers: [otlp]
+      processors: [batch]
+      exporters: [debug, otlp/jaeger]

examples/testing-context-propagation/automatic-instrumentation/service-a/.gitignore

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+_venv
+.env
+
+node_modules
+
+# Byte-compiled / optimized / DLL files
+__pycache__/
+*.py[cod]
+*$py.class
+
+# C extensions
+*.so
+
+# Distribution / packaging
+.Python
+build/
+develop-eggs/
+dist/
+downloads/
+eggs/
+.eggs/
+lib/
+lib64/
+parts/
+sdist/
+var/
+wheels/
+share/python-wheels/
+*.egg-info/
+.installed.cfg
+*.egg
+MANIFEST
+
+# PyInstaller
+#  Usually these files are written by a python script from a template
+#  before PyInstaller builds the exe, so as to inject date/other infos into it.
+*.manifest
+*.spec
+
+# Installer logs
+pip-log.txt
+pip-delete-this-directory.txt
+
+# Unit test / coverage reports
+htmlcov/
+.tox/
+.nox/
+.coverage
+.coverage.*
+.cache
+nosetests.xml
+coverage.xml
+*.cover
+*.py,cover
+.hypothesis/
+.pytest_cache/
+cover/
+
+# Translations
+*.mo
+*.pot
+
+# Django stuff:
+*.log
+local_settings.py
+db.sqlite3
+db.sqlite3-journal
+
+# Flask stuff:
+instance/
+.webassets-cache
+
+# Scrapy stuff:
+.scrapy
+
+# Sphinx documentation
+docs/_build/
+
+# PyBuilder
+.pybuilder/
+target/
+
+# Jupyter Notebook
+.ipynb_checkpoints
+
+# IPython
+profile_default/
+ipython_config.py
+
+# pyenv
+#   For a library or package, you might want to ignore these files since the code is
+#   intended to run in multiple environments; otherwise, check them in:
+# .python-version
+
+# pipenv
+#   According to pypa/pipenv#598, it is recommended to include Pipfile.lock in version control.
+#   However, in case of collaboration, if having platform-specific dependencies or dependencies
+#   having no cross-platform support, pipenv may install dependencies that don't work, or not
+#   install all needed dependencies.
+#Pipfile.lock
+
+# poetry
+#   Similar to Pipfile.lock, it is generally recommended to include poetry.lock in version control.
+#   This is especially recommended for binary packages to ensure reproducibility, and is more
+#   commonly ignored for libraries.
+#   https://python-poetry.org/docs/basic-usage/#commit-your-poetrylock-file-to-version-control
+#poetry.lock
+
+# pdm
+#   Similar to Pipfile.lock, it is generally recommended to include pdm.lock in version control.
+#pdm.lock
+#   pdm stores project-wide configurations in .pdm.toml, but it is recommended to not include it
+#   in version control.
+#   https://pdm.fming.dev/latest/usage/project/#working-with-version-control
+.pdm.toml
+.pdm-python
+.pdm-build/
+
+# PEP 582; used by e.g. github.com/David-OConnor/pyflow and github.com/pdm-project/pdm
+__pypackages__/
+
+# Celery stuff
+celerybeat-schedule
+celerybeat.pid
+
+# SageMath parsed files
+*.sage.py
+
+# Environments
+.env
+.venv
+env/
+venv/
+ENV/
+env.bak/
+venv.bak/
+
+# Spyder project settings
+.spyderproject
+.spyproject
+
+# Rope project settings
+.ropeproject
+
+# mkdocs documentation
+/site
+
+# mypy
+.mypy_cache/
+.dmypy.json
+dmypy.json
+
+# Pyre type checker
+.pyre/
+
+# pytype static type analyzer
+.pytype/
+
+# Cython debug symbols
+cython_debug/
+
+# PyCharm
+#  JetBrains specific template is maintained in a separate JetBrains.gitignore that can
+#  be found at https://github.com/github/gitignore/blob/main/Global/JetBrains.gitignore
+#  and can be added to the global gitignore or merged into this file.  For a more nuclear
+#  option (not recommended) you can uncomment the following to ignore the entire idea folder.
+#.idea/
+node_modules/
+/test-results/
+/playwright-report/
+/blob-report/
+/playwright/.cache/

examples/testing-context-propagation/automatic-instrumentation/service-a/.python-version

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+3.12

examples/testing-context-propagation/automatic-instrumentation/service-a/Dockerfile

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+FROM python:3.12.4-slim
+
+WORKDIR /opt/app
+COPY requirements.txt ./
+
+RUN pip install --no-cache-dir -r requirements.txt
+RUN opentelemetry-bootstrap -a install
+
+COPY . .