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Container Apps Environment Variables Reference

Use this reference to understand variables injected by Azure Container Apps and common application/runtime variables used in Python workloads.

Prerequisites

  • Python app running in Azure Container Apps
  • Basic understanding of app configuration and secrets

Port mismatches cause startup and ingress failures

If your application listens on a different port than the configured ingress target, the revision may stay unhealthy. Ensure app binding and CONTAINER_APP_PORT expectations are aligned.

Debug variable state from inside the running container

Use az containerapp exec to inspect runtime environment values when behavior differs between local and cloud. Validate expected names, defaults, and secret references directly in the replica.

Environment variable resolution flow

flowchart TD
    A[Container App Configuration] --> B[Platform Injected Variables]
    A --> C[User-defined Env Vars]
    A --> D[Secret References]
    D --> C
    B --> E[Container Runtime Environment]
    C --> E
    E --> F[Application Startup]
    F --> G[os.getenv or framework config loader]
    G --> H[Effective Runtime Configuration]

Platform-injected variables

These variables are provided by the platform at runtime.

Variable Description Default Example
CONTAINER_APP_NAME Container App resource name None ca-myapp
CONTAINER_APP_REVISION Active revision name None ca-myapp--0000001
CONTAINER_APP_REPLICA_NAME Replica identifier None ca-myapp--0000001-646779b4c5-bhc2v
CONTAINER_APP_PORT Expected listening port for app container 8000 (if configured that way) 8000
CONTAINER_APP_HOSTNAME Internal hostname for app service discovery None ca-orders-api.internal
CONTAINER_APP_ENV_DNS_SUFFIX Environment-level internal DNS suffix None <hash>.<region>.azurecontainerapps.io
CONTAINER_APP_JOB_NAME Job name (jobs only) None job-data-sync
CONTAINER_APP_JOB_EXECUTION_NAME Job execution id (jobs only) None job-data-sync-xxxxxxxx
CONTAINER_APP_JOB_TRIGGER_TYPE Trigger type for job execution None Schedule

Verified runtime values from real deployment

The following values were observed from a real Azure Container Apps deployment and container runtime (PII scrubbed):

CONTAINER_APP_NAME=ca-myapp
CONTAINER_APP_REVISION=ca-myapp--0000001
CONTAINER_APP_REPLICA_NAME=ca-myapp--0000001-646779b4c5-bhc2v
CONTAINER_APP_ENV_DNS_SUFFIX=<hash>.<region>.azurecontainerapps.io
CONTAINER_APP_PORT=8000

Health and info endpoint outputs from the same revision:

{"status":"healthy","timestamp":"2026-04-04T11:32:37.322216+00:00"}

{
  "containerApp": "ca-myapp",
  "environment": "development",
  "python": "3.11.15",
  "revision": "ca-myapp--0000001",
  "version": "1.0.0"
}

Common app configuration variables

Variable Description Default Example
ENV App environment identifier development production
LOG_LEVEL Logging verbosity info warning
APP_VERSION Deployed app version string None 2026.04.04.1
FEATURE_FLAGS Comma-separated feature toggles None checkout_v2,recommendations
STORAGE_ACCOUNT_URL Blob service endpoint None https://storders.blob.core.windows.net
REDIS_HOST Redis hostname None orders-redis.redis.cache.windows.net
DB_SERVER Database server hostname None sql-orders.database.windows.net

Gunicorn and Flask variables

Variable Description Default Example
GUNICORN_CMD_ARGS Extra Gunicorn command arguments None --workers 4 --timeout 120
WEB_CONCURRENCY Gunicorn worker process count Gunicorn default 4
PYTHONUNBUFFERED Unbuffer stdout/stderr logs 0 1
PYTHONDONTWRITEBYTECODE Disable .pyc creation 0 1
FLASK_ENV Flask environment mode production production
FLASK_DEBUG Flask debug mode toggle 0 0

OpenTelemetry variables

Variable Description Default Example
OTEL_SERVICE_NAME Logical service name App name orders-api
OTEL_EXPORTER_OTLP_ENDPOINT OTLP collector endpoint None http://otel-collector:4317
OTEL_EXPORTER_OTLP_PROTOCOL OTLP transport protocol grpc http/protobuf
OTEL_RESOURCE_ATTRIBUTES Resource attributes list None service.namespace=commerce,deployment.environment=prod
OTEL_TRACES_SAMPLER Sampling strategy parentbased_always_on traceidratio
OTEL_TRACES_SAMPLER_ARG Sampler argument value None 0.1

Example: reading variables in Python

import os
from flask import Flask, jsonify

app = Flask(__name__)

@app.get("/runtime")
def runtime_info():
    return jsonify(
        appName=os.getenv("CONTAINER_APP_NAME"),
        revision=os.getenv("CONTAINER_APP_REVISION"),
        replica=os.getenv("CONTAINER_APP_REPLICA_NAME"),
        port=os.getenv("CONTAINER_APP_PORT", "8000"),
        logLevel=os.getenv("LOG_LEVEL", "info")
    ), 200

Advanced Topics

  • Prefer secretref: for sensitive values instead of plain env values.
  • Keep environment variable names consistent across local/dev/prod.
  • Use schema validation on app startup to fail fast on missing critical configuration.

Establish a configuration contract

Keep a versioned list of required environment variables per service. This helps teams detect breaking configuration changes before deployment.

See Also

Sources